Ablation of atrial fibrillation with the Epicor system: a prospective observational trial to evaluate safety and efficacy and predictors of success

BACKGROUND: High intensity focused ultrasound (HIFU) energy has evolved as a new surgical tool to treat atrial fibrillation (AF). We evaluated safety and efficacy of AF ablation with HIFU and analyzed predictors of success in a prospective clinical study. METHODS: From January 2007 to June 2008, 110 patients with AF and concomitant open heart surgery were enrolled into the study. Main underlying heart diseases were aortic valve disease (50%), ischemic heart disease (48%), and mitral valve disease (18%). AF was paroxysmal in 29%, persistent in 31%, and long standing persistent in 40% of patients, lasting for 1 to 240 months (mean 24 months). Mean left atrial diameter was 50 ± 7 mm. Each patient underwent left atrial ablation with the Epicor system prior to open heart surgery. After surgery, the patients were treated with amiodarone and coumadin for 6 months. Follow-up studies including resting ECG, 24 h Holter ECG, and echocardiography were obtained at 6 and 12 months. RESULTS: All patients had successful application of the system on the beating heart prior to initiation of extracorporeal circulation. On average, 11 ± 1 ultrasound transducer elements were used to create the box lesion. The hand-held probe for additional linear lesions was employed in 83 cases. No device-related deaths occurred. Postoperative pacemaker insertion was necessary in 4 patients. At 6 months, 62% of patients presented with sinus rhythm. No significant changes were noted at 12 months. Type of AF and a left atrial diameter > 50 mm were predictors for failure of AF ablation. CONCLUSION: AF ablation with the Epicor system as a concomitant procedure during open heart surgery is safe and acceptably effective. Our overall conversion rate was lower than in previously published reports, which may be related to the lower proportion of isolated mitral valve disease in our study population. Left atrial size may be useful to determine patients who are most likely to benefit from the procedure.