A recent study published in JAMA has provided robust evidence confirming the efficacy of pulmonary vein isolation (PVI) in treating symptomatic atrial fibrillation (Afib). The SHAM-PVI trial, a double-blind, sham-controlled, randomized clinical trial, demonstrated that PVI significantly reduces Afib burden and improves quality of life compared to a sham procedure.
The study, conducted at two tertiary centers in the U.K. between January 2020 and March 2024, enrolled 126 patients with symptomatic paroxysmal or persistent Afib. Participants were randomized to undergo PVI with cryoablation (n=64) or a sham procedure with phrenic nerve pacing (n=62). The primary endpoint was the change in Afib burden at 6 months, measured by an implantable loop recorder.
Significant Reduction in Atrial Fibrillation Burden
The results showed a significant reduction in Afib burden in the PVI group compared to the sham group. The absolute mean Afib burden change from baseline to 6 months was 60.31% in the ablation group and 35.0% in the sham group (geometric mean difference, 0.25; 95% CI, 0.15-0.42; P < .001).
Improvements in Quality of Life and Symptoms
In addition to the reduction in Afib burden, the PVI group experienced significant improvements in quality of life and symptoms. The estimated difference in the overall Atrial Fibrillation Effect on Quality of Life (AFEQT) score at 6 months, favoring catheter ablation, was 18.39 points (95% CI, 11.48-25.30 points). The Short Form 36 general health score also improved substantially more with ablation, with an estimated difference of 9.27 points at 6 months (95% CI, 3.78-14.76 points).
Addressing the Placebo Effect
Previous concerns have been raised regarding a potential placebo effect in catheter ablation for Afib. This sham-controlled trial directly addresses these concerns, providing evidence that the benefits of PVI are not primarily due to a placebo effect. According to Rajdip Dulai, MBBS, of Eastbourne District General Hospital and University College London, "At 6 months follow-up, the SHAM-PVI study has demonstrated no clinically relevant placebo effect with PVI ... This study provides reassurance that PVI works."
Study Details and Patient Population
The study population consisted of adults with symptomatic paroxysmal (20.6%) or persistent Afib (79.4%) who had been treated with at least one Class I or III antiarrhythmic drug or had an intolerance to such drugs. Major exclusion criteria included long-standing persistent Afib, prior left atrium ablation, other arrhythmias requiring ablative therapy, a left atrium size of 5.5 cm or larger, and an ejection fraction of less than 35%.
Safety Profile
Regarding safety, one patient in the sham procedure group died of an intracranial hemorrhage, deemed unrelated to the study procedures. In the ablation group, one patient experienced pericarditis post-procedure, one had an aortic pressure tracing on transseptal puncture without further adverse consequence, and one had transient leg weakness/numbness due to lidocaine.
Implications for Clinical Practice
The SHAM-PVI trial provides compelling evidence supporting the use of PVI for the treatment of symptomatic Afib. The results confirm that PVI is an effective intervention for reducing Afib burden and improving patients' quality of life. Electrophysiologist Peter Kistler, MBBS, PhD, of The Alfred Hospital in Melbourne, Australia, noted that the findings "strongly support the established role of ablation in the management of atrial fibrillation."
