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Determining the most effective AF management presents many challenges
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Effective management of atrial fibrillation cannot be overstated, but physicians striving to deliver optimal care face many challenges.
The burden of AF continues to increase, consuming considerable financial and health care resources. Each year in the United States, AF contributes to about 5 million office visits, 500,000 outpatient and ED visits, and 350,000 hospitalizations. In 2006, AF treatment costs were $6.65 billion. A recent report (Am J Cardiol. 2009;104:1534–1539) estimated that approximately 3.5 million individuals have AF and the projected prevalence is more than 8 million for 2050. These estimates are linked to increases in the aging population, hypertension, diabetes and HF. Sizable literature documents significant associations between AF and mortality as well as morbidity, including nearly fivefold increased risk for stroke, increased risks for hospitalization and HF, and decreased quality of life.
Management, however, is challenging — even as new information and treatments become available. Multiple randomized trials (AFFIRM, RACE, PIAF, and STAF) showed no difference in mortality between rate and rhythm control strategies.
Two very recent randomized trials add important data. The J-RHYTHM study showed that in patients with paroxysmal AF, the primary outcome [first occurrence of all-cause mortality (all cause), symptomatic cerebral infarction, systemic embolism, major bleeding, HF hospitalization, or physical/psychological disability requiring alteration of treatment strategy] was significantly reduced in rhythm control vs. rate control patients. In the small CAFÉ-II trial of patients with chronic AF and HF, researchers found patients assigned rhythm control had significantly improved left ventricular function, NT-proBNP concentration and quality of life vs. those assigned rate control. Greatest improvement occurred when sinus rhythm was maintained, leading to the conclusion that restoring sinus rhythm in AF patients with HF may improve quality of life and LV function vs. a rate control strategy.
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Two large registries (RecordAF and AFFECTS) document that among cardiologists the initial treatment strategy assigned in the majority of AF patients is rhythm control. The preference to assign rhythm control decreased with increasing age in both registries. Rhythm control patients were more frequently symptomatic and more likely to have recently diagnosed or AF compared to rate control patients. A rate control strategy was more common in patients with a heart failure history or valve disease and persistent AF.
At one year, more than 80% of RecordAF patients treated with rhythm control vs. only 33% treated with rate control were in sinus rhythm. Additionally, only 13% of patients progressed to permanent AF in the rhythm control strategy vs. more than half in the rate control strategy. The primary measure of therapeutic success was defined as either sinus rhythm in the rhythm control strategy or a rate <80 beats per minute in the rate control strategy, no switch of treatment strategy, and no clinical adverse outcome. Sixty percent of rhythm control and only 47% of rate control patients had therapeutic success, a statistically significant difference. Although patients treated with rhythm control were more likely to be hospitalized for arrhythmias (recurrent AF), those treated with rate control were more likely to be hospitalized for HF, but these outcomes trends did not reach statistical significance with only one-year follow-up. In the AFFECTS registry, there were too few deaths and other CV-related events for meaningful comparison.
Among several newer antiarrhythmic agents, dronedarone was recently shown to reduce death, hospitalizations, acute coronary syndrome and stroke in AF patients in ATHENA.
Stroke risk is pronounced in many AF patients, and anticoagulation with warfarin is recommended for those who are not low risk. The AFFECTS registry documented initiation of anticoagulation in most AF patients, but patients at low stroke risk may have been overprescribed warfarin. Yet, a considerable proportion of patients at high risk for stroke did not receive warfarin. These practice patterns likely relate to dissatisfaction with warfarin.
Additional information in this regard from the ACTIVE W trial confirmed that warfarin was superior to clopidogrel plus aspirin for stroke reduction in AF patients with stroke risk factors. ACTIVE A showed that aspirin plus clopidogrel was superior to aspirin alone in patients with contraindications to or refusing to take warfarin. The RE-LY results showed significant benefit in stroke reduction with the oral direct thrombin inhibitor dabigatran vs. warfarin in AF patients. Interestingly, the low dose was not only more effective for reducing stroke risk but also safer than warfarin.
With a multitude of new data, as well as varying patient characteristics, the successful management of AF remains a clinical challenge. Understanding the needs of each patient, with continued collaboration of electrophysiologists and cardiologists, continued physician education and timely delivery of the best possible care remain priorities to address this challenge.
Carl J. Pepine, MD, is Professor of Medicine, Division of Cardiovascular Medicine at the University of Florida, Gainesville. He is also Chief Medical Editor of Cardiology Today.