Effect of stereotactic body radiation therapy on left ventricular diastole function in symptomatic patients with hypertrophic obstructive cardiomyopathy

Abstract

Abstract Background We applied stereotactic body radiotherapy (SBRT) for the first time in the treatment of patients with hypertrophic obstructive cardiomyopathy (HOCM), and significant improvements in symptoms and diastolic function were observed after treatment. Objectives To evaluate the impact of SBRT on cardiac structure, function, and clinical indicators in patients with HOCM. Methods This study included 12 drug-refractory symptomatic HOCM patients (6 who underwent SBRT and 6 who received pharmacological treatment alone) and conducted a retrospective analysis of their clinical data. Transthoracic echocardiography was used to assess various ultrasound parameters, including interventricular septal thickness, left ventricular outflow tract diameter, peak pressure gradient and diastolic function before treatment and at 1, 3, and 6 months after treatment. Additionally, assessments were made for symptoms; laboratory test results (NT-proBNP, cTnT, CK-mb, and CRP); 6-minute walk test results; New York Heart Association (NYHA) functional classification; and Kansas score before and 6 months after treatment. Results HOCM patients showed significant improvement in mitral valve systolic anterior motion after SBRT. Compared to that at baseline, the interventricular septum thickness gradually decreased at 1, 3, and 6 months after treatment (-8.8%, -8.0%, -14.4%, respectively) (P<0.05). Compared to those in the drug group, the left ventricular diastolic function and structural parameters, including the interventricular septum thickness (mean change from baseline of -3 mm [95% CI: -5.2 to -0.8 mm] and 1.3 mm [95% CI: 0.5 to 2.2 mm]; P<0.05), and the LA GLS (change of 2.1% [-0.03% to 4.2%] and -0.9% [-3.1% to 1.3%]; P<0.05), were significantly improved in HOCM patients at 6 months posttreatment. Similarly, the clinical indicators, including KCCQ, increased from baseline (61 (range, 47.3-70) to 84 (range, 70-89.5) at 6 months posttreatment (P<0.05), and the 6-minute walk test score increased from 187 meters (range, 50-370) to 401 meters (range, 280-540) (P<0.05). Conclusion SBRT significantly improved left ventricular diastolic function and reduced interventricular septum thickness in HOCM patients. Symptoms, exercise capacity and clinical indicators improved after SBRT in HOCM patients.