Differences between diabetic and non-diabetic hypertensive patients with first acute non-ST elevation myocardial infarction and predictors of in-hospital complications

Abstract

This investigation was undertaken to compare diabetic and non-diabetic hypertensive patients with a first acute non-ST segment elevation myocardial infarction (NSTEMI) and to assess the impact of clinical and laboratory parameters on the occurrence of in-hospital complications. The study population comprised 112 consecutive male hypertensive patients with their first NSTEMI, who were divided into two groups according to the presence of type 2 diabetes mellitus. All patients underwent echocardiography and 24-h electrocardiographic (ECG) and blood pressure monitoring within 48 h from admission. Diabetic hypertensive patients had significantly higher mean daytime, night-time, 24-h systolic blood pressure and heart rate and hypertensive peaks (P < 0.01), more episodes of asymptomatic ST segment depression (P < 0.05), which were also more severe and prolonged (P < 0.01), and more episodes of non-sustained ventricular tachycardia (P = 0.01). Diabetic patients showed a greater left ventricular mass index (LVMI) and a lower left ventricular ejection fraction (LVEF) (P < 0.01). In-hospital adverse clinical events were more frequent in diabetic hypertensives compared to non-diabetics (40.3% versus 18.1%, P = 0.01). In particular, heart failure occurred during hospitalization in 33.3% versus 14.5% (P = 0.02). The difference in transient cerebral ischaemic attacks did not reach statistical significance (7.0% versus 1.8%, P = 0.18). Multivariate Cox proportional hazards analysis showed that the only independent predictors for the occurrence of in-hospital adverse clinical events in diabetic patients were: 24-h systolic blood pressure variability [relative risk (RR) = 1.013, 95% confidence interval (CI) = 1.001-1.025, P = 0.03]; mean 24-h heart rate (RR = 7.05, 95% CI = 1.35-35.9, P = 0.02) and the LVMI (RR = 1.9, 95% CI = 1.121-3.785, P = 0.02). This study indicates that in-hospital complications, including heart failure and transient cerebral ischaemia, occur frequently during the acute phase of a first NSTEMI in patients with both diabetes and hypertension. The coexistence of diabetes and hypertension doubles the risk of complications with respect to hypertension alone. In addition, adverse events may appear despite an initial uncomplicated clinical presentation, which can be predicted by the early assessment of heart rate and blood pressure behaviour and by the echocardiographic assessment of left ventricular mass.