Percutaneous Intramyocardial Septal Radiofrequency Ablation for Interventricular Septal Reduction: An Ovine Model with 1-Year Outcomes

<b><i>Background:</i></b> Percutaneous intramyocardial (PIM) septal radiofrequency ablation (SRA) is a novel treatment approach for hypertrophic obstructive cardiomyopathy patients, but there has been lack of a large animal model to study PIM-SRA. We aimed to validate the long-term safety and efficacy of PIM-SRA and to observe pathological changes of the ablated interventricular septum (IVS) in a healthy sheep model. <b><i>Methods and Results:</i></b> Twelve sheep were randomized to the PIM-SRA group (<i>n</i> = 6) and the sham group (<i>n</i> = 6). In the PIM-SRA group, a radiofrequency (RF) electrode was inserted into the IVS with a maximum power of 80 W for 5 min. In the sham group, the RF electrode tip was positioned in the IVS segment but without RF power delivery. Septal hypokinesis was seen in all PIM-SRA group animals immediately after the procedure; the systolic wall thickening rate and motion amplitude of the ablated region decreased (<i>p</i> &#x3c; 0.01), and the diastolic IVS thickness also decreased significantly over time (<i>p</i> &#x3c; 0.01). ECG showed that all the sheep had normal sinus rhythm during the follow-up. Pathological examinations revealed scar tissue in the ablated region as expected. <b><i>Conclusions:</i></b> PIM-SRA produced precisely ablated myocardial tissue, reduced the IVS thickness significantly, preserved the global LV function, and avoided the incidence of conduction system damage in the long term. PIM-SRA was found to be a safe and effective minimally invasive septal reduction therapy.