Purpose: The aim of this study was to establish the significance of diabetes mellitus on left ventricular function, heart rate variability and freqency of supraventricular arrhythmias in patients after myocardial infarction (MI).
Methods: We studied 337 patients after MI, in the sinus rhythm without AV blocks or branch blocks. 112 patients were with diabetes mellitus, and 225 were without diabetes. Patients were of similar age, site of infarction and baseline stress test duration. In all subjects 24-hour ECG recording and echocardiographic examination were performed. From the holter record, the analysis of the heart rate variability was performed by software. Four parameters of the time domain heart rate variability were assessed: SDNN, SDANN, RMS-SD and NN>50 ms.
Results: Patients with diabetes had a higher percentage of frequent (>10 supraventricular premature complexes / hour) and complex supraventricular arrhythmias (38.5 vs 19.2%, p<0.001) and supraventricular tachycardias (28.8 vs 6.1%, p<0.001) than in those without diabetes. Patients with diabetes also had significantly lower values of followed parameters of the heart rate variability (78.6 ± 20.1 vs 102.1 ± 28.7 ms, p<0.001 for SDNN; 66.9 ± 18.7 vs 85.6 ± 29.7 ms, p<0.001 for SDANN; 24.7 ± 10.6 vs 35.4 ± 14.9 ms, p<0.001 for RMS-SD and 5.8 ± 5.6 vs 12.2 ± 10.3, p<0.001 for NN>50ms) in comparison to those without diabetes. Patients with diabetes also had significantly lower values of left ventricular ejection fraction (45.0 ± 9.6 vs 54.3 ± 13.8 %, p<0.001) and significantly higher values of left ventricular end-systolic diameter (39.5 ± 5.6 vs 35.6 ± 6.8 mm, p<0.001), left ventricular end-diastolic diameter (55.8 ± 5.4 vs 53.1 ± 5.6 mm, p<0.001) and left atrium (43.2 ± 5.6 vs 39.2 ± 4.7 mm, p<0.001), in comparison to those without diabetes.
Conclusions: The study showed that in patients after MI, diabetes mellitus have a significant impact on left ventricular function, heart rate variability and supraventricular arrhythmias. The reason for that is more severe degree of the left ventricle dysfunction, diabetic neuropathy and greater inhomogeneous repolarization of myocardium.