Left ventricular outflow tract obstruction with abnormal papillary muscles

Abstract

IntroductionAbnormal papillary muscle (PM) is an unusual cause of left ventricular outflow tract (LVOT) obstruction [1], and is often found in patients with hypertrophic cardiomyopathy (HCM) [2]. Cardiac magnetic resonance (CMR) imaging has been reported to be useful for diagnosis of abnormalities of the PM and mitral valve in HCM patients [3][4][5]. Abnormal PMs with LVOT obstruction are usually treated by surgical correction [6,7], and therefore, reports on medical treatment are limited [8]. In the present report, we describe the case of an HCM patient associated with LVOT obstruction due to abnormal PMs, which was accurately diagnosed by CMR imaging and successfully treated with a betablocker. Case reportA 65-year-old man with a history of hypertension was admitted to our hospital with fainting and syncope. The patient had experienced recurrent syncope since 20 years of age, and was diagnosed with epilepsy at 49 years of age. Treatment with anticonvulsants was soon discontinued because of skin rash. He had been taking amlodipine (5 mg/day) for hypertension. On admission, his blood pressure was 158/93 mmHg, pulse rate was 61 beats per minute, and systolic heart murmur of grade 4/6 was audible at the apex of the heart. Chest radiography showed mild cardiomegaly, and electrocardiography showed high voltage and mild ST-segment depression. A B S T R A C TA 65-year-old man with a history of hypertension was admitted to our hospital with fainting and syncope. He had experienced recurrent syncope since 20 years of age. On admission, systolic heart murmur was audible at the apex of the heart. Echocardiography revealed anteriorly displaced papillary muscles (PMs), elongation of the anterior mitral valve leaflet (AML), and systolic anterior motion (SAM) of the AML. Color Doppler imaging showed accelerated flow with a pressure gradient (PG) of 56 mmHg at the left ventricular outflow tract (LVOT). Cardiac magnetic resonance imaging revealed mild asymmetric septal hypertrophy and multiple accessory PMs. Cine images clearly demonstrated SAM and LVOT obstruction due to anteriorly displaced PMs. Based on these findings, the patient was diagnosed as having hypertrophic cardiomyopathy and LVOT obstruction due to abnormal PMs. Oral administration of bisoprolol (2.5 mg/day) was initiated, because the patient rejected surgical treatment. Follow-up echocardiography revealed a gradual decrease in the LVOT-PG to 24 mmHg, and no episodes of fainting or syncope have recurred for 2 years after the initiation of bisoprolol. <Learning objective: Abnormal papillary muscle (PM) is an unusual cause of left ventricular outflow tract (LVOT) obstruction, and cardiac magnetic resonance (CMR) imaging has been reported to be useful for diagnosis of abnormal PM. Abnormal PMs with LVOT obstruction are usually treated by surgical correction, and therefore, reports on medical treatment are limited. We report a case of LVOT obstruction due to abnormal PMs, which was accurately diagnosed by CMR imaging and successfully treated with a beta-blocker.>