Symptomatic Hypertrophic Obstructive Cardiomyopathy Research Articles

Mavacamten: Real-World Experience from 22 Months of the Risk Evaluation and Mitigation Strategy (REMS) Program

Background: Mavacamten is the only cardiac myosin inhibitor approved by the US FDA for treatment of symptomatic New York Heart Association class II-III obstructive hypertrophic cardiomyopathy (HCM) patients. Under the risk evaluation and mitigation strategy (REMS) program for mavacamten, patients are required to be monitored for development of systolic heart failure, and reduction of left ventricular ejection fraction (LVEF) to <50%. We report results from the mavacamten REMS database (28-Apr-2022 to 27-Feb-2024). Methods: Data on healthcare providers and pharmacy certification, patient monitoring (from Patient Status Forms, based partly on echocardiograms), and screening for drug interactions prior to each dispense were collected. Results: Of 6,299 patients who received ≥1 dose of mavacamten, 60.0% were women; 64.6% were >60 years of age. Of 5,573 patients with submitted Patient Status Forms, 256 (4.6%) developed LVEF <50% and 71 (1.3%) experienced heart failure requiring hospitalization (HFH). On the 29,111 status forms in these patients, each representing an assessment of an echocardiogram, LVEF <50% was reported on 276 (0.9%) and HFH was reported on 86 (0.3%). Of 1,929 patients with ≥1 year of treatment, 78 (4.0%) had an LVEF reduction to <50% and 4 (0.2%) experienced LVEF <50% + HFH but later resumed treatment. Of 3,228 patients initiated on 5 mg/day mavacamten and were treated for at least 6 months, 2,391 (74.1%) remained at 5 or 10 mg/day. At 3- and 6-months following mavacamten treatment initiation, 57.2% and 70.3%, respectively, demonstrated post-Valsalva LV outflow tract gradient <30 mmHg. Conclusions: We describe the feasibility and experience of the first 22 months of the REMS program for prescribing mavacamten in >6,000 symptomatic obstructive HCM patients. The need for temporary interruption for LVEF <50% was low, including for patients on therapy ≥1 year, with even fewer LVEF reductions associated with HFH.

Phase 3 Open-Label Study Evaluating the Efficacy and Safety of Mavacamten in Japanese Adults With Obstructive Hypertrophic Cardiomyopathy - The HORIZON-HCM Study.

Mavacamten, a cardiac myosin inhibitor, significantly improved symptoms and cardiac function vs. placebo in patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) in EXPLORER-HCM. However, the efficacy and safety profiles of mavacamten in Japanese patients are unclear. HORIZON-HCM is a Phase 3 single-arm study in Japanese patients with symptomatic obstructive HCM. The mavacamten starting dose was 2.5 mg; individualized dose titration occurred in Weeks 6-20 based on Valsalva left ventricular outflow tract (LVOT) gradient and resting left ventricular ejection fraction (LVEF). Overall, 38 patients were treated; 36 completed the 30-week primary treatment analysis period. Clinically significant improvements in postexercise LVOT gradient were observed after 30 weeks of treatment (mean change from baseline -60.7 mmHg). Improvements in N-terminal pro B-type natriuretic peptide, New York Heart Association class, and Kansas City Cardiomyopathy Questionnaire-23 Clinical Summary Score were observed over 30 weeks, and mean LVEF was ≥74% at all visits. Treatment-emergent adverse events (TEAEs) and serious TEAEs were reported in 63.2% and 7.9% of patients, respectively; none resulted in treatment discontinuation. One patient experienced a transient asymptomatic reduction in LVEF to <50%. No deaths occurred during the study. In Japanese patients with obstructive HCM, mavacamten was associated with similar improvements in LVOT gradients, cardiac biomarkers, and symptoms to those observed in EXPLORER-HCM. Treatment was well tolerated with no new safety concerns.

Association between impaired left ventricular global longitudinal strain and B-type natriuretic peptide in obstructive hypertrophic cardiomyopathy

Abstract Background Left ventricular global longitudinal strain (LV-GLS) is considered valuable in explaining impaired left ventricular contractility in hypertrophic cardiomyopathy (HCM) with preserved ejection fraction and is associated with worse outcome. Elevated B-type natriuretic peptide (BNP) is a biomarker of increased LV wall stretch and a risk factor of heart failure, mortality, and other adverse cardiovascular events. However, relationship between GLS and BNP has not received sufficient attention in the obstructive variant of HCM. Purpose This study aimed to determine the association between echocardiographic LV-GLS and plasma BNP in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods A total of 145 consecutive patients (32% females) with symptomatic HOCM were enrolled in the retrospective study. HOCM was defined with a maximum end-diastolic wall thickness ≥15mm without other etiologies for LV hypertrophy, and peak LV outflow tract (LVOT) gradient ≥30mmHg. The echocardiographic parameters regarding LV geometry, loading conditions, and GLS were evaluated according to guidelines. Patients were divided into two groups according to absolute GLS values (greater or lower than median LV-GLS). Patient baseline clinical data, echocardiographic parameters, and BNP were compared. Univariate and multivariable regression analysis were applied to identify the independent determinator of LV-GLS. Results The median value of LV-GLS of this study cohort was -13.4%. Eighty-one patients (47.6±13.4 years-old) had a |GLS|≥13.4% and 64 individuals (48.7±12.6 years-old) had a |GLS|&amp;lt;13.4%. No differences were found in age, gender, physical examinations, LVEF, cardiovascular comorbidities, or active medications between the two groups, except for body mass index (BMI). Patients with |GLS|≥13.4% had statistically lower BMI (24.58±2.42 vs. 26.00±3.12kg/m², p=0.030). BNP was found significantly elevated in patients with |GLS|&amp;lt;13.4% when compared with individuals with |GLS|≥13.4% {median (IQR); 550.05 (214.50, 899.35) vs. 182.40 (78.90, 479.90)pg/mL, p=0.004}. In univariate regression analysis, decreased |GLS| was associated with male gender, maximum and mean LV wall thickness, peak LVOT gradient, reduced mitral annular e’ velocity, elevated BNP and cardiac troponin I. In multivariable regression analysis, GLS was found independently associated with mean LV wall thickness and BNP. Conclusions In patients with symptomatic HOCM with preserved ejection fraction, impaired LV-GLS was found to be associated with plasma BNP and mean LV wall thickness, independent of gender, age, loading conditions, LVEF, or LVOT gradient. Reduced GLS may be a more sensitive surrogate in assessing increased myocardial wall tension or stretch, rather than LV contractility in these patients. Therefore, the interpretation of GLS in HOCM should shift away from systolic interest toward emphasizing its potential value in risk stratification of diastolic heart failure with preserved LVEF.Figure 1

