Percutaneous Intramyocardial Septal Radiofrequency Ablation for Obstructive Hypertrophic Cardiomyopathy in Children

Percutaneous Intramyocardial Septal Radiofrequency Ablation for Drug-refractory Obstructive Hypertrophic Cardiomyopathy in Children and Adolescents: An Early Feasibility Study

The primary purpose of this study was to demonstrate the safety and efficacy of percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) in children and assessed its performance and functional outcomes in the follow-up. This is a single-arm, single-center study.

The prevalence of hypertrophic cardiomyopathy (HCM) ranks second among cardiomyopathies in children. The prognosis of HCM has been previously demonstrated to be closely correlated with age. HCM in childhood is frequently associated with severe symptoms and high mortality rates, exhibiting a 36% higher incidence of malignant ventricular arrhythmias compared to adults, and being twice as likely to necessitate advanced heart failure therapies such as heart transplantation or left heart assist devices. Surgical septal myectomy can effectively help patients with drug-refractory symptoms but carries risks inherent to invasive procedures and requires expertise that is not universally available. Alcohol septal ablation is not recommended for applications in the young patient group.

Percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) is a new method for the treatment of HCM using a special diagnosis and treatment device on the target area of the heart under the guidance of echocardiography. The method breaks through the worldwide problem of minimally invasive treatment of the myocardium on the beating heart, thus avoiding X-ray radiation and contrast agent damage. Previous research has illustrated the effectiveness and safety of PIMSRA for adult patients with obstructive HCM. We have found that PIMSRA results in sustained improvement in exercise capacity, persistent reduction in left ventricle outflow tract (LVOT) gradient, and sustained improvement in cardiac function.

This is an early feasibility study to evaluate the clinical safety and efficacy of PIMSRA in pediatric patients, as well as to assess postoperative cardiac function and exercise capacity.

Inclusion Criteria:

• Clinical diagnosis of hypertrophic obstructive cardiomyopathy
• Age younger than 18 years
• Resting or provoking left ventricular outflow tract gradient ≥ 50 mmHg
• Drug-refractory symptoms or intolerable to pharmaceutical therapies
• Heart function of New York Heart Association ≥ class II

Exclusion Criteria:

• Secondary left ventricular hypertrophy (LVH) related to subaortic stenosis or aortic stenosis
• Presence of concomitant heart disease requiring surgery
• Left ventricular ejection fraction <40%
• Cardiac resynchronization therapy within 3 months