Cardioneuroablation for Vagally Mediated Coronary Artery Spasm With High-Grade Atrioventricular Block and Vasovagal Syncope.

BACKGROUND: Coronary artery spasm (CAS) may cause ischemia, malignant arrhythmias, and syncope without obstructive coronary disease; a parasympathetic-dominant phenotype is increasingly recognized. CASE SUMMARY: A 64-year-old man with >7 years of recurrent syncope had Holter documentation of transient inferior ST-segment elevation during sleep followed by high-grade atrioventricular block. Coronary angiography showed no significant stenosis, and head-up tilt testing was positive (mixed type). Cardioneuroablation (CNA) targeting atrial ganglionated plexi abolished vagal responses and improved electrophysiologic indices. Postprocedural Holter showed no recurrent ST-segment elevation or atrioventricular block, and he remained symptom-free at 1-month follow-up. DISCUSSION: The close sequence of ST-segment elevation and functional atrioventricular block supports a unified vagally mediated mechanism linking CAS and reflex syncope; CNA may be a mechanistically targeted option in selected refractory cases. TAKE-HOME MESSAGES: Nocturnal ST-segment elevation with bradyarrhythmia suggests parasympathetic-dominant CAS. CNA can interrupt this autonomic cascade in carefully selected patients.