A comprehensive evaluation of available evidence of mavacamten in obstructive HCM: a meta-analysis of randomised controlled trials

Abstract Introduction Obstructive hypertrophic cardiomyopathy (HCM) poses a significant clinical challenge, characterized by left ventricular hypertrophy and impaired cardiac function. mavacamten, a novel medication targeting the sarcomere protein myosin, has emerged as a promising therapeutic option for patients with symptomatic obstructive HCM. Despite its potential efficacy, the comparative effectiveness and safety of Mavacamten remain uncertain, necessitating a comprehensive evaluation of available evidence. Purpose We aimed to give a comprehensive appraisal on mavacamten as a treatment option for patients with obstructive HCM informing clinical decision-making. Methods We systematically searched PubMed, Web of Science, Scopus, and Cochrane Central, and EMBASE from inception until February 2024. We included randomised controlled trials (RCTs) comparing mavacamten versus placebo in patients with obstructive HCM. The primary outcomes were improvement in NYHA class, Change from baseline in KCCQ-CSS, and the incidence of atrial fibrillation. All data were pooled as either Mean difference in the random effect model with the corresponding SD or pooled as RR and 95% CI for dichotomous data. Results Four randomised controlled trials involving 503 patients were included in the final analysis. the overall odds ratio demonstrated a substantial preference for Mavacamten in achieving more than a one-level improvement in NYHA functional class from baseline (OR: 3.83 (95% CI [2.54 to 5.77], P=0.0001). However, there was no significant difference in terms of KCCQ-CSS (MD= 1.06, 95% CI [ -0.03 to 2.15], P=0.06) or the incidence of atrial fibrillation (OR=1.27, 95% CI [0.51 to 3.14], P=0.60). Conclusion Mavacamten showed a significant improvement on NYHA functional class, with no observed significance in terms of reducing the incidence of AF, or improving the KCCQ-CSS score.KCCQ-CSSNYHA

Functional capacity by cardiopulmonary exercise testing is not related to health status in obstructive hypertrophic cardiomyopathy

Abstract Background In obstructive hypertrophic cardiomyopathy (HCM), the primary goal of therapy is to improve patient quality of life by decreasing symptom burden. Increasingly, cardiopulmonary exercise testing (CPET), with peak oxygen consumption (pVO2) and ventilator efficacy (VE/VCO2), is used to assess efficacy of novel therapies in clinical studies and selectively in clinical practice to determine treatments. However, the relationship of CPET variables to symptom burden in HCM is not well established. Therefore, we examined the relationship between CPET variables and health status measured by Kansas City Cardiomyopathy Questionnaire (KCCQ) and NYHA functional classification in a cohort of obstructive HCM patients. Methods Consecutive patients with HCM and resting left ventricular outflow tract (LVOT) obstruction (≥50 mmHg) underwent CPET between October 2022 to January 2024. Patients with a peak RER &amp;lt;1.0 were excluded (n=4). To investigate distribution of patient reported health status (KCCQ) and NYHA functional classification, patients were stratified into groups for pVO2 (&amp;lt;14, 14-20, and &amp;gt;20 mL/kg/min) to reflect moderate to severe, mild to moderate, and little to no functional limitation, respectively. Results Of 58 patients, clinical evaluation was at 59 ± 13 years of age, 55% male, with LVOT gradient of 83 ± 28 mmHg at rest with 84% NYHA class II or III and 76% with KCCQ overall summary (OS) &amp;lt;75. Both pVO2 and VE/VCO2 had significant but weak correlation with NYHA class and KCCQ scores (Table 1), with the strongest correlation observed with pVO2 and KCCQ-OS (R2= 0.13, p=0.004). In contrast, % predicted pVO2 was not significantly correlated with NYHA or KCCQ. Notably, despite 14 patients being classified as having little to no limitations by pVO2, 29% of these patients had mild to moderate disability and 29% had moderate to severe disability by KCCQ-OS (Figure 1). Conclusion In patients with symptomatic obstructive HCM, objective measures of exercise performance, including pVO2 and VE/VCO2, correlate poorly with measurements of health status. These data suggest that CPET results should not be considered a surrogate marker of heart failure symptom burden in obstructive HCM.

