Hybrid Surgical-Electrophysiological Epicardial Cryoablation for Ventricular Tachycardia Storm from a Deep Intramural Substrate in Hypertrophic Cardiomyopathy: A Case Report
Tadashi Fujino, Shintaro Yao, Kenji Okubo, Tomohiro Mizuno, Takanori IkedaAbstract
Background
Ventricular tachycardia (VT) associated with hypertrophic cardiomyopathy (HCM) may arise from deep intramural substrates and remains challenging to treat when conventional endocardial or percutaneous epicardial approaches are ineffective or infeasible.
Case summary
A 63-year-old man with HCM presented with drug-resistant VT storm. Endocardial mapping showed marked narrowing of the left ventricular (LV) cavity at the midventricular level, without abnormal potentials. Pace mapping demonstrated the closest match at the distal anterolateral coronary venous branch, suggesting a deep intramural origin. A subxiphoid epicardial approach was precluded by prior esophageal reconstruction; therefore, minimally invasive cardiac surgery (MICS) via left thoracotomy enabled epicardial cryoablation using the cryoICE® system. Epicardial mapping during VT revealed a low-voltage area with fractionated electrograms at the apicolateral LV. Activation time did not span the full VT cycle length, suggesting an epicardial exit with a deep intramural isthmus. VT terminated during the first cryoapplication, followed by two additional applications (total 15 min). No VT recurrence was observed during 1 year of follow-up after discontinuation of amiodarone. Post-procedural cardiac magnetic resonance (CMR) demonstrated transmural enhancement at the cryoablation target site despite a myocardial thickness of approximately 15 mm, suggesting successful deep lesion formation.
Discussion
This case demonstrates that hybrid surgical-electrophysiological cryoablation can provide effective treatment for VT arising from deep intramural substrates when conventional endocardial and percutaneous epicardial approaches are ineffective or infeasible. Surgical cryoablation was associated with transmural enhancement despite marked myocardial hypertrophy and resulted in durable arrhythmia suppression.