Race and Sex Differences in the Incidence and Prognostic Significance of Silent Myocardial Infarction in the Atherosclerosis Risk in Communities (ARIC) Study
Background—Race and sex differences in silent myocardial infarction (SMI) are not well-established.
Methods and Results—The analysis included 9,498 participants from the ARIC study who were free of cardiovascular disease at baseline (visit-1; 1987-1989). Incident SMI was defined as ECG-evidence of MI without clinically documented MI (CMI) after the baseline until ARIC visit-4 (1996-1998). Coronary heart disease (CHD) and all-cause deaths were ascertained starting from ARIC visit-4 until 2010. During a median follow-up of 8.9 years, 317 (3.3%) participants developed SMI while 386 (4.1%) developed CMI. The incidence rates of both SMI and CMI were higher in men (5.08 and 7.96 per 1000-person years, respectively) than in women (2.93 and 2.25 per 1000-person years, respectively); p-value <.0001 for both. Blacks had non-significantly higher rate of SMI than whites (4.45 vs. 3.69 per 1000-person years; p-value=0.217) but whites had higher rate of CMI than blacks (5.04 vs. 3.24 per 1000-person years; p-value=0.002). SMI and CMI (vs. no MI) were associated with increased risk of CHD death (HR(95%CI): 3.06(1.88-4.99) and 4.74(3.26-6.90), respectively) and all-cause mortality (HR(95%CI):1.34(1.09-1.65) and 1.55(1.30-1.85), respectively). However, SMI and CMI were associated with increased mortality among both men and women, with potentially greater increased risk among women (interaction p-value= 0.089 and 0.051, respectively). No significant interactions by race were detected.
Conclusions—SMI represents over 45% of incident MIs and is associated with poor prognosis. Race and sex differences in the incidence and prognostic significance of SMI exist which may warrant considering SMI in personalized assessment of CHD risk.
- Received December 23, 2015.
- Revision received March 29, 2016.
- Accepted April 4, 2016.