Stimulant Use Precipitates Antidromic Atrioventricular Reentrant Tachycardia While Subsequent Evaluation Reveals Underlying Ebstein Anomaly

Background: Ebstein anomaly (EA) or congenital atrialization of the right ventricle occurs in 0.005% of the population. Developmental tricuspid valve malformations in EA can establish accessory pathways (APs) in 10-30% of these patients. These APs can lead to atrioventricular reentrant tachycardia (AVRT) with sometimes consequent fatal complications (2.7% if untreated). Case: A healthy 23-year-old woman presented with dyspnea and palpitations after cocaine use. Her initial EKG demonstrated wide complex tachycardia with a HR of 200 bpm and BP of 70/40 mmHg. She received electrical cardioversion and amiodarone. Subsequent EKG demonstrated antidromic AVRT versus pathway-pathway tachycardia ( Figure 1A-B ). TTE demonstrated right ventricular atrialization consistent with EA ( Figure 1D-E ). Dual right anterolateral and mid-septal APs were mapped ( Figure 1F ) and ablated. Conclusion: Antidromic AVRT is a life-threatening, wide complex tachycardia that can be mistaken for ventricular tachycardia, with the potential for catastrophic outcomes if mismanaged. Demonstrative EKG findings reveal the diagnosis ( Figure 1-2 ), while hemodynamic stability guides acute management ( eg , IV procainamide vs cardioversion, Figure 2C ), followed by AP ablation for definitive management. Rapid recognition with evaluation for structural disease (herein as EA) is essential to affording optimal management in AVRT.