Diabetes and haemodynamic reactions to acute coronary occlusion.

BACKGROUND: The risk of early sudden death before hospital admission is higher in diabetic than non-diabetic men with acute myocardial infarction and autonomic nervous activity may modify the clinical outcome of abrupt coronary occlusion. Since diabetes mellitus may interfere with autonomic and myocardial function, we decided to study whether diabetes alters autonomic and haemodynamic responses to acute coronary occlusion. METHODS: We analyzed the changes in heart rate, heart rate variability and blood pressure, and the occurrence of ventricular ectopy during a 2-min coronary occlusion in 238 non-diabetic and 32 diabetic patients referred for single vessel coronary angioplasty. The ranges of non-specific responses were determined by analyzing a control group of 19 patients with no ischaemia during a 2-min balloon inflation in a totally occluded coronary artery. RESULTS: Diabetic patients were more often (p<0.05) female, but there were no significant differences in the occluded vessel or incidence of ST changes or chest pain during coronary occlusion between the groups. Incidence of significant heart rate reactions and ventricular arrhythmias was comparable in both groups. Systolic blood pressure decreased (p=0.01) in the diabetic patients during coronary occlusion, but did not change significantly in the non-diabetic group. Coronary occlusion caused more often (34% vs. 14%, p<0.01) a significant decrease in blood pressure in diabetic patients. Logistic regression models developed to analyze the significance of diabetes while controlling for baseline variables and signs of ischaemia identified diabetes to be an independent predictor of hypotensive reactions (odds ratio [OR] 2.9, 95% confidence intervals 1.1-7.8, p<0.05), while female gender and high short-term heart rate variability were other independent predictors of hypotensive reactions. CONCLUSIONS: Diabetic patients often develop significant hypotension during the early phase of acute coronary occlusion. This abnormality may be related to diabetic cardiomyopathy and impairment of baroreflex-mediated regulation of circulation. Predisposition to hypotension may contribute to the observed differences in the clinical presentation and outcome of acute coronary events.