The utility of silent myocardial infarction on electrocardiogram as an ASCVD risk enhancer for primary prevention: The multi-ethnic study of atherosclerosis.

Abstract Background The 2018 AHA/ACC cholesterol guidelines introduced a new list of markers called “risk enhancers” that, if present, confer an increased risk of atherosclerotic cardiovascular disease (ASCVD). Silent myocardial infarction (SMI) on electrocardiogram (ECG) is notably absent, even though it associated with future ASCVD. Methods We assessed the utility of SMI on ECG as a risk-enhancer in intermediate-risk participants in MESA (Multi-Ethnic Study of Atherosclerosis) – those with 10-year ASCVD risk of 5–20% by the pooled cohort equation (PCE). SMI was defined as major Q-wave abnormality or minor Q/QS waves in the setting of major ST-T abnormalities without prevalent clinical cardiovascular disease. Results Among 2946 participants (mean age 63.1 ± 7.6, 53.9% women, 36% white, 11% Chinese-American, 33% African-American, 19% Hispanic), 66 (2.2%) had SMI at baseline. After a median 15.8 years of follow-up, incident ASCVD events occurred in 431/2876 (15.0%) of those without SMI and 16/66 (24.2%) of those with SMI. In a multivariable-adjusted Cox proportional hazards model, baseline SMI was associated with an increased risk of incident ASCVD events (HR 1.68, 95% CI 1.02–2.77, p = 0.04). However, adding SMI to the PCE did not improve discrimination and reclassification was modest—net reclassification improvement was 0.0161 (95% CI 0.002–0.034, p = 0.08). Conclusion Our findings suggest that the prevalence of SMI is 2.2% among those without known clinical cardiovascular disease considered intermediate-risk by the PCE. In our analysis, SMI only modestly improved classification of risk, suggesting that it may not be very useful as an ASCVD risk enhancer.