Symptomatic Hypertrophic Cardiomyopathy Research Articles

Sacubitril/valsartan for the treatment of non-obstructive hypertrophic cardiomyopathy: An open label randomized controlled trial (SILICOFCM).

Sacubitril/valsartan treatment reduces mortality and hospitalizations in heart failure with reduced ejection fraction but has limited application in hypertrophic cardiomyopathy (HCM). The aim of this study was to evaluate the effect of sacubitril/valsartan on peak oxygen consumption (VO2) in patients with non-obstructive HCM. This is a phase II, randomized, open-label multicentre study that enrolled adult patients with symptomatic non-obstructive HCM (New York Heart Association class I-III) who were randomly assigned (2:1) to receive sacubitril/valsartan (target dose 97/103 mg) or control for 16 weeks. The primary endpoint was a change in peak VO2. Secondary endpoints included echocardiographic measures of cardiac structure and function, natriuretic peptides and other cardiac biomarkers, and Minnesota Living with Heart Failure quality of life. Between May 2018 and October 2021, 354 patients were screened for eligibility, 115 patients (mean age 58 years, 37% female) met the study inclusion criteria and were randomly assigned to sacubitril/valsartan (n = 79) or control (n = 36). At 16 weeks, there was no significant change in peak VO2 from baseline in the sacubitril/valsartan (15.3 [4.3] vs. 15.9 [4.3] ml/kg/min, p = 0.13) or control group (p = 0.47). No clinically significant changes were found in blood pressure, cardiac structure and function, plasma biomarkers, or quality of life. In patients with HCM, a 16-week treatment with sacubitril/valsartan was well tolerated but had no effect on exercise capacity, cardiac structure, or function.

Aficamten for Symptomatic Obstructive Hypertrophic Cardiomyopathy.

One of the major determinants of exercise intolerance and limiting symptoms among patients with obstructive hypertrophic cardiomyopathy (HCM) is an elevated intracardiac pressure resulting from left ventricular outflow tract obstruction. Aficamten is an oral selective cardiac myosin inhibitor that reduces left ventricular outflow tract gradients by mitigating cardiac hypercontractility. In this phase 3, double-blind trial, we randomly assigned adults with symptomatic obstructive HCM to receive aficamten (starting dose, 5 mg; maximum dose, 20 mg) or placebo for 24 weeks, with dose adjustment based on echocardiography results. The primary end point was the change from baseline to week 24 in the peak oxygen uptake as assessed by cardiopulmonary exercise testing. The 10 prespecified secondary end points (tested hierarchically) were change in the Kansas City Cardiomyopathy Questionnaire clinical summary score (KCCQ-CSS), improvement in the New York Heart Association (NYHA) functional class, change in the pressure gradient after the Valsalva maneuver, occurrence of a gradient of less than 30 mm Hg after the Valsalva maneuver, and duration of eligibility for septal reduction therapy (all assessed at week 24); change in the KCCQ-CSS, improvement in the NYHA functional class, change in the pressure gradient after the Valsalva maneuver, and occurrence of a gradient of less than 30 mm Hg after the Valsalva maneuver (all assessed at week 12); and change in the total workload as assessed by cardiopulmonary exercise testing at week 24. A total of 282 patients underwent randomization: 142 to the aficamten group and 140 to the placebo group. The mean age was 59.1 years, 59.2% were men, the baseline mean resting left ventricular outflow tract gradient was 55.1 mm Hg, and the baseline mean left ventricular ejection fraction was 74.8%. At 24 weeks, the mean change in the peak oxygen uptake was 1.8 ml per kilogram per minute (95% confidence interval [CI], 1.2 to 2.3) in the aficamten group and 0.0 ml per kilogram per minute (95% CI, -0.5 to 0.5) in the placebo group (least-squares mean between-group difference, 1.7 ml per kilogram per minute; 95% CI, 1.0 to 2.4; P<0.001). The results for all 10 secondary end points were significantly improved with aficamten as compared with placebo. The incidence of adverse events appeared to be similar in the two groups. Among patients with symptomatic obstructive HCM, treatment with aficamten resulted in a significantly greater improvement in peak oxygen uptake than placebo. (Funded by Cytokinetics; SEQUOIA-HCM ClinicalTrials.gov number, NCT05186818.).

