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Mainstay ablation procedure for atrial fibrillation shows substantial benefit over sham procedure

SHAM-PVI trial finds common ablation procedure significantly reduces time in atrial fibrillation compared to sham procedure

Atrial Fibrillation


Key take-aways 

  • First double-blind randomised trial of its kind finds widely used ablation procedure significantly reduces atrial fibrillation burden and substantially improves symptoms and quality of life compared to sham treatment. 
  • Authors say that there is now conclusive evidence that the cornerstone of catheter ablation treatment for symptomatic atrial fibrillation—pulmonary vein isolation—actually works, putting widespread concern about a substantial placebo effect to rest. 
     

London, United Kingdom – 2 September 2024: A catheter ablation procedure widely used to treat the most common heart rhythm disorder significantly reduces the burden of atrial fibrillation (AF) and results in clinically important improvements in symptoms and quality of life compared with a sham (placebo) procedure, according to late breaking research presented in a Hot Line Session at this year’s ESC Congress 2024 in London, UK (30 Aug – 2 Sept).  

“Despite being widely performed in clinical practice, pulmonary vein isolation ablation has never been compared with a sham procedure,” said principal investigator Dr Rick Veasey. “Our results provide conclusive evidence for the benefit of pulmonary vein isolation ablation in individuals with symptomatic atrial fibrillation, putting concerns about a substantial placebo effect to rest.” 

AF is the most common type of abnormal heart rhythm, affecting 2% of people worldwide [1]. If left untreated it can result in symptoms including palpitations and breathlessness and can lead to serious complications such as stroke or heart failure. Treatment options include drugs or ablation, which involves burning or freezing a small area of the heart to create a scar and prevent the spread of abnormal electrical impulses, often from the pulmonary veins, from causing AF. 

Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for both symptomatic paroxysmal (intermittent episodes of AF) and persistent AF. During the procedure, catheters are inserted into the heart to deliver radiofrequency energy or cryoballoon ablation to destroy tissue on the veins that is causing disruptive electrical signals. 

Despite numerous clinical trials advocating PVI for symptomatic AF, there are concerns that PVI has a substantial placebo effect, and there have been no trials comparing PVI with a sham procedure.  
 
To fill this important evidence gap, the SHAM-PVI trial enrolled and randomised 126 patients with symptomatic paroxysmal or persistent AF, previously treated with at least one antiarrhythmic drug who had been referred for catheter ablation at two NHS trusts in the UK.  

The patients were randomised in a 1:1 ratio to undergo either PVI using cryoablation, during which a balloon filled with liquid nitrogen is used to freeze the heart tissue that is causing the irregular heartbeat (64 patients), or a sham procedure involving phrenic nerve pacing to simulate an ablation procedure (62 patients). Demographic and clinical characteristics were well balanced between the groups. 

The main measure of interest was AF burden (% time in AF) at 6-months (excluding an initial 3-month blanking period) assessed using a tiny implantable heart monitor placed under the skin. Other outcomes included important quality of life measures reported by patients, such as physical and social functioning, AF symptoms such as palpitations and breathlessness, and time to arrhythmia events. 

The researchers found that at 6 month follow-up, average change in AF burden from the start of the trial was 60% in the ablation group and 35% in the sham intervention group.  

In patients with persistent AF, there was an average reduction in AF burden of 71% in the ablation group and 45% in the sham intervention group.  

In patients with intermittent AF, the average reduction in AF burden was 16% in the ablation group compared with an average increase of almost 3% in the sham intervention group. 

Overall quality of life scores were found to be substantially in favour of catheter ablation at 6 months. Similarly, scores based on symptoms, daily activities, and treatment concern were also in favour of ablation.  

In addition, measures of health-related quality of life (e.g., physical functioning, vitality, emotional well-being, social functioning) also improved much more in the ablation group than in the sham intervention group at 6 months. 

“We expected that PVI would be more effective than a placebo procedure in patients with symptomatic AF, and indeed, the results proved our hypothesis was correct,” said lead author Dr Rajdip Dulai. “Going forward we would expect that patients with symptomatic AF be referred for ablation treatment without hesitation.” 

 

ENDS  

Notes to editor

This press release accompanies both a presentation and an ESC press conference at ESC Congress 2024. It does not necessarily reflect the opinion of the European Society of Cardiology. 

 

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Funding: Eastbourne Cardiology Research Charity Fund & Medtronic LTD. 

Disclosures:  Dr Neil Sulke is a trustee of Eastbourne Cardiology Research Charity Fund. Prof Pier Lambiase receives research grants from Medtronic, Abbott, and Boston Scientific. Prof Nick Freemantle receives consulting fees from ALK, Sanofi Aventis, Gedeon Richter, Abbott, Galderma, AstraZeneca, Ipsen, Vertex, Thea, Novo Nordisk, Aimmune and sits on a DSMB for Orion. Dr Neil Srinivasan receives research grants from Abbott. Dr Rick Veasey receives research grants from Medtronic. The remaining authors declare no conflict of interest. 

 

References and notes 

‘SHAM-PVI - A randomised sham-controlled study of pulmonary vein isolation in symptomatic atrial fibrillation’ will be discussed during Hot Line 10 on Monday 2 September in room London. 

 

About ESC Congress 2024 

It is the world’s largest gathering of cardiovascular professionals, disseminating ground-breaking science both onsite in London and online – from 30 August to 2 September. Explore the scientific programme. More information is available from the ESC Press Office at press@escardio.org. 

About the European Society of Cardiology

The ESC brings together health care professionals from more than 150 countries, working to advance cardiovascular medicine and help people to live longer, healthier lives.