Orlando, FL - A pilot study from the German Strategies of Treatment of Atrial Fibrillation (STAF) trial comparing rhythm and rate control in patients with atrial fibrillation (AF) has found no persuasive differences over 1 to 3 years of follow-up. The results were presented here in a late-breaking clinical trials symposium at the American College of Cardiology 50th Annual Scientific Session on March 20, 2001.

The pilot study will no doubt fuel the debate over which method is better for the treatment of AF over the long-term. Controlling sinus rhythm through the use of antiarrhythmic drugs and cardioversion has traditionally been the therapy of choice. Maintaining sinus rhythm helps relieve symptoms and may slow or prevent the transition from intermittent to permanent AF, but carries the risk of proarrhythmic effects from the antiarrhythmic drugs. By contrast, controlling ventricular rate but allowing atrial fibrillation to persist does not suppress AF symptoms, but does reduce the risk of life-threatening arrhythmias produced by an adverse drug reaction. Patients treated with ventricular rate control, however, must be placed on permanent anticoagulation.

Trial sought patients at high risk of AF recurrence

The STAF pilot study, presented by Dr Joerg Carlsson (Klinkum Lippe-Detmold, Muenster, Germany) was a prospective, open, randomized trial conducted at 11 German institutions. To be eligible for trial entry, patients had to be at high risk of AF recurrence, defined as having one or more of the inclusion criteria. These were: AF of more than 4 weeks' duration (necessitating at least one instance of cardioversion), a left atrial size between 45 mm and 70 mm, congestive heart failure class > NYHA II, and an LV ejection fraction greater than 20%, but less than 45%.

The investigators randomized 100 patients to rhythm control with external or internal cardioversion (with anticoagulation administered before and after cardioversion, according to international guidelines), followed by prophylactic therapy for recurrence, with amiodarone and class I antiarrhythmic drugs according to presence or absence of LV dysfunction and/or coronary artery disease. Another 100 patients were randomized to rate control using permanent anticoagulation and ventricular regulation using digitalis, beta blockers, or calcium antagonists, or, in cases of drug-refractory ventricular control, AV node ablation and/or pacemaker implantation.

At a mean follow-up period of approximately 20 months postenrollment, Carlsson et al found no significant differences between the two treatment groups in terms of the primary endpoint of death, stroke/TIA, cardiopulmonary resuscitation, or systemic embolization. No differences were seen in any of the secondary endpoints (including bleeding, worsening CHF, or changes in LV function, atrial size, or quality of life) with the exception of number of hospital visits/length of stay, which was significantly longer in the rhythm control group than in the rate control group, attributed to repeat cardioversions and adjustment of antiarrhythmic therapies.


Comparison of events in both the rhythm and rate control groups

Endpoint Rhythm control group Rate control group Composite endpoint 9 10 Death 4 8 Stroke/TIA 5 1 Systemic embolization 0 1

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Remaining equals?

Digging deeper into the study results, Carlsson noted that, after 3 years of follow-up, only 23% of patients remained or were maintained in sinus rhythm in the rhythm control group, "and this is in spite of up to 4 cardioversions per patients and up to 4 antiarrhythmic drug trials." Carlsson added that of the 19 events that occurred in the total study population, only 1 occurred during sinus rhythm and this was in a patient who had had a stroke following successful cardioversion.

	The two treatment strategies showed no difference in all secondary endpoints except hospitalization.

"I can conclude from this pilot trial that we did not see any difference between the rhythm control strategy and the rate control strategy regarding the composite primary endpoint," Carlsson concluded. "In addition, the two treatment strategies showed no difference in all secondary endpoints except hospitalization."

The fact that all but one of the primary endpoints occurred during episodes of AF tips the otherwise balanced findings, notes Carlsson: "Since all but one primary endpoint occurred in atrial fibrillation, the strategies appear equal, not because AF and sinus rhythm are equal, rather because sinus rhythm simply cannot be maintained in the long run, despite repeated cardioversion and antiarrhythmic drugs."

Asked during the question period about the risk/benefits of permanent anticoagulation - conventionally viewed as a drawback of rhythm control - Carlsson concurred with speculation that someone going in and out of AF, and starting and stopping anticoagulation therapy, might be at a higher risk of bleeding complications or stroke than someone on permanent anticoagulation therapy. In the ongoing Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial, both the rhythm and rate control groups are receiving permanent anticoagulation.

Shelley Wood shelley@conceptis.com

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