Mavacamten: A Review of a Novel Therapeutic Approach for Hypertrophic Cardiomyopathy.

Hypertrophic Cardiomyopathy (HCM) is a heart disease that can cause left ventricular hypertrophy, arrhythmias, heart failure, and sudden cardiac death. Currently, pharmacological treatment is limited and ineffective. Mavacamten (CamzyosTM) is a cardiac myosin inhibitor developed as a therapeutic option to reduce myocardial contractility and restoration of myocardial function. The Food and Drug Administration (FDA) approved the use of Mavacamten in 2022 for HCM symptoms. Clinical studies have proven that Mavacamten can reduce Left Ventricular Outflow Tract (LVOT) involvement, cardiac hypercontraction, and hypertrophy. This review provides an overview of HCM, its pathophysiology, current treatments, synthesis of Mavacamten, and the clinical trials of Mavacamten.

Structural and Functional Impact of Adrenoceptor Beta-1 Gene Polymorphism in Patients with Hypertrophic Cardiomyopathy and Response to Beta-Blocker Therapy.

Hypertrophic cardiomyopathy (HCM) is a genetically inherited cardiac disorder with diverse clinical presentations. Adrenergic activity, primarily mediated through beta-adrenoceptors, plays a central role in the clinical course of HCM. Adrenergic stimulation increases cardiac contractility and heart rate through beta-1 adrenoceptor activation. Beta-blocker drugs are recommended as the primary treatment for symptomatic HCM patients to mitigate these effects. This prospective study aimed to investigate the impact of common ADRB-1 gene polymorphisms, specifically serine-glycine at position 49 and arginine-glycine at position 389, on the clinical and structural aspects of HCM. Additionally, the study explored the association between these genetic variations and the response to beta-blocker therapy in HCM patients. A cohort of 147 HCM patients was enrolled, and comprehensive assessments were performed. The findings revealed that the Ser49Gly polymorphism significantly influenced ventricular ectopic beats, with beta-blocker therapy effectively reducing them in Ser49 homozygous patients. Moreover, natriuretic peptide levels decreased, particularly in Ser49 homozygotes, indicating improved cardiac function. Left ventricular outflow obstruction, a hallmark of HCM, was also reduced following beta-blocker treatment in all patient groups. In contrast, the Arg389Gly polymorphism did not significantly impact baseline parameters or beta-blocker response. These results emphasize the role of the Ser49Gly polymorphism in the ADRB-1 gene in shaping the clinical course and response to beta-blocker therapy in HCM patients. This insight may enable a more personalized approach to managing HCM by considering genetic factors in treatment decisions. Further research with larger populations and longer follow-up periods is needed to confirm and expand upon these findings.

Effect of Mavacamten in Women Compared With Men With Obstructive Hypertrophic Cardiomyopathy: Insights From EXPLORER-HCM.

