Atrial fibrillation: A risk factor for increased mortality - An AVID registry analysis

Emerging evidence suggests that atrial fibrillation is not a benign arrhyth mia. It is associated with increased risk of death. The magnitude of associ ation is controversial and potential causes remain unknown. Patients in the registry of the Antiarrhythmics Versus Implantable Defibrillators (AVID) T rial form the basis for this report. Baseline variables, in particular the presence or absence of a history of atrial fibrillation/flutter, were exami ned in relation to survival. Multivariate Cox regression was used to adjust for differences in important baseline co-variables using 27 pre-selected v ariables. There were 3762 subjects who were followed for an average of 773 +/- 420 days; 1459 (39 %) qualified with ventricular fibrillation and 2303 (61 %) with ventricular tachycardia. A history of atrial fibrillation/flutt er was present in 24.4 percent. There were many differences in baseline var iables between those with and those without a history of atrial fibrillatio n/flutter. After adjustment for baseline differences, a history of atrial f ibrillation/flutter remained a significant independent predictor of mortali ty, (relative risk=1.20; 95 % confidence intervals=1.03-1.40; p=0.020). Ant iarrhythmic drug use, other than amiodarone or sotalol, was also a signific ant independent predictor of mortality (relative risk 1.34; 95 % confidence intervals 1.07-1.69, p=0.011. Atrial fibrillation/flutter is a significant independent risk factor for increased mortality in patients presenting wit h ventricular tachyarrhythmias. This risk may have been overestimated in pr evious studies that could not adjust for the proarrhythmic effects of antia rrhythmic drugs other than amiodarone or sotalol.