Sham-Controlled Trial Reveals Catheter Ablation Cuts Atrial Fibrillation Burden but Not Symptoms

A landmark sham-controlled trial has delivered one of the most provocative results in modern cardiology: catheter ablation reliably reduces the recurrence and burden of atrial fibrillation, yet it did not significantly outperform an active sham procedure in improving patient-reported symptoms and quality of life at six months. The PVI-SHAM-AF trial, a randomised, double-blind, multicentre study, has prompted an editorial discussion in Clinical Research in Cardiology led by Ulrich Laufs, Michael Böhm, Felix Mahfoud and Rolf Wachter, who address the controversial findings and the many questions clinicians have raised since the results were published. Their analysis offers a nuanced interpretation that resists both triumphalism and premature dismissal of a guideline-recommended therapy.

The trial enrolled 262 patients with symptomatic paroxysmal or persistent atrial fibrillation and randomised them in a 2:1 ratio to pulmonary vein isolation or to a sham procedure. The primary endpoint was the between-group difference in the change from baseline to six months in the AFEQT summary score, a well-established questionnaire measuring atrial fibrillation-related quality of life. At six months, the mean AFEQT score improved from 61 to 81 in the ablation group and from 59 to 75 in the sham group. Both improvements were clinically meaningful, but the difference in change between the groups was not statistically significant. Meanwhile, ablation demonstrated clear objective efficacy: atrial fibrillation was detected in 21 percent of ablated patients versus 41 percent of sham patients, an absolute difference of 20 percent, with a favourable safety profile.

What distinguishes PVI-SHAM-AF from earlier research is the rigor of its control condition. The sham intervention was not an inert experience but an active clinical pathway encompassing hospital admission, deep sedation and analgesia, venous access, a stay in the catheterization laboratory, cardioversion for patients who arrived in atrial fibrillation, and structured follow-up. The trial therefore tested catheter ablation against this comprehensive procedural and clinical-care package, not against no treatment at all. The investigators emphasise that the study did not evaluate conventional non-invasive ambulatory care. Within the six-month observation window, however, the superior rhythm control achieved by ablation simply did not translate into a statistically significant improvement in patient-reported quality of life beyond what the active sham pathway delivered.

Compared with the two previous sham-controlled ablation trials, SHAM-PVI and PFA-SHAM, PVI-SHAM-AF was substantially larger, exceeding the combined sample size of both predecessors. Baseline quality of life was impaired to a similar degree as in the major open-label trials CABANA and EARLY-AF. Intriguingly, while the improvement within the ablation arms was broadly consistent across all these studies, the improvement observed in the sham arm of PVI-SHAM-AF was markedly lower than in SHAM-PVI and PFA-SHAM. The editorial authors suggest this discrepancy indicates that patient management in PVI-SHAM-AF may have been more comprehensive than in the other two sham trials, intensifying the care received by the control group and thereby narrowing the apparent treatment effect on symptoms.

The findings echo a broader pattern in cardiovascular medicine. Previous reports have documented clinically relevant placebo effects in randomised trials of invasive procedures across settings as varied as resistant hypertension, percutaneous coronary intervention and vertebroplasty for osteoporotic vertebral fractures. A systematic review and meta-analysis found that only about a third of placebo-controlled trials of cardiovascular interventions demonstrated significant superiority of the invasive procedure over placebo. Against this backdrop, PVI-SHAM-AF is less an outlier than a striking confirmation that subjective, patient-reported endpoints are acutely susceptible to contextual healing, expectation and the attention that accompanies any hospital-based intervention.

Why did both groups improve so substantially? The editorial points to a likely combination of placebo and Hawthorne effects, regression to the mean, and optimised concomitant care driven by protocol-adherent assessments and intensive follow-up. Symptoms in atrial fibrillation, the authors argue, may not be determined solely by arrhythmia physiology but also by symptom perception, atrial or ventricular ectopy, anxiety and depression. Quantifying the individual contributions of these mechanisms is difficult, and PVI-SHAM-AF was not designed to isolate them. Disentangling how much of the improvement stems from the procedure itself, from heightened clinical attention, or from psychological factors remains a critical objective for future research and could reshape how symptom-directed therapies are evaluated.

