( A ) An ECG showing DDD pacing with ventriculo-atrial retrograde conduction. The atrial spikes were not followed by atrial activity. ( B ) An ECG, after reprogramming, showing VVI pacing with hysteresis at 30 beats per minute. HR = 33 bpm; QT = 0.72″, QTcF = 0.59″, T waves inversion in V3 to V6 and in II, III, aVF.