Abstract 2442: Substrate Predictors of Outcomes after Catheter Ablation for Atrial Fibrillation in Patients with Hypertrophic Cardiomyopathy
Background: Hypertrophic cardiomyopathy (HCM) is often accompanied by atrial fibrillation (AF) due to diastolic dysfunction, elevated left atrial (LA) pressure and LA enlargement. Although catheter ablation for drug-refractory atrial fibrillation(AF) is an effective treatment, the efficacy in HCM remains to be established.
Methods: 33 consecutive patients (25 male, age 51± 11 years) with HCM (8 obstruction at rest, gradient 35±34 mmHg) underwent pulmonary vein isolation (PVI, n=15) or wide area circumferential ablation (WACA, n=18) for drug refractory AF. 2 lead and 24-hour ambulating ECGs, echocardiograms, event monitor strips, SF 36 quality of life (QOL) surveys were obtained before ablation and for routine follow-up.
Results: 21(64%) patients had paroxysmal AF and 12(36%) had persistent/permanent AF for a duration of 6.2±5.2 years. The average ejection fraction was 63±12% with a LA volume index of 66±24cc/m^2. In 26 patients diastolic function was determined (2 grade 1, 18 grade 2, 5 grade 3, 1 grade 4). Over a follow-up of 1.5±1.2 years, AF was eliminated in 16(48%) without medications and in an additional 8(24%) with medications. AF control was achieved in 78% of the WACA and 67% of the PVI groups (p=0.69). AF control was inversely related to LA volume index (<32 (4/4, 100%), 33– 40 (5/6, 83%), >40 (11/19, 58%)cc/m^2, p=0.154). LA size decreased nonsignificantly after ablation to 57±16cc/m^2. The average grade of diastolic dysfunction was 1.5±0.7 in those with AF control in comparison to 2.2±0.4 with recurrence (p=0.011). Furthermore, in the 9 that failed ablation, 8 (89%) had significantly elevated filling pressures (E/e’>15). 2 patients had a periprocedureal TIA, 1 pulmonary vein stenosis (1 vein), and 1 after mitral valve replacement died from prosthetic valve thrombosis. QOL scores improved from baseline at 3 and 12 months [physical health 54±18, 62±16, 78±21 (p=0.002), mental health 53±17, 66±19, 82±24 (p=0.004)].
Conclusion: Despite significant LA enlargement and diastolic dysfunction, catheter ablation for AF with HCM was successful in the majority of patients and resulted in an improved QOL. HCM patients with smaller LA dimensions, lower grades of diastolic dysfunction, and normal filling pressures may be better candidates for the procedure.