Effect of inpatient cardiac rehabilitation on QT dispersion in patients with acute myocardial infarction.

QT dispersion is an indicator of lack of ventricular repolarization homogeneity and an independent predictor for ventricular arrhythmia and sudden cardiac death. In this study, we evaluated the effect of inpatient cardiac rehabilitation on QT dispersion in patients admitted to Afshar hospital CCU with diagnosis of acute myocardial infarction (AMI), including ST elevation or non-ST elevation MI. Sixty patients with diagnosis of AMI were randomly divided into two 30-subject groups. The subjects in the first group were undergone inpatient cardiac rehabilitation, and the subjects in the control group received only conventional treatments. QT interval dispersion was measured in two occasions: once in the first day of admission and once before discharge from hospital. In this study there was a significant reduction in QT dispersion in patients undergoing inpatient cardiac rehabilitation (48.4 vs. 42.4 ms, P<0.001), but in the control group, QT dispersion was not significantly reduced (49.2 vs. 46.2 ms, P>0.05). The reduction was not significantly different regarding gender. The effectiveness of the rehabilitation on the reduction of QT dispersion was not affected by such variables as age, gender, hypertension, positive family history, hyperlipidemia, type of AMI (with ST-elevation or non-ST-elevation) and left ventricular ejection fraction. Diabetes caused a resistance to the beneficial effects of inpatient cardiac rehabilitation, so as non-diabetic patients showed more reduction in QT dispersion in response to inpatient cardiac rehabilitation comparing non-diabetic patients and the difference was statistically significant.