Do the results mean ablation fails to relieve symptoms, or that it should be withheld from patients with preserved left ventricular function? The editorial authors firmly reject both conclusions. The trial demonstrates that ablation reduces atrial fibrillation recurrence and burden safely, and it does not challenge indications in settings where reducing arrhythmia burden may improve clinically relevant outcomes, such as tachycardia-induced or atrial fibrillation-aggravated cardiomyopathy and heart failure with reduced ejection fraction, populations that were not the focus of this study. The results are confined to patient-reported outcomes rather than morbidity or mortality, reflecting a familiar divergence in cardiology where effects on hard endpoints and on how patients feel can part ways, as seen with beta-blockers, inotropes and implantable cardioverter-defibrillators in heart failure.

Questions about patient selection and follow-up duration also deserve scrutiny. Data on the 937 patients who declined randomisation were insufficient for comparison, and willingness to accept an invasive sham procedure may have selected individuals with particular symptom burdens, expectations or treatment preferences; patients with severe symptoms might have declined to guarantee receiving ablation. Yet the mean baseline AFEQT score of 60 mirrored those in CABANA, EARLY-AF and STOP AF First, beta-blocker use remained high and balanced between groups, and no treatment effect heterogeneity by baseline score was observed. The six-month primary endpoint was chosen deliberately to minimise the impact of repeat procedures, but the authors concede it may have been too short to capture the full treatment effect, and it does not exclude longer-term benefits in rhythm control, medication use, healthcare utilisation or clinical outcomes. Twelve-month follow-up is ongoing.

For clinical practice, the implications centre on shared decision-making. PVI-SHAM-AF shows that the objective rhythm-control benefits of catheter ablation should be clearly distinguished from its effects on patient-reported quality of life at six months, information that is essential for counselling patients whose primary goal is symptom relief. The results also underscore the therapeutic power of comprehensive, attentive clinical care. Crucially, the authors stress that invasive sham procedures are research tools for delineating true treatment effects and must never be translated into clinical practice. Instead, the challenge is to identify which components of the sham-associated care pathway improved symptoms and how those elements can be incorporated into routine, non-invasive care.

Perhaps the trial’s most enduring lesson is methodological. The editorial demonstrates that randomised, blinded evaluation of an established, guideline-recommended invasive procedure is accepted by patients, accepted by many expert physicians, and feasible across multiple centres and countries. Sham-controlled designs are particularly important when evaluating subjective or patient-reported outcomes, because such endpoints are vulnerable to placebo effects, expectations, regression to the mean and the effects of intensified clinical care. Just as placebo controls are indispensable for drug therapies, the incremental effect of an invasive or surgical procedure on how patients feel cannot be reliably determined without an appropriate sham control. PVI-SHAM-AF may thus be remembered less for what it says about ablation alone and more for how it resets the standard of evidence for procedural medicine.

Subject of Research: A sham-controlled randomised trial evaluating catheter ablation for symptom relief and rhythm control in patients with symptomatic atrial fibrillation.

Article Title: PVI-SHAM-AF: what does this trial tell us about catheter ablation and symptoms in patients with atrial fibrillation?

Article References: Laufs, U., Böhm, M., Mahfoud, F., & Wachter, R. (2026). PVI-SHAM-AF: what does this trial tell us about catheter ablation and symptoms in patients with atrial fibrillation?. Clinical Research in Cardiology. https://doi.org/10.1007/s00392-026-03016-z

Image Credits: AI Generated

DOI: 10.1007/s00392-026-03016-z

Keywords: atrial fibrillation, catheter ablation, pulmonary vein isolation, sham-controlled trial, quality of life, AFEQT score, placebo effect, rhythm control, patient-reported outcomes, PVI-SHAM-AF, cardiology, clinical trial