How effective is cryoablation for atrial fibrillation during concomitant cardiac surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether performing cryoablative procedures during concomitant cardiac surgical procedures is effective for the treatment of atrial fibrillation (AF). Altogether 291 papers were found using the reported search, of which nine represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. All studies showed that cryoablation during concomitant surgery had a significant effect on return to sinus rhythm (SR) conversion rate. One study showed that cryoablation was significantly more effective than mitral valve surgery alone at a 12-month follow-up (73.3% vs. 42.9%, respectively, P=0.013). The use of a concomitant cryoablative procedure has also been shown to be far superior to subsequent catheter based cryoablation in returning patients to SR at a 12-month follow-up (82% and 55.2%, respectively, P<0.001). Another study showed a significant return to AF over a three-year period (91.8% and 84.1% at discharge and three years, respectively). Return to SR was significantly decreased in those patients suffering from permanent rather than paroxysmal AF (47% vs. 85%, P<0.001). Paucity of level 1 evidence was a major limitation to this analysis. All nine papers were either small randomised controlled trials or retrospective studies with small sample sizes (57-521) and varied follow-up regimens. Six of nine studies suggested that cryoablation is most successful in patients suffering from paroxysmal rather than permanent AF. A lack of 24-h monitoring in seven of nine studies prevented effective elucidation of the rate of paroxysmal AF following cryoablation. Only one study suggested an increased complication rate from cryoablation, however, none suggested any negative impact on mortality or morbidity. We conclude that cryoablation during concomitant surgery is a safe and acceptable intervention for the treatment of AF with an SR conversion rate of between 60% and 82% at 12-months postsurgery.