Women who received catheter ablation in the FIRE AND ICE trial were 37 percent more likely than men to have a recurrence of atrial arrhythmia and 36 percent more likely to be rehospitalized for cardiovascular causes, according to an analysis published April 26 in Circulation: Arrhythmia and Electrophysiology.
The researchers hypothesized referral bias could be present in which atrial fibrillation (AFib) ablation is deferred in women until they reach more advanced disease states. Women in the study were an average of seven years older (64 versus 57) at the time of ablation and had a lower glomerular filtration rate than men, with a trend toward more hypertension prevalence (62 percent versus 55 percent). But the women also had more favorable characteristics, such as less history of atrial flutter and coronary artery disease and smaller left atria.
“Although a host of poorly understood, sex-dependent physiological and pathophysiological mechanisms may predispose women to develop AFib later in life, a review of differences between men and women who underwent cardiac ablation procedures suggested that women are referred to catheter ablation less frequently and at more symptomatic disease states than men, which may play a role in the observed age difference between sexes,” wrote lead author Karl-Heinz Kuck, MD, PhD, and colleagues.
Kuck et al. studied the rates of arrhythmia recurrence, cardiovascular rehospitalization and repeat ablation among 750 patients with paroxysmal AFib enrolled in FIRE AND ICE. The original trial randomized patients to either cryoballoon ablation or radiofrequency current ablation, but this analysis pooled outcomes from both modalities based on 22 baseline characteristics.
Sex had the largest impact on outcomes of all the characteristics studied, although prior direct current cardioversion (DCCV) was associated with continued arrhythmia, hypertension was linked to more cardiovascular rehospitalizations and the duration of pre-ablation AFib was associated with repeat ablation.
“Collectively, these data suggest that female sex, a history of DCCV or hypertension and a longer history of AF are indicative of a lower success rate of catheter ablation for AFib and may substantiate specialized monitoring or earlier treatment for certain patient populations to maximize treatment success,” the authors wrote.
Kuck and colleagues pointed out the difference in baseline characteristics wasn’t enough to explain the significantly worse outcomes among women. Propensity-score matching only increased the gender disparity—nudging the relative differences in recurrent arrhythmia and cardiovascular rehospitalization to 51 and 40 percent, respectively.
“Our data indicate that early primary efficacy of catheter ablation for AFib is similar in both men and women up until approximately six months, at which point ablation efficacy diverges in favor of men,” the researchers wrote. “This sex-dependent late divergence in longer term efficacy is not well understood, but it may indicate a less-durable lesion in women and a propensity for developing non–pulmonary vein triggers after catheter ablation.”