Rhythm control is often the preferred treatment in atrial fibrillation patients. However, rhythm control requires electrical cardioversion, particularly in patients with persistent atrial fibrillation. Cardioversions frequently fail due to fibrillatory recurrence, which in turn makes antiarrhythmic agents unavoidable. Furthermore, rhythm control comes with risk of specific side effects, such as torsades de pointes.

The hypothesis of the Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study is that a rate control approach is not inferior to rhythm control. The study included 522 patients enrolled in 35 centers throughout the Netherlands.

Patients in RACE had persistent atrial fibrillation or atrial flutter for at least 24 hours but not longer than 1 year. They had undergone 1 or 2 electrical cardioversions in the previous 2 years.

The primary endpoint was the composite of cardiovascular death, hospital admission for heart failure, pacemaker implantation, severe bleeding, thrombo-embolic complications, or severe adverse effects of therapy (for example, drug induced ventricular pro-arrhythmia or syncope).

Investigators randomized patients (mean age 68 years, 63% male) to rate or rhythm control and followed them for 36 months.

Rate control consisted of drugs such as beta-blockers, digitalis and calcium antagonists. If symptoms remained intolerable, patients underwent electrical cardioversion or atrio-ventricular node ablation.

Rhythm control consisted of electrical cardioversion and prophylactic sotalol. In the case of early or late recurrence, investigators followed a specific treatment algorithm incorporating repeat cardioversion and other modalities.

Results showed that 17.2% of rate control patients reached the primary endpoint, compared with 22.6% of rhythm control patients. This was a risk difference of -5.4% in favor of rate control. Rate control was non-inferior to rhythm control for patient with persistent atrial fibrillation.

About 7% of patients died in each group. The cause was sudden death for about half the patients in each group. The second most common reason for death in the rhythm control group was thrombo-embolic complications. In rate control, patients died more frequently from bleeding or heart failure.

The difference in the primary composite endpoint was mainly due to a difference in non-fatal endpoints (10% and 15% of the rate and rhythm control groups, respectively). There was a difference in rate of severe adverse events and pacemaker implantation in favor of rate control.

A subgroup analysis suggested hypertensive patients might do better on rate control. However, this post-hoc hypothesis must be evaluated. For now, results of RACE suggest that rate control is an attractive alternative for patients at high risk of recurrence of atrial fibrillation.