Tackling rhythm control early, with ablation or antiarrhythmic medication in the first year after atrial fibrillation (Afib) diagnosis, helped outcomes in people with heart failure (HF), a prespecified subanalysis of the EAST-AFNET 4 trial showed.

The early strategy cut the composite of cardiovascular death, stroke, or hospitalization for worsening HF or for acute coronary syndrome by a relative 26% compared with usual care in HF patients in the trial over the median 5.1 years of follow-up (5.7 vs 7.9 per 100 patient-years, P=0.03).

Benefits were not altered by HF status (P=0.63 for interaction), reported Andreas Rillig, MD, of Universitäres Herzzentrum Hamburg in Germany, at the hybrid Heart Rhythm Society (HRS) meeting, held online and in Boston. The findings were published simultaneously in Circulation.

“Finally, in our opinion, we can say that early rhythm control is beneficial in patients with recently diagnosed atrial fibrillation and concomitant disease in heart failure patients,” he said. “We should offer that at least to our patients.”

While the low ejection-fraction group had somewhat more events, they appeared to benefit to a similar degree as those with mid-range or preserved ejection fraction.

Early rhythm control also appeared safe with, if anything, fewer primary safety outcome events — a composite of death, stroke, or serious adverse events related to rhythm control therapy — than in the usual care group (17.9% vs 21.6%, HR 0.85, 95% CI 0.62-1.17).

“This study already has started to move the needle” on use of antiarrhythmic medication use in HF, said HRS press conference moderator Jodie Hurwitz, MD, of the Medical City Hospital in Dallas. “The initial study itself was incredibly important and many of us had already in some ways considered early rhythm control in this group of patients.”

“The main trials we have focus on catheter ablation,” Rillig said. “So it’s important to learn more about the patients with better ejection fraction but still having heart failure.”

Main results from EAST-AFNET 4 showed a significant benefit of early rhythm control for the overall trial population of 2,789 patients at 135 sites in 11 European countries, about 73% of whom had asymptomatic Afib.

The prespecified analysis homed in on the 798 patients with stable HF, of whom 56% had preserved ejection fraction, 27% had mid-range ejection fraction, and 17% had reduced ejection fraction.

While rhythm control medication was allowed in the usual care group, only 5.8% received it at randomization and less than 20% had gotten it by year 2 of follow-up. These drugs were prescribed following guidelines and at recommended doses.

Catheter ablation for Afib in the HF group was done in 88 early rhythm control group patients and 52 getting usual care.

“Approximately 17% of patients randomized to early rhythm control were treated with atrial fibrillation ablation in the first two years after randomization,” Rillig’s group wrote. “This suggests that the clinical benefit found in this subanalysis can be achieved using antiarrhythmic drugs as initial therapy. It is worthwhile to note that flecainide was used in a relatively high number of patients without safety concerns.”

Participants were largely in class II HF; only 15% had class III disease. But benefits of early rhythm control were significant in both groups. Left ventricular ejection fraction improvement was similar between treatment groups. HF medication characteristics didn’t differ significantly between treatment arms.

As to the benefits seen in the trial, Rillig’s group speculated that early initiation might have been one of the reasons antiarrhythmic drugs were successful.

As the CABANA trial suggested that catheter ablation could be even better than antiarrhythmic drug therapy in the HF subgroup, “it is tempting to speculate that early rhythm control using catheter ablation could convey even larger clinical benefit than the treatment pattern chosen by the investigators of the EAST-AFNET4 trial,” they wrote.

“Alternatively, antiarrhythmic drugs may be sufficient to achieve early rhythm control therapy due to the lower risk of recurrent atrial fibrillation,” they added. “The value of catheter ablation for early rhythm control awaits testing in a controlled clinical trial.”