- QTc prolongation (defined as a QTc ≥ 450 msecs) or other significant ECG abnormalities including 2nd degree AV block type II, 3rd degree AV block, or bradycardia (ventricular rate less than 50 beats/min). If the screening ECG has a QTc ≥ 450 msecs, the ECG can be submitted for a centralized, cardiologic evaluation.