BACKGROUND: Left ventricular summit ventricular tachycardia (LVSVT) originates in the epicardium of the superior left ventricular wall, between the origins of the main coronary arteries, with characteristic findings on 12-lead electrocardiogram (ECG) that can guide ablation. This report describes a 66-year-old man with dizziness and palpitations diagnosed with LVSVT using ECG and managed with radiofrequency ablation.

CASE REPORT: A 66-year-old man presented with 24 hours of dizziness and palpitations. He was hemodynamically stable, and the initial ECG showed frequent premature ventricular complexes with left bundle branch block-like morphology, inferior axis, and early precordial transition. Continuous monitoring and 24-hour Holter recording documented a high ventricular ectopic burden (~65%), with episodes of sustained and nonsustained monomorphic ventricular tachycardia of identical morphology. Echocardiography showed preserved left ventricular systolic function, and coronary angiography and cardiac magnetic resonance imaging excluded obstructive coronary disease, myocardial fibrosis, and scar. Because symptoms and arrhythmia burden persisted, an electrophysiological study was performed on day 4. Isoproterenol infusion induced ventricular tachycardia, activation mapping localized the earliest ventricular activation to the left ventricular summit, and radiofrequency ablation was performed from the great cardiac vein and adjacent left ventricular outflow tract and left coronary cusp sites after coronary angiography confirmed a safe distance from the coronary arteries. Ventricular ectopy was immediately suppressed, and no arrhythmia was inducible after ablation. At 30-day follow-up, the patient remained asymptomatic without recurrent ventricular arrhythmia on Holter monitoring.

CONCLUSIONS: Systematic ECG interpretation can localize LVSVT and guide effective catheter ablation.

Keywords: Bundle-Branch Block, Electrocardiography, Electrophysiology, Tachycardia, Ventricular