Interventional treatment of patients with hypertrophic obstructive cardiomyopathy: the immediate and long-term results

Abstract Background Alcohol septal ablation (ASA) is a widely accepted and effective procedure for reducing septal thickness in patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM) who do not respond to medical treatment and have significant outflow tract gradients. Despite numerous studies confirming its safety and efficacy, as well as current guidelines from 2020 recommending ASA as a class 1 treatment option alongside surgical myectomy[1], the decision between these methods is still a subject of debate. Methods From 2009 to 2022 154 ASA performed in 145 patients (91 males, 54 females) with HOCM at our centre. Mean age of pts. was 42 [6;77] years. All pts. had right ventricle pacing lead with pacemaker backup and myocardial contrast ECHO(MCE) before procedure. Mean peak pressure gradient (PG) on LVOT was 93,5 ± 8,2 mm. Hg. Mitral valve regurgitation (MR) from moderate to severe was in all pts. Mean interventricular septum thickness was 2,5сm [1,6; 3,8]. Results Mean PG on LVOT decreased from 93,5 ± 8,2 mmHg to 31,7±4,3 mmHg. The grade of MR reduced from at least moderate to mild or even trivial. The procedure – related mortality was 1,3%. In 3 cases (2%) the procedure was aborted by he MCE data. Mean follow up for 145pts (100%)was 91±4,6 months. 112(77,3%) pts had PG reduction (to ≤30 mtmHg) – regarded as good result of procedure. 19 (13,1%) pts had PG &amp;gt; 30mmHg, but significant improvement in symptoms. Long term mortality in ASA pts. was 2.7%. 10(6.9%) pts needed redo procedure due to residual LVOTO, which was effective. 13(8,9%) patients had complete AV block and required permanent pacemaker. Mean interventricular wall thickness decreased from 2,5±0,3сm to 1,8±0,2cm. MR decreased from at least moderate to mild or complete disappearance. NYHA class reduced from 2,9 to 1,2. Conclusions ASA is effective and safe method of HOCM treatment. Accumulation of the experience can lead to a reduction in procedure time, a decrease in the number of complications, and an overall improvement in the outcomes of interventional HOCM treatment.

Hemodynamic effects of right and biventricular pacing during exercise in hypertrophic obstructive cardiomyopathy

Abstract Background One third of patients with hypertrophic cardiomyopathy present with dynamic left ventricular outflow tract obstruction (LVOTO), referred to as hypertrophic obstructive cardiomyopathy (HOCM). Symptomatic treatment aims at reducing LVOTO with either medications, invasive septal reduction, or pacing. The importance of pacing site is unclear, and effects of pacing during physical activity have not been investigated. Purpose To determine the effect of right ventricular (RV) and biventricular (BiV) pacing, respectively, on LVOTO and cardiac output (CO) during exercise in patients with HOCM. Methods Patients with symptomatic HOCM, sinus rhythm, and no bundle branch block, scheduled for alcohol septal ablation (ASA), were eligible for inclusion. The day before ASA, we placed temporary pacing leads in the right atrium, the RV apex, and on the left ventricle’s lateral wall via the coronary sinus. LVOTO was assessed by echocardiography, and CO was measured by thermodilution with a pulmonary artery catheter. Patients performed supine cycling for 2 minutes until heart rate (HR) increased ≥20 bpm. We measured LVOTO and CO in sinus rhythm, and during cycling with atrial sensed RV pacing, and atrial sensed BiV pacing. The order of pacing sites was randomized, and the personnel performing echocardiography and CO measurements were blinded to the order of pacing. Results We included six patients (54±15 years) with a mean maximal left ventricular wall thickness of 16.7±1.8 mm. Resting LVOTO was 55.7±30.9 mmHg. The figures show LVOTO and CO in sinus rhythm (HR 85±10 bpm), RV pacing (HR 90±10 bpm), and BiV pacing (HR 91±9 bpm) during supine cycling. The LVOTO declined from 56±34 mmHg in sinus rhythm to 27±12 mmHg and 25±5 mmHg respectively for atrial sensed RV and BiV pacing. CO remained unchanged during sinus rhythm (9.0±1.2 L/min), atrial sensed RV pacing (9.0±1.7 L/min), and BiV pacing (8.9±1.5 L/min). Conclusion In this ongoing study evaluating cardiac pacing in HOCM, preliminary data indicate that both RV and BiV pacing are effective in reducing LVOTO during exercise, without compromising CO.

Real-world experience with mavacamten in obstructive hypertrophic cardiomyopathy: observations from a tertiary care center

