Investigators Ammar et al found that there was no significant differences between men and women in the incidence of periprocedural stroke and transient ischaemic attack (1.8 vs. 0.9%; p=0.35), tamponade (3.6 vs. 1.5%; p=0.12), severe haematoma (1.8 vs. 0.9%; p=0.3), pseudoaneurysm (0.6 vs. 0.6%; p=ns) or pulmonary vein stenosis (0.6 vs. 0.3; p=ns). Additionally, after a mean follow-up of 3.4±2.7 years, 51% of women and 55% of men were free from atrial arrhythmias without antiarrhythmic drugs (p=0.34).
The results of the new study are in contrast to previous studies, which have shown that women have more frequently persistent atrial fibrillation, complications and procedural failures than men. However, the lead investigator of the new study, Sonia Ammar, German Heart Center, Hospital rechts der Isar at the Technical University of Munich, said that her study may have had a more homogeneous population than had previous studies (which possibly explained why no differences in outcomes were observed between men and women). She explained that in her study, the duration of atrial fibrillation before ablation was about six years in both men and women and, unlike other studies, women were not referred later for catheter ablation despite being significantly older than men (61±9 years vs. 55±10 years). “In regard to acute complications, there was a tendency toward more tamponades in women without a statistical difference. It is important to say that we reported our experience [of catheter ablation] since 1998. In the early years, complications of catheter ablation for atrial fibrillation were more frequent. In the last few years, we had an incidence of tamponades of less than 1% in paroxysmal atrial fibrillation ablation. Therefore, the difference is disappearing.” According to Ammar, some specificities of the German population in the study may also have affected the result.
The women in her study, as well as being older, had a higher CHADS2 (Congestive heart failure, hypertension, age ≥75 years, and prior stroke) score but this baseline characteristic did not appear to significantly increase the incidence of stroke in women compared with men (2.4% vs. 3.5%). “Eighty seven per cent of strokes occurred in patients with atrial fibrillation recurrence and/or no adequate oral anticoagulation. Atrial fibrillation ablation seems to modify the course of the disease and the rate of stroke, particularly in women.”
Although gender does not appear to have a significant effect, according to this study at least, on the outcome of catheter ablation, it does significantly influence the pathophysiology, epidemiology, and clinical presentation of many cardiac arrhythmias. Ammar said: “Women have significantly longer QT intervals than men, despite having higher heart rates. In contrast, men have a higher incidence of atrial fibrillation, Brugada syndrome, early repolarisation syndrome and sudden death compared with women.” Additionally, as women have a greater risk of drug-induced QT prolongation, antiarrhythmic drugs have to be “prescribed very carefully” in women. Ammar concluded: “Differences in gender hormones may explain some of these findings, but the reasons for these gender differences are not completely understood.”