Impact of diabetes mellitus on long-term outcome after unstable angina and non-ST-segment elevation myocardial infarction treated with a very early invasive strategy

We sought to evaluate the impact of diabetes mellitus on long-term outcome in patients with unstable angina and non-ST-segment elevation myocardial infarction treated with a very early invasive strategy.

We carried out a prospective cohort study in 270 diabetic and 1163 non-diabetic patients with unstable angina and non-ST-segment elevation myocardial infarction. All patients underwent coronary angiography and, if appropriate, subsequent revascularisation within 24 hours of admission. The primary endpoint was all-cause mortality during follow-up for up to 60 months.

Diabetic patients had less favourable baseline characteristics including more advanced coronary artery disease and more severe unstable angina and non-ST-segment elevation myocardial infarction. Percutaneous coronary intervention was performed in 53% of diabetic patients and 56% of non-diabetic patients. Coronary artery bypass grafting was done in 21% of diabetic patients and 12% of non-diabetic patients. In-hospital mortality (4.1% vs 1.3%; hazard ratio 3.47; 95% CI: 1.57 to 7.64; p=0.002) and long-term mortality (9.7% vs 4.9%; hazard ratio 2.11; 95% CI: 1.33 to 3.36; p=0.002) were significantly higher in diabetic patients. After adjustment for differences in baseline characteristics, diabetes mellitus was no longer an independent predictor of long-term mortality (hazard ratio 1.43; 95% CI: 0.74 to 2.78; p=0.292).

Diabetic patients treated with a very early invasive strategy for unstable angina and non-ST-segment elevation myocardial infarction have a higher in-hospital and long-term mortality that is largely explained by their less favourable baseline characteristics including more advanced coronary artery disease and more severe unstable angina and non-ST-segment elevation myocardial infarction.