Delayed Reduction in Left Ventricular Outflow Tract Gradient After Endocardial Radiofrequency Ablation for Septal Hypertrophy In a Patient with Hypertrophic Obstructive Cardiomyopathy: A Case Report

Background: Left ventricular outflow tract (LVOT) obstruction can cut down cardiac output in hypertrophic obstructive cardiomyopathy (HOCM). Patients with HOCM who undergo successful endocardial radiofrequency ablation for septal hypertrophy (ERASH) usually present with quick relief of LVOT obstruction. However, a delayed reduction in the LVOT gradient after ERASH has never been reported previously. Case Description: We present a case of a 79-year-old woman diagnosed with HOCM, characterized by diffuse thickening of the interventricular septum and systolic anterior motion (SAM) of the anterior mitral valve leaflet. And A result indicating a distance of less than 50 meters was observed during the 6-minute walk test. Considering less trauma, the patient underwent a successful ERASH procedure with the assistance of CARTO3 and CARTOSOUND system. The ablation was performed at a power of 50 W and a temperature of 30℃. During the procedure, we observed the disappearance of SAM and a rapid reduction in the LVOT gradient from 93 mmHg to 43 mmHg. The patient exhibited a progressive enhancement in exercise capacity, accompanied by the absence of any symptoms. Transthoracic echocardiography (TTE) revealed a delayed reduction LVOT gradient during the follow-up assessments. Conclusions: The delayed reduction of LVOT gradient possibly induced by the post-ablation myocardial edema and no significant adverse effect on prognosis was observed. Further investigations are warranted to explore the potential impact of high ablation power and precautionary measures.