Percutaneous Intramyocardial Septal Cryoablation: A Canine Model with 6 months Follow-up

BACKGROUNDEchocardiography-guided percutaneous intramyocardial septal radiofrequency ablation (PIMSRA, Liwen procedure) is a novel treatment option for hypertrophic obstructive cardiomyopathy (HOCM). The safety and feasibility of using this procedure for cryoablation are unknown. OBJECTIVETo establish a canine model for echocardiography-guided percutaneous intramyocardial septal cryoablation (PIMSCA). METHODSEight canines underwent PIMSCA and had electrocardiography, echocardiography, myocardial contrast echocardiography (MCE), (ECG), serological and pathological examinations during the preoperative, immediate postoperative, and in 6-month follow-up. RESULTSAll eight canines underwent successful cryoablation and continued to be in sinus rhythm during ablation and without malignant arrhythmias. MCE showed that ablation area had decreased myocardial perfusion after procedure. Troponin I levels were significantly elevated [0.010 (0.005, 0.297) ng/mL vs. 3.122 (1.152,7.990) ng/mL, p < 0.05)]. At follow-up 6-months after procedure, all animals were alive, with thinning of the interventricular septum (7.26 {+/-} 0.52 mm vs. 3.86 {+/-} 0.29 mm, p < 0.05). Echocardiography showed no significant decrease in left ventricular ejection fractions (LVEF) (54.32 {+/-} 2.93 %vs. 54.70 {+/-} 2.47 %, p > 0.05) or changes by pulse-wave Doppler E/A (1.17 {+/-} 0.43 vs. 1.07 {+/-} 0.43, p > 0.05), E/e(8.09 {+/-} 1.49 vs. 10.05 {+/-}2.68, p > 0.05). Pathological findings proved effective cryoablation in myocardial tissues. We observed pericardial effusions and premature ventricular complexes (PVCs) associated with the procedure. CONCLUSIONOur findings provide preliminary evidence of the safety and feasibility of PIMSACA in interventricular septum reduction, which provides a potentially new treatment option for HOCM.