A quarter of all myocardial infarctions are silent in T2D patients
In patients with type 2 diabetes mellitus, one in four of all myocardial infarction (MI) events are silent, characterized as the presence of pathological Q waves in the absence of typical cardiac symptoms, a recent study has shown.
Researchers performed a prospective cohort study on participants of the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes trial. The study sample included 1,648 patients (mean age 64±10 years; 53 percent male), in whom the median duration of diabetes was 7.1 years.
Twenty-two patients (1.3 percent) were determined to have silent MI, while 65 (3.9 percent) had symptomatic MI. No MI event was reported in the remaining 1,561 patients.
The incidence rate of symptomatic MI was calculated to be 4.26 per 1,000 person-years, while that of silent MI was 1.44 per 1,000 person-years. Thus, 25 percent of the total MI cases were silent. The difference in incidence rates reached statistical significance (p<0.001).
In terms of baseline characteristics, patients with symptomatic MI tended to be older (mean age 69±10 vs 66±9) and have longer diabetes duration (median, 8.9 vs 8.2 years), while smoking (59 percent vs 55 percent) and the use of calcium channel blockers (59 percent vs 45 percent) were greater in those with silent MI.
Multivariable Cox proportional hazards models identified risk factors for symptomatic MI: age (hazard ratio [HR], 1.06; 95 percent CI, 1.03–1.10; p=0.0004) and duration of diabetes (HR, 1.04; 1.01–1.07; p=0.01). On the other hand, no factors emerged as significantly predictive of silent MI.