Does cryomaze injure the circumflex artery?: a preliminary search for occult postprocedure stenoses

Ensuring the transmurality of the mitral isthmus lesion, a critical component of the cryomaze, entails mirror-image application of the cryoprobe both on endocardial and epicardial surfaces when carrying out ablation. Concerns of circumflex artery injury have been expressed during the epicardial application of the cryoprobe over the coronary sinus as the artery courses on the posterior surface of the sinus in the atrioventricular (AV) groove. The objective of this study was to analyze the incidence of significant injury to the circumflex artery and its impact on outcomes, if any, in those patients who have undergone cryomaze.

Between August 2004 and December 2009, a total of 223 patients underwent argon-based cryoablation (120-second application at -140°C). After Western Institutional Review Board approval, 20 consecutive patients with normal results of preoperative coronary angiograms (right dominance, 75%; left dominance, 15%; codominant circulation, 10%) and who were at least 6 months postablation were enrolled in this study. The mean ± SD age was 60.74 ± 14.99 years, 35% were men, and 50% belonged to New York Heart Association class III/IV. The mean ± SD atrial fibrillation duration was 23.83 ± 36.28 months (65% were paroxysmal). Ten percent (n = 2) underwent primary cryomaze, 40% (n = 8) underwent cryomaze plus mitral valve repair, and 50% (n = 10) underwent two or more concomitant valvular procedures. Twelve patients underwent biatrial cryomaze, and eight underwent only left-sided cryomaze. All patients underwent a 24-hour Holter monitoring, electrocardiogram stress test, and a coronary computed tomographic angiogram, as per the protocol of this study.

At discharge, 85% had normal sinus rhythm, whereas 15% of the patients were paced. On a mean ± SD follow-up at 32.57 ± 19.51 months, the Holter and/or pacemaker interrogation revealed AV synchrony in all patients-16 in sinus rhythm and 4 with heart block who converted to AV synchrony after subsequent pacemaker implantation. The stress test was available for 18 patients, and its results were negative in all of them. On the computed tomographic angiogram, 95% of the patients had a completely patent circumflex artery. Stenosis was noticed in only one patient (right dominant circulation), with a 30% to 40% tubular stenosis of the circumflex artery. However, this lesion corresponded to the P1 area of the mitral annulus and was significantly proximal on the circumflex to the P3 area, where the cryoprobe was applied during the cryomaze procedure.

Barring one case of partial circumflex stenosis, likely due to the ongoing normal progression of coronary artery disease, these data derived from a limited prospective trial suggest that epicardial application during the cryomaze procedure does not cause anatomic or physiological compromise of the circumflex artery. Nevertheless, laboratory and anecdotal evidence exist that conflict with this conclusion, and caution should be exercised when applying cryothermy in the vicinity of coronary arteries.