Nearly 17% of newly diagnosed type 2 diabetes patients have silent MI

About one in six patients with newly diagnosed type 2 diabetes had evidence of a silent myocardial infarction (SMI), a new study found.

U.K. researchers examined data from the 5,102 patients who were in the U.K. Prospective Diabetes Study and used regression analysis to determine the effect of SMI on the outcomes of death or subsequent fatal or nonfatal MI. SMI was defined as the presence of pathological Q-waves without typical cardiac symptoms and was detected by electrocardiogram (ECG) screening. Results were published online Jan. 29 by Circulation.

Nearly 2,000 study patients (n=1,967) had complete baseline data. Of these, 16.6% (n=326) had ECG evidence of SMI at enrollment; these patients were more likely to be older, female and sedentary than those without SMI. They were also more likely to be taking aspirin and lipid-lowering therapy, had a greater prevalence of microangiopathy, and had a higher mean blood pressure even with more intensive antihypertensive treatment.

SMI was associated with a 49% increased rate of subsequent fatal MI and a 26% increased rate of all-cause mortality, a significant difference after adjustment for conventional cardiovascular risk factors. SMI at diagnosis of type 2 diabetes, however, was not associated with a first non-fatal MI. Though SMI at diagnosis was more common in females, the SMI-associated increase in risk of subsequent fatal MI was independent of sex. Adding SMI to the factors in the original study's cardiovascular “risk engine” (which included age at diagnosis, ethnicity, gender, smoking, hemoglobin A1c level, systolic blood pressure and total HDL cholesterol ratio) only marginally improved the engine's ability to predict key cardiovascular outcomes.

Based on the study results, clinicians who find evidence of SMI on routine ECG screening of patients with type 2 diabetes should carefully review the adequacy of management of modifiable cardiovascular risk factors, the study authors concluded.