B-PO02-201 ELECTRICAL CARDIOVERSION: KEEP AN EYE ON THE T!

Abstract

Torsades de pointes (TdP) often seen in the setting of QT prolongation is an uncommon arrhythmia after synchronized electrical cardioversion (CV). Report a case of unexpected TdP after successful electrical CV. NA A 78-year-old man with coronary artery disease and prior CABG, ischemic cardiomyopathy with prior LVEF 50-55% was admitted with acute decompensated heart failure with newly depressed LVEF 20-25% and new-onset atrial flutter (AF) with 2:1 AV conduction (Fig. A). Due to persistent rapid ventricular rates despite digoxin and metoprolol, he underwent synchronized CV with successful restoration of sinus rhythm (Fig. B, QTc 478 ms). He experienced an episode of TdP 33 hours after CV, initiated by a short-long-short sequence, preceded by giant T-U waves (Fig. C). He underwent CPR / defibrillation with successful return of spontaneous circulation within 5 minutes. Post-arrest ECG showed sinus rhythm with prolonged QTc (500-620 ms) and macroscopic T-wave alternans (Fig. D); another showed junctional rhythm with giant T-U waves preceding frequent ventricular ectopic beats (Fig. E). Electrolytes were normal. He was treated with isoproterenol; digoxin and metoprolol were discontinued. Coronary angiogram showed no new stenoses. He underwent implantation of secondary prevention dual-chamber ICD with backup pacing rate set at 70 bpm, with no TdP recurrence at 2 months. CV is a common, effective procedure for termination of AF. There is increased risk of TdP due to repolarization abnormalities post CV. Macroscopic T-wave alternans and giant T-U waves are ominous ECG signs of impending ventricular arrhythmias.