- Significant screening ECG abnormalities, including unstable cardiac arrhythmia requiring medication, atrial fibrillation/flutter, left bundle-branch block, 2nd-degree atrioventricular (AV) block type II, 3rd degree AV block, Grade ≥2 bradycardia, or QT corrected for heart rate (QTc) >450 msec (for men) or >470 msec (for women).