The Ablate and Pace Trial: a prospective study of catheter ablation of the AV conduction system and permanent pacemaker implantation for treatment of atrial fibrillation. APT Investigators.

BACKGROUND

The Ablate and Pace Trial (APT) prospectively assessed the effects of catheter ablation of the AV conduction system and permanent pacemaker implantation on health-related quality of life, survival, exercise capacity, and ventricular function in 156 patients with symptomatic atrial fibrillation.

METHODS

All patients referred for catheter ablation and permanent pacemaker implantation because of medically-refractory atrial fibrillation at 16 centers were screened for enrollment in a prospective registry. Baseline assessment prior to ablation included measurement of quality of life, including the Health Status Questionnaire, the Quality of Life Index and the Symptom Checklist: Frequency and Severity. Exercise capacity was assessed with metabolic treadmill exercise testing and ventricular function was quantitated with echocardiography. The quality of life instruments, exercise capacity, and echocardiography were repeated at 3 and 12 months after catheter ablation.

RESULTS

The APT population included 90 men and 66 women (66.1 +/- 11.5 years of age) with either chronic (n = 70), recurrent (n = 31), or paroxysmal atrial fibrillation (n = 55). Structural heart disease was present in 78.2% of patients. Successful ablation of AV conduction was achieved in 155 of 156 patients (99.4%). Survival at 1 year was 85.3%, with 5 of 23 deaths being sudden cardiac deaths. Survival over the first year of follow-up was significantly lower for patients with a baseline left ventricular ejection fraction (LVEF) < 0.45 (0.73) than for patients with a LVEF > or = 0.45 (0.88, p = 0.03). The NYHA functional class improved from 2.1 at baseline to 1.8 at 3 months and 1.9 at 12 months of followup (p = 0.0001). Significant improvement in quality of life scores were noted for all 8 subscales of the Health Status Questionnaire, for the overall rating of the Quality of Life Index, the Health and Function subscales; Arrhythmia-related symptoms were markedly reduced as measured by the Symptom Checklist: Frequency and Severity scale. The mean LVEF improved from 0.50 +/- 0.20 at baseline to 0.54 +/- 0.20 at 3 months (p = 0.03). The LVEF 12 months after ablation was 0.52 +/- 0.20, not statistically different from baseline. Individuals with reduced systolic function at baseline had the greatest improvement, from LVEF 0.31 +/- 0.20 at baseline to 0.41 +/- 0.20 at 3 months and 0.41 +/- 0.30 at 12 months (p = 0.0001). There were no significant changes in treadmill exercise duration (10.0 +/- 4.3 min at baseline and 11.6 +/- 3.6 min at 12 months) or VO2max (1467 +/- 681 ml O2 min baseline and 1629 +/- 739 ml O2 min at 12 months).

CONCLUSIONS

Catheter ablation of the AV conduction system and permanent pacemaker implantation were associated with improved quality of life and left ventricular function in this population of highly symptomatic patients with atrial fibrillation refractory to medical therapy.