The optimal dosage of cryotherapy during cryoballoon ablation of pulmonary veins is still unclear. This trial tested the noninferiority of a novel, individualized, cryotherapy-dosing strategy for each vein.Methods and Results
This prospective, randomized, multicenter, noninferiority study included 140 patients with paroxysmal atrial fibrillation, which was refractory to antiarrhythmic drugs. Patients were randomly assigned to a conventional strategy of 180-second cryoballoon applications per vein with a bonus freeze (control group, n=70) or to a shorter-time application protocol, with 1 application that lasted the time required for electric block time to effect plus 60- and a 120-second freeze bonus (study group, n=70). Patients were followed with a long-term monitoring system of 30 days. At 1-year follow-up, no difference was observed in terms of free atrial fibrillation-recurrence rates: 79.4% in control versus 78.3% in study group (Δ=1.15%; 90% confidence interval, −10.33% to 12.63%; P=0.869). Time to effect was detected in 72.1% of veins. The control and study groups had similar mean number of applications per patient (9.6±2 versus 9.9±2.4; P=0.76). Compared with controls, the study group had a significantly shorter cryotherapy time (28.3±7 versus 19.4±4.3 minutes; P<0.001), left atrium time (104±25 versus 92±23 minutes; P<0.01), and total procedure time (135±35 versus 119±31 minutes; P<0.01). No differences were observed in complications or acute reconnections.Conclusions
The new time-to-effect–based cryotherapy dosage protocol led to shorter cryotherapy and procedure times, with equal safety, and similar acute and 1-year follow-up results, compared with the conventional approach.Clinical Trial Registration
URL: https://clinicaltrials.gov. Unique identifier: NCT02789358.