P640Impact of short-term exercise training on QT dispersion and double product in patients after surgical aortic valve replacement

Abstract

Background/Introduction: QT dispersion (QTd) represents the heterogeneity in the repolarization of the ventricular myocardium and electrical instability of the myocardium, reflecting the increased tendency towards ventricular arrhythmias. Abnormally high QTd has been correlated with risk of cardiac death. Purpose: The aim of this study was to establish the influence of short‐term exercise training on QT dispersion and double product (DP), in patients after surgical aortic valve replacement (SAVR). Methods: The study involved 91 patients after SAVR, in the sinus rhythm without AV blocks or branch blocks. Average age of patients was 61.2 years. Patients were randomly divided into the physical training group (training group: 76 patients) and control group (non‐training group: 15 patients). Patients were similar as to age and baseline stress test duration. In all subjects clinical examination, standard ECG and exercise test on treadmill according to Bruce protocol were performed and after that training group patients were included in physical training program for three weeks. Training group patients were instructed to follow a training program using the bicycle ergometer (10 min, 2 times a day), gymnastic exercises and walking. The patients continued to take the same medicaments in same doses. From standard ECG corrected QT dispersion (QTdc) was calculated. Results: After three weeks, we have found significant reduction of QTdc from 78.6±19.4 to 70.4±20.8 ms; p<0.02 in the training group. Also, in the training group, we have found significant reduction of heart rate from 75.8±6.9 to 66.7±5.8 beats/min (p<0.001), of systolic blood pressure from 135.3±12.8 to 126.3±11.4 mmHg (p<0.025), of diastolic blood pressure from 87.2±8.8 to 83.7±7.5 mmHg (p<0.01) and of double product from 11852.3±1184.3 to 10733.8±735.2 beat/min x mmHg; p<0.001. In contrast, the non‐training group showed no significant changes. Conclusions: The study showed that short‐term exercise training have favourable effects on QT dispersion and double product in patients after SAVR. Physical training led to the significant decrease of myocardial oxygen uptake at rest and probably decreased the possibility of arrhythmia events in patients after SAVR.