Faculty Bibliography

Background There is limited research on hypertrophic cardiomyopathy (HCM), which is the most common inherited cardiac disorder, in diverse populations, including Black individuals. Current literature lacks comprehensive data on HCM disease expression, comorbidities, and outcomes in this historically disadvantaged group. The purpose of this study was to examine structural HCM characteristics, comorbidities, and outcomes in a Black and White cohort with HCM. Methods and Results The study was a subgroup analysis from a longitudinal, prospective study on HCM, with supplemental chart review. The sample included adults (≥18 years) with a clinical diagnosis of HCM, who self-identified as Black/African American or White. The study sample comprised 434 individuals; 57 (13.1%) were Black, and 180 (41.5%) were women. Black patients were younger than White patients, 54.6 (13.4) versus 62.5 (14.8) years, P=0.001. Black patients were more likely to have sub-basal and diffuse hypertrophy, 22 (38.6%) versus 56 (14.9%), P<0.001, 6 (10.5%) versus 15 (4%), P=0.017, mid-LV obstruction, 7 (12.3%) versus 21 (5.5%), P=0.025, and cardiac fibrosis ≥15%, 10 (22.2%) versus 19 (8.8%), P=0.009, than White patients. Black patients were more likely to experience appropriate implantable cardioverter defibrillator interventions, 5 (38.5) versus 5 (6.8), P<0.001 and were more likely to have ≥2 sudden death risk factors. Comorbidities were largely similar between groups, though more Black participants had Class II obesity, 12 (21.8) versus 30 (8.1), P<0.001. Both groups had similar rates of genetic testing usage. Conclusions This study underscores the need for continued research of HCM in Black populations, including tailored approaches to diagnosis and precise evaluation of cardiac anatomy.

Left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM) is often caused by systolic anterior motion (SAM) of the mitral valve caused by the interplay between increased left ventricular (LV) wall thickness and an abnormal mitral valve anatomy and geometry. Three-dimensional (3D) echocardiographic imaging of the mitral valve has revolutionized the practice of cardiology, paving the way for new methods to see and treat valvular heart disease. Here we present the novel and incremental value of 3D transesophageal echocardiography (TEE) of SAM visualization. This review first provides step-by-step instructions on acquiring and optimizing 3D TEE imaging of SAM. It then describes the unique and novel findings using standard 3D TEE rendering as well as dynamic mitral valve modeling of SAM from 3D data sets, which can provide a more detailed visualization of SAM features. The findings include double-orifice LVOT caused by the residual leaflet, the dolphin smile phenomenon, and delineation of SAM width. Finally, the review discusses the essential role of 3D TEE imaging for preprocedural assessment and intraprocedural guidance of surgical and novel percutaneous treatments of SAM.

BACKGROUND:Patients with nonobstructive hypertrophic cardiomyopathy (nHCM) often experience a high burden of symptoms; however, there are no proven pharmacological therapies. By altering the contractile mechanics of the cardiomyocyte, myosin inhibitors have the potential to modify pathophysiology and improve symptoms associated with HCM. OBJECTIVES/OBJECTIVE:MAVERICK-HCM (Mavacamten in Adults With Symptomatic Non-Obstructive Hypertrophic Cardiomyopathy) explored the safety and efficacy of mavacamten, a first-in-class reversible inhibitor of cardiac-specific myosin, in nHCM. METHODS:The MAVERICK-HCM trial was a multicenter, double-blind, placebo-controlled, dose-ranging phase II study in adults with symptomatic nHCM (New York Heart Association functional class II/III), left ventricular ejection fraction (LVEF) ≥55%, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) ≥300 pg/ml. Participants were randomized 1:1:1 to mavacamten at a pharmacokinetic-adjusted dose (targeting plasma levels of 200 or 500 ng/ml), or placebo for 16 weeks, followed by an 8-week washout. Initial dose was 5 mg daily with 1 dose titration at week 6. RESULTS:Fifty-nine participants were randomized (19, 21, 19 patients to 200 ng/ml, 500 ng/ml, placebo, respectively). Their mean age was 54 years, and 58% were women. Serious adverse events occurred in 10% of participants on mavacamten and in 21% participants on placebo. Five participants on mavacamten had reversible reduction in LVEF ≤45%. NT-proBNP geometric mean decreased by 53% in the pooled mavacamten group versus 1% in the placebo group, with geometric mean differences of -435 and -6 pg/ml, respectively (p = 0.0005). Cardiac troponin I (cTnI) geometric mean decreased by 34% in the pooled mavacamten group versus a 4% increase in the placebo group, with geometric mean differences of -0.008 and 0.001 ng/ml, respectively (p = 0.009). CONCLUSIONS:Mavacamten, a novel myosin inhibitor, was well tolerated in most subjects with symptomatic nHCM. Furthermore, treatment was associated with a significant reduction in NT-proBNP and cTnI, suggesting improvement in myocardial wall stress. These results set the stage for future studies of mavacamten in this patient population using clinical parameters, including LVEF, to guide dosing. (A Phase 2 Study of Mavacamten in Adults With Symptomatic Non-Obstructive Hypertrophic Cardiomyopathy [MAVERICK-HCM]; NCT03442764).

Cardiac amyloid A (AA) amyloidosis is rare. We present the case of a 72-year-old woman with obstructive hypertrophic cardiomyopathy (HCM) and biopsy-proven renal AA amyloidosis whose dyspnea and exercise intolerance had worsened over the previous year. Her AA amyloidosis was suspected to be secondary to chronic diverticulitis for which she had undergone hemicolectomy and sigmoidectomy 3 years prior. Echocardiographic findings were consistent with worsening left ventricular outflow tract obstruction at rest. Cardiac magnetic resonance imaging revealed patchy areas of midwall late gadolinium enhancement. Right ventricular endomyocardial biopsy did not reveal amyloid deposition, and cardiac technetium-99m pyrophosphate scintigraphy did not suggest transthyretin amyloidosis. The patient underwent septal myectomy with resection of an accessory papillary muscle. Pathological examination of the myectomy specimen was consistent with HCM. In addition, there was a thick layer of diffuse endocardial and vascular amyloid deposition that was identified as AA type by laser-microdissection with liquid chromatography-coupled tandem-mass spectrometry. This case report highlights the presence of 2 distinct disease processes occurring simultaneously and the importance of tissue diagnosis of AA amyloidosis, a condition that is not commonly associated with HCM.