Abstract 3314: Efficacy of Pulmonary Vein Isolation in Patients with Hypertrophic Cardiomyopathy
There are few data regarding outcome of pulmonary vein isolation (PVI) in patients with hypertrophic cardiomyopathy (HCM). We identified pts with HCM who had PVI for drug refractory atrial fibrillation (AF) between 11/01/00 and 7/31/05. PV and non-PV triggers for AF were identified (isoproterenol infusion and induction of AF followed by cardioversion). During initial procedures, only PVs exhibiting AF triggers were isolated; during repeat procedures, all PVs were isolated independent of AF triggers. Segmental PVI was performed, verified by PV entrance and exit block. Procedures were guided by intracardiac echocardiography and 3D mapping. Post ablation follow up included extensive transtelephonic rhythm monitoring and office visits at 6 weeks, 6 and 12 months and yearly telephone contact.
Results: 11 HCM patients (1.8%) were identified of 611 who had PVI procedures. Acute entrance and exit block were confirmed in all targeted PVs. HCM had larger left atrial (LA) diameters than reference pts (5.4 ± 0.7 vs. 4.4 ± 0.7 cm, p < 0.002), were more likely to exhibit non-PV triggers (55% vs. 19%, p < .01) and were less likely to have AF control after PVI, despite a high incidence of multiple procedures (Chi square p < .001). AF control: 90% reduction in AF episodes on or off meds HCM vs. non-HCM AF control total: p < .001; off meds: p < .001
Conclusions: Pts with HCM often have an unsatisfactory outcome after PVI, even when compared to non-HCM pts with extensive atrial enlargement. Possible explanations for this observation includes: 1. late PV reconnection is favored in HCM because of particularly thick atrial tissue and/or 2. the mechanism for AF in HCM is less dependent on PV triggers than in non-HCM pts.