Potential pro-arrhythmic effect of cardiac resynchronization therapy

ABSTRACT

A decline in mortality due to pump failure has been clearly documented after cardiac resynchronization therapy [CRT], however the impact on sudden cardiac death and the development of malignant ventricular arrhythmias remains questionable. Our study aims to investigate this alleged pro-arrhythmic effect of CRT using surface electrocardiogram [ECG] markers of pro-arrhythmia. Seventy five patients, who received CRT were included in this study. Manual measurement of corrected QT interval [QTc], T[peak-end] T[p-e] interval, QT dispersion [QTd] and T[peak-end] dispersion during baseline 12 lead surface ECG and after applying atrial-biventricular pacing were done. Arrhythmias post CRT was recorded from ECG, 24 h holter monitoring or pacemaker programmer event recorder. QTc interval showed significant prolongation after CRT [498.9 +/- 50.8 vs. 476.2 +/- 41.6 msec, P = 0.0001]. Comparing patients with major arrhythmogenic events [MAE] and increased frequency of premature ventricular contractions [PVCs] post CRT pacing to those patients without arrhythmias, there was a significant prolongation of the QTc interval [527 +/- 63.29 vs. 496.95 +/- 45.2 msec, P = 0.043] and T p-e interval [94.16 +/- 9 vs. 87.41 +/- 16.37 msec, P = 0.049]. While in the arrhythmogenic group, there was an insignificant decrease in QTd and T[peak-end] dispersion. QTc and T[p-e] intervals are a potential predictor of occurrence of MAE and PVCs. On the other hand, T[p-e] dispersion and QTd did not show a predictive potential for arrhythmia