Pulmonary vein isolation by high-intensity focused ultrasound: first-in-man study with a steerable balloon catheter

High-intensity focused ultrasound (HIFU) applied via a steerable balloon catheter (ProRhythm, Ronkonkoma, NY) is a novel technology for pulmonary vein (PV) isolation.

The purpose of this study was to assess the short-term and long-term success rates of PV isolation in patients with paroxysmal atrial fibrillation (AF) using the steerable HIFU balloon catheter.

A total of 15 patients (7 female), mean age 59 +/- 8 years, with a long (8 +/- 5 years) history of drug-refractory, symptomatic paroxysmal AF were enrolled. After double transseptal puncture, a lasso catheter and the 16F HIFU balloon catheter (11F shaft) were inserted into the left atrium (LA). After PV angiography, phrenic nerve (PN) pacing (10 V, 2.9 ms) was conducted. In case of PN capture at the right superior PV ostium, patients were excluded (n = 3). To achieve complete PV isolation, HIFU was repeatedly applied with an acoustic power of 45 W for 40 to 90 seconds. Follow-up included telephonic interviews, transtelephonic Holter electrocardiogram, and office visits after 1, 3, and 6 months.

Complete electrical PV isolation was achieved in 41 of 46 (89%) PVs. Median follow-up time was 387 days (range 120 to 424 days). Seven of 12 (58%) patients were free of AF without antiarrhythmic drugs. In 2 patients, only a single AF episode was documented, resulting in an overall chronic success of 75%. Despite negative PN pacing, 2 patients experienced right-sided PN palsy, which had not resolved after 12 months.

In patients with paroxysmal AF, acute PV isolation can be achieved in 89% using a steerable HIFU balloon; 58% of all patients were free of AF and 75% reached the primary end point defined as a reduction of AF episodes to less than 50%. However, further studies need to improve identification of patients at risk for PN palsy.