April 21, 2025Open Access
The Interaction Between Atrial Fibrillation and Mitral Regurgitation: Insights from the CABANA Randomized Clinical Trial
Key Result
Catheter ablation did not significantly reduce mortality and cardiovascular hospitalization (HR 0.88) compared to drug therapy, but significantly reduced atrial fibrillation recurrence (OR 0.56).
Study Design
Type
RCT (n=1,423)
Blinding
Open-label
Randomization
1:1 ratio (permuted block with stratification by clinical site)
Multicenter
Yes
Structured PICO
Does catheter ablation improve clinical outcomes, reduce AF recurrence, and decrease mitral regurgitation severity in patients with atrial fibrillation compared to pharmacological therapy?
P
Population
1423 patients with atrial fibrillation and available baseline echocardiography from the CABANA trial cohort, including 722 (52%) with baseline mitral regurgitation.
I
Intervention
Catheter ablation
C
Comparator
Pharmacological therapy
O
Outcome
Composite of all-cause mortality and cardiovascular hospitalizationcomposite
Catheter ablation for atrial fibrillation is superior to pharmacological therapy for rhythm control and may additionally reduce mitral regurgitation severity and improve functional status in patients with coexisting MR.
Main Result
Effect estimate: HR 0.88 (95% CI 0.76-1.01)
Absolute Event Rate: 52% vs 59%
p-value: p=0.073
Limitations
- Exploratory sub-analysis not specifically powered to study mitral regurgitation
- Baseline echocardiographic data was missing for approximately 35% of the CABANA population
- Absence of a centralized echocardiographic core laboratory
- Echocardiographers were not blinded to treatment allocation
- Clinical conditions during echo acquisition were not systematically recorded
- Drug arm allowed for rate control, leaving uncertainty regarding comparison to strict rhythm control
Abstract
AIMS: Atrial fibrillation (AF) and mitral regurgitation (MR) frequently coexist. While catheter ablation is a key rhythm-control strategy in AF, its impact on MR severity remains uncertain. This study evaluates the effects of catheter ablation on AF recurrence, functional status, and MR progression in patients with AF and baseline MR. METHODS AND RESULTS: This sub-analysis included 1423 patients (65% of the overall CABANA cohort) with available baseline echocardiography. Participants were randomized to catheter ablation or pharmacological therapy. The primary endpoint was the composite of all-cause mortality and cardiovascular hospitalization. Secondary endpoints included AF recurrence, changes in MR severity, and functional status. At baseline, 722 patients (52%) had MR, including 582 with mild and 140 with ≥moderate MR, with characteristics suggestive of an atrial functional mechanism. Catheter ablation significantly reduced AF recurrence compared to pharmacological therapy (odds ratio OR 0.56, 95% confidence interval CI 0.50-0.62, p < 0.001). The presence or absence of MR did not interact with randomization in terms of its neutral effect on all-cause mortality and cardiovascular hospitalization (p for interaction = 0.115). Baseline MR increased the risk of AF recurrence (OR 1.46, 95% CI 1.40-1.74, p < 0.001). However, the benefit of ablation on functional status was greater in patients with MR compared to those without (p for interaction < 0.001). Follow-up echocardiography (n = 248) showed a greater reduction in MR severity in the ablation group versus drug therapy (p for interaction = 0.040). CONCLUSION: Catheter ablation was superior to pharmacological therapy in rhythm control and may reduce MR severity over time. These findings highlight ablation's potential structural and symptomatic benefits, pending specifically designed clinical trials.