Pulmonary Vein Isolation Versus Sham Intervention in Symptomatic Atrial Fibrillation - SHAM-PVI

Sep 02, 2024
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Author/Summarized by Author:
Amit Saha, MD
Summary Reviewer:
Dharam J. Kumbhani, MD, SM, FACC
Trial Sponsor:
Eastbourne Cardiology Research Charity Fund
Date Presented:
09/02/2024
Date Published:
09/02/2024
Original Posted Date:
09/02/2024
References

Contribution To Literature:

The SHAM-PVI trial showed that in patients with symptomatic paroxysmal or persistent AF, cryoballoon PVI was associated with reduced AF burden and symptomatic improvement compared with a sham procedure.

Description:

The goal of the trial was to compare the clinical efficacy of cryoballoon pulmonary vein isolation (PVI) to a sham procedure in the treatment of symptomatic atrial fibrillation (AF).

Study Design

  • Double-blind
  • Randomized

Patients with AF referred for catheter ablation were randomized in a 1:1 fashion to undergo cryoballoon PVI (n = 64) or sham phrenic nerve pacing (n = 62) via identical femoral venous approaches. AF burden pre- and post-procedure was assessed by insertion of an implantable loop recorder (ILR), which recorded AF episodes longer than 2 minutes. Antiarrhythmic drugs (AAD) were discontinued prior to the conclusion of the post-intervention 3-month blanking period.

  • Total number of enrollees: 126
  • Duration of follow-up: 6 months
  • Mean patient age: 67 years
  • Percentage female: 29%

Inclusion criteria:

  • Age ≥18 years
  • Symptomatic paroxysmal or persistent AF despite ≥1 class I or III AAD or beta-blocker or with AAD intolerance

Exclusion criteria:

  • Longstanding persistent AF (continuous AF ≥1 year)
  • Prior AF ablation
  • Other arrhythmias requiring ablation
  • Left atrial diameter ≥5.5 cm
  • Left ventricular ejection fraction <35%

Other salient features/characteristics:

  • Persistent AF: 79%
  • Medication history: Beta-blockers (93%), amiodarone (24%); any prior class I/III AAD use: 58%; median number of prior cardioversions: 1.5
  • Median CHA2DS2-VASc score: 2.0
  • Median time since AF diagnosis: 24.5 months
  • LVEF: 55%
  • Median time from ILR insertion to intervention: 28 days
  • Median procedural time for PVI vs. sham: 63 vs. 60 min

Principal Findings:

The primary outcome, AF burden at 6 months, for cryoballoon PVI vs. sham, was: 18.2% vs. 43.2%, reduction from baseline 60.3% vs. 35.0%, geometric mean difference 0.25 (95% confidence interval [CI] 0.15-0.42, p < 0.001). Benefit was similar for paroxysmal and persistent AF.

Secondary outcomes for cryoballoon PVI vs. sham at 6 months:

  • AF Effect on Quality of Life (AFEQT) score: 77.4 vs. 58.3, estimated difference 18.39 (95% CI 11.48-25.30) favoring PVI
  • Mayo AF-Specific Symptom Inventory (MAFSI) severity score: 5.2 vs. 10.2, estimated difference -4.84 (95% CI -6.43 to -3.26) favoring PVI
  • MAFSI frequency score: 7.2 vs. 13.9, estimated difference -6.36 (95% CI -8.46 to -4.26) favoring PVI
  • 36-Item Short Form Health Survey (SF-36) general health score: 58.3 vs. 47.2, estimated difference 9.27 (95% CI 3.78-14.76) favoring PVI

Other outcomes for cryoballoon PVI vs. sham:

  • Repeat direct current cardioversion (DCCV) during 3-month blanking period: 39.7% vs. 48.4%
  • Started on class I/III AAD after 3 months: 32.3% vs. 54.1%

Interpretation:

Although prior studies have demonstrated that PVI is associated with reduction in AF burden and symptomatic improvement either alone or compared to medical therapy, SHAM-PVI is the first trial to demonstrate superiority of cryoballoon PVI to a sham procedure. Investigator assessment immediately post-procedure confirmed highly successful patient blinding to treatment arm assignment, providing novel evidence against a placebo effect influencing the symptomatic and quality of life improvements observed with PVI at 6 months. Moreover, reduction in AF burden was objectively demonstrated by ILR monitoring, and there were no crossover events during the study period to bias toward the null hypothesis. Given the comparable efficacy of cryoballoon, radiofrequency, and pulsed field ablation, the authors posit that the current data may be generalizable across PVI techniques. These findings, however, may not extend to patients in whom initial or subsequent PVI may be less successful, such as those with longstanding persistent or permanent AF or severe left atrial dilation.

References:

Dulai R, Sulke N, Freemantle N, et al. Pulmonary Vein Isolation vs Sham Intervention in Symptomatic Atrial Fibrillation: The SHAM-PVI Randomized Clinical Trial. JAMA 2024;Sep 2:[Epub ahead of print].

Presented by Dr. Rajdip Dulai at the European Society of Cardiology Congress, London, UK, September 2, 2024.

Clinical Topics: Arrhythmias and Clinical EP, EP Basic Science, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Ablation, Anti-Arrhythmia Agents, Atrial Fibrillation


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