Baseline ST elevation and myocardial scar: Results from the multi-ethnic study of atherosclerosis.

BACKGROUND: The mechanism of ST elevation on baseline electrocardiograms (ECG) unknown but it may be associated with abnormal myocardial substrate. This paper evaluates whether clinically unrecognized myocardial scar on cardiac magnetic resonance imaging (CMR) is associated with ST elevation at baseline. METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) study is a population-based cohort in the United States. Participants were aged 45 through 84 years and free of clinical cardiovascular disease at enrollment in 2000-2002. Our cohort included 1365 participants who underwent both ECG and contrast enhanced CMR in the 5th examination (2010-2012). Multivariable logistic regression examined the association of ST elevation and CMR defined regional myocardial scar after adjusting for cardiovascular risk factors. RESULTS: Of 1365 participants (58 ±9 years, 52% men), 105 (8%) had scar on CMR. Of these, the scar in 40 participants followed an ischemic pattern and in the other 65 participants followed a non-ischemic pattern. ST elevation at the 5th examination was present in 435 participants: 40 (0.9%) had ST elevations in inferior and 427 (98%) in lateral leads. 2/40 (5%) and 22/427 (5%) participants with inferior and lateral ST elevations, respectively, had evidence of scar. 15 (1.0%) had myocardial scar noted in the basal anterior region. In the fully adjusted models, ST elevation was associated with scar in basal anterior region (OR 18.2, p = 0.031). CONCLUSIONS: In a community population, ST elevation at baseline in the inferior or lateral leads was associated with myocardial scar in the basal inferior and anterior segments. The previously described association between ST elevation and increased mortality may be mediated by myocardial scar.