Abstract Background In symptomatic obstructive hypertrophic cardiomyopathy (oHCM) patients, mavacamten is commercially approved to help improve left ventricular (LV) outflow tract (LVOT) gradients, symptoms, and reduce eligibility for septal reduction therapy (SRT) under the risk evaluation and mitigation strategy (REMS) program. We sought to prospectively report the initial real-world clinical experience with the use of commercially available mavacamten in a multi-hospital tertiary healthcare system. Methods We studied the first 150 consecutive oHCM patients (mean age 65 years, 53% women, 83% on betablockers and 61% in New York Heart Association [NYHA] class III) who were initiated on 5 mg of mavacamten with dose titrations using symptom assessment and echocardiographic measurements of LVOT gradient and LV ejection fraction (LVEF) measurements. We measured changes in NYHA class, LVEF, LVOT gradients (resting and Valsalva) at baseline, 4, 8 and 12 weeks. Results At 261±143 days (range of 31-571 days), 69 (46%) patients had ≥1 NYHA class, 27 (18%) additional patients had ≥2 NYHA class improvement and 40 (27%) reported a no change in symptoms. The mean LVOT gradient at rest decreased from 41±33 mmHg at baseline to 16±17 mmHg at 4 weeks, 16±16 mmHg at 8 weeks and 15±16 mmHg at 12 weeks. The mean drop in resting LVOT gradient from baseline to last follow-up was 26±3 mmHg (p&amp;lt;0.0001). The mean Valsalva LVOT gradient decreased from 72±43 mmHg at baseline to 29±31 mmHg at 4 weeks, 29±28 mmHg at 8 weeks and 30±29 mmHg at 12 weeks (p&amp;lt;0.001). The mean reduction in post Valsalva LVOT gradient from baseline to last follow-up was 43±4 mmHg (p&amp;lt;0.0001). At baseline, 100% patients had Valsalva LVOT gradients ≥ 30 mm Hg and 142 (95%) had ≥ 50 mm Hg. After initiation of mavacamten therapy, Valsalva LVOT gradient ≥ 30 mm Hg was observed in 44/150 (29%) at 4 weeks, 40/141 (28%) at 8 weeks and 41/136 (30%) at 12 weeks. In 40 patients who reported no symptomatic improvement, the mean Valsalva LVOT gradient decreased from 73±39 mmHg at baseline to 34± 27 mmHg at 4 weeks, 35±28 mmHg at 8 weeks and 30±24 mmHg at 12 weeks (P&amp;lt;0.001). The mean LVEF at baseline was 66±6% and changed to 64±5% at 4 weeks, 63±5% at 8 weeks and 62±7% at 12 weeks (p&amp;lt;0.0001). No patient underwent SRT, developed LVEF ≤30% or developed heart failure requiring admission. Three (2%) patients needed temporary interruption of mavacamten due to LVEF&amp;lt;50. During follow up, dose reduction or discontinuation of background HCM therapy (betablockers, calcium channel blockers and disopyramide) occurred in 33 (22%) patients. The breakdown of various drug doses of mavacamten, at last follow-up, is as follows: 2.5 mg (n=29, 19%), 5 mg (n=80, 53%), 10 mg (n=37, 25%) and 15 mg (n=3, 2%). Conclusions In a real-world study in symptomatic oHCM patients at a multi-hospital tertiary care referral center, we demonstrate the efficacy and safety of prescribing mavacamten under the REMS program.

Serial changes in left and right ventricular global longitudinal strain in symptomatic obstructive hypertrophic cardiomyopathy treated with mavacamten: insights from VALOR-HCM trial

Abstract Background In severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), the VALOR-HCM phase 3 randomized, double-blind, placebo-controlled clinical trial demonstrated that mavacamten, reduces the need for septal reduction therapy with sustained improvement in left ventricular outflow tract gradients and symptoms. As a cardiac myosin inhibitor, mavacamten’s mechanism of action reduces myocardial hypercontractility. Global longitudinal strain (GLS), a measure of regional myocardial function, is a more sensitive marker of systolic function and can complement left ventricular ejection fraction (LVEF). Objective We sought to assess serial changes in LV and right ventricular (RV)-GLS in patients enrolled in the VALOR-HCM study. Methods VALOR-HCM included 112 symptomatic obstructive HCM patients (mean 60 years, 51% male, LVEF 68%). Patients assigned to mavacamten at baseline continued the drug for 56 weeks (n=56) and those assigned to placebo crossed over to mavacamten (n=52) from week 16-56 (40-week exposure). LV and RV-GLS assessment was performed according to the current American and European guideline recommendations using a vendor-neutral post processing software. Non-foreshortened apical (4, 3 and 2-chamber) views were used to obtain peak value of LV-GLS. For RV-GLS, RV focused 4-chamber view was used to calculate RV 4-chamber and free wall strain. A more negative strain value is favorable. Results Serial changes in LVEF, average LV-GLS, and RV-GLS (4-chamber and free wall) from baseline to week 56 are shown in the Figure. Despite preserved LVEF at baseline, average baseline LV-GLS was abnormal. There were significant and continued improvements in LV-GLS in the total group from baseline to week 56. 12 patients had transient reduction in LVEF (&amp;lt;50%) requiring temporary drug interruption (permanent discontinuation in 3). The LV-GLS in this subgroup was worse at baseline compared to the total study population, with no significant worsening from baseline through week 56. In the overall population, excluding these 12 patients, LV-GLS demonstrated an improvement sustained through week 56. Both free wall and 4-chamber RV-GLS were abnormal at baseline and remained unchanged from baseline to week 56. Conclusions In the VALOR-HCM trial, despite hypercontractile LVEF at baseline, average baseline LV-GLS was worse than normal reference values. Treatment with mavacamten resulted in an improvement in LV-GLS from baseline through Week 56 (with no significant worsening of LV-GLS in the subgroup who experienced any reduction in LVEF &amp;lt;50%), suggesting a favorable long-term impact on regional LV systolic function due to the reduction of cardiac hypercontractility. Additionally, there was no significant detrimental impact on RV systolic function on serial GLS assessment.Serial changes in LV and RV GLS in VALOR

Serial changes in left atrial strain in symptomatic obstructive hypertrophic cardiomyopathy treated with mavacamten: insights from VALOR-HCM trial

