EXERCISE CAPACITY AFTER HIS-BUNDLE ABLATION AND RATE RESPONSE VENTRICULAR PACING FOR DRUG-REFRACTORY CHRONIC ATRIAL-FIBRILLATION

Objective-To evaluate exercise capacity of patients with chronic atria l fibrillation in whom His bundle ablation followed by ventricular rat e response pacing (VVIR) was carried out because of drug refractorines s. Design-Prospective study. Patients-25 consecutive patients, all wit h chronic symptomatic drug refractory atrial fibrillation, underwent H is bundle ablation. Before this intervention all patients were on anti arrhythmic drugs to attain acceptable heart rate control and to relief symptoms. Main outcome measures-Exercise capacity, including measurem ents of V over dot O-2, was examined before and after a mean interval of seven months following His bundle ablation. Results-Exercise capaci ty after His bundle ablation increased from a mean of 109 (SD 49) W to 118 (46) W (P < 0.002), but V over dot O-2 at peak exercise did not c hange significantly. Maximum exercise capacity was achieved with a sig nificantly lower maximum driven heart rate than the spontaneous heart rate before ablation. Conclusions-Exercise capacity of patients who un derwent His bundle ablation followed by VVIR pacing remained unchanged or improved during a mean follow up of seven months. Larger patient p opulations with longer follow up are necessary to examine determinants improved exercise capacity.