Prevalence and Correlates of Myocardial Scar
What is the prevalence of and factors associated with myocardial scar in middle- and older-aged individuals in the United States?
The MESA (Multi-Ethnic Study of Atherosclerosis) study is a population-based cohort in the United States. Participants were ages 45-84 years and free of clinical cardiovascular disease (CVD) at baseline in 2000-2002. In the 10th year examination (2010-2012), 1,840 participants underwent cardiac magnetic resonance (CMR) imaging with gadolinium to detect myocardial scar. CVD risk factors and coronary artery calcium (CAC) scores were measured at baseline and year 10. Logistic regression models were used to estimate adjusted odds ratios (ORs) for myocardial scar. CV risk factors, CAC scores, left ventricle size and function, and carotid intima-media thickness were exposures of interest. The main outcome measure was myocardial scar detected by CMR imaging. Both cross-sectional and longitudinal models were constructed to evaluate the association of age- and sex-adjusted CAC score with the presence of a CMR-defined scar in comparison with clinically adjudicated MI.
Of 1,840 participants (mean [SD] age, 68  years, 52% men), 146 (7.9%) had myocardial scars, of which 114 (78%) were undetected by electrocardiogram or by clinical adjudication. In adjusted models, age, male sex, body mass index, hypertension, and current smoking at baseline were associated with myocardial scar at year 10. The OR per 8.9-year increment was 1.61 (95% confidence interval [CI], 1.36-1.91; p < 0.001); for men vs. women: OR, 5.76 (95% CI, 3.61-9.17; p < 0.001); per 4.8-SD body mass index: OR, 1.32 (95% CI, 1.09-1.61, p = 0.005); for hypertension: OR, 1.61 (95% CI, 1.12-2.30; p = 0.009); and for current vs. never smokers: 2.00 (95% CI, 1.22-3.28; p = 0.006). Age-, sex-, and ethnicity-adjusted CAC scores at baseline were also associated with myocardial scar at year 10. Compared with a CAC score of 0, the OR for scores from 1-99 was 2.4 (95% CI, 1.5-3.9); from 100-399, 3.0 (95% CI, 1.7-5.1); and 400 or higher, 3.3 (95% CI, 1.7-6.1) (p ≤ 0.001). The CAC score significantly added to the association of myocardial scar with age, sex, race/ethnicity, and traditional CVD risk factors (C statistic, 0.81 with CAC vs. 0.79 without CAC, p = 0.01).
The authors concluded that prevalence of myocardial scars in a US community-based multiethnic cohort was 7.9%, of which 78% were unrecognized by electrocardiography or clinical evaluation.
This study reports that the prevalence of myocardial scars in a US community-based multiethnic cohort was 7.9%, of which the majority were unrecognized by electrocardiography or clinical evaluation. Further studies are needed to understand the clinical consequences, if there are any, of these CMR-defined scars.
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