Relation of glycemic status with unrecognized MI and the subsequent risk of mortality: The Jackson Heart Study

Background: Almost 1/3 to 1/2 of initial myocardial infarctions (MI) may be silent or unrecognized (UMI), which forecasts future clinical events. Further, limited data exist to describe the potential risk for UMI in African-Americans. The relationship of glucose status with UMI was examined in the Jackson Heart Study: a cohort of African-American individuals. Methods and results: At baseline, there were 5,073 participants with an initial 12-lead electrocardiogram (ECG) and fasting glucose measured. Of these participants, 106(2.1%) had a UMI, and 268(4.2%) had a recognized MI. This population consisted of 3,233 (63.7%) participants with normal fasting glucose (NFG), 533 (10.5%) with IFG, and 1,039 (20.4%) with DM. Logistic regression investigated the relationship between glucose status and UMI. Cox proportional hazard models determined the significance of all-cause mortality during follow-up by MI status. The sample was 65% female with a mean age of 55.3 ± 12.9 years. Over a mean follow-up of 10.4 years, there were 795 deaths. Relative to NFG, the crude odds ratio (OR) estimates for UMI at baseline with IFG and DM were 1.00(95% CI:0.48-2.14) and 3.22(2.15-4.81), respectively. With adjustment, DM continued to be significantly associated with UMI [2.30 (1.42-3.71)]. Overall, participants with a baseline UMI had an adjusted Hazard ratio (HR) of 2.00(1.39-2.78) of death compared to no prior MI. Compared to those with no MI, those with a recognizedMI had an adjusted HR of 1.70(1.31-2.17) for mortality. Conclusions: DM is associated with UMI in African-Americans. Further, a UMI carried similar risk of death compared to those with a recognized MI.