Comparison of Epicardial Cryoablation and Irrigated Radiofrequency Ablation in a Swine Infarct Model

Epicardial Cryoablation in Swine. Introduction: Cryoablation is an alternative to radiofrequency (RF) energy used in some ablation procedures. Its role and effectiveness compared to irrigated RF in epicardial tissue and epicardial substrates is not yet fully established. Methods and Results: Using a swine chronic infarct model, we compared RF lesions produced by an open-irrigated 3.5 mm tip catheter with those produced by an 8 mm tip cryocatheter in epicardial infarct border zone, epicardial normal tissue, and normal endocardium. In the infarct border zone, cryolesions were larger than RF lesions in maximum diameter (9.3 +/- 2.9 mm vs 6.2 +/- 2 mm, P < 0.001) and volume (171.7 +/- 173.1 mm3 vs 77 +/- 53.5 mm3, P = 0.021). In normal epicardial tissue, cryolesions were larger in maximum diameter (11.2 +/- 4.3 mm vs 7.7 +/- 3.1 mm, P = 0.012), depth (5.8 +/- 1.6 mm vs 4.7 +/- 1.4 mm, P = 0.034), and volume (274.7 +/- 242.2 mm3 vs 112 +/- 102.9 mm3, P = 0.002). In normal endocardium, no significant differences were found. Conclusions: Epicardial cryoablation with an 8 mm tip cryocatheter led to larger lesion volume in infarcted myocardium compared to a 3.5 mm irrigated RF catheter. This is likely related to a combination of cryoadherence, more efficient energy delivery with horizontal orientation, and lack of warming by circulating blood. Cryoablation merits further investigation as a modality for treating ventricular tachycardia of epicardial origin in humans. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1016-1023, September 2012)