Abstract Background In severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), the VALOR-HCM phase 3 randomized, double-blind, placebo-controlled clinical trial demonstrated that mavacamten, a cardiac myosin inhibitor, reduces the eligibility for septal reduction therapy with sustained improvement in left ventricular (LV) outflow tract gradients and symptoms. Mavacamten also resulted in favorable cardiac remodeling, including improvement in left atrial volume index (LAVI), LV diastolic function, and biomarkers (NT-proBNP and troponin T). However, the impact of mavacamten on LA function is not known. Objective We sought to assess serial changes in LA strain measures in patients enrolled in the VALOR-HCM trial. Methods VALOR-HCM included 112 symptomatic obstructive HCM patients (mean age 60 years, 51% male). Patients assigned to mavacamten at baseline (n=56) continued therapy for 56 weeks and those assigned to placebo crossed over to mavacamten (n=52) from week 16-56 (40-week exposure). Echocardiographic LA strain assessment was performed according to the current American and European guideline recommendations, using a vendor-neutral post processing software. For assessment of LA strain components (reservoir, conduit, and contraction), the non-foreshortened apical 4-chamber view was utilized. The zero reference was set at end-diastole. Results Serial changes in LAVI and all components of mean LA strain from baseline to week 56 are shown in the Figure. At baseline, LAVI and all mean LA strain values were worse than reported normal mean thresholds. There was a continued and significant improvement in all 3 LA strain values, from baseline to week 56, along with a significant reduction in LAVI. Improvement in LAVI was seen earlier than improvements in LA strain. There was a significant inverse correlation between change in mean LAVI and LA reservoir strain from baseline to week 56 (r= -0.42, p&amp;lt;0.001). Conclusions In the VALOR-HCM trial, average LAVI and baseline LA strain values were significantly worse than reported normal thresholds. Treatment with mavacamten resulted in an improvement in LAVI and LA strain values from baseline through week 56 suggesting a sustained favorable impact on cardiac remodeling. The advantageous cardiac remodeling associated with long-term treatment with mavacamten may in turn have a favorable impact on the observed high burden of atrial tachyarrhythmias in HCM.Serial changes in LA strain in VALOR-HCM

Effect of stereotactic body radiation therapy on left ventricular diastole function in symptomatic patients with hypertrophic obstructive cardiomyopathy

Abstract Background We applied stereotactic body radiotherapy (SBRT) for the first time in the treatment of patients with hypertrophic obstructive cardiomyopathy (HOCM), and significant improvements in symptoms and diastolic function were observed after treatment. Objectives To evaluate the impact of SBRT on cardiac structure, function, and clinical indicators in patients with HOCM. Methods This study included 12 drug-refractory symptomatic HOCM patients (6 who underwent SBRT and 6 who received pharmacological treatment alone) and conducted a retrospective analysis of their clinical data. Transthoracic echocardiography was used to assess various ultrasound parameters, including interventricular septal thickness, left ventricular outflow tract diameter, peak pressure gradient and diastolic function before treatment and at 1, 3, and 6 months after treatment. Additionally, assessments were made for symptoms; laboratory test results (NT-proBNP, cTnT, CK-mb, and CRP); 6-minute walk test results; New York Heart Association (NYHA) functional classification; and Kansas score before and 6 months after treatment. Results HOCM patients showed significant improvement in mitral valve systolic anterior motion after SBRT. Compared to that at baseline, the interventricular septum thickness gradually decreased at 1, 3, and 6 months after treatment (-8.8%, -8.0%, -14.4%, respectively) (P&amp;lt;0.05). Compared to those in the drug group, the left ventricular diastolic function and structural parameters, including the interventricular septum thickness (mean change from baseline of -3 mm [95% CI: -5.2 to -0.8 mm] and 1.3 mm [95% CI: 0.5 to 2.2 mm]; P&amp;lt;0.05), and the LA GLS (change of 2.1% [-0.03% to 4.2%] and -0.9% [-3.1% to 1.3%]; P&amp;lt;0.05), were significantly improved in HOCM patients at 6 months posttreatment. Similarly, the clinical indicators, including KCCQ, increased from baseline (61 (range, 47.3-70) to 84 (range, 70-89.5) at 6 months posttreatment (P&amp;lt;0.05), and the 6-minute walk test score increased from 187 meters (range, 50-370) to 401 meters (range, 280-540) (P&amp;lt;0.05). Conclusion SBRT significantly improved left ventricular diastolic function and reduced interventricular septum thickness in HOCM patients. Symptoms, exercise capacity and clinical indicators improved after SBRT in HOCM patients.

Procedural Volume and Outcomes After Septal Reduction Therapies in Hypertrophic Obstructive Cardiomyopathy.

Septal myectomy and alcohol septal ablation (ASA) are septal reduction therapies for patients with symptomatic obstructive hypertrophic cardiomyopathy. Operator and hospital volume may influence outcomes, but contemporary data on this relationship are limited. This retrospective cohort study used data from the Vizient Clinical Data Base (2016-2022). Patients with undergoing septal myectomy and ASA were identified using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes and stratified into low-, medium-, and high-volume groups based on annualized operator and hospital volumes. The outcomes were 30-day in-hospital mortality and 90-day readmission, analyzed using multivariable adjusted logistic and Cox models. Among 5725 patients with hypertrophic cardiomyopathy (3990 septal myectomy; 1735 ASA), most operators and hospitals performed <10 procedures annually. For septal myectomy, low-volume operators were associated with higher odds of 30-day mortality (adjusted odds ratio [aOR], 1.86 [95% CI, 1.11-3.15]) and greater risk for 90-day readmission (aOR, 1.51 [95% CI, 1.22-1.88]), and medium-volume operators had higher odds of 30-day mortality (aOR, 1.93 [95% CI, 1.05-3.55]). Medium-volume hospitals had higher 30-day mortality (aOR, 2.29 [95% CI, 1.32-3.99]), with low-volume hospitals showing greater risk for 90-day readmission (aOR, 1.60 [95% CI, 1.14-2.23]). For ASA, low- and medium-volume operators had increased 30-day mortality (aOR, 2.99 [95% CI, 1.15-7.75] and aOR, 3.86 [95% CI, 1.30-11.46]), but the risk of 90-day readmission was similar. Hospital volumes did not significantly impact outcomes for ASA. Low operator and hospital volumes were associated with worse outcomes for septal reduction therapies, emphasizing the need to refer patients with hypertrophic cardiomyopathy to high-volume centers with experienced operators.

