Repolarization Dispersion as a Predictor for Life-Threatening Ventricular Arrhythmias in Short-Term Experimental Diabetes Mellitus

Diabetes mellitus (DM) is a well-known risk factor for cardiovascular diseases (CVDs). It can cause myocardial metabolic dysfunction, oxidative stress, inflammation, cardiomyocyte apoptosis, structural remodeling, ventricular dysfunction and lethal arrhythmias. The aim of this study was to find a model for diabetes mellitus increasing the frequency of ventricular arrhythmias induced by myocardial ischemia/reperfusion and to study the electrophysiological properties of the ventricular myocardium in the obtained models. Materials and Methods. The study was conducted on 32 rats with uncontrolled streptozotocin-induced diabetes mellitus lasting 4 (short-term) and 8 (long-term) weeks. The control group consisted of 23 rats. During epicardial mapping, depolarization and repolarization parameters, and ventricular myocardial repolarization dispersion were measured. Left ventricular myocardial ischemia and reperfusion were caused by coronary artery ligation to provoke ventricular tachycardia and/or ventricular fibrillation. Results. The repolarization duration was significantly higher in both groups of rats with diabetes mellitus compared to the control. However, the repolarization dispersion differed from the control only in the group with short-term diabetes mellitus (4 weeks). In this group, reperfusion ventricular arrhythmias developed significantly more often compared with the group with long-term diabetes mellitus (8 weeks). Conclusions: The incidence of reperfusion-induced ventricular tachycardia and/or ventricular fibrillation was higher in rats with short-term diabetes mellitus (4 weeks). It may be due to greater dispersion of left ventricular myocardial repolarization in this group.