Course and prognostic implications of QT interval and QT interval variability after primary coronary angioplasty in acute myocardial infarction

OBJECTIVES The aim of this study was to determine the influence of early re perfusion on the course of QT interval and QT interval variability in patie nts undergoing primary percutaneous transluminal coronary angioplasty (PTCA ) in acute myocardial infarction (AMI) and its prognostic implications on m ajor arrhythmic events during one-year follow-up. BACKGROUND Although early coronary artery recanalization by primary angiopl asty is an established therapy in AMI, a substantial number of patients is still threatened by malignant arrhythmias even after early successful reper fusion, which may be caused by an inhomogeneity of ventricular repolarizati on despite reperfusion. METHODS Temporal fluctuations of ventricular repolarization were studied pr ospectively in 97 consecutive patients with a first AMI by measurements of QT interval and QT interval variability during and after successful PTCA (T hrombolysis in Myocardial Infarction flow grades 2 and 3). Continuous beat- to-beat QT interval measurement was performed from 24-h Holter monitoring, which was initiated at admission before PTCA. RESULTS Reperfusion caused a significant continuous increase of mean RR int erval (738 +/- 98 to 808.5 +/- 121 ms; p < 0.001) and a significant decreas e of parameters of QT interval (QTc: 440 +/- 32 to 416.5 +/- 37ms; p < 0.00 1) and QT interval variability (QTcSD: 27.5 +/- 3 to 24.9 +/- 6 ms; p < 0.0 01) in the majority of patients. However, in patients with major arrhythmic events at the one-year follow-up (sudden cardiac death, ventricular fibril lation or sustained ventricular tachycardia, n = 15), parameters of QT inte rval remained unaltered after successful reperfusion (QTc: 447.3 +/- 41 to 432.9 +/- 45 ms, p = NS; QTcSD: 35.1 +/- 13.4 to 29.0 +/- 9.1 ms, p = NS). CONCLUSIONS Reduction of QT interval and QT interval variability after time ly reperfusion of the infarct-related artery may be a previously unreported beneficial mechanism of primary PTCA in AMI, indicating successful reperfu sion. (J Am Cell Cardiol 2001;37:44-50) (C) 2001 by the American College of Cardiology.