Compared with men, women with hypertrophic cardiomyopathy (HCM) have a higher incidence of heart failure and worse outcomes. We investigated baseline clinical and echocardiographic characteristics and response to mavacamten among women compared with men in the EXPLORER-HCM study (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy). A prespecified post hoc analysis of sex from the blinded, randomized EXPLORER-HCM trial of mavacamten versus placebo in symptomatic patients with obstructive HCM was performed. Baseline characteristics were compared with t tests for continuous variables (expressed as mean values) and χ2 tests for categorical variables. Prespecified primary, secondary, and exploratory end points and echocardiographic measurements from baseline to end of treatment (week 30) were analyzed with ANCOVA for continuous end points and a generalized linear model with binomial distribution for binary end points, with adjustment for each outcome's baseline value, New York Heart Association class, β-blocker use, and ergometer type. At baseline, women (n=102) were older (62 years versus 56 years; P<0.0001), had lower peak oxygen consumption (16.7 mL·kg-1·min-1 versus 21.3 mL·kg-1·min-1; P<0.0001), were more likely to be assigned New York Heart Association class III (42% versus 17%; P<0.0001), had worse health status (Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score 64 versus 75; P<0.0001), and had higher baseline plasma NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels (1704 ng/L versus 990 ng/L; P=0.004) than men (n=149). After 30 weeks of mavacamten treatment, similar improvements were observed in women and men in the primary composite end point (percentage difference on mavacamten versus placebo, 22% versus 19%, respectively; P=0.759) and in the secondary end points of change in postexercise left ventricular outflow tract gradient (-42.4 mm Hg versus -33.6 mm Hg; P=0.348), change in peak oxygen consumption (1.2 mL·kg-1·min-1 versus 1.6 mL·kg-1·min-1; P=0.633), and percentage achieving ≥1 New York Heart Association class improvement (41% versus 28%; P=0.254). However, women had greater improvement in health status (Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score 14.8 versus 6.1; P=0.026) and in the exploratory end point of NT-proBNP levels (-1322 ng/L versus -649 ng/L; P=0.0008). Although at baseline women with symptomatic obstructive HCM enrolled in EXPLORER-HCM were older and had worse heart failure and health status than men, treatment with mavacamten resulted in similar improvements in the primary and most secondary EXPLORER-HCM end points and greater improvements in health status and NT-proBNP. URL: https://www.clinicaltrials.gov; Unique identifier: NCT03470545.

Long-term effects of mavacamten treatment in obstructive hypertrophic cardiomyopathy (HCM): updated cumulative analysis of the EXPLORER cohort of MAVA-long-term extension (LTE) study up to 120 weeks

Abstract Introduction Mavacamten was efficacious and well tolerated in patients (pts) with obstructive HCM over a median follow-up of 62 weeks in a previous interim analysis of the ongoing MAVA-LTE study (NCT03723655) (data cut-off; August 31, 2021). Here, we report an updated cumulative analysis of the EXPLORER cohort of MAVA-LTE up to 120 weeks. Methods Pts who completed EXPLORER-HCM (NCT03470545) could enroll in MAVA-LTE. All pts initiated the study with mavacamten 5 mg/day per protocol; dose adjustments to 2.5, 10, or 15 mg were based on site-read Valsalva left ventricular outflow tract (LVOT) gradient and LV ejection fraction (LVEF). Results In total, 231 pts (median age, 61 years; 39% female) enrolled in the EXPLORER cohort of MAVA-LTE. Median time on study was 101 weeks at data cut-off (May 31, 2022) with variations due to differences in enrollment timing. At data cut-off, 215 pts remained on treatment (total adjusted exposure: 475 pt-years). Mavacamten dosing of pts who reached week 120 (n=80) was: 2.5 mg (27.5%); 5 mg (31.3%); 10 mg (26.3%); 15 mg (12.5%). Between weeks 48–120, 34 of 231 (14.7%) pts underwent dose adjustments. Mavacamten treatment showed sustained improvements in mean [SD] change from baseline to week 120 in LVOT gradients (resting, −35.3 [33.0] mmHg; Valsalva, −47.0 [37.3] mmHg), left atrial volume index (−8.5 [10.3] mL/m2) and E/e’ average (−3.9 [5.0]) (Table). At week 120, 83.5% of pts had a Valsalva LVOT gradient ≤30 mmHg. Mavacamten was associated with sustained reduction from baseline to week 120 in N-terminal pro B-type natriuretic peptide (NT-proBNP) level (Table); 75.9% of pts improved by ≥1 class New York Heart Association class (Figure). Mean (SD) LVEF decreased by 9.1% (7.1) from baseline to week 120 but remained in the normal range. Since the previous interim analysis (data cut-off: August 31, 2021), 1 additional transient reduction in LVEF &amp;lt;50% occurred resulting in temporary treatment interruption (a total of 13 pts [5.6%] experienced LVEF &amp;lt;50% from study initiation). The pt resumed treatment at a lower dose 4 weeks after the event. In total, 74 serious adverse events (SAE) were reported in 47 pts (20.3%), with 18 new SAEs and 13 additional pts (5.6%) with SAEs since the previous interim analysis, including 1 new SAE (atrial fibrillation) considered drug related. No new safety signals were identified. One additional death (leading to a total of 4) occurred, due to intracranial hemorrhage. Like the previous 3 deaths (due to acute myocardial infarction, cardiac arrest, and bacterial endocarditis) the event was considered unrelated to the study drug. Conclusions Long-term mavacamten treatment up to 120 weeks showed sustained improvements in LVOT obstruction, symptoms, and NT-proBNP levels in pts with symptomatic obstructive HCM consistent with the findings of the parent study. Mavacamten treatment continues to be well tolerated with no new safety signals observed.

