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SHAM-PVI

A Randomized Sham-Controlled Study of Pulmonary Vein Isolation in Symptomatic Atrial Fibrillation (SHAM-PVI)

Patient / Population Intervention / Exposure Comparison Outcome

In 126 patients with symptomatic paroxysmal or persistent atrial fibrillation, cryoballoon pulmonary vein isolation reduced atrial fibrillation burden at 6 months compared with a sham procedure.

N
126patients
Design
Double-blind randomised trial at two UK tertiary centres, January 2020 to March 2024; cryoballoon pulmonary vein isolation (n = 64) vs a sham procedure with phrenic nerve pacing (n = 62); every participant received an implantable loop recorder; long-standing persistent AF, prior left atrial ablation, left atrium ≥ 5.5 cm and ejection fraction < 35% excluded
Endpoint
Atrial fibrillation burden at 6 months, excluding a 3-month blanking period, measured by implantable loop recorder
Relevance
1Practice-defining — the trial the guideline rests on.
ResultAbsolute mean AF burden fell 60.3% after ablation and 35.0% after the sham (geometric mean difference 0.25, 95% CI 0.15-0.42; P < 0.001). AFEQT favoured ablation by 18.4 points (95% CI 11.5-25.3) and SF-36 general health by 9.3 points (3.8-14.8) at 6 months.
Dulai R, Sulke N, Freemantle N, et al. JAMA. 2024;332(14):1165-1176. 10.1001/jama.2024.17921
Discussion & critique

The first double-blind test of an ablation against a sham, and it answered the placebo question in ablation's favour: burden fell further and patients felt better by 18 AFEQT points, twice what counts as clinically important. Two features make it a small answer to a large question — 126 patients at two centres, and a sham consisting of phrenic nerve pacing rather than a full procedural experience. PVI-SHAM-AF, four times the size with a deeper sham, then found the symptom advantage gone while the rhythm advantage remained; the two trials are now read together, and the burden result is what survives both.