Aficamten and Cardiopulmonary Exercise Test Performance

Impaired exercise capacity is a cardinal manifestation of obstructive hypertrophic cardiomyopathy (HCM). The Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic Obstructive HCM (SEQUOIA-HCM) is a pivotal study characterizing the treatment effect of aficamten, a next-in-class cardiac myosin inhibitor, on a comprehensive set of exercise performance and clinical measures. To evaluate the effect of aficamten on exercise performance using cardiopulmonary exercise testing with a novel integrated measure of maximal and submaximal exercise performance and evaluate other exercise measures and clinical correlates. This was a prespecified analysis from SEQUOIA-HCM, a double-blind, placebo-controlled, randomized clinical trial. Patients were recruited from 101 sites in 14 countries (North America, Europe, Israel, and China). Individuals with symptomatic obstructive HCM with objective exertional intolerance (peak oxygen uptake [pVO2] ≤90% predicted) were included in the analysis. Data were analyzed from January to March 2024. Randomized 1:1 to aficamten (5-20 mg daily) or matching placebo for 24 weeks. The primary outcome was change from baseline to week 24 in integrated exercise performance, defined as the 2-component z score of pVO2 and ventilatory efficiency throughout exercise (minute ventilation [VE]/carbon dioxide output [VCO2] slope). Response rates for achieving clinically meaningful thresholds for change in pVO2 and correlations with clinical measures of treatment effect (health status, echocardiographic/cardiac biomarkers) were also assessed. Among 282 randomized patients (mean [SD] age, 59.1 [12.9] years; 115 female [40.8%], 167 male [59.2%]), 263 (93.3%) had core laboratory-validated exercise testing at baseline and week 24. Integrated composite exercise performance improved in the aficamten group (mean [SD] z score, 0.17 [0.51]) from baseline to week 24, whereas the placebo group deteriorated (mean [SD] z score, -0.19 [0.45]), yielding a placebo-corrected improvement of 0.35 (95% CI, 0.25-0.46; P <.001). Further, aficamten treatment demonstrated significant improvements in total workload, circulatory power, exercise duration, heart rate reserve, peak heart rate, ventilatory efficiency, ventilatory power, and anaerobic threshold (all P <.001). In the aficamten group, large improvements (≥3.0 mL/kg per minute) in pVO2 were more common than large reductions (32% and 2%, respectively) compared with placebo (16% and 11%, respectively). Improvements in both components of the primary outcome, pVO2 and VE/VCO2 slope throughout exercise, were significantly correlated with improvements in symptom burden and hemodynamics (all P <.05). This prespecified analysis of the SEQUOIA-HCM randomized clinical trial found that aficamten treatment improved a broad range of exercise performance measures. These findings offer valuable insight into the therapeutic effects of aficamten. ClinicalTrials.gov Identifier: NCT05186818.

Mavacamten for Obstructive Hypertrophic Cardiomyopathy: Rationale for Clinically Guided Dose Titration to Optimize Individual Response.

Mavacamten is the first and only cardiac myosin inhibitor approved in 5 continents for the treatment of adults with symptomatic New York Heart Association class II and III obstructive hypertrophic cardiomyopathy. An evidence-based rationale was used to develop individualized mavacamten dosing, guided by commonly used clinical parameters. Echocardiography is recommended as part of routine clinical assessment of patients with hypertrophic cardiomyopathy, and left ventricular (LV) outflow tract gradient and LV ejection fraction are parameters that can be readily assessed and monitored by echocardiography. Therefore, an echocardiography-based, clinically guided dose-titration strategy was developed to optimize patient benefit from mavacamten for the treatment of symptomatic obstructive hypertrophic cardiomyopathy while minimizing the risk of LV ejection fraction reduction. Results from clinical trials paired with extensive modeling and simulation analyses support a dose-titration and monitoring strategy based on serial echocardiographic measures of Valsalva LV outflow tract gradient and LV ejection fraction. This dosing approach allows for the identification of the lowest individualized mavacamten dose and exposure required to provide improvements in LV outflow tract obstruction, functional capacity, and symptoms. Mavacamten is primarily metabolized by CYP2C19 (cytochrome P450 2C19), and CYP2C19 metabolizer phenotype has an effect on mavacamten exposure. Therefore, this approach has also been demonstrated to provide a favorable safety profile irrespective of patients' CYP2C19 metabolizer status. The dose-titration strategy includes additional considerations for the potential onset of systolic dysfunction in the context of intercurrent illness, and for the potential of drug-drug interactions with inhibitors and substrates of cytochrome P450 enzymes. This posology is reflected in the mavacamten US prescribing information.

Impact of Aficamten on Echocardiographic Cardiac Structure and Function in Symptomatic Obstructive Hypertrophic Cardiomyopathy

