A Modified Endocardial Radiofrequency Ablation Approach For Hypertrophic Obstructive Cardiomyopathy Guided By Transthoracic Echocardiography: A Case Series

Background: A series of studies showed that endocardial radiofrequency ablation (ERFA) could reduce the left ventricular outflow tract (LVOT) gradient in patients with septal hypertrophy. This study aimed to determine the safety and efficacy of a modified ERFA approach guided by transthoracic echocardiography (TTE) as an alternative to ablation performed under a three-dimensional (3D) electroanatomical system or intracardiac echocardiography (ICE). Methods: Twenty-five patients with hypertrophic obstructive cardiomyopathy (HOCM) underwent ERFA of septal hypertrophy, guided by echocardiography. The LVOT gradient, left ventricular ejection fraction (LVEF), LV thickness, New York Heart Association (NYHA) class, and biochemical laboratory values were recorded before ablation and during follow-up. Results: The patients' peak and stress-induced LVOT gradients were significantly reduced after 12 months of follow-up (resting gradient: from 123.2 +/- 17.7 to 15.7 +/- 7.8 mmHg, P<0.05; provocative gradient: from 140.2 +/- 20.8 to 18.4 +/- 8.0 mmHg, P<0.05). Compared with baseline, the septal diameter was reduced slightly after 12 months, but the difference was not significant (24.8 +/- 3.5 vs. 24.2 +/- 3.4 mm, P>0.05). The reduction in LVOT gradient was associated with an improvement in NYHA functional classification (from 3.0 +/- 0.0 to 1.6 +/- 0.7, P<0.05), the 6-minute walking distance (413 +/- 129 m at baseline; 458 +/- 108 m immediately after ERFA; 471 +/- 139 m after 12 months, P<0.05), and pro B-type natriuretic peptide levels (from 924.00 +/- 139 to 137.45 +/- 75.73 pg/mL, P<0.05). After the procedure, the patients showed no worsening of LVEF compared with baseline (64%+/- 5.3%), and no cases of bundle branch block nor complete heart block occurred. Conclusions: ERFA guided by TTE provides a new treatment option for HOCM which can achieve symptomatic improvement as well as a significant and sustained reduction of the LVOT gradient. Moreover, by avoiding the use of the 3D electroanatomical system or ICE, this treatment has an acceptable cost.