Background: Symptomatic left ventricular outflow obstruction (LVOTO)resulting from hypertrophic cardiomyopathy (HCM) in childhood is currently managed by surgical myectomy.
Aims: To present the immediate and intermediate-term follow-up of RF catheter ablation of septal hypertrophy.
Patients and Methods: 18 patients (7 female; age range 4 to 18 years; weight 15 to 60kg) presenting with HCM (LVOT gradients ranging from 50 to 140mm Hg) underwent transcatheter RF ablation using a standard 7F cooled-tip irrigated catheter. The His bundle was initially plotted and marked on a LocaLisa mapping system. Thereafter, 3 lines of lesions (individual RF lesions ranging from 10 to 60) were made in the left ventricle, starting at the most distal location of the obstruction and moving to the aortic valve.
Results: One patient developed LV dysfunction (LVEDP 26 - 34mm Hg)and severe MR. She subsequently died without recovery of LV function, despite ECMO. One other patient developed AV block requiring pacing. In all survivors, there was a significant decrease in LVOT gradient (to <20mm Hg in 12/16, and to <50mm Hg in the remainder), within 2 weeks of ablation. The cardiac troponin T values (normal range <0.1 micrograms/litre) ranged from 5.1 to 25, suggesting significant myocardial necrosis. All survivors showed symptomatic improvement. Over a median follow-up of 2 years, 4 patients have had recurrence of LVOTO, of whom 2 have had a re-do RF procedure.
Conclusions: In young patients who are unsuitable for septal alcohol ablation, endocavitary RF ablation appears to offer reasonable palliation, without the onset of new arrhythmias.