BackgroundAficamten, a next-in-class cardiac myosin inhibitor, improved peak oxygen uptake (pVO2) and lowered resting and Valsalva left ventricular outflow (LVOT) gradients in adults with symptomatic obstructive hypertrophic cardiomyopathy (oHCM) in SEQUOIA-HCM (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM), a phase 3, multicenter, randomized, double-blinded, placebo-controlled study. ObjectivesThe authors sought to evaluate the effect of aficamten on echocardiographic measures of cardiac structure and function in SEQUOIA-HCM. MethodsSerial echocardiograms were performed over 28 weeks in patients randomized to receive placebo or aficamten in up to 4 individually titrated escalating doses (5-20 mg daily) over 24 weeks based on Valsalva LVOT gradients and left ventricular ejection fraction (LVEF). ResultsAmong 282 patients (mean age 59 ± 13 years; 41% female, 79% White, 19% Asian), mean LVEF was 75% ± 6% with resting and Valsalva LVOT gradients of 55 ± 30 mm Hg and 83 ± 32 mm Hg, respectively. Over 24 weeks, aficamten significantly lowered resting and Valsalva LVOT gradients, and improved left atrial volume index, lateral and septal eʹ velocities, and lateral and septal E/eʹ (all P ≤ 0.001). LV end-systolic volume increased and wall thickness decreased (all P ≤ 0.003). Aficamten resulted in a mild reversible decrease in LVEF (−4.8% [95% CI: −6.4% to −3.3%]; P < 0.001) and absolute LV global circumferential strain (−3.7% [95% CI: 1.8%-5.6%]; P < 0.0010), whereas LV global longitudinal strain was unchanged. Several measures, including LVEF, LVOT gradients, and E/eʹ returned to baseline following washout. Among those treated with aficamten, improved pVO2 and reduction in N-terminal pro–B-type natriuretic peptide (NT-proBNP) were associated with improvement in lateral eʹ velocity and septal and lateral E/eʹ (all P < 0.03), whereas improvement in Kansas City Cardiomyopathy Questionnaire Clinical Summary Scores (KCCQ-CSS) was associated with a decrease in both LVOT gradients (all P < 0.001). ConclusionsCompared with placebo, patients receiving aficamten demonstrated significant improvement in LVOT gradients and measures of LV diastolic function, and several of these measures were associated with improvements in pVO2, KCCQ-CSS, and NT-proBNP. A modest decrease in LVEF occurred yet remained within normal range. These findings suggest aficamten improved multiple structural and physiological parameters in oHCM without significant adverse changes in LV systolic function. (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM [SEQUOIA-HCM]; NCT05186818)

Serial Changes in Ventricular Strain in Symptomatic Obstructive Hypertrophic Cardiomyopathy Treated With Mavacamten: Insights From the VALOR-HCM Trial.

In severely symptomatic patients with obstructive hypertrophic cardiomyopathy, VALOR-HCM (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) demonstrated that mavacamten reduces the need for septal reduction therapy with sustained improvement in left ventricular (LV) outflow tract gradients and symptoms. Global longitudinal strain (GLS), a measure of regional myocardial function, is a more sensitive marker of systolic function. In VALOR-HCM, we assessed serial changes in LV and right ventricular (RV) strain. VALOR-HCM included 112 patients with symptomatic obstructive hypertrophic cardiomyopathy (mean, 60 years; 51% male; LV ejection fraction, 68%). Patients assigned to mavacamten at baseline continued the drug for 56 weeks (n=56) and those assigned to placebo (n=52) transitioned to mavacamten from weeks 16 to 56 (40-week exposure). LV-GLS and RV-GLS assessment was performed using a vendor-neutral software. Non-foreshortened apical (4-, 3-, and 2-chamber) views were used to obtain peak LV-GLS. RV focused 4-chamber view was used to calculate RV 4-chamber and free wall strain. A more negative strain value is favorable. At baseline, the mean LV-GLS, RV 4-chamber, and free wall strain values were -14.7%, -22.2%, and -16.8%, respectively (all worse than reported normal means). In the total study sample, LV-GLS significantly improved from baseline to week 56 (P=0.02). Twelve patients had transient reduction in LV ejection fraction (<50%) requiring temporary drug interruption (including 3 permanent discontinuations). The LV-GLS in this subgroup was worse at baseline versus total study population (-11.4%), with no significant worsening from baseline through week 56 (P=0.64). Both free wall and 4-chamber RV-GLS remained unchanged from baseline to week 56 (P=0.62 and P=0.56, respectively). In VALOR-HCM, treatment with mavacamten improved LV-GLS from baseline through week 56 (with no significant worsening of LV-GLS in patients with a reduction in LV ejection fraction ≤50%), suggesting a favorable long-term impact on regional LV systolic function. Additionally, there was no detrimental impact on RV systolic function. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04349072.

Mavacamten-Associated Temporal Changes in Left Atrial Function in Obstructive HCM: Insights From the VALOR-HCM Trial

BackgroundIn severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), the VALOR-HCM (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) trial showed that mavacamten reduced the eligibility for septal reduction therapy with sustained improvement in left ventricular outflow tract gradients. Mavacamten also resulted in favorable cardiac remodeling, including improvement in biomarkers (eg, N-terminal pro–B-type natriuretic peptide and troponin T). However, the impact of mavacamten on left atrial (LA) function is unknown. ObjectivesThe aim of this study was to assess serial changes in LA strain measures in patients enrolled in the VALOR-HCM trial. MethodsVALOR-HCM included 112 symptomatic patients with obstructive HCM (mean age 60 years; 51% male). Patients assigned to receive mavacamten at baseline (n = 56) continued therapy for 56 weeks and those assigned to placebo transitioned to mavacamten (n = 52) from week 16 to week 56. Echocardiographic LA strain (reservoir, conduit, and contraction) was measured by using a vendor-neutral postprocessing software. ResultsAt baseline, the mean LA volume index (LAVI) and LA strain values (conduit, contraction, and reservoir) were 41.3 ± 16.5 mL/m2, −11.8% ± 6.5%, −8.7% ± 5.0%, and 20.5% ± 8.7%, respectively (all worse than reported normal). LAVI significantly improved by −5.6 ± 9.7 mL/m2 from baseline to week 56 (P < 0.001). There was a significant (P < 0.05) improvement in absolute LA strain values from baseline to week 56 (conduit [−1.7% ± 6%], contraction [−1.2% ± 4.5%], and reservoir [2.8% ± 7.7%]). Patients originally receiving placebo had no differences in LA measurements up to week 16. There was no significant improvement in LA strain values (conduit [−0.9% ± 3.8%], contraction [−0.4% ± 3.4%], and reservoir [1.4% ± 6.1%]; all; P = NS) from baseline to week 56 in patients with history of atrial fibrillation. ConclusionsIn VALOR-HCM, mavacamten resulted in an improvement in LAVI and LA strain at week 56, suggesting sustained favorable LA remodeling and improved function, except in the atrial fibrillation subgroup. Whether the advantageous LA remodeling associated with long-term treatment with mavacamten results in a favorable impact on the observed high burden of atrial tachyarrhythmias in HCM remains to be proven. (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy [VALOR-HCM]; NCT04349072)

Differences in Healthcare Resource Use and Cost by Pharmacotherapy Among Patients with Symptomatic Obstructive Hypertrophic Cardiomyopathy: Real-World Analysis of Claims Data.

