CONGRESS ABSTRACT

A 27-year-old male was diagnosed at the age of 15 with sarcomeric hypertrophic obstructive cardiomyopathy (HOCM) (MYH-7 gene, variant c1816 G>A). No comorbidities. Patient underwent periodic follow-ups showing a predominant mid-ventricular obstruction with evolution in apical aneurysm. He was on beta-blockers. Due to massive septal hypertrophy (30 mm), extensive late gadolinium enhancement (LGE) on MRI evaluation and apical aneurysm, at the age of 22 he underwent S-ICD implantation for primary prevention of SD. At most recent evaluation, the patient showed dyspnea on moderate exertion (NYHA II), on a regimen of Metoprolol 100 mg 1 +1/2 cp. EKG showed sinus bradycardia, left ventricular hypertrophy (LVH), marked repolarization abnormalities with giant negative T waves in the antero-lateral leads (Fig.1a). Echocardiogram showed a marked asymmetric hypertrophy of the interventricular septum (IVS) in the mid-portion (28 mm) with midventricular obstruction and apical aneurysm leading to an hourglass-shaped ventricular cavity (Fig.2a). Ejection fraction (EF) was 68%. Basal dynamic mid-ventricular obstruction with a peak gradient (Gmax) of 50 mmHg was present together with latent dynamic left outflow tract obstruction due to SAM on Valsalva maneuver of 54 mmHg (Fig.3a). Moderate left atrial dilation and a triphasic transmitral pattern were reported. Lab test showed NT-proBNP 971 pg/ml. Due to LVOT obstruction and functional class, compassionate therapy with Mavacamten was proposed and started with progressive up-titration according to protocol. At 24 weeks follow-up, on Mavacamten 10 mg, patient was in functional class NYHA I. NT-proBNP was markedly reduced (155 pg/ml). EKG showed significant reduction of the antero-lateral repolarization abnormalities (Fig.1b). Echocardiogram revealed no more LVOT and mid-ventricular dynamic obstruction (Gmax of 8 mmHg, Fig.3b), left ventricular remodeling with larger left ventricular cavity size, reduced IVS hypertrophy (mid-IVS 21 mm) and reduced left atrial dimensions (Fig.2b). EF was 72%. Diastolic function was improved.  In conclusion, Mavacamten dramatically improved the clinical and morpho-functional characteristics of this patient. We noticed not only a reduction of the gradients but also a positive remodeling of left ventricular cavity associated with a clear improvement in diastolic function, EKG alterations and Lab tests. We hope that this also implies a change in the natural history of the disease in the long term.