ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation

There are two approaches to the treatment of atrial fibrillation: one is cardioversion and treatment with antiarrhythmic drugs to maintain sinus rhythm, and the other is the use of rate-controlling drugs, allowing atrial fibrillation to persist. In both approaches, the use of anticoagulant drugs is recommended. We conducted a randomized, multicenter comparison of these two treatment strategies in patients with atrial fibrillation and a high risk of stroke or death. The primary end point was overall mortality. A total of 4060 patients (mean [+/-SD] age, 69.7+/-9.0 years) were enrolled in the study; 70.8 percent had a history of hypertension, and 38.2 percent had coronary artery disease. Of the 3311 patients with echocardiograms, the left atrium was enlarged in 64.7 percent and left ventricular function was depressed in 26.0 percent. There were 356 deaths among the patients assigned to rhythm-control therapy and 310 deaths among those assigned to rate-control therapy (mortality at five years, 23.8 percent and 21.3 percent, respectively; hazard ratio, 1.15 [95 percent confidence interval, 0.99 to 1.34]; P=0.08). More patients in the rhythm-control group than in the rate-control group were hospitalized, and there were more adverse drug effects in the rhythm-control group as well. In both groups, the majority of strokes occurred after warfarin had been stopped or when the international normalized ratio was subtherapeutic. Management of atrial fibrillation with the rhythm-control strategy offers no survival advantage over the rate-control strategy, and there are potential advantages, such as a lower risk of adverse drug effects, with the rate-control strategy. Anticoagulation should be continued in this group of high-risk patients. Copyright 2002 Massachusetts Medical Society

To describe the effect of atrial fibrillation on long-term morbidity and mortality. The Renfrew/Paisley Study surveyed 7052 men and 8354 women aged 45-64 years between 1972 and 1976. All hospitalizations and deaths occurring during the subsequent 20 years were analyzed by the presence or absence of atrial fibrillation at baseline. Lone atrial fibrillation was defined in the absence of other cardiovascular signs or symptoms. Cox proportional hazards models were used to adjust for age and cardiovascular conditions. After 20 years, 42 (89%) of the 47 women with atrial fibrillation had a cardiovascular event (death or hospitalization), compared with 2276 (27%) of the 8307 women without this arrhythmia. Among men, 35 (66%) of 53 with atrial fibrillation had an event, compared with 3151 (45%) of 6999 without atrial fibrillation. In women, atrial fibrillation was an independent predictor of cardiovascular events (rate ratio [RR] = 3.0; 95% confidence interval [CI]: 2.1-4.2), fatal or nonfatal strokes (RR = 3.2; 95% CI: 1.0-5.0), and heart failure (RR = 3.4; 95% CI: 1.9-6.2). The rate ratios among men were 1.8 (95% CI: 1.3-2.5) for cardiovascular events, 2.5 (95% CI: 1.3-4.8) for strokes, and 3.4 (95% CI: 1.7-6.8) for heart failure. Atrial fibrillation was an independent predictor of all-cause mortality in women (RR = 2.2; 95% CI: 1.5-3.2) and men (RR = 1.5; 95% CI: 1.2-2.2). However, lone atrial fibrillation (which occurred in 15 subjects) was not associated with a statistically significant increase in either cardiovascular events (RR = 1.5; 95% CI: 0.6-3.6) or mortality (RR = 1.8; 95% CI: 0.9-3.8). Atrial fibrillation is associated with an increased long-term risk of stroke, heart failure, and all-cause mortality, especially in women.

In this study we tested the hypothesis that atrial fibrillation (AF) causes electrophysiological changes of the atrial myocardium which might explain the progressive nature of the arrhythmia. Twelve goats were chronically instrumented with multiple electrodes sutured to the epicardium of both atria. Two to 3 Weeks after implantation, the animals were connected to a fibrillation pacemaker which artificially maintained AF. Whereas during control episodes of AF were short lasting (6 +/- 3 seconds), artificial maintenance of AF resulted in a progressive increase in the duration of AF to become sustained (> 24 hours) after 7.1 +/- 4.8 days (10 of 11 goats). During the first 24 hours of AF the median fibrillation interval shortened from 145 +/- 18 to 108 +/- 8 ms and the inducibility of AF by a single premature stimulus increased from 24% to 76%. The atrial effective refractory period (AERP) shortened from 146 +/- 19 to 95 +/- 20 ms (-35%) (S1S1, 400 ms). At high pacing rates the shortening was less (-12%), pointing to a reversion of the normal adaptation of the AERP to heart rate. In 5 goats, after 2 to 4 weeks of AF, sinus rhythm was restored and all electrophysiological changes were found to be reversible within 1 week. Artificial maintenance of AF leads to a marked shortening of AERP, a reversion of its physiological rate adaptation, and an increase in rate, inducibility and stability of AF. All these changes were completely reversible within 1 week of sinus rhythm.