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Cryoballoon ablation noninferior to radiofrequency energy ablation for pulmonary vein isolation
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BOSTON — Cryoballoon ablation was noninferior to radiofrequency energy ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation, according to results of the FreezeAF study presented at the Heart Rhythm Society Annual Scientific Sessions.
Researchers conducted the prospective, randomized, controlled, noninferiority study to compare the safety and effectiveness of a cryoballoon ablation catheter (Arctic Front, Medtronic) to radiofrequency ablation.
In total, 322 patients (mean age, 60 years; 60.5% men) with documented symptomatic paroxysmal AF and at least one failed antiarrhythmic drug therapy were randomly assigned to cryoballoon or radiofrequency ablation for pulmonary vein isolation. Clinical follow-up was performed at 3, 6, 9 and 12 months; Holter ECG and event recordings were performed for at least 7 days at 6 months and 12 months. MRI and CT scans were performed before and after 3 months to determine pulmonary vein stenosis.
The primary endpoint was freedom from paroxysmal AF without antiarrhythmic drugs or persistent complications at 6 months and 12 months. The researchers defined a failure as a paroxysmal AF episode lasting longer than 30 seconds.
Armin Luik, MD, from Staedtisches Klinkum Karlsruhe, Karlsruhe, Germany, and colleagues reported that redo procedures were performed in 19.9% of the cryoballoon group vs. 19.5% of the radiofrequency group.
The rate of procedural success at 6 months was 63% for the cryoballoon group vs. 62% for the radiofrequency group (P for noninferiority = .006) and at 12 months was 68% vs. 65%, respectively (P for noninferiority < .001), Luik said during a presentation.
In a per-protocol analysis, there was no difference between the groups in the primary outcome at 6 months (cryoballoon group, 65%; radiofrequency group, 64%; P for noninferiority = .005) or at 12 months (cryoballoon group, 74%; radiofrequency group, 72%; P for noninferiority = .001), he said.
In addition, the researchers found that no pulmonary vein stenosis, CV death, stroke or transient ischemic attack occurred. Phrenic nerve palsy occurred in 5.8% of the cryoballoon group vs. 0% in the radiofrequency group (P = .002), Luik said. He noted that six of the nine cases of phrenic nerve palsy were resolved by 6 months.
“[Pulmonary vein] isolation with the cryoballoon in patients with paroxysmal [AF] was as effective as open irrigated radiofrequency in combination with a 3-D mapping system,” Luik said. “It is faster regarding the procedure time, but it takes [a higher level of] X-ray evidence to prove the balloon’s occlusion, and has a higher complication rate due to a higher rate of phrenic nerve palsies.” – by Erik Swain
Reference:
Luik A, et al. Abstract LBCT01-03. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 13-16, 2015; Boston.
Disclosure: Luik reports receiving consultant fees/honoraria from Medtronic and St. Jude Medical and serving on the speakers’ bureau for Biotronik and Boston Scientific.
Perspective
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Jagmeet Singh, MD, DPhil
This was a very well-conducted study which prospectively randomized 322 patients to a cryoballoon ablation arm to a radiofrequency energy ablation arm. It showed that freedom from AF at the 6-month mark as well as the 12-month mark was comparable between the radiofrequency and cryoballoon approaches. Even the absence of complications was comparable between the two arms. Of note, the incidence of phrenic nerve injury was higher in the cryoballoon arm, as would have been expected. However, the risk for any major phrenic nerve injury was less than 2%. So I think the cryoballoon approach is still a very safe and efficacious procedure.
The results prove that the two energy systems are comparable and that balloon-based technology is here to stay. For those who were not believers in cryo, this will make them more aware that the results are pretty comparable with radiofrequency. On the flipside, those who are cryoablators alone will recognize that radiofrequency has the same efficacy as cryo does. I think this opens up the market for different strategies. It allows us to choose different strategies and individualize the adoption of the energy as well as the technology based on the patient and the patient’s anatomy.
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