A case of percutaneous septal myocardial ablation in a patient with obstructive hypertrophic cardiomyopathy with accessory mitral valve tissue

Accessory mitral valve tissue (AMVT) is a rare congenital anomaly that sometimes causes left ventricular outflow tract (LVOT) obstruction. We report the case of a 72-year-old woman with hypertrophic obstructive cardiomyopathy (HOCM) complicated by AMVT. The patient presented at our hospital with palpitations and shortness of breath. Transthoracic echocardiography revealed a diagnosis of HOCM and an abnormal structure inside the LVOT. Transesophageal echocardiography revealed an AMVT. We initially treated the patient with oral medication, but due to side effects, the patient could not take the target dose and her symptoms did not improve. We suggested surgical treatment, but the patient refused. By evaluating the relationship between AMVT and the surrounding tissues using three-dimensional transesophageal echocardiography, we determined that percutaneous septal myocardial ablation (PTSMA) might be successful. The first PTSMA was not effective, but the second procedure showed significant improvement in the pressure gradient and symptoms. The patient with HOCM and concomitant AMVT had a severe LVOT pressure gradient, and PTSMA was performed with excellent results. Since we experienced a rare case and were able to treat it percutaneously, we report our findings in relation to the literature.