AP-452681-3 VENTRICULAR TACHYCARDIA ORIGINATING NEAR THE HIS-BUNDLE: ELECTROCARDIOGRAPHIC, CATHETER ABLATION CHARACTERISTICS AND LONG-TERM OUTCOME

Abstract

Ventricular Arrhythmias (VAs) not uncommonly originate from the Para Hisian (PH) region. The clinical and electrophysiological (EP) characteristics of these VAs are important to recognize given risk of injury to the conduction system. Define the clinical and EP characteristics of these VAs and long-term outcome of catheter ablation. 43 patients (Pts.) had VAs activation mapped to the PH region. The electrocardiographic and EP characteristics of these PH VAs were compared in 50 patients with VAs originating from right ventricular outflow tract (RVOT). Mean QRS width was narrower in PH VAs (P=0.02) and the R wave amplitude was lower in the inferior leads (P = 0.01) as compared to RVOT VAs. PH VAs had an R wave amplitude greater in lead I (P= 0.001) and lead aVL (P= 0.02) than RVOT VAs. For PH VAs earliest in RV, the R wave amplitude ratio in leads II/III was greater than those in LV (P= 0.02). All left sided PH VAs (12pts) had early transition (≤Lead V2) and were infra-hisian in location. 27/31 Right sided VAs had later transition (≥ Lead V3), 22 (70%) were infra-hisian and 9 (30%) were supra-hisian in location. Inferior Lead discordance was seen in 75% of all pts and was similar in left and right sided VAs. Radiofrequency ablation (RFA) was used upfront in 39 pts. Cryo-ablation used upfront in 2 pts and after RFA in 1 pt. In 30 pts (70%) VAs were eliminated; 9 (21%) had significant suppression (≤5% total residual burden) and 3 (9%) had acute recurrence (<48 hours) and 1 pt. ablation was not attempted given immediate proximity to HB. During follow up of 46±8 months, EF normalized in 37/43 (85%). 2 Pts. developed transient heart block with no treatment needed and 1 with pre-existing pacemaker (PM) had complete heart block. 2 required PM implantations at 39 ± 2 months post ablation due to conduction system disease unrelated to ablation. VAs originating near the His-bundle have distinctive ECG characteristics which aid in recognition and mapping. Catheter ablation can generally be performed safely and effectively.