Performing additional catheter ablations targeting diseased myocardium along with the standard approach of pulmonary vein isolation (PVI) to treat persistent atrial fibrillation (AFib) did not reduce the recurrence of AFib at one year, based on findings from the SUPPRESS-AF trial presented at ESC Congress 2024 in London. A separate trial – CRABL-HF – found cryoballoon (CB) ablation to be as safe and effective as radiofrequency (RF) ablation for correcting the root cause of AFib in patients with heart failure with reduced ejection fraction (HFrEF).

In the SUPPRESS-AF trial, researchers in Japan randomly assigned 343 patients (median age 74; 49% women) with left atrial low-voltage areas (LVAs) to receive conventional PVI alone (n=171) or to LVA ablation following PVI (n=170). Post-ablation, researchers used 24-hour continuous ECG monitoring at six and 12 months and twice-daily home ECG recordings for one year to identify recurrence of arrhythmias.

Overall results showed no significant difference between the two groups in terms of the primary endpoint of recurrence of AFib and atrial tachycardia without antiarrhythmic drugs at one year, with 61% of patients in the additional LVA ablation group being recurrence free, compared with 50% of those receiving PVI alone. Similarly, freedom from AFib and atrial tachycardia recurrence with antiarrhythmic drugs was not different between the two groups (63% LVA ablation vs. 55% PVI alone). However, in a subgroup of patients with left atrium enlargement (diameter ≥45 mm) LVA ablation reduced the recurrence of AFib or atrial tachycardia by 40%. Researchers observed no difference in the rate of serious complications such as stroke, which were very low in both groups (1.7% vs. 1.8%).

"Ablation targeting the diseased myocardium is widely performed, but our results show that routine addition to PVI is not recommended," said Masaharu Masuda, MD, the study's lead author. "This ablation should be performed only in cases of advanced atrial remodelling. An important next step will be to try to understand how this procedure can be improved for patients with the persistent type of AFib."

In CRABL-HF, also out of Japan, researchers randomized 110 patients with HFrEF and AFib (aged 20-85 years; 79% men) to either RF ablation (n=55 patients) or CB ablation (n=55 patients). Patients with cardiac implantable electronic devices were continuously monitored for AFib episodes via adapted home monitoring. In patients without implanted devices, ambulatory ECGs were recorded twice daily for one-year post-procedure, after a blanking period of 90 days.

Results showed no significant difference in rates of atrial tachyarrhythmias (lasting 30 seconds or more), occurring in 21.8% of patients receiving RF ablation and 22.2% of CB patients. Additionally, researchers found CB ablation could be performed with significantly shorter procedure time (median 101 vs. 165 minutes), and less fluid volume during catheter ablation without increasing left atrial pulse pressure, indicating that the risk of worsening heart failure due to infusion load during ablation may be reduced.

Across both groups, there were similar rates of LVEF improvements and significant decreases in left arterial volume index following the procedures. Procedure-related complications occurred in one patient in each group. There were no procedure-related exacerbations of heart failure, symptomatic cerebral infarctions, transient ischemic attacks, pulmonary vein stenosis, or procedure-related deaths, according to the researchers. Similarly, there were also no significant differences in patient reported quality of life at one year.

"The underlying pathophysiology differs between patients with and without HFrEF, and the fundamental mechanisms of catheter ablation differ between CB and RF," said Koji Miyamoto, MD, lead investigator. "As our trial has shown that clinical outcomes and quality of life are similar after CB, this simplified procedure should be warranted to treat [AFib] in most patients with HFrEF."