Promising Study Results for Ablation Alternatives for Patients with Atrial Fibrillation

Results from 2 trials presented at the recent Heart Rhythm Society meeting suggest that 2 alternative ablation technologies work about as well as those that are commonly used on patients with atrial fibrillation (AF).

The first of the devices allows users to guide a balloon catheter into place via endoscope video before zapping pulmonary veins with a laser (rather than standard radiofrequency energy). The second uses very cold liquid stored in a “cryoballoon” to aid the process.

Both produced success rates that were nearly identical to standard radiofrequency ablation, researchers announced at this year’s meeting of the Heart Rhythm Society, but there were some differences in complication profiles.

The trial of the visually guided laser balloon (VGLB) randomized 178 patients to a single pulmonary vein isolation-only ablation with the new device and another 175 patients to 1 or 2 pulmonary vein isolation procedures with traditional radiofrequency technology.

Researchers followed all patients for a year, using trans-telephonic monitoring (TTM) to spot AF every week and at any hint of patient symptoms. They also monitored heart rhythm with 24-hour Holter ECGs at months 1, 3, 6 and 12.

At the end of the study, 61.1% of the patients treated with VGLB technology and 61.7% of the patients treated with standard technology showed no signs of AF or either atrial flutter or tachycardia lasting more than 60 seconds.

There was no statistical difference between the 2 treatments in the rate of single-procedure success, with or without the use of use of antiarrhythmic-drug therapy.

The adverse-event rate, which includes cardioversion, was 11.8% for VGLB patients and 14.5% for patients in the control arm. VGLB patients were more likely to suffer phrenic-nerve injuries (including 3 that persisted throughout the year-long follow-up), while control patients were relatively more likely to suffer asymptomatic pulmonary-vein stenosis.

The primary endpoint of the trial was non-inferiority to standard ablation, but the ultimate goal of the VGLB technology (which goes by the brand name HeartLight) is to provide an easier alternative to traditional ablation surgery, which has a steep learning curve.

The second trial (known as FreezeAF) randomized 156 patients to cryoballoon ablation and another 159 patients to pulmonary vein isolation with standard radiofrequency ablation. Those patients — who all began the study with symptomatic paroxysmal AF and at least 1 failed treatment with antiarrhythmic drugs — then underwent clinical follow-ups at months 3,6,9 and 12. Researchers also used Holter ECGs and 7-day to 14-day event monitors at months 6 and 12.

After 6 months, 63% of the cryoballoon arm and 64% of the control arm were free from AF. After 12 months, 68% of the cryoballoon arm and 65% of the control arm were free from AF. (Redo procedures were performed on 19.9% of cryoballoon patients and 19.5% of control patients. Also, fewer patients showed up for the 12-month follow-up [92.4%] than the 6-month follow-up [98.4%]).

P values for non-inferiority were 0.011 at 6 months and 0.001 at 12 months.

Neither cardiovascular death nor stroke occurred in either arm of the study. Phrenic nerve palsy occurred in 5.1% of all cryoballoon patients and 0% of control patients while pulmonary vein stenosis occurred in 0% of cryoballoon patients and 1.9% of control group patients.