The effects of trimetazidine on heart rate variability and signal-averaged electrocardiography in early period of acute myocardial infarction

Background: Acute myocardial infarction (AMI) is accompanied by electrophysiological changes in cardiovascular system as well as those in autonomic cardiac control. Heart rate variability (HRV) is depressed due to increased sympathetic activity and/or decreased parasympathetic activity following AMI. Moreover, the frequency of ventricular late potentials (VLP) is increased due to the electrophysiological changes. Based on the hypothesis that the treatments increasing HRV and decreasing the frequency of VLP can improve the prognosis of AMI, we investigated the short-term effects of trimetazidine (TMZ) on HRV and VLP in patients with AMI. Methods: The study group consisted of 64 patients (men 49, mean age 55±12 years, range 26–70) suffering from first Q-wave AMI. Thirty-one of them were treated with conventional therapy (thrombolytic therapy, aspirin, beta-blocker, heparin and intravenous nitroglycerin) plus TMZ 20 mg tid. The remaining 33 patients served as controls. Holter monitorization between 24 and 48 h, echocardiography at average day 6 (range 4–7 days) and SAECG and sub-maximal exercise at average day 7 (range 6–9 days) were performed to all patients. Results: While HRV parameters reflecting parasympathetic activity (SDSD: 43±16 ms–35±13 ms, RMSSD: 34±14 ms–27±8 ms, HF: 7.8±5 ms2 –4.3±4 ms2, P<0.05) were of significantly higher levels in TMZ group, the low frequency component mainly reflecting sympathetic activity (LF: 10±6 ms2–10±5 ms2, P>0.05) was similar in both groups. In addition, LF/HF ratio showing sympatho–vagal balance was significantly decreased in TMZ group (1.5–3.0, P=0.005). About VLP, the mean FQRS (105±8 ms–107±10 ms), LAS (28±10 ms–30±11 ms) and RMS-40 (34±15 μV–41±12 μV) were not different in both two groups (P>0.05). Conclusion: Our results suggest that TMZ treatment causes changes in sympatho–vagal balance in favor of vagal activity by increasing parasympathetic activity in AMI at early period; however, no effect on VLP was observed.