The influence of type 2 diabetes mellitus on the frequency and complexity of ventricular arrhythmias and heart rate variability in patients after myocardial infarction.

Abstract

After myocardial infarction arrhythmic cardiac deaths are significantly more frequent compared to non-arrhythmic ones. The aim of the study was to investigate the influence of type 2 diabetes mellitus (T2DM) on the frequency and complexity of ventricular arrhythmias after myocardial infarction. The study included 293 patients, mean age 59.5 ± 9.21 years, who were at least six months after acute myocardial infarction with the sinus rhythm, without atrioventricular blocks and branch blocks. In the clinical group 95 (32.42%) patients were with T2DM, while 198 (67.57%) patients were without diabetes. All of the patients were subjected to the following procedures: standard ECG according to which the corrected QT dispersion (QTdc) was calculated, exercise stress test, and 24-hour holter monitoring according to which, the four parameters of time domain of heart rate variability (HRV) were analyzed: standard deviation of all normal RR intervals during 24 hours (SDNN), standard deviation of the averages of normal RR intervals in all five-minute segments during 24 hours (SDANN), the square root of the mean of the sum of the squares of differences between adjacent normal (RMS-SD), and percentage of consequtive RR intervals which differed for more than 50 ms during 24 hours (NN > 50 ms). In patients after myocardial infarction, patients with T2DM had significantly higher percentage of frequent and complex ventricular arrhythmias compared to the patients without diabetes (p < 0.001). The patients with T2DM had significantly higher percentage of residual ischemia (p < 0.001), and arterial hypertension (p < 0.001), compared to patients without diabetes. The patients with T2DM had significantly lower values of HRV parameters: SDNN (p < 0.001); SDANN (p < 0.001); RMS-SD (p < 0.001), and NN > 50 ms (p < 0.001), and significantly higher values of QTdc (p < 0.001) compared to the patients without diabetes. The study showed that type 2 diabetes mellitus has significant influence on ventricular arrhythmias, HRV parameters and QT dispersion in patients after myocardial infarction.