Association of silent myocardial infarction on electrocardiogram and coronary artery calcium: The Multi-Ethnic Study of Atherosclerosis

Background: Silent myocardial infarction (SMI) on electrocardiogram (ECG) is associated with atherosclerotic cardiovascular disease, but the relationship between SMI on ECG and coronary artery calcium (CAC) remains poorly understood.

Objective: Characterize the relationship between SMI on ECG and CAC.

Methods: Eligible participants from the Multi-Ethnic Study of Atherosclerosis study had ECG and CAC scoring at study enrollment (2000-2002). SMI was defined as ECG evidence of myocardial infarction in the absence of a history of clinical cardiovascular disease. CAC was modeled both continuously and categorically. The cross-sectional relationships between SMI on ECG and CAC were assessed using logistic regression and linear regression.

Results: Among 6705 eligible participants, 178 (2.7%) had baseline SMI. Compared to participants without SMI, those with SMI had higher CAC (median [IQR]: 61.2 [0-261.7] vs. 0 [0-81.5]; p < .0001). Participants with SMI were more likely to have non-zero CAC (74% vs. 49%) and were more likely to have CAC ≥ 100 (40% vs. 23%). In a multivariable-adjusted logistic model, SMI was associated with higher odds of non-zero CAC (odds ratio 2.17, 95% CI 1.48-3.20, p < .0001) and 51% higher odds of CAC ≥ 100 (odds ratio 1.51, 95% CI 1.06-2.16, p = .02).

Conclusion: An incidental finding of SMI on ECG may serve to identify patients who have a higher odds of significant CAC and may benefit from additional risk stratification to further refine their cardiovascular risk. Further exploration of the utility of CAC assessment in this patient population is needed.