Cryoballoon pulmonary vein isolation as first line treatment for typical atrial flutter (CRAFT): study protocol for a randomised controlled trial

Wern Yew Ding,Dhiraj Gupta,Christina Ronayne,Richard Balasubramaniam,Guy Haywood,Lilith Tovmassian,Nichola Clarkson,Tobias Reichlin,Emmanuel Williams,Ian Peter Temple,Moloy Das,Christian Sticherling,Kim Rajappan,Muzahir Tayebjee,Saagar Mahida,Zhong Chen,Matthew Bates,Claire Martin

doi:10.1007/s10840-020-00746-6

Abstract

PurposeTreatment of typical atrial flutter (AFL) with cavo-tricuspid isthmus (CTI) ablation is associated with a high occurrence rate of new onset atrial fibrillation (AF) during follow-up. There are data to support the addition of pulmonary vein isolation (PVI) to CTI ablation in patients with both AF and AFL, but the role of cryoballoon PVI only, with no CTI ablation, in AFL patients with no prior documentation of AF has not been studied.MethodsCRAFT is an international, prospective, randomised, open with blinded assessment, multicentre superiority study comparing radiofrequency CTI ablation and cryoballoon PVI in patients with typical AFL. Participants with typical AFL are randomised in a 1:1 ratio to either treatment arm, with patients randomised to PVI not receiving CTI ablation. Post-procedural cardiac monitoring is performed using an implantable loop recorder. The primary endpoint is time to first recurrence of sustained symptomatic atrial arrhythmia. Key secondary endpoints include (1) total arrhythmia burden at 12 months, (2) time to first episode of AF lasting ≥ 2 min, (3) time to recurrence of AFL or AT and (4) procedural and fluoroscopy times. The primary safety endpoint is the composite of death, stroke/transient ischaemic attack, cardiac tamponade requiring drainage, atrio-oesophageal fistula, requirement for a permanent pacemaker, serious vascular complications requiring intervention or delaying discharge and persistent phrenic nerve palsy lasting > 24 h.ConclusionThis study compares the outcomes of 2 different approaches to typical AFL—the conventional ‘substrate’-based strategy of radiofrequency CTI ablation versus a novel ‘trigger’-based strategy of cryoballoon PVI.Trial registration(ClinicalTrials.gov ID: NCT03401099)

Highlights

Typical atrial flutter (AFL) is a macro-reentrant tachycardia with a circuit within the right atrium involving the cavo-tricuspid isthmus (CTI) as the critical isthmus
The primary hypothesis of the CRAFT study is that cryoballoon pulmonary vein isolation (PVI) is superior to CTI ablation as first-line treatment for typical AFL in terms of recurrence of all atrial arrhythmias; it offers the prospect of more complete arrhythmia elimination with a single procedure, while resulting in no increase in procedural risk, or incatheter laboratory resource utilisation
The primary endpoint is defined as time to first recurrence of sustained (> 30 s) symptomatic atrial arrhythmia, including atrial fibrillation (AF), AFL and atrial tachycardia (AT), following a blanking period of 4 weeks as assessed by implantable loop recorder (ILR) data

Summary

Introduction

Typical atrial flutter (AFL) is a macro-reentrant tachycardia with a circuit within the right atrium involving the cavo-tricuspid isthmus (CTI) as the critical isthmus. In patients with AFL, the use of anti-arrhythmic drugs (AADs) to maintain sinus rhythm has limited success [1]. Radiofrequency ablation (RFA) of the CTI has a very high acute success rate and is often used as first line treatment. As many as half of these patients go on to develop atrial fibrillation (AF) during follow-up [2, 3]. The elevated risk of AF among patients with AFL indicates the presence of shared underlying disease processes that remain unchanged with only CTI ablation. There is evidence to suggest that pulmonary vein (PV) ectopy is a common initiating trigger for both arrhythmias [4, 5]

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Discussion

Conclusion