Atrial fibrillation could be an independent predictor of worse outcomes in heart patients with implantable cardioverter-defibrillators (ICDs), according to a meta-analysis published this November in the Journal of the American Heart Association.
First author Usman Mustafa, MD, and colleagues with Louisiana State University Health Sciences Center-Shreveport said ICDs, which are used primarily for the prevention of sudden cardiac death in at-risk patients, have historically had a good track record for improving survival in individuals with heart failure.
“The rate of ICD implantation has increased in recent years,” the authors wrote in JAHA. “However, whether ICD is placed for primary or secondary prevention, atrial fibrillation (AF) is a frequently found supraventricular arrhythmia in these patients. Nonetheless, whether AF, which is an independent predictor of mortality in the general population, heralds worse outcomes in patients with ICD is not fully established.”
Mustafa et al. included 25 observational studies in their meta-analysis, comparing ICD patients with AF to those exhibiting a normal sinus rhythm (NSR). The researchers analyzed a total of 63,283 patients with the goal of determining rates of all-cause mortality and appropriate shock therapy in both patient groups.
The authors found all-cause mortality and incidence of appropriate shock therapy were significantly higher in ICD patients with AF versus ICD patients with NSR—2.11-fold higher and 1.77-fold higher, respectively. Based on a separate meta-analysis of three studies, they saw no statistically significant mortality benefit from ICDs compared with regular guideline-directed medical therapy for AF patients.
“Our pooled analysis suggests that there is no difference in mortality when comparing AF patients with ICD to those AF patients who otherwise meet criteria for ICD but are only on goal-directed medical therapy,” Mustafa and coauthors reported. “It is important to note that the interpretation of the results of this particular analysis (with three studies and 387 patients) is limited because the lack of statistical significance may stem from a low statistical power.
“On the other hand, the comparison of similar-sized trials that tested the benefit of ICD in the general population shows only one of three trials that showed a significant mortality benefit.”
The team concluded the impact of ICDs on all-cause mortality in AF patients compared to guideline-directed therapy is “unclear” based on available data. They said randomized controlled trials are necessary to move the research forward.
“Atrial fibrillation may be a marker of worse outcome in patients with implantable cardioverter-defibrillators,” they wrote. “Therefore, ICD patients with AF may need tailored programming and close monitoring.”