Progressive outcomes of bundle branch reentrant ventricular tachycardia in patients without structural heart disease

BACKGROUND Ablation strategies to treat bundle branch reen-trant ventricular tachycardia (BBRT) are well described. However, reports of long-term follow-up outcomes in BBRT patients without structural heart disease (SHD) are limited.OBJECTIVE The purpose of this study was to investigate the long-term follow-up prognosis of BBRT patients without SHD.METHODS Changes in electrocardiographic and echocardiographic parameters were used to evaluate progression during follow-up. Po-tential pathogenic candidate variants were screened using a specific gene panel.RESULTS Eleven consecutive BBRT patients without obvious SHD based on echocardiographic and cardiovascular magnetic resonance imaging results were enrolled. Median age was 20 (11-48) years, and median follow-up time was 72 months. During follow-up, PR in-terval [206 (158-360) ms vs 188 (158-300) ms; P = .018] and QRS duration [187 (155-240) ms vs 164 (130-178) ms; P = .008] each increased significantly compared with postablation. Right-and left-sided chamber dilation and reduced left ventricular ejection fraction (LVEF) also were observed. Clinical deterioration or events occurred in 8 patients: 1 sudden death; 3 both complete heart block and reduced LVEF; 2 significantly reduced LVEF; and 2 prolonged PR in-terval. Genetic testing results showed that 6 of 10 patients (excluding the patient with sudden death) had >1 potential path-ogenic candidate variants.CONCLUSION Further deterioration of His-Purkinje system con-duction was observed in young BBRT patients without SHD after ablation. The His-Purkinje system may be the first target of genetic predisposition.