Of the 112,678 patients who met our inclusion criteria, 971 were excluded for missing data. Of the remaining 111,707 initial primary prevention ICD implants that occurred between January 1, 2006 and June 30, 2009, 25,145 (22.5%) were for a non–evidence-based indication. Of these, 9257 (36.8%) were implanted in patients within 40 days from an MI, 814 (3.2%) were implanted in patients within 3 months from CABG, 3022 (12.0%) were implanted in patients with NYHA class IV symptoms, and 15,604 (62.1%) were implanted in patients with newly diagnosed heart failure.
The baseline characteristics of patients receiving any non–evidence-based ICD implant are presented in . The median age of these patients was 67 years (25th, 75th percentiles 57, 75 years). The majority were men (75.4%) and white (77.5%). Most patients had heart failure (91.8%) and ischemic heart disease (77.2%). The median ejection fraction was 25% (20%, 30%). The government was the primary insurance payer for 66% of these patients. In 63.3% of the patients, the ICD was a dual-chamber device.
As shown in , patients who received a non–evidence-based ICD were significantly older and sicker than patients who received an evidence-based ICD. Specifically, patients who received a non–evidence-based ICD were more likely to have heart failure, atrial fibrillation/flutter, ischemic heart disease, cerebrovascular disease, chronic lung disease, diabetes, and end-stage renal disease. In addition, patients who received a non–evidence-based ICD were more likely to belong to a racial minority group (other than black) and to receive a dual-chamber ICD.
The demographic and clinical characterisics of the different subgroups are presented in . The median age ranged from 64.0 to 68.0 years. The majority of patients in all subgroups were male and white. The vast majority of patients had heart failure and ischemic heart disease in all subgroups except the subgroup of patients with NYHA class IV symptoms who were more likely to have non-ischemic dilated cardiomyopathy. The majority of patients received a dual-chamber ICD. Some patients (n=869) with NYHA class IV symptoms and a QRS duration of >120 ms who could have been potentially eligible for a cardiac resynchronization therapy device did not receive one.
Baseline Characteristics of the 4 Subgroups of Patients Who Received a Non–evidence-based ICD.
As shown in , the risk of in-hospital death was significantly higher in patients who received a non–evidence-based device than patients who received an evidence-based device (0.6% [95% confidence interval (CI) 0.5, 0.7] vs. 0.2% [95% CI 0.1, 0.2]; p<0.0001). Likewise, the risk of any post-procedure complication was significantly higher in the non–evidence-based ICD group (3.2% [95% CI 3.0, 3.5] vs. 2.4% [95% CI 2.3, 2.5]; p<0.0001). Hematoma involving the ICD pocket was more common in patients receiving a non–evidence-based device (0.9% [95% CI 0.8, 1.0] vs. 0.7% [95% CI 0.7, 0.8]; p=0.0093). There was a trend toward a higher incidence of device-related infection in the non–evidence-based ICD group (0.04% [95% CI 0.02, 0.07] vs. 0.02% [95% CI 0.01, 0.03]; p=0.056). The risk of cardiac tamponade and pneumothorax was not significantly different between the 2 groups (p=0.11 and p=0.56, respectiviely). Adjusting for potential confounders, any adverse event and death were significantly higher in patients who received a non-evidence-based device (p<0.0001). There was a trend toward a higher risk of hematoma in the non-evidence-based ICD group (p=0.066). The median length of hospital stay was significantly longer for patients who received a non–evidence-based ICD compared with patients who received an evidence-based ICD (3 days vs. 1 day; p<0.0001). When these analyses were repeated after excluding patients with NYHA class IV symptoms, the rates of any post-procedure complication, death, and hematoma were significantly higher in patients who received a non–evidence-based ICD ().
As displayed in , there was significant variation in the distribution of non–evidence-based ICD implants across sites with no clustering of such implants at a subset of sites. The proportion of ICD implants performed by the different types of physician specialty was as follows: 66,309 (66.6%) electrophysiologists, 24,706 (24.8%) non-electrophysiology cardiologists, 2561 (2.6%) thoracic surgeons, and 6041 (6.1%) other specialists. The rate of non–evidence-based ICD implants was significantly lower for electrophysiologists (20.8% [95% CI 20.5, 21.1]) than non-electrophysiologists (24.8% [95% CI 24.2, 25.3] for non-electrophysiology cardiologists, 36.1% [95% CI 34.3, 38.0] for thoracic surgeons, 24.9% [95% CI 23.8, 25.9] for other specialties) (p<0.0001 for all comparisons).
Rates of non–evidence-based ICD implants across sites.
There was no clear decrease in the overall number of non–evidence-based ICD implants over time; 24.5% (6908/28,233) in 2006, 21.8% (7395/33,965) in 2007, 22.0% (7245/32,960) in 2008, and 21.7% (3597/16,549) in 2009 (p<0.0001 for a trend from 2006 to 2009 and p=0.94 for a trend from 2007 to 2009). The only subgroup that showed a significant decrease in non–evidence-based ICD implants over time as a proportion of all implants was patients within 40 days of an MI (10.5% in 2006, 7.7% in 2007, 7.9% in 2008, and 6.6% in 2009; p<0.0001 for a trend from 2006 to 2009 and p=0.0003 for a trend from 2007 to 2009). These results are displayed in .
Temporal changes in non–evidence-based ICD implants. The 2009 data are for the first 6 months only.