Abstract 13963: Short-Coupled Variant of Torsade de Pointes: A Rare Entity With Unknown Etiology and Malignant Phenotype

Abstract

Introduction: Torsade de Pointe (TdP) is defined as a polymorphic VT (pVT) typically associated with QTc prolongation. However, not all pVT occur in the presence of QTc prolongation and respond to different forms of therapy. Hence defining their etiology is important. Case: A 48-yo Female with H/O resolved peripartum cardiomyopathy, hypertension & obesity presented to the hospital following a syncopal episode. Her BP was 207/125 mmHg, and ECG showed sinus rhythm with a QTc of 436. No history of heart disease or SCD in her family. Physical exam was unremarkable, labs showing K-3.2 without troponin elevation. On day 2, she developed a pVT requiring defibrillation and amiodarone. Telemetry revealed a PVC causing R on T phenomenon with a coupling interval of 260 msec prior to initiation of SVT with QTc 484 and K-2.8. On day 3, despite electrolyte correction, she had multiple non-sustained pVTs with QTc 482. Amiodarone was switched to lidocaine and QTc normalized to 447. TTE and LHC were unremarkable with a small LV aneurysm on cMRI. On day 4, the patient continued to have incessant runs of pulseless pVT requiring defibrillation and started on verapamil. A 12 lead ECG during VT demonstrated left bundle branch mimicry with a left axis consistent with a VT exit site along the RV moderator band. The patient underwent emergent ablation with targets along the right anterolateral papillary muscle. AICD was placed prior to discharge. Discussion: The critical timing of PVC falling on the peak of the preceding T wave differentiates ‘Short-coupled TdP’ from other malignant VTs with normal QTc. These PVCs typically originate from distal ramifications of Purkinje fibers in both ventricles. PVC morphology with LBBB pattern, left axis and late precordial R-S transition points to the moderator band as the source of idiopathic VT. Contrasting with typical TdP, medical management with Quinidine and Verapamil may be efficacious. Catheter ablation is curative in most cases.