Current atrial fibrillation (AF) guidelines support either a rate or rhythm control strategy for patients with AF. The appropriate criteria for selecting a management strategy in patients with AF have not been well-defined; it is largely left to providers to determine which patients are suitable for rhythm versus rate control alone.

International data, as well as the AFFECTS registry in the United States, have suggested significant differences in the population of patients selected for rate versus rhythm control, as well as differences in outcomes across a broad spectrum of AF patient types. The Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) is collecting data from patients in the United States managed by a variety of providers, including internists, cardiologists, and electrophysiologists.¹

Investigators used data from more than 10,000 patients in the ORBIT-AF registry to:

• measure the rates of use of different management strategies in AF patients in the United States;
• identify factors associated with the selection of a rhythm control strategy versus rate control only;
• and describe the medical management of patients with rhythm versus rate control, including antiarrhythmic and anticoagulant therapies.

Follow-up occurred every 6 months out to 3 years.

US Clinical Practice

As seen in the accompanying table, there were significant differences in the baseline characteristics of male and female patients, demonstrating different patterns of disease. Whereas men were more likely to be smokers and have coronary disease and obstructive sleep apnea, women were more likely to have hypertension, prior stroke or transient ischemic attack (TIA), and a family history of AF.

Specifically:

• Women had more paroxysmal AF (54% vs. 48%) and men were more likely to have persistent and permanent AF.
• Women had higher stroke risk as codified in the CHADS2 risk score: men had more scores of 0 and 1 while women had higher scores of 2 and above (both had scores of 3 equally).
• When it came to major symptoms, women demonstrated significantly higher rates of several, including dyspnea with exertion, dyspnea at rest, fatigue, and chest discomfort. There was no significant difference between men and women in terms of the occurrence of syncope and exercise intolerance.

Also, the broad spectrum of patients with AF in the United States is much more commonly managed with a rate control strategy (68% vs. 32%). Many patients treated with rate control had failed prior attempts at rhythm control. Patients selected for rhythm control are younger, have less comorbidity, more recent-onset AF, and higher symptom burden, and were more likely treated by electrophysiologists.

There were significant differences in the rhythm management treatments received. Men were more likely to have undergone cardioversion (p = 0.0003), catheter ablation (p = 0.0084), beta blockade (p = 0.002), and amiodarone (p = 0.01), while women more often received calcium channel blockers (p < 0.0001).

And while men and women received oral anticoagulation appropriately per AF performance measures at the same rate (65%), men were much more likely to be in therapeutic range (INR 2-3) than women (p < 0.0001). That translated to higher rates of TIA/stroke/systemic embolism (1.96 vs. 1.28) and new-onset heart failure (2.14 vs. 1.90) in women, although the difference was not significant in either case.

So, compared with men, women with AF have:

• higher stroke risk
• less time in therapeutic range on oral anticoagulation
• more symptoms
• more functional limitation
• worse quality of life

Men, however, experienced higher rates of overall and CV-related death (2.15 vs. 1.49; p < 0.0001).

Failure to Use Evidence-based Rx

A significant proportion of AF patients, regardless of treatment strategy, were not treated with anticoagulation for thromboembolism prophylaxis. For example, one-third of rhythm-controlled patients were not on systemic anticoagulation while only 12% had a contraindication to its use. This seems to suggest that patients managed with rhythm control do not have significant risk for stroke, but that observation was disproved by both the AFFIRM and RACE trials.

Investigators analyzed registry data and, in August 2013, reported on the overall use of other therapies for treating existing cardiovascular risk factors in patients with AF.² They found low use of evidence-based therapies among these patients with AF. More than 93% of those in the registry were eligible for at least one recommended therapy for other risk factors, but only 46% received all of the recommended treatments. Just over half of the patients had controlled hypertension and approximately 75% with hyperlipidemia received a statin. Fewer than half of the patients with CAD, HF, or peripheral vascular disease received all of the recommended therapies for their other conditions. Researchers believe that improving the use of recommended therapies to treat other cardiovascular conditions could help improve outcomes for patients with AF.

References

1. Steinberg BA, Holmes DN, Ezekowitz MD, et al. Am Heart J. 2013;165:622-9.
2. Hess PL, Kim S, Piccini JP, et al. Am J Med. 2013;126:625-32.

To listen to an interview with Jonathan P. Piccini, MD, on the primary results of the ORBIT-AF registry, visit youtube.cswnews.org. The interview was conducted by Raymond J. Gibbons, MD.