For symptomatic obstructive hypertrophic cardiomyopathy (oHCM), limited evidence exists on healthcare resource utilization (HRU) and cost for patients with symptomatic oHCM by treatment categories. We evaluated whether HRU and costs vary by initial treatment in symptomatic oHCM. This is a retrospective study of medical and pharmacy claims from 2016 to 2021 to identify (per International Classification of Disease Tenth Revision diagnosis codes) adult patients in the USA with symptomatic oHCM. Patients included in the study cohort were required to be treatment naïve (≥ 12 months' activity before first treatment) and symptomatic (fatigue, chest pain, syncope, dyspnea, heart failure, or palpitations within 3 months of index date). Patients were grouped by first index treatment [beta blocker (BB), calcium channel blockers (CCB), disopyramide, combination therapy], and HRU and costs [per person per year (PPPY), in USD] by initial treatment were reported. Among 7334 patients with symptomatic oHCM, initial treatment included BB (65.8%), CCB (21.1%), disopyramide (1.2%), or BB + CCB (11.9%). Overall, 87.2% were prescribed monotherapy. Outpatient visits were the main driver of all-cause HRU (mean 11.5 PPPY), and varied by initial treatment (BB: 11.0, CCB: 10.5, disopyramide: 7.2, combination therapy: 12.1). All-cause urgent care visits were more frequent than inpatient visits (means: 5.4 and 0.83 PPPY, respectively). All-cause incurred costs were $46,628 PPPY overall and varied by treatment (BB: $47,029, CCB: $42,124, disopyramide: $27,007, combination therapy: $54,024). In this large, US-based cohort of patients with symptomatic oHCM, initial therapy was most commonly BB and CCB monotherapy. Costs and HRU were high for most patients, but greater for those treated initially with combination therapy.

Characterization of mavacamten pharmacokinetics in patients with hypertrophic cardiomyopathy to inform dose titration.

Mavacamten is a selective, allosteric, reversible cardiac myosin inhibitor that has been developed for the treatment of adults with symptomatic obstructive hypertrophic cardiomyopathy (HCM). A population pharmacokinetic (PopPK) model was developed to characterize mavacamten pharmacokinetics (PK) and the variation in mavacamten exposure associated with intrinsic and extrinsic factors. Data from 12 clinical studies (phases 1, 2, and 3) were used. Evaluable participants were those who had at least one mavacamten concentration measurement with associated sampling time and dosing information. The base model included key covariates: body weight, cytochrome P450 isozyme 2C19 (CYP2C19) phenotype with respect to PK, and formulation. The final model was generated using stepwise covariate testing and refinement processes. Simulations were performed to evaluate PK: apparent clearance (CL/F); apparent central and peripheral volumes of distribution; and steady-state average, trough, and maximum concentrations. Overall, 9244 measurable PK observations from 497 participants were included. A two-compartment model structure was selected. After stepwise covariate model building and refinement, additional covariates included were: specified mavacamten dose, omeprazole or esomeprazole administration, health/disease status, estimated glomerular filtration rate, fed status, and sex. The final PopPK model accurately characterized mavacamten concentrations. At any given dose, CYP2C19 phenotype was the most influential covariate on exposure parameters (e.g., median CL/F was reduced by 72% in CYP2C19:poor metabolizers compared with the reference participant [CYP2C19:normal metabolizer]). CL/F was also approximately 16% higher in women than in men but lower in participants receiving concomitant omeprazole or esomeprazole (by 33% and 42%, respectively) than in participants not receiving such concomitant therapy.

Mavacamten in real-life practice: Initial experience at a hypertrophic cardiomyopathy centre.

In clinical trials, mavacamten reduced left ventricular outflow tract obstruction (LVOTO) and improved symptoms in patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). We aimed to share our real-world experience with the efficacy and safety of mavacamten in this patient population. This retrospective, single-centre study included patients with symptomatic oHCM from March 2023 to November 2023. Inclusion criteria were oHCM, age >18years, significant LVOTO (gradient >50mmHg at rest or with Valsalva), New York Heart Association (NYHA) class ≥II despite maximally tolerated medical therapy, and left ventricular ejection fraction (LVEF) >55%. Patients were evaluated by echocardiography, NYHA class, electrocardiography and Holter monitor on each monthly visit for 3months. A total of 31 patients were included in this study. The mean (SD) age was 58 (16.5) years, and 14 (45%) were female. Mean provoked left ventricular outflow tract gradient (LVOTG) reduced by -49.4mmHg (P<0.001) at 4weeks, -59.2mmHg (P<0.001) at 8weeks, and -60.8mmHg (P<0.001) at 12weeks. Twenty-six of the 31 patients (83.8%) achieved an LVOTG ≤30mmHg at Week 12. No major side effects were reported. Sixty-seven percent experienced ≥2 NYHA class improvements, LVEF remained above 55% and no dose titration was made. Our real-world experience aligns with established mavacamten trial outcomes. Continuous vigilance and longitudinal investigations are needed to further assess potential long-term impacts.