Ventricular Tachycardia or Not?: Decoding Post-Cardioversion Wide Complex Tachycardia in a CRT-D Patient

Wide complex tachycardia (WCT) in patients with structural heart disease is often presumed to be ventricular tachycardia (VT). However, supraventricular tachycardia with aberrant conduction accounts for a substantial proportion of WCT presentations and remains an important diagnostic consideration.

A 74-year-old man with nonischemic cardiomyopathy and cardiac resynchronization therapy-defibrillator underwent cardioversion for persistent atrial fibrillation. Several hours later, he developed sustained WCT initiated by a premature ventricular complex. Although initially concerning for monomorphic VT, careful comparison with underlying baseline nonpaced electrocardiograms demonstrated nearly identical QRS morphology. Tachycardia terminated with 5 mg intravenous metoprolol.

This case highlights key electrocardiographic principles for differentiating VT from supraventricular tachycardia with aberrancy in patients with paced QRS, the diagnostic value of baseline QRS comparison, and important limitations of morphological Brugada criteria and device detection algorithms.

Systematic underlying electrocardiogram analysis remains critical in the evaluation of WCT, to prevent inappropriate therapies.