Catheter ablation has become an accepted treatment strategy for patients with paroxysmal atrial fibrillation (AF). A multicentre prospective andomised trial showed a dramatic and significant improvement in freedom from AF after catheter ablation compared with anti-arrhythmic drug therapy.1 The Heart Rhythm Society/Eueopean Heart Rhythm Association/European Cardiac Arrhythmia Society guidelines2 currently list catheter ablation as an accepted treatment modality for paroxysmal AF after a patient has broken through a single anti-arrhythmic drug. The foundation of the current ablation strategy is electrical isolation of the pulmonary veins. Currently, catheters originally designed for ablating focal tachycardias and single accessory pathways are being used to deliver multiple radiofrequency lesions in a connect the dots pattern around the pulmonary veins. The procedure typically uses an electroanatomical mapping system, intracardiac echocardiography, an irrigated radiofrequency ablation catheter and requires considerable operator expertise. In addition, the Achilles' heel of the procedure is the problem of pulmonary vein reconnection after ablation, which accounts for the majority of AF recurrences.3

Newer technologies are evolving that are designed specifically for pulmonary vein isolation. However, despite the inherent attraction of balloon-based ablation strategies, early technologies struggled to achieve safety and efficacy endpoints. The first ultrasound balloon ablation technology never made it to market.4 A later ‘focused’ ultrasound balloon entered clinical trials but was abandoned because of the higher than expected complication of left atrial–oesophageal fistula.5 The cryoballoon catheter became the first balloon catheter …