Importance of rate control or rate regulation for improving exercise capacity and quality of life in patients with permanent atrial fibrillation and normal left ventricular function: a randomised controlled study

Abstract

Objective: To determine the importance of rhythm regulation or rate control in patients with permanent atrial fibrillation (AF) and normal left ventricular function.

Patients and interventions: Thirty six patients with a mixed fast and slow ventricular response rate to their AF were randomised to either His bundle ablation (HBA) and VVIR pacemaker (HBA group) or VVI pacemaker and atrioventricular modifying drugs (Med group). Outcomes assessed at one, three, six, and 12 months included exercise duration and quality of life.

Results: Exercise duration significantly improved from baseline in both groups. There was no difference in outcome between the groups (Med +40% v HBA +20%, p = NS). The heart rate profile on exercise was similarly slowed in both groups compared to baseline. Quality of life significantly improved in both treatment arms for the modified Karolinska questionnaire (KQ) (Med +50% v HBA +50%, p = NS) and the Nottingham health profile (NHP) (Med +40% v HBA +20%, p = NS). However, for the individual symptom scores of each questionnaire more were improved in the Med group (KQ-Med 6 improved v HBA 4, NHP-Med 3 v HBA 1). Left ventricular function was equally preserved by both treatments during follow up.

Conclusion: In these patients control of ventricular response rate with either HBA + VVIR pacemaker or atrioventricular modifying drugs + VVI pacemaker will lead to a significant improvement in exercise duration and quality of life. Rhythm regulation by HBA did not confer additional benefit, suggesting rate control alone is necessary for the successful symptomatic treatment of these patients in permanent AF.

Figure 1

Exercise duration in seconds on treadmill testing for both groups (Med, medical; HBA, ablation) at baseline and at all follow ups. Intra-group comparison for Med and HBA group showed a significant improvement compared to baseline at all follow ups. Inter-group comparison (Med v HBA) showed no significant difference at any time.

Figure 2

Example of heart rate profile on exercise in both groups for baseline (Med B, medical group baseline; HBA B, ablation group baseline) and at six months follow up (Med 6, medical group at six months; HBA 6, ablation group at six months). Profile shown at one minute intervals for the first three minutes. Intra-group comparison (Med B v Med 6 and HBA B v HBA 6) showed a significant slowing in heart rate at all time intervals for both groups except the resting heart rate in the medical group at six months that had not significantly changed from baseline. Inter-group comparison at baseline (Med B v HBA B) showed no significant difference in heart rate profile for any of the time intervals, while at six months (Med 6 v HBA 6) the only significant difference was in the resting heart rate (p = 0.015).

Figure 3

Example of part 2 NHP results at baseline and six months showing the percentage of patients answering yes to each question. There was no significant difference either intra-group or inter-group. Med B, medical group baseline; Med 6, medical group at six months; HBA B, ablation group baseline; HBA 6, ablation group at 6 months; J, occupation; H, ability to perform jobs around the home; SL, social life; HL, home relationships; SE, sex life; IH, interest/hobbies; H, holidays.