Changes in standard of care (SOC) medication during long-term mavacamten treatment for obstructive hypertrophic cardiomyopathy (HCM): results from the EXPLORER cohort of MAVA-Long-Term Extension (LTE)

Abstract Introduction Mavacamten is efficacious and well tolerated in patients with obstructive HCM in the ongoing MAVA-LTE study (NCT03723655) as shown in previous interim analyses. Here, we present exploratory data from the EXPLORER cohort of MAVA-LTE investigating the effect of changes in SOC treatment on the efficacy and safety of mavacamten. Methods Patients who completed EXPLORER-HCM (NCT03470545) could enroll in MAVA-LTE and comprised the EXPLORER cohort. All patients in the EXPLORER cohort received mavacamten. Patients could receive beta blockers or nondihydropyridine calcium channel blockers (verapamil/diltiazem) as SOC treatment. After 24 weeks on study, SOC treatment could be adjusted. A cumulative interim analysis (data cut-off: May 31, 2022) was performed on patients who: received no SOC, discontinued SOC, had any reduction in SOC and had ≥50% reduction in SOC from baseline to data cut-off. Results In total, 231 patients (mean age, 60 years; 39% female) comprised the EXPLORER-LTE cohort (median time on study: 101 weeks at data cut-off). At baseline, 176 patients (76.2%) received beta blockers and 38 (16.5%) received nondihydropyridine calcium channel blockers. At data cut-off, 12 (5.2%) patients had received no SOC treatment from baseline, 11 (4.8%) patients had discontinued SOC, 27 (11.7%) patients had any dose reduction in SOC, 18 (7.8%) patients had a ≥50% reduction in SOC and 14 (6.1%) patients had an increase in SOC. In the no SOC subgroup, mavacamten treatment was associated with improvements from baseline to last visit in resting and Valsalva left ventricular outflow tract (LVOT) gradients, left atrial volume index (LAVI), and N-terminal pro B-type natriuretic peptide (NT-proBNP) levels (Table 1). Improvements in these parameters were also observed in the SOC discontinuation and SOC dose reduction subgroups (Table 1). In the SOC discontinuation subgroup, improvements in resting and Valsalva LVOT gradients, LAVI, and NT-proBNP levels from baseline were maintained after SOC discontinuation (Table 1). SOC medications were discontinued or reduced over a mean (range) period of 63 (9–96) and 62 (3–133) weeks, respectively. At data cut-off, left ventricular ejection fraction remained within the normal range for all patients regardless of the SOC subgroup. Patients who reduced SOC medication had small increases in heart rate (within normal range) from baseline to last visit (Table 2). Overall, blood pressure remained stable across subgroups throughout the observation period (Table 2). No patients experienced worsening of NYHA class from baseline to last visit or from withdrawal to last visit. Conclusions Beneficial and sustained effects on LVOT obstruction, NT-proBNP levels and symptoms in patients with symptomatic obstructive HCM were observed with long-term mavacamten treatment alone or after SOC discontinuation or dose reduction.

Sacubitril/valsartan for treatment of symptomatic non-obstructive hypertrophic cardiomyopathy: a randomised, controlled, phase II clinical trial (SILICOFCM)

Abstract Aim To evaluate the effect of sacubitril/valsartan on exercise capacity, cardiac structure, and function in patients with hypertrophic cardiomyopathy (HCM). Methods Phase II, randomised, open-label multicentre study enrolled adult patients with symptomatic non-obstructive HCM (NYHA class I–III) who were randomly assigned (2:1) to receive sacubitril/valsartan (target dose 97/103mg) or usual care for 16 weeks. Primary endpoint was a change in peak oxygen consumption (peak VO2). Secondary endpoints included echocardiography measures of cardiac structure and function, natriuretic peptides and other biomarkers, and Minnesota Living with Heart Failure quality of life (QoL). Results Between May 2018 and November 2021, 354 patients were screened for eligibility, 115 patients (mean age 58 years [SD 11], 37% women) met the study inclusion criteria and were randomly assigned to sacubitril/valsartan (N=79) or usual care (N=36). At 16 weeks, there was no significant change in peak VO2 from baseline in sacubitril/valsartan (15.3 [4.3] vs 15.9 [4.3] ml/kg/min, p=0.13), or usual care group (p=0.47). There was a significant reduction in ventilatory efficiency slope (30.1 [7] vs 28.4 [4.9], p=0.03), but not in the control group (p=0.09). No significant changes were found in systolic or diastolic function, cardiac structure, or plasma biomarkers. The QoL score decreased significantly in the sacubitril/valsartan by 6 points (p=0.005) but not in the usual care group (p=0.66). Conclusion In patients with hypertrophic cardiomyopathy, 16 weeks of treatment with sacubitril/valsartan was well tolerated and contributed to a significant improvement in ventilatory efficiency and quality of life but not in exercise capacity or cardiac function.

The Efficacy of Cardiac Myosin Inhibitors Versus Placebo in Patients With Symptomatic Hypertrophic Cardiomyopathy: A Meta-Analysis and Systematic Review

We aimed to assess the overall clinical impact of cardiac myosin inhibitors in hypertrophic cardiomyopathy (HCM). We performed a meta-analysis of published trials assessing the effect of cardiac myosin inhibitors (Mavacamten and Aficamten) on resting and Valsalva LVOT gradients and functional capacity in symptomatic HCM. The co-primary outcomes were mean percent change (mean difference, MD) from baseline in resting LVOT gradient and Valsalva LVOT gradient, as well as proportion of patients achieving NYHA Class improvement ≥ 1. Secondary outcomes included mean percent change from baseline NT ProBNP, Troponin I, and left ventricular ejection fraction (LVEF). Four studies (all randomized-control trials, including 3 Mavacamten-focused and 1 Aficamten-focused trials) involving 463 patients were included in the meta-analysis. Compared to placebo, the cardiac myosin inhibitor group demonstrated statistically significant differences in baseline percent change in mean resting LVOT gradient (MD -62.48, CI -65.44, -59.51, p <0.00001) and Valsalva LVOT gradient (MD -54.21, CI -66.05, -42.36, p <0.00001), as well as proportion of patients achieving NYHA Class improvement ≥ 1 (OR 3.43, CI 1.90, 6.20, p <0.0001). Regarding secondary outcomes, the intervention group demonstrated statistically significant reductions in mean percent change from baseline in NT-proBNP (MD -69.41, CI -87.06, -51.75, p < 0.00001), Troponin I (MD, -44.19, CI -50.59, -37.78, p < 0.00001), and LVEF (MD -6.31, CI -10.35, -2.27, p = 0.002). In conclusion, cardiac myosin inhibitors may confer clinical and symptomatic benefits in symptomatic HCM, at the possible expense of LVEF. Further trials with large sample sizes are needed to confirm our findings.

Patient-Level Artificial Intelligence–Enhanced Electrocardiography in Hypertrophic Cardiomyopathy: Longitudinal Treatment and Clinical Biomarker Correlations

BackgroundArtificial intelligence (AI) applied to 12-lead electrocardiographs (ECGs) can detect hypertrophic cardiomyopathy (HCM). ObjectivesThe purpose of this study was to determine if AI-enhanced ECG (AI-ECG) can track longitudinal therapeutic response and changes in cardiac structure, function, or hemodynamics in obstructive HCM during mavacamten treatment. MethodsWe applied 2 independently developed AI-ECG algorithms (University of California-San Francisco and Mayo Clinic) to serial ECGs (n = 216) from the phase 2 PIONEER-OLE trial of mavacamten for symptomatic obstructive HCM (n = 13 patients, mean age 57.8 years, 69.2% male). Control ECGs from 2,600 age- and sex-matched individuals without HCM were obtained. AI-ECG output was correlated longitudinally to echocardiographic and laboratory metrics of mavacamten treatment response. ResultsIn the validation cohorts, both algorithms exhibited similar performance for HCM diagnosis, and exhibited mean HCM score decreases during mavacamten treatment: patient-level score reduction ranged from approximately 0.80 to 0.45 for Mayo and 0.70 to 0.35 for USCF algorithms; 11 of 13 patients demonstrated absolute score reduction from start to end of follow-up for both algorithms. HCM scores were significantly associated with other HCM-relevant parameters, including left ventricular outflow tract gradient at rest, postexercise, and with Valsalva, and NT-proBNP level, independent of age and sex (all P < 0.01). For both algorithms, the strongest longitudinal correlation was between AI-ECG HCM score and left ventricular outflow tract gradient postexercise (slope estimate: University of California-San Francisco 0.70 [95% CI: 0.45-0.96], P < 0.0001; Mayo 0.40 [95% CI: 0.11-0.68], P = 0.007). ConclusionsAI-ECG analysis longitudinally correlated with changes in echocardiographic and laboratory markers during mavacamten treatment in obstructive HCM. These results provide early evidence for a potential paradigm for monitoring HCM therapeutic response.

Efficacy and Safety of Mavacamten in the Treatment of Hypertrophic Cardiomyopathy: A Systematic Review.

Current pharmacological options for hypertrophic cardiomyopathy (HCM) are not disease-specific; while it treats symptoms, mavacamten targets the underlying pathology. We aim to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive HCM. This systematic review of the literature followed the PRISMA guidelines. Title/abstract and topics were searched using the following term: "mavacamten". The electronic research literature databases included the Cochrane Library, MedLine, and clinicaltrials.gov from July to August 2022. Primary efficacy endpoint was to assess clinical response at the end of treatment compared with baseline, defined as, at least one New York Heart Association (NYHA) class reduction. Two secondary endpoints from baseline were determined. The first was defined as improvement in mixed venous oxygen pressure (pVO2). The second was defined as reduction of the post-exercise left ventricular outflow tract (LVOT) gradient. We included in our analyses data from four studies that met our review eligibility criteria. There were three randomised placebo-controlled clinical trials and one non-randomised open-label clinical trial. All four studies showed a reduction in NYHA class from mavacamten use. Three out of four studies demonstrated >1 NYHA functional class improvement ranging from 34% to 80%, while only one study showed a smaller percentage of patients remaining at class 3. Three out of four studies measured pVO2 as an outcome, and all three studies noticed an increase in peak oxygen consumption after mavacamten treatment. Additionally, three out of four studies measured post-exercise LVOT gradient reduction as an outcome and all three found significant reduction in the post-exercise LVOT gradient after treatment. The most commonly observed adverse side effects were atrial fibrillation and decreased left ventricular ejection fraction, but all participants recovered without long-term sequelae and only one patient dropped out of the trial. Mavacamten has a greater efficacy than placebo in the treatment of HCM. It also showed promising tolerability and efficacy profiles in the treatment of HCM in adults. The three endpoints used in the evaluation of studies were reduction in NYHA class, increase in pVO2, and post-exercise LVOT gradient reduction. Mavacamten showed greater reduction in NYHA, larger effects on increase of pVO2, and significant reduction of the LVOT gradient. Mavacamten was also found to be well tolerated, like the placebo. The side effect profile was limited for the majority of individuals taking mavacamten. In the future, authors recommended dose-optimisation studies, and studies that evaluate mavacamten both in comparison to, and in conjunction with other current treatments.

Mavacamten in Patients With Hypertrophic Cardiomyopathy Referred for Septal Reduction

There is an unmet need for novel medical therapies before recommending invasive therapies for patients with severely symptomatic obstructive hypertrophic cardiomyopathy (HCM). Mavacamten has been shown to improve left ventricular outflow tract (LVOT) gradient and symptoms and may thus reduce the short-term need for septal reduction therapy (SRT). To examine the cumulative longer-term effect of mavacamten on the need for SRT through week 56. This was a double-blind, placebo-controlled, multicenter, randomized clinical trial with placebo crossover at 16 weeks, conducted from July 2020 to November 2022. Participants were recruited from 19 US HCM centers. Included in the trial were patients with obstructive HCM (New York Heart Association class III/IV) referred for SRT. Study data were analyzed April to August 2023. Patients initially assigned to mavacamten at baseline continued the drug for 56 weeks, and patients taking placebo crossed over to mavacamten from week 16 to week 56 (40-week exposure). Dose titrations were performed using echocardiographic LVOT gradient and LV ejection fraction (LVEF) measurements. Proportion of patients undergoing SRT, remaining guideline eligible or unevaluable SRT status at week 56. Of 112 patients with highly symptomatic obstructive HCM, 108 (mean [SD] age, 60.3 [12.5] years; 54 male [50.0%]) qualified for the week 56 evaluation. At week 56, 5 of 56 patients (8.9%) in the original mavacamten group (3 underwent SRT, 1 was SRT eligible, and 1 was not SRT evaluable) and 10 of 52 patients (19.2%) in the placebo crossover group (3 underwent SRT, 4 were SRT eligible, and 3 were not SRT evaluable) met the composite end point. A total of 96 of 108 patients (89%) continued mavacamten long term. Between the mavacamten and placebo-to-mavacamten groups, respectively, after 56 weeks, there was a sustained reduction in resting (mean difference, -34.0 mm Hg; 95% CI, -43.5 to -24.5 mm Hg and -33.2 mm Hg; 95% CI, -41.9 to -24.5 mm Hg) and Valsalva (mean difference, -45.6 mm Hg; 95% CI, -56.5 to -34.6 mm Hg and -54.6 mm Hg; 95% CI, -66.0 to -43.3 mm Hg) LVOT gradients. Similarly, there was an improvement in NYHA class of 1 or higher in 51 of 55 patients (93%) in the original mavacamten group and in 37 of 51 patients (73%) in the placebo crossover group. Overall, 12 of 108 patients (11.1%; 95% CI, 5.87%-18.60%), which represents 7 of 56 patients (12.5%) in the original mavacamten group and 5 of 52 patients (9.6%) in the placebo crossover group, had an LVEF less than 50% (2 with LVEF ≤30%, one of whom died), and 9 of 12 patients (75%) continued treatment. Results of this randomized clinical trial showed that in patients with symptomatic obstructive HCM, mavacamten reduced the need for SRT at week 56, with sustained improvements in LVOT gradients and symptoms. Although this represents a useful therapeutic option, given the potential risk of LV systolic dysfunction, there is a continued need for close monitoring. ClinicalTrials.gov Identifier: NCT04349072.

Abstract P2138: Long-Term Clinical Value And Impact Of Mavacamten In Symptomatic Obstructive Hypertrophic Cardiomyopathy: A Systematic Review And Meta-Analysis

Introduction: Hypertrophic cardiomyopathy (HCM) is a common genetic cardiac disorder involving the cardiac sarcomere. Mavacamten is the first-in-class oral cardiac myosin inhibitor approved for treating HCM in adults targeting sarcomere hypercontractility. We aimed to evaluate the efficacy and safety of mavacamten in symptomatic obstructive HCM. Methods: We conducted a systematic literature search in Embