C62 Challenging Diagnosis of a Triple Cardiac Pathology: Transthyretin Amyloidosis With Aspects of Hypertrophic Obstructive Cardiomyopathy and Anomalous Coronary Artery

Abstract

A 70 years–old man with a history of systemic hypertension and surgically treated bilateral carpal tunnel was referred for dyspnea on exertion for few months. At physical examination a systolic heart murmur exacerbated by Valsalva maneuver was appreciated; no signs of heart failure. EKG with low–voltage QRS is shown in Fig.1A. Blood tests showed elevated NT–proBNP (1434 pg/ml). Transthoracic echo (ETT) revealed hyperdynamic left ventricle (LV) with severe asymmetric hypertrophy (interventricular septum 23 mm, posterior wall 17 mm), ‘granular sparkling’ appearance of myocardium, grade 2 diastolic dysfunction and ‘apical sparing’ pattern at global longitudinal strain (GLS, Fig.1B). Moreover, elongated mitral leaflets, anomalies of mitral sub–valvular apparatus with apically displaced papillary muscles and systolic anterior motion of the mitral valve (SAM) with dynamic outflow tract obstruction (20 mmHg at rest and 90–100 mmHg with Valsalva maneuver) were seen (Fig. 2A–B–C). For ETT suspicion of a coronary artery anomaly (Fig.3A), the patient underwent coronary CT angiography that confirmed a separate origin of left anterior descending artery (LAD) from right coronary sinus with a long mid–proximal intramyocardial bridge (Fig.3B–C). As a part of evaluation of the hypertrophic phenotype, a 99mTC–HDP bone scintigraphy was performed with high–grade of cardiac uptake (Perugini Score 2, Fig.1C). Screening for monoclonal gammopathy and genetic testing for hereditary amyloidosis resulted negative. Cardiac MRI revealed late gadolinium enhancement (LGE) in midwall septum, diffuse endocardial LGE in the LV basal inferior and posterolateral walls (Fig.1D), elevated T1 mapping and ECV (40–42%) and confirmed the asymmetric hypertrophy with apically displaced papillary muscles (Fig.2D) and SAM. These clinical, EKG and imaging features led to a non–invasive diagnosis of wild–type transthyretin cardiac amyloidosis (ATTRwt) with aspects of hypertrophic obstructive cardiomyopathy (HOCM). The patient started a disease–modifying therapy with Tafamidis and, cautiously, Metoprolol tartrate, with good tolerance and relevant reduction of LVOT obstruction at follow–up. Genetic testing for HCM was also performed. In conclusion, in rare cases hypertrophic phenotype may be challenging, showing features overlap between ATTR and HOCM. Multimodality evaluation is crucial for a correct diagnosis, thus identifying the most effective target–therapy for the underlying hypertrophic phenotype.