Inclusion of silent myocardial infarction (SMI) in diabetes risk stratification improves risk discrimination over and beyond traditional factors, according to study results published in Diabetes Care.
Although type 2 diabetes is associated with a 2- to 4-fold increase in risk for cardiovascular disease (CVD), the risk is heterogeneous in distribution, emphasizing the need for cardiovascular risk markers in this population. Prior studies have not determined an effective blood biomarker for risk prediction, but it is possible that information from routine electrocardiograms (ECGs) could inform this risk. Due to impaired nociceptive capabilities, individuals with diabetes are more prone to SMIs than the general population. The risk for atherosclerotic CVD (ASCVD) in individuals with prior SMI and diabetes had not yet been determined.
Patient-level data from 5539 individuals from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study and its follow-up study were analyzed to assess SMI as a predictor for ASCVD risk. Patients were eligible if they had no history of prevalent CVD, including myocardial infarction, stroke, coronary revascularization, carotid or peripheral revascularization, or positive stress test. The average patient age was 62.8±5.8 years, 45% were women, and 61% were of non-Hispanic white descent. The majority (94.7%) did not have SMI at baseline.
Individuals were enrolled between 2001 and 2005 and followed for a median of 3.5 years. Participation in the follow-up study brought the total time of participation to an average of 9.3±2.2 years. ECG measurements were used to determine SMI, which was defined as the presence of a major Q-wave abnormality or minor Q/QS waves in the setting of major ST-T abnormalities.
In the 51,654 person-years of follow-up, there were 1902 events. The presence of SMI at baseline was associated with an increased risk for all-cause mortality (hazard ratio [HR], 1.49; 95% CI, 1.15-1.93; P =.003), cardiovascular mortality (HR, 2.48; 95% CI, 1.64-3.75; P <.001), congestive heart failure (HR, 2.24; 95% CI, 1.44-3.51; P =.0004) and major coronary heart disease (HR, 1.48; 95% CI, 1.11-1.97; P =.007) in the model adjusted for the most covariates. Inclusion of SMI in receiver operative characteristic curves and net reclassification risk models significantly improved discrimination.
Overall, the study found that SMI was associated with cardiovascular events and that inclusion of SMI in risk models improved risk discrimination. Inclusion of SMI in risk prediction models may improve identification of patients with diabetes who will benefit from preventive treatments for ASCVD. The additional discovery of a pathological Q-wave on ECG may also help identify high-risk patients who would benefit from additional therapeutic interventions.
Singleton MJ, German CA, Bertoni AG, et al. Association of silent myocardial infarction with major cardiovascular events in diabetes: the ACCORD trial [published online March 16, 2020]. Diabetes Care. doi:10.2337/dc19-2201