Atrial Fibrillation and Advanced Heart Failure
ABSTRACT & COMMENTARY
Synopsis: Class I antiarrhythmics should be avoided in patients with atrial fibrillation and heart failure.
Source: Stevenson WG, et al. J Am Coll Cardiol 1996;28:1458-1463.
The effect of atrial fibrillation on survival in patients with heart failure remains controversial. In this report, Stevenson et al retrospectively analyzed survival in a large group of heart failure patients followed in a specialized treatment center. They divided the patients into two groups: those who were first evaluated between 1985 and 1989, and those first seen between 1990 and 1993. Each group was then subdivided into patients with or without atrial fibrillation. These time periods were selected because different arrhythmia management strategies were used during each. In the earlier period, class I antiarrhythmic drugs were used to suppress atrial fibrillation; after 1990, amiodarone was the drug of choice. Although baseline clinical and hemodynamic profiles were similar for the two groups, other changes in heart failure therapy were also introduced, including more use of ACE inhibitors, anticoagulants, and digoxin. Only a small number of patients during either time period received implantable defibrillators.
In the period of 1985-89, atrial fibrillation was associated with an increased two-year mortality (55% vs 39%). However, in the 1990-93 group, atrial fibrillation had no influence on survival. When the atrial fibrillation groups from the two periods were compared, the 1990-93 group did substantially better. The authors conclude that survival for patients with advanced heart failure and atrial fibrillation is improving with changes in medical management.
COMMENT BY JOHN P. DIMARCO, MD
Atrial fibrillation frequently complicates the management of patients with advanced heart failure. This study demonstrates that current treatment strategies can reduce or eliminate any independent adverse effect of atrial fibrillation on mortality. When the authors performed a multivariate analysis of survival predictors in the patients seen after 1989 (group II), atrial fibrillation was no longer a prognostic factor.
There were many potential reasons for these findings. It has been recognized that class I antiarrhythmic drugs can adversely impact survival in patients with ischemic heart disease and/or heart failure, and these drugs were used much less frequently in the 1990-93 group. In these patients, amiodarone was the antiarrhythmic drug of choice. Amiodarone may benefit some patients with heart failure, even though this has not been shown in all studies. These changes in antiarrhythmic strategy probably accounted for only a small proportion of the total improvement in survival. Survival at two years among the patients without atrial fibrillation also improved dramatically, from 55% in the early group to 75% in the later group. As mentioned by the authors, increased use of ACE inhibitors, digoxin, and anticoagulation also occurred during the course of the study and these factors probably also favorably influenced survival.
This study does not answer the question of whether or not efforts to restore sinus rhythm in patients with atrial fibrillation and heart failure should be made. Even with the use of amiodarone, 52% of atrial fibrillation patients in group II still had the arrhythmia at the time of discharge, and we can assume that many of those who converted to sinus rhythm would have experienced recurrences during follow-up. We also cannot tell whether the benefit of amiodarone is due to effects on atrial or ventricular arrhythmias. What is shown clearly in this study, however, is that class I antiarrhythmics should be avoided in patients with atrial fibrillation and heart failure.