Objective

To relate circulating biomarkers of extracellular matrix (ECM) turnover to site-specific measures of carotid artery atherosclerosis on duplex ultrasound.

Background

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) regulate ECM remodeling, a key feature of atherosclerosis, and their circulating concentrations can be assayed. MMP-9, TIMP-1 and protocollagen-III n-terminal propeptide (PIIINP) may relate differentially to the severity of atherosclerosis at different carotid artery sites. However, data examining this premise are sparse.

Design/Methods

We related circulating MMP-9, TIMP-1 and/or PIIINP concentrations to carotid atherosclerosis on duplex ultrasound in1006 Framingham Offspring (mean age 58 years, 56% women) who attended a routine examination from 1995–1998. We used multivariable regression to relate MMP-9 (detectable versus undetectable), and TIMP-1 and PIIINP (age- and sex-specific quartiles) to internal carotid artery stenosis (>25%), and log-transformed common and internal carotid intima-media thickness (CC-IMT, IC-IMT, respectively).

Results

Detectable MMP-9 was associated with carotid stenosis (OR 1.71, p=0.032) but not with IMT. Higher TIMP-1 was associated with carotid stenosis (OR for Q4 versus Q1-3, 1.63, p=0.022) and a higher IC-IMT (β 0.057 ±0.025, Q4 versus Q1-3, p=0.023). Higher PIIINP (Q4 versus Q1-3) showed a borderline association with carotid stenosis (OR 1.45 for Q4 versus Q1-3, p=0.095) but not with IMT. TIMP-1 was not associated with CC-IMT.

Conclusions

In our community-based sample of middle-aged to older adults, higher circulating biomarkers of matrix remodeling were associated with a greater prevalence of carotid stenosis, and subclinical atherosclerosis in the IC artery. Our findings are consistent with regional differences in matrix remodeling in the carotid artery.

Background and Purpose

Prior estimates of the prevalence of silent cerebral infarction (SCI) on magnetic resonance imaging (MRI) in community-based samples have varied between 5.8 and 17.7% depending on age, ethnicity, presence of co-morbidities and imaging techniques. We document the prevalence and risk factors associated with SCI at midlife in the community-based Framingham sample.

Methods

2040 Framingham Offspring (53% F; mean age 62±9 yrs) who attended the 6th examination (1996–98), underwent volumetric brain MRI (1999–2005) and were free of clinical stroke at MRI, constituted our study sample. We examined the age- and sex-specific prevalence and the clinical correlates of SCI using multivariable logistic regression models.

Results

At least one SCI was present in 10.7% of participants. 84% had a single lesion. SCI were largely located in the basal ganglia (52%), other subcortical (35%) and cortical areas (11%). Prevalent SCI was associated with the Framingham Stroke Risk Profile score (OR: 1.27; 95% CI: 1.10 – 1.46); Stage I hypertension by JNC-VII criteria (OR:1.56; CI:1.15 – 2.11)), an elevated plasma homocysteine in the highest quartile (OR: 2.23; CI: 1.42 – 3.51), atrial fibrillation (OR: 2.16; CI: 1.07 – 4.40), carotid stenosis >25% (OR: 1.62; 1.13 – 2.34)) and increased carotid intimal-medial thickness above the lowest quintile (OR: 1.65; CI: 1.22 – 2.24).

Conclusion

The prevalence and distribution of SCI in the Framingham Offspring.is comparable to prior estimates. Risk factors previously associated with clinical stroke were also found to be associated with midlife SCI. Our results support current guidelines emphasizing early detection and treatment of stroke risk factors.