Initiation of rhythm control with antiarrhythmic drugs and/or ablation in patients with early, recently diagnosed atrial fibrillation (AFib) led to a significantly lower risk of major adverse cardiovascular outcomes, compared with a rate-control strategy, during more than 5 years of follow-up in the large randomized EAST-AFNET 4 trial, Paulus Kirchhof, MD, said at the virtual annual congress of the European Society of Cardiology.
Previous trials of rate versus rhythm control in AFib, such as AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management), failed to show an advantage for rhythm over rate control in terms of clinical outcomes. Why was EAST-AFNET 4 different? Dr. Kirchhof offered two major reasons: The study incorporated AFib ablation as an option in the rhythm control strategy, and treatment started soon after diagnosis of the arrhythmia. Indeed, nearly 40% of patients had their first-ever AFib episode at the time of randomization, and the median time from diagnosis to randomization was just 36 days.
“Once you are in AFib for a few months, the atrium suffers severe damage, some of it irreversible, so it becomes more difficult to restore and maintain sinus rhythm when you wait longer,” explained Dr. Kirchhof, director of the department of cardiology at the University Heart and Vascular Center in Hamburg (Ger.) and professor of cardiovascular medicine at the University of Birmingham, England.
Also, epidemiologic studies show that the risk of cardiovascular complications is heightened in the first year following diagnosis of AFib. “So there’s a window of opportunity to prevent complications,” he added.
The impetus for conducting EAST-AFNET 4 (Early Treatment of Atrial Fibrillation for Stroke Prevention Trial ) was straightforward, according to the cardiologist: “The question of whether rhythm control is beneficial or not has been in the field for several decades. Most people, like me, always believed that maintaining sinus rhythm would help, but we didn’t have the data to show it.”
Early rhythm control shows sustained benefits
EAST-AFNET 4 was a prospective, open, blinded-outcome-assessement trial. It included 2,789 patients with early AFib and an average CHA2DS2-VASc score of 3.4 who were randomized at 135 sites in 11 European countries to early rhythm control or guideline-recommended rate control. At a median 5.1 years of follow-up, the primary outcome – a composite of cardiovascular death, stroke, acute coronary syndrome, or hospitalization for worsening heart failure – occurred at a pace of 3.9% per year in the rhythm control group and 5% per year with rate control. This translated to a statistically significant and clinically meaningful 21% relative risk reduction favoring early rhythm control.
The 28% reduction in cardiovascular death with rhythm control was statistically significant, as was the 35% reduction in stroke. However, the 19% reduction in heart failure hospitalizations and 17% decrease in hospitalizations for acute coronary syndrome were not.
The co–primary endpoint – the mean number of nights spent in the hospital per year, which served as a proxy for the cost of treatment to a health care system – didn’t differ between the two treatment arms, at roughly 5 nights per year.
The clinical benefit of early rhythm control was consistent across all 19 prespecified patient subgroups, including those who were asymptomatic and patients with or without heart failure.
Serious adverse events related to rhythm control therapy – most often drug-related bradycardia – occurred in 4.9% of patients over the course of 5.1 years, compared to a 1.4% serious event rate in patients assigned to rate control. Dr. Kirchhof called the roughly 1% per year serious event rate in the rhythm control group quite acceptable.
“To put that in perspective, the annualized rate of severe bleeds on oral anticoagulation – a very beneficial therapy used by more than 90% of participants at 2 years – is about 2%,” the cardiologist noted.
Only 8% of patients randomized to rhythm control received AFib ablation as initial therapy, consistent with current clinical practice. By 2 years, 19.4% of the rhythm control group had undergone AFib ablation. Also at that time, 15% of the rate control group was receiving rhythm control therapy to help manage AFib-related symptoms.
One of the big surprises in the study, he said, was that nearly three-quarters of patients in both groups were asymptomatic at 2 years.
“I think that shows how well we control symptoms, even without rhythm control,” he observed.