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1.  Three-dimensional hip cartilage quality assessment of morphology and dGEMRIC by planar maps and automated segmentation 
The quantitative interpretation of hip cartilage MRI has been limited by the difficulty of identifying and delineating the cartilage in a 3D dataset, thereby reducing its routine usage. In this paper a solution is suggested by unfolding the cartilage to planar 2D maps on which both morphology and biochemical degeneration patterns can be investigated across the entire hip joint.
Morphological TrueFISP and biochemical dGEMRIC hip images were acquired isotropically for 15 symptomatic subjects with mild or no radiographic osteoarthritis. A multi-template based label fusion technique was used to automatically segment the cartilage tissue, followed by a geometric projection algorithm to generate the planar maps. The segmentation performance was investigated through a leave-one-out study, for two different fusion methods and as a function of the number of utilized templates.
For each of the generated planar maps, various patterns could be seen, indicating areas of healthy and degenerated cartilage. Dice coefficients for cartilage segmentation varied from 0.76 with four templates to 0.82 with 14 templates. Regional analysis suggests even higher segmentation performance in the superior half of the cartilage.
The proposed technique is the first of its kind to provide planar maps that enable straightforward quantitative assessment of hip cartilage morphology and dGEMRIC values. This technique may have important clinical applications for patient selection for hip preservation surgery, as well as for epidemiological studies of cartilage degeneration patterns. It is also shown that 10-15 templates are sufficient for accurate segmentation in this application.
PMCID: PMC4404159  PMID: 25278060
Osteoarthritis; hip; dGEMRIC; MRI; segmentation; label fusion
2.  Can Radiographic Morphometric Parameters for the Hip Be Assessed on MRI? 
Although morphometric hip parameters measured on radiographs are valuable tools guiding diagnosis and therapy in patients with hip disorders, some clinicians use MRI for such measurements, although it is unclear whether the parameters assessed on MRI differ from those assessed on radiographs.
We asked whether the lateral center-edge angle (LCE), Tönnis angle, extrusion index, and anterior center-edge angle (ACE) are similar on MRI and radiography.
We retrospectively reviewed the imaging data of 103 hips from 103 patients: 46 with femoroacetabular impingement and 57 with hip dysplasia. We manually measured the LCE, Tönnis angle, extrusion index, and ACE from radiographs and MRI in all 103 hips. Four straight coronal (Ant-10 mm, Ant-5 mm, Center, and Post-5 mm), three straight sagittal (S-Med-5 mm, S-Center, S-Lat-5 mm), and three 25º oblique sagittal (OS-Med-5 mm, OS-Center, OS-Lat-5 mm) reformats were reconstructed from a three-dimensional isotropic morphologic MRI sequence. MRI measurements were compared against the gold standard radiographic measurements.
We found good agreement for the LCE angle, Tönnis angle, and extrusion index between radiographic and coronal slice MRI measurements. The mean differences between radiographic and MRI measurements were 5º or less or 5% or less (for the extrusion index) in all coronal MRI slices. However, the differences between ACE angles on sagittal MRI slices and radiographs ranged from 5° to 28º.
LCE, Tönnis angle, and extrusion index can be measured on MRI with comparable results to radiography. The ACE angle on radiographs cannot be estimated reliably from MRI.
Clinical Relevance
MRI provides similar morphometric measurements as radiography for most hip parameters, except for the ACE angle.
PMCID: PMC3563814  PMID: 23100186
3.  Is the Damage of Cartilage a Global or Localized Phenomenon in Hip Dysplasia, Measured by dGEMRIC? 
The mechanism of damage in osteoarthritis is believed to be multifactorial where mechanical and biological factors are important in its initiation and progression. Hip dysplasia is a classic model of increased mechanical loading on cartilage attributable to insufficient acetabular coverage that leads to osteoarthritis. If the damage is all attributable to direct mechanical damage then one initially would expect only local, not global changes.
We hypothesize that in hip dysplasia although the elevated cumulative contact stresses are localized, the damage to cartilage is biologically mediated, therefore, biochemical changes will be global.
Thirty-two patients with symptomatic hip dysplasia were scanned using a 1.5-T MRI scanner. We used a high-resolution three-dimensional dGEMRIC technique to characterize the distribution of cartilage damage in dysplastic hips. High-resolution isotropic acquisition was reformatted around the femoral neck axis and the dGEMRIC index was calculated separately for femoral and acetabular cartilages. Joint space widths also were evaluated in each reformatted slice. Each hip was characterized by the presence or absence of joint migration and by Tönnis grade.
The global dGEMRIC index correlated with the dGEMRIC indices of individual regions with the highest correlations occurring in the anterosuperior to posterosuperior regions. The corresponding correlations for joint space width were uniformly lower, suggesting that tissue loss is a more local phenomenon. Higher Tönnis grades and hips with joint migration were associated with lower dGEMRIC indices.
The dGEMRIC index shows a global decrease, whereas tissue loss is more localized. This suggests that hip osteoarthritis in acetabular dysplasia is a biologically mediated event that affects the entire joint.
PMCID: PMC3528925  PMID: 23079789
4.  Anterior Delayed Gadolinium-enhanced MRI of Cartilage Values Predict Joint Failure After Periacetabular Osteotomy 
Several available compositional MRIs seem to detect early osteoarthritis before radiographic appearance. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) has been most frequently used in clinical studies and reportedly predicts premature joint failure in patients undergoing Bernese periacetabular osteotomies (PAOs).
We asked, given regional variations in biochemical composition in dysplastic hips, whether the dGEMRIC index of the anterior joint would better predict premature joint failure after PAOs than the coronal dGEMRIC index as previously reported.
We retrospectively reviewed 43 hips in 41 patients who underwent Bernese PAO for hip dysplasia. Thirty-seven hips had preserved joints after PAOs and six were deemed premature failures based on pain, joint space narrowing, or subsequent THA. We used dGEMRIC to determine regional variations in biochemical composition. Preoperative demographic and clinical outcome score, radiographic measures of osteoarthritis and severity of dysplasia, and dGEMRIC indexes from different hip regions were analyzed in a multivariable regression analysis to determine the best predictor of premature joint failure. Minimum followup was 24 months (mean, 32 months; range, 24–46 months).
The two cohorts were similar in age and sex distribution. Severity of dysplasia was similar as measured by lateral center-edge, anterior center-edge, and Tönnis angles. Preoperative pain, joint space width, Tönnis grade, and coronal and sagittal dGEMRIC indexes differed between groups. The dGEMRIC index in the anterior weightbearing region of the hip was lower in the prematurely failed group and was the best predictor.
Success of PAO depends on the amount of preoperative osteoarthritis. These degenerative changes are seen most commonly in the anterior joint. The dGEMRIC index of the anterior joint may better predict premature joint failure than radiographic measures of hip osteoarthritis and coronal dGEMRIC index.
Level of Evidence
Level II, prognostic study. See Instructions for Authors for a complete description of levels of evidence.
PMCID: PMC3492640  PMID: 22907475
5.  A Prospective, Randomized Comparison of Promus Everolimus-Eluting and TAXUS Liberte Paclitaxel-Eluting Stent Systems in Patients with Coronary Artery Disease Eligible for Percutaneous Coronary Intervention: The PROMISE Study 
Journal of Korean Medical Science  2013;28(11):1609-1614.
We aimed comparing two-year clinical outcomes of the Everolimus-Eluting Promus and Paclitaxel-Eluting TAXUS Liberte stents used in routine clinical practice. Patients with objective evidence of ischemia and coronary artery disease eligible for PCI were prospectively randomized to everolimus-eluting stent (EES) or paclitaxel-eluting stent (PES) groups. The primary end-point was ischemia-driven target vessel revascularization (TVR) at 2 yr after intervention, and the secondary end-point was a major adverse cardiac event (MACE), such as death, myocardial infarction (MI), target lesion revascularization (TLR), TVR or stent thrombosis. A total of 850 patients with 1,039 lesions was randomized to the EES (n=425) and PES (n=425) groups. Ischemic-driven TVR at 2 yr was 3.8% in the PES and 1.2% in the EES group (P for non-inferiority=0.021). MACE rates were significantly different; 5.6% in PES and 2.5% in EES (P = 0.027). Rates of MI (0.8% in PES vs 0.2% in EES, P = 0.308), all deaths (1.5% in PES vs 1.2% in EES, P = 0.739) and stent thrombosis (0.3% in PES vs 0.7% in EES, P = 0.325) were similar. The clinical outcomes of EES are superior to PES, mainly due to a reduction in the rate of ischemia-driven TVR.
PMCID: PMC3835502  PMID: 24265523
Everolimus-Eluting Stent; Paclitaxel-Eluting Stent
6.  Low Early Failure Rates Using a Surgical Dislocation Approach in Healed Legg-Calvé-Perthes Disease 
Hip deformity secondary to Legg-Calvé Perthes disease (LCPD) may result in femoroacetabular impingement (FAI) and ultimately osteoarthritis. Observations made with the surgical hip dislocation approach have improved our understanding of the pathologic mechanics of FAI. However, owing to concerns about complications related to the vascularity, the role of surgical hip dislocation in the treatment of healed LCPD remains controversial.
We present an algorithm to treat deformities associated with healed LCPD and asked (1) whether femoral head-neck osteochondroplasty and other procedures performed with the surgical hip dislocation approach provide short-term clinical improvement; and (2) is the complication rate low enough to be acceptable.
We retrospectively reviewed 29 patients (19 males, 10 females; mean age, 17 years; range, 9–35 years) with symptomatic LCPD between 2001 and 2009. All patients underwent a surgical hip dislocation approach and femoral head-neck osteochondroplasty and 26 patients had 37 additional procedures performed. Clinical improvement was assessed using the WOMAC index. The minimum followup was 12 months (mean, 3 years; range, 12–70 months).
WOMAC scores improved at final followup (8 to 4 for pain, 21 to 13 for function, and 4 to 2 for the stiffness subscales). No patients had osteonecrosis, implant failure, deep infection, or nonunion. Three patients underwent THA at 1, 3, and 6 years after their index procedure.
Using the surgical hip dislocation approach as a tool to dynamically inspect the hip for causes of FAI, we were able to perform a variety of procedures to treat the complex deformities of healed LCPD. In the short term, we found improvement in WOMAC scores with a low complication rate.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3830106  PMID: 22125243
7.  Diffusion-weighted MRI Reveals Epiphyseal and Metaphyseal Abnormalities in Legg-Calvé-Perthes Disease: A Pilot Study 
Legg-Calvé-Perthes disease (LCP) is thought to be associated with ischemic events in the femoral head. However, the types and patterns of reperfusion after these ischemic events are unclear.
We therefore determined whether (1) there would be any age-related diffusion changes; (2) diffusion-weighted MR imaging would reveal ischemic damage; and (3) diffusion changes are correlated with prognostic MR findings in patients with LCP.
We prospectively performed conventional, perfusion, and diffusion-weighted MR imaging studies in 17 children with unilateral LCP. We then measured the apparent diffusion coefficient (ADC) values in the epiphysis and the metaphysis, and compared them with those of the contralateral normal side. Based on perfusion MR imaging, we assessed reperfusion to the epiphysis as either periphyseal or transphyseal. We studied T2-signal intensity changes in the metaphysis and the presence of focal physeal irregularity. We correlated diffusion changes with reperfusion to the epiphysis, T2-signal intensity change, and focal physeal irregularity.
Normal diffusion decreased with age. In LCP hips, epiphyseal diffusion increased early and remained elevated through the healing stage. Six of the 17 patients who had a metaphyseal ADC greater than 50% over the normal side had 13 times greater odds of having an association with transphyseal reperfusion to the epiphysis. The increase of metaphyseal ADC also was associated with an increased T2-signal intensity in the metaphysis and presence of focal physeal irregularity.
Diffusion-weighted MR imaging can be used as a complimentary modality to evaluate ischemic tissue damage with a potential prognostic value in patients with LCP.
PMCID: PMC3171554  PMID: 21660596
8.  The Bernese Periacetabular Osteotomy: Is Transection of the Rectus Femoris Tendon Essential? 
The Bernese periacetabular osteotomy (PAO) traditionally is performed using the iliofemoral or the ilioinguinal approach with transection of the rectus femoris tendon attachments. Although a rectus-preserving approach has been developed, there is limited direct comparison data regarding the surgical safety, radiographic correction, and improvement in hip pain and function between the rectus-preserving and the classic approaches.
The purposes of this study were to determine whether preserving the rectus femoris tendon attachment would (1) reduce intraoperative blood loss and length of surgery; (2) improve Harris hip scores (HHS); (3) decrease the rate of complications; and (4) affect the radiographic correction when compared with the classic approach.
A retrospective matched cohort study was used to compare the endpoints listed above after PAO using a rectus-preserving approach versus the classic approach. Operative blood loss, preoperative and postoperative hematocrit, duration of surgery, HHS, and postoperative complications were recorded for the two groups. Pelvic radiographs were reviewed for measurement of the lateral center-edge angle, anterior center-edge angle, and Tönnis acetabular inclination angle. A total of 64 patients were included (32 in each group). Followup was at a minimum of 1 year (mean, 20 months; range, 13–44 months).
Blood loss (p = 0.2405), hematocrit change (p = 0.3277), and operative time (p = 0.3960) were similar between groups. At latest followup, the HHS improved in the rectus-preserving (mean improvement, 25; 95% CI, 21–29; p < 0.0001) and control groups (mean improvement, 21; 95% CI, 17–25; p < 0.0001) with no difference in HHS improvement between the groups (mean difference, 4.3; 95% CI, −1.6 to 10.1; p = 0.1523). The complication rate was 12.5% (four of 32) in the rectus-preserving group and 25% (eight of 32) in the classic approach groups, respectively (p = 0.2002). The rectus-preserving approach allowed for similar lateral center-edge angle (p = 0.4463), anterior center-edge angle (p = 0.0936), and Tönnis angle (p = 0.7953) improvement when compared with the classic approach.
The rectus-preserving approach for PAO is as safe and effective as the classic approach to achieve radiographic correction and HHS improvement at minimum 1 year. Additional investigation is needed to determine whether the rectus-preserving approach allows for improvement in functional recovery including hip flexion strength.
Level of Evidence
Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.
PMCID: PMC4160480  PMID: 25053288
9.  A Novel Risk Stratification Model for Patients with Non-ST Elevation Myocardial Infarction in the Korea Acute Myocardial Infarction Registry (KAMIR): Limitation of the TIMI Risk Scoring System 
Chonnam Medical Journal  2011;47(1):20-26.
The Thrombolysis in Myocardial Infarction (TIMI) risk score (TRS) has proven value in predicting prognosis in unstable angina/non ST-elevation myocardial infarction (NSTEMI) as well as in ST-elevation myocardial infarction. The TRS system has little implication, however, in the extent of myocardial damage in high-risk patients with NSTEMI. A total of 1621 patients (63.6±12.2 years; 1043 males) with NSTEMI were enrolled in the Korea Acute Myocardial Infarction Registry (KAMIR). We analyzed the risk for major adverse cardiac events (MACE) during a 6-month follow-up period. The TRS system showed good correlation with MACE for patients in the low and intermediate groups but had poor correlation when the high-risk group was included (p=0.128). The MACE rate was 3.8% for TRS 1, 9.4% for TRS 2, 10.7% for TRS 3, and 12.3% for TRS 4 (HR=1.29, p=0.026). Among the biomarkers and clinical risk factors, elevated N-terminal pro-brain natriuretic peptide (NT-proBNP) (HR=2.61, p=0.001) and Killip class above III showed good correlation with MACE (HR=0.302, p<0.001). Therefore, we revised an alternative clinical scoring system by including these two variables that reflect left ventricular dysfunction: age > 65 years, history of ischemic heart disease, Killip class above III, and elevated pro-BNP levels above the 75th percentile. This modified scoring system, when tested for validity, showed good predictive value for MACE (HR=1.64, p<0.001). Compared with the traditional TRS, the novel alternative scoring system based on age, history of ischemic heart disease, Killip class, and NT-proBNP showed a better predictive value for 6-month MACE in high-risk patients with NSTEMI.
PMCID: PMC3214861  PMID: 22111052
Angina, unstable; Mortality; Myocardial Infarction
10.  Relationship Between Obesity and N-Terminal Brain Natriuretic Peptide Level as a Prognostic Value After Acute Myocardial Infarction 
Korean Circulation Journal  2010;40(11):558-564.
Background and Objectives
Recently, the prognostic value of N-terminal brain natriuretic peptide (NT-proBNP) in acute coronary syndrome has been demonstrated in many studies. However, NT-proBNP levels are influenced by various factors such as sex, age, renal function, heart failure severity, and obesity. NT-proBNP concentrations tend to decrease with higher body mass index (BMI). The aim of this study was to examine the influence of obesity on NT-proBNP as a predictive prognostic factor in acute myocardial infarction (AMI) patients.
Subjects and Methods
Using data from the Korea Acute Myocardial Infarction Registry (January 2005 to September 2008), 2,736 AMI patients were included in this study. These patients were divided into men (n=1,972, 70%) and women (n=764, 30%), and were grouped according to their BMIs. Major adverse cardiac events (MACE) during 1 year clinical follow-up were evaluated.
NT-proBNP was significantly higher in lower BMI (p<0.001). Mean NT-proBNP levels of each obesity group were 2,393±4,022 pg/mL in the lean group (n=875), 1,506±3,074 pg/mL in the overweight group (n=724) and 1,100±1,137 pg/mL in the obese group (n=1,137) (p<0.01). NT-proBNP was an independent prognostic factor of AMI in obese patients by multivariative analysis of independent risk factors of MACE (p=0.01).
NT-proBNP is lower in obese AMI patients than in non-obese AMI patients, but NT-proBNP is still of independent prognostic value in obese AMI patients.
PMCID: PMC3008826  PMID: 21217932
Brain natriuretic peptide; Obesity; Myocardial infarction
11.  Clinical Benefit of Low Molecular Weight Heparin for ST-segment Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Intervention with Glycoprotein IIb/IIIa Inhibitor 
Journal of Korean Medical Science  2010;25(11):1601-1608.
The efficacy of low molecular weight heparin (LMWH) with low dose unfractionated heparin (UFH) during percutaneous coronary intervention (PCI) with or without glycoprotein (Gp) IIb/IIIa inhibitor compared to UFH with or without Gp IIb/IIIa inhibitor has not been elucidated. Between October 2005 and July 2007, 2,535 patients with ST elevation acute myocardial infarction (STEMI) undergoing PCI in the Korean Acute Myocardial Infarction Registry (KAMIR) were assigned to either of two groups: a group with Gp IIb/IIIa inhibitor (n=476) or a group without Gp IIb/IIIa inhibitor (n=2,059). These groups were further subdivided according to the use of LMWH with low dose UFH (n=219) or UFH alone (n=257). The primary end points were cardiac death or myocardial infarction during the 30 days after the registration. The primary end point occurred in 4.1% (9/219) of patients managed with LMWH during PCI and Gp IIb/IIIa inhibitor and 10.8% (28/257) of patients managed with UFH and Gp IIb/IIIa inhibitor (odds ratio [OR], 0.290; 95% confidence interval [CI], 0.132-0.634; P=0.006). Thrombolysis In Myocardial Infarction (TIMI) with major bleeding was observed in LMHW and UFH with Gp IIb/IIIa inhibitor (1/219 [0.5%] vs 1/257 [0.4%], P=1.00). For patients with STEMI managed with a primary PCI and Gp IIb/IIIa inhibitor, LMWH is more beneficial than UFH.
PMCID: PMC2966997  PMID: 21060749
Myocardial Infarction; Heparin; Blood Platelets; Prognosis
12.  Comparative Study of Low Doses of Rosuvastatin and Atorvastatin on Lipid and Glycemic Control in Patients with Metabolic Syndrome and Hypercholesterolemia 
This multicenter, open-labeled, randomized trial was performed to compare the effects of rosuvastatin 10 mg and atorvastatin 10 mg on lipid and glycemic control in Korean patients with nondiabetic metabolic syndrome.
In total, 351 patients who met the modified National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria for metabolic syndrome with low-density lipoprotein cholesterol (LDL-C) levels ≥ 130 mg/dL were randomized to receive either rosuvastatin 10 mg (n = 173) or atorvastatin 10 mg (n = 178) for over 6 weeks.
After 6 weeks of treatment, greater reductions in total cholesterol (- 35.94 ± 11.38 vs. - 30.07 ± 10.46%, p < 0.001), LDL-C (48.04 ± 14.45 vs. 39.52 ± 14.42%, p < 0.001), non-high-density lipoprotein cholesterol (- 42.93 ± 13.15 vs. - 35.52 ± 11.76%, p < 0.001), and apolipoprotein-B (- 38.7 ± 18.85 vs. - 32.57 ± 17.56%, p = 0.002) levels were observed in the rosuvastatin group as compared to the atorvastatin group. Overall, the percentage of patients attaining the NCEP ATP III goal was higher with rosuvastatin as compared to atorvastatin (87.64 vs. 69.88%, p < 0.001). Changes in glucose and insulin levels, and homeostasis model assessment of insulin resistance index were not significantly different between the two groups. The safety and tolerability of the two agents were similar.
Rosuvastatin 10 mg was more effective than atorvastatin 10 mg in achieving NCEP ATP III LDL-C goals in patients with nondiabetic metabolic syndrome, especially in those with lower NCEP ATP III target level goals.
PMCID: PMC2829413  PMID: 20195400
Metabolic syndrome X; Hypercholesterolemia; Rosuvastatin; Atorvastatin
13.  Surgical Dislocation in the Management of Pediatric and Adolescent Hip Deformity 
The surgical dislocation approach is useful in assessing and treating proximal femoral hip deformities commonly due to pediatric conditions. We sought to demonstrate the efficacy and problems associated with this technique. Diagnoses included slipped capital femoral epiphysis, Perthes disease, developmental dysplasia of the hip, osteonecrosis, and exostoses. Through this approach, femoral head-neck osteoplasty (22), intertrochanteric osteotomy (eight), femoral head-neck osteoplasty plus intertrochanteric osteotomy (15), femoral neck osteotomy (five), open reduction and internal fixation of an acute slipped capital femoral epiphysis with callus resection (five), open reduction and internal fixation of an acetabular fracture (one), trapdoor procedure (one), and acetabular rim osteoplasty (one) were performed. The average patient age was 16 years. The minimum followup was 12 months (average, 41.6 months; range, 12–73 months). Patients with Perthes disease and SCFE had preoperative and postoperative WOMAC scores of 9.6 and 5.1, and 7.9 and 3.5 respectively. In patients with unstable SCFEs, the average postoperative WOMAC score was 1.2. Seven patients underwent THAs and two patients underwent hip fusion. Complications in the 58 procedures included four cases of osteonecrosis: three after femoral neck osteotomy and one after intertrochanteric osteotomy. The surgical dislocation technique can be utilized to effectively treat these deformities and improve short-term symptoms. Although the technique is demanding, we believe surgical dislocation offers sufficient advantages in assessing and treating these complex deformities that it justifies judicious application.
Level of Evidence: Level IV, retrospective study, case series. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2635463  PMID: 19002743
14.  Capital Realignment for Moderate and Severe SCFE Using a Modified Dunn Procedure 
Moderate to severe slipped capital femoral epiphysis leads to premature osteoarthritis resulting from femoroacetabular impingement. We believe surgical correction at the site of deformity through capital reorientation is the best procedure to fully correct the deformity but has traditionally been associated with high rates of osteonecrosis. We describe a modified capital reorientation procedure performed through a surgical dislocation approach. We followed 40 patients for a minimum of 1 year and 3 years from two institutions. No patient developed osteonecrosis or chondrolysis. Slip angle was corrected to 4° to 8° and the mean alpha angle after correction was 40.6°. Articular cartilage damage, full-thickness loss, and delamination were observed at the time of surgery, especially in the stable slips. This technique appears to have an acceptable complication rate and appears reproducible for full correction of moderate to severe slipped capital femoral epiphyses with open physes.
Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2635450  PMID: 19142692
15.  Clinical Effects of Hypertension on the Mortality of Patients with Acute Myocardial Infarction 
Journal of Korean Medical Science  2009;24(5):800-806.
The incidence of ischemic heart disease has been increased rapidly in Korea. However, the clinical effects of antecedent hypertension on acute myocardial infarction have not been identified. We assessed the relationship between antecedent hypertension and clinical outcomes in 7,784 patients with acute myocardial infarction in the Korea Acute Myocardial Infarction Registry during one-year follow-up. Diabetes mellitus, hyperlipidemia, cerebrovascular disease, heart failure, and peripheral artery disease were more prevalent in hypertensives (n=3,775) than nonhypertensives (n=4,009). During hospitalization, hypertensive patients suffered from acute renal failure, shock, and cerebrovascular event more frequently than in nonhypertensives. During follow-up of one-year, the incidence of major adverse cardiac events was higher in hypertensives. In multi-variate adjustment, old age, Killip class ≥III, left ventricular ejection fraction <45%, systolic blood pressure <90 mmHg on admission, post procedural TIMI flow grade ≤2, female sex, and history of hypertension were independent predictors for in-hospital mortality. However antecedent hypertension was not significantly associated with one-year mortality. Hypertension at the time of acute myocardial infarction is associated with an increased rate of in-hospital mortality.
PMCID: PMC2752759  PMID: 19794974
Hypertension; Myocardial infarction; Mortality
16.  A functional difficulty and functional pain instrument for hip and knee osteoarthritis 
Arthritis Research & Therapy  2009;11(4):R107.
The objectives of this study were to develop a functional outcome instrument for hip and knee osteoarthritis research (OA-FUNCTION-CAT) using item response theory (IRT) and computer adaptive test (CAT) methods and to assess its psychometric performance compared to the current standard in the field.
We conducted an extensive literature review, focus groups, and cognitive testing to guide the construction of an item bank consisting of 125 functional activities commonly affected by hip and knee osteoarthritis. We recruited a convenience sample of 328 adults with confirmed hip and/or knee osteoarthritis. Subjects reported their degree of functional difficulty and functional pain in performing each activity in the item bank and completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Confirmatory factor analyses were conducted to assess scale uni-dimensionality, and IRT methods were used to calibrate the items and examine the fit of the data. We assessed the performance of OA-FUNCTION-CATs of different lengths relative to the full item bank and WOMAC using CAT simulation analyses.
Confirmatory factor analyses revealed distinct functional difficulty and functional pain domains. Descriptive statistics for scores from 5-, 10-, and 15-item CATs were similar to those for the full item bank. The 10-item OA-FUNCTION-CAT scales demonstrated a high degree of accuracy compared with the item bank (r = 0.96 and 0.89, respectively). Compared to the WOMAC, both scales covered a broader score range and demonstrated a higher degree of precision at the ceiling and reliability across the range of scores.
The OA-FUNCTION-CAT provided superior reliability throughout the score range and improved breadth and precision at the ceiling compared with the WOMAC. Further research is needed to assess whether these improvements carry over into superior ability to measure change.
PMCID: PMC2745788  PMID: 19589168
17.  Extraarticular Fractures after Periacetabular Osteotomy 
Extraarticular fractures of the pelvic ring after periacetabular osteotomy could impair stability of the acetabular fragment and cause poor clinical and radiographic outcomes. We evaluated 17 patients (17 hips) with fractures of either the ipsilateral os pubis (n = 12) or os ischium (n = 5) during the postoperative period after periacetabular osteotomy. Ischial fractures seemed more debilitating with two of five resulting in painful nonunions for which additional surgery was performed. In contrast, only one patient with pubic fracture had additional surgery. Ischial fractures took almost twice as long to achieve resolution of symptoms compared with pubic fractures, and when left untreated, asymptomatic nonunions developed in three of five. However, we observed no effect on acetabular fragment positioning or long-term clinical outcome. It is essential to be aware of this potential complication and realize it could be accompanied by substantial morbidity for patients during the rehabilitation period after periacetabular osteotomy, but does not seem to influence the longer-term outcome.
Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2505263  PMID: 18465184
18.  The Prognostic Value of the Left Ventricular Ejection Fraction Is Dependent upon the Severity of Mitral Regurgitation in Patients with Acute Myocardial Infarction 
Journal of Korean Medical Science  2015;30(7):903-910.
The prognostic value of the left ventricle ejection fraction (LVEF) after acute myocardial infarction (AMI) has been questioned even though it is an accurate marker of left ventricle (LV) systolic dysfunction. This study aimed to examine the prognostic impact of LVEF in patients with AMI with or without high-grade mitral regurgitation (MR). A total of 15,097 patients with AMI who received echocardiography were registered in the Korean Acute Myocardial Infarction Registry (KAMIR) between January 2005 and July 2011. Patients with low-grade MR (grades 0-2) and high-grade MR (grades 3-4) were divided into the following two sub-groups according to LVEF: LVEF ≤ 40% (n = 2,422 and 197, respectively) and LVEF > 40% (n = 12,252 and 226, respectively). The primary endpoints were major adverse cardiac events (MACE), cardiac death, and all-cause death during the first year after registration. Independent predictors of mortality in the multivariate analysis in AMI patients with low-grade MR were age ≥ 75 yr, Killip class ≥ III, N-terminal pro-B-type natriuretic peptide > 4,000 pg/mL, high-sensitivity C-reactive protein ≥ 2.59 mg/L, LVEF ≤ 40%, estimated glomerular filtration rate (eGFR), and percutaneous coronary intervention (PCI). However, PCI was an independent predictor in AMI patients with high-grade MR. No differences in primary endpoints between AMI patients with high-grade MR (grades 3-4) and EF ≤ 40% or EF > 40% were noted. MR is a predictor of a poor outcome regardless of ejection fraction. LVEF is an inadequate method to evaluate contractile function of the ischemic heart in the face of significant MR.
PMCID: PMC4479944  PMID: 26130953
Mitral Regurgitation; Acute Myocardial Infarction; Left Ventricular Ejection Fraction
19.  Clinical Characteristics and Outcomes of Acute ST-Segment Elevation Myocardial Infarction in Younger Korean Adults 
Korean Circulation Journal  2015;45(4):275-284.
Background and Objectives
This study aims to investigate the clinical features, angiographic findings, and outcomes of younger Korean ST-segment elevation myocardial infarction (STEMI) patients.
Subjects and Methods
We analyzed major adverse cardiac events (MACE) in the Korea Acute Myocardial Infarction Registry from November 2005 to October 2010. The registered patients were divided into two groups; young age group (<65 years) and old age group (≥65 years).
The young age group included 5281 patients (age, 53±7.8 years), and the old age group included 4896 patients (age, 74.3±6.5 years). Male gender, smoking, family history, dyslipidemia, and metabolic syndrome were more frequently observed in the young age group than in the old age group (89.5% vs. 59.3%, p<0.001; 77.3% vs. 47.2%, p<0.001; 11% vs. 4.6%, p<0.001; 11.2% vs. 7.7%, p<0.001; 67.6% vs. 62.9%, p<0.001). Most of the young Korean adults with STEMI complained of typical chest pain (89.8%), and they had a shorter symptom-to-door time (12±53.2 hours vs. 17.3±132 hours, p=0.010). The young age group showed a favorable prognosis, which was represented by the MACE, compared with the old age group at one month (1.8% vs. 2.8%, p=0.028), six months (6.8% vs. 8.2%, p<0.001), and twelve months (10.1% vs. 11.9%, p=0.025). However, there was no significant difference in the adjusted MACE rate at one month {hazard ratio (HR) 0.95, 95% confidence interval (CI) 0.60-1.51, p=0.828} and twelve months (HR 0.86, 95% CI 0.68-1.10, p=0.233).
Younger Korean adults with STEMI have clinical outcomes similar to old aged patients, and therefore, they should be treated intensively like the elderly patients.
PMCID: PMC4521105  PMID: 26240581
Myocardial infarction; Young adult; Prognosis
20.  The Epidemiological and Clinical Characteristics of Patients Admitted for Coronary Angiography to Evaluate Ischemic Heart Disease 
Most of the known risk factors associated with ischemic heart disease are based on studies from Western countries; there is only limited information on Korean populations. This study was designed to analyze age related differences in epidemiologic and clinical characteristics in patients who were admitted for coronary angiography for the evaluation of ischemic heart disease.
As part of the multicenter KCAR (Korean Coronary Artery disease Registry) Study, the clinical data of 6,549 patients, who were evaluated at the cardiac catheterization laboratory by coronary angiography, at seven university hospitals in Korea from March 1999 to December 2005, were registered into the KCAR database and analyzed. All patients were divided into three groups according to age: age ≤40, age 41-70 and age ≥71. All demographic and coronary angiographic features were analyzed for the different groups.
The demographic data showed that compared to the older patients young patients ≤40 had a higher prevalence of males and smokers, but a lower prevalence of hypertension, diabetes and prior history of stroke and myocardial infarction. For the lipid profiles, the younger patients had much higher levels of total cholesterol, triglycerides and LDL-cholesterol than the older groups; however, there was no difference in the HDL-cholesterol levels among the three age groups. The most common component of the metabolic syndrome was obesity (79%) in the younger patients and hypertension (92%) in the older patients. The most common reason for presentation was ST-segment elevated myocardial infarction in the younger patients and unstable angina in the older patients.
Ischemic heart disease in younger adults ≤40 had different demographic characteristics and clinical presentation than older patients.
PMCID: PMC2687617  PMID: 17616023
Ischemic heart disease; Epidemiologic study characteristics
21.  Hypertrophic Cardiomyopathy Complicated by Left Ventricular Apical Necrosis and Aneurysm in a Young Man: FDG-PET Findings 
A 29-year old male was transferred to our hospital with an abnormal chest X-ray finding diagnosed as hypertrophic cardiomyopathy with apical necrosis and aneurysm formation. Four years after the initial hospitalization, we confirmed the aneurysm and necrosis using both integrated positron emission tomography (PET) and computed tomography (CT) scanning. The F-18 2-fluoro-2-deoxy-D-glucose (FDG) PET/CT enabled precise localization of the aneurysm, which was found to be composed of semi-lunar calcification of non-metabolic myocardium. A contrast-enhanced CT angiography showed an hour-glass appearance of the left ventricular cavity. The integrated PET/CT fusion scanner is a novel multimodality technology that allows for a comprehensive analysis of the anatomical and functional status of complex heart disease. Based on these findings, long standing mechanical and physiologic abnormalities may have led to chronic ischemia in the hypertrophied myocardium, induced necrosis and calcification at the cardiac apex.
PMCID: PMC2687601  PMID: 17427643
Hypertrophic Cardiomyopathy; Aneurysm; Positron Emission Tomography
22.  Comparison of clinical outcomes between culprit vessel only and multivessel percutaneous coronary intervention for ST-segment elevation myocardial infarction patients with multivessel coronary diseases 
The clinical significance of complete revascularization for ST segment elevation myocardial infarction (STEMI) patients during admission is still debatable.
A total of 1406 STEMI patients from the Korean Myocardial Infarction Registry with multivessel diseases without cardiogenic shock who underwent primary percutaneous coronary intervention (PPCI) were analyzed. We used propensity score matching (PSM) to control differences of baseline characteristics between culprit only intervention (CP) and multivessel percutaneous coronary interventions (MP), and between double vessel disease (DVD) and triple vessel disease (TVD). The major adverse cardiac event (MACE) was analyzed for one year after discharge.
TVD patients showed higher incidence of MACE (14.2% vs. 8.6%, P = 0.01), any cause of revascularization (10.6% vs. 5.9%, P = 0.01), and repeated PCI (9.5% vs. 5.7%, P = 0.02), as compared to DVD patients during one year after discharge. MP reduced MACE effectively (7.3% vs. 13.8%, P = 0.03), as compared to CP for one year, but all cause of death (1.6% vs. 3.2%, P = 0.38), MI (0.4% vs. 0.8%, P = 1.00), and any cause of revascularization (5.3% vs. 9.7%, P = 0.09) were comparable in the two treatment groups.
STEMI patients with TVD showed higher rate of MACE, as compared to DVD. MP performed during PPCI or ad hoc during admission for STEMI patients without cardiogenic shock showed lower rate of MACE in this large scaled database. Therefore, MP could be considered as an effective treatment option for STEMI patients without cardiogenic shock.
PMCID: PMC4460162  PMID: 26089843
Culprit only intervention; Multivessel intervention; Multivessel coronary disease; Myocardial infarction; Primary percutaneous coronary intervention
23.  Biologically Derived Soft Conducting Hydrogels Using Heparin-Doped Polymer Networks 
ACS Nano  2014;8(5):4348-4357.
The emergence of flexible and stretchable electronic components expands the range of applications of electronic devices. Flexible devices are ideally suited for electronic biointerfaces because of mechanically permissive structures that conform to curvilinear structures found in native tissue. Most electronic materials used in these applications exhibit elastic moduli on the order of 0.1–1 MPa. However, many electronically excitable tissues exhibit elasticities in the range of 1–10 kPa, several orders of magnitude smaller than existing components used in flexible devices. This work describes the use of biologically derived heparins as scaffold materials for fabricating networks with hybrid electronic/ionic conductivity and ultracompliant mechanical properties. Photo-cross-linkable heparin–methacrylate hydrogels serve as templates to control the microstructure and doping of in situ polymerized polyaniline structures. Macroscopic heparin-doped polyaniline hydrogel dual networks exhibit impedances as low as Z = 4.17 Ω at 1 kHz and storage moduli of G′ = 900 ± 100 Pa. The conductivity of heparin/polyaniline networks depends on the oxidation state and microstructure of secondary polyaniline networks. Furthermore, heparin/polyaniline networks support the attachment, proliferation, and differentiation of murine myoblasts without any surface treatments. Taken together, these results suggest that heparin/polyaniline hydrogel networks exhibit suitable physical properties as an electronically active biointerface material that can match the mechanical properties of soft tissues composed of excitable cells.
PMCID: PMC4046800  PMID: 24738911
hydrogel; polymer; biomaterial; electronically active
24.  Impact of Smoking on Clinical Outcomes in Female Patients with Acute Myocardial Infarction 
Korean Circulation Journal  2015;45(1):22-27.
Background and Objectives
Cigarette smoking has been recognized as a prominent threat to women's health. We investigated the impact of smoking on clinical outcomes in Korean female patients after acute myocardial infarction (AMI).
Subjects and Methods
Out of the AMI patients who enrolled in the Korea AMI Registry, 4444 female patients were included in this study. Patients were divided into two groups-non-smoker and smoker-according to their current smoking status. We compared in-hospital mortality and major adverse cardiac events (MACE), including cardiac death, myocardial infarction, repeated percutaneous coronary intervention (PCI), or coronary artery bypass grafting during the one-year clinical follow-up period between two groups.
The non-smoker group had more hypertension (HTN) and diabetes mellitus. The levels of total cholesterol, triglyceride, and low-density lipoprotein cholesterol were higher in the non-smoker group. However, in-hospital mortality was significantly higher in the smoker group (1.0% vs. 2.4%, p=0.002), and cardiac death during the 12-month clinical follow-up was significantly more frequent in the smoker group (2.2% vs. 4.5%, p=0.003). Total MACEs during the 12 months were higher in the smoker group (4.9% vs. 6.8%, p=0.014). Smoking and HTN were independent predictors of MACE {odds ratio (OR): 1.742, 95% confidence interval (CI): 1.010-3.000, p=0.046; OR: 1.573, 95% CI: 1.003-2.466, p=0.049, respectively}.
Female smokers with AMI showed significantly higher in-hospital mortality and MACE rates during the one-year clinical follow-up period.
PMCID: PMC4310976  PMID: 25653700
Hospital mortality; Myocardial infarction; Female; Smoking
25.  The scientific achievements of the decades in Korean Acute Myocardial Infarction Registry 
The Korea Acute Myocardial Infarction Registry (KAMIR) was the first nationwide registry data collection designed to track outcomes of patients with acute myocardial infarction (AMI). These studies reflect the current therapeutic approaches and management for AMI in Korea. The results of KAMIR could help clinicians to predict the prognosis of their patients and identify better diagnostic and treatment tools to improve the quality of care. The KAMIR score was proposed to be a predictor of the prognosis of AMI patients. Triple antiplatelet therapy, consisting of aspirin, clopidogrel and cilostazol, was effective at preventing major adverse clinical outcomes. Drug-eluting stents were effective and safe in AMI patients with no increased risk of stent thrombosis. Statin therapy was effective in Korean AMI patients, including those with very low levels of low density cholesterol. The present review summarizes the 10-year scientific achievements of KAMIR from admission to outpatient care during long-term clinical follow-up.
PMCID: PMC4219958  PMID: 25378967
Acute myocardial infarction; Prognosis; Therapeutics

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