V > A: When the paradigm fails!
A Filipino 45-year-old man with a history of coronary heart disease and congestive heart failure (CHF), who previously received a biventricular cardioverter defibrillator (Quadra Assura MP 3371-40C St. Jude Medical, Abbott, St. Paul, MN, USA), was admitted for palpitations. He was receiving optimal medical therapy for CHF (namely loop diuretic, beta-blocker, angiotensin-converting-enzyme [ACE]-inhibitor, aldosterone antagonist, and ivabradine) besides aspirin. The electrocardiogram (ECG) showed wide QRS tachycardia at 160 beats per minute (bpm) with a singular bigeminal rhythm (see Fig. 1). The patient was hemodynamically stable (arterial blood pressure [ABP] 130/80 mmHg). Continuous ECG monitoring and a peripheral venous access were obtained. QRS complexes had a typical right bundle branch block with left anterior hemiblock morphology, suggesting supraventricular tachycardia (SVT) with aberrancy. Analysis of lead V1 (where P wave was better observable) was not conclusive for atrial flutter/atrial tachycardia diagnosis or atrio-ventricular (AV) dissociation. A clear P wave was seen after the second QRS complex of any couple. Other atrial activity waves could have been partially hidden by wide QRS complexes. Previous ECGs were not immediately available. Telemetry-supported pacemaker control was performed in order to facilitate a diagnosis. It showed 3 arrhythmic episodes in VT2 zone, each one interrupted after single burst of antitachycardia pacing therapy (ATP; see Fig. 2). Surprisingly, ventricular rate was double than atrial activity, suggesting ventricular tachycardia (VT) diagnosis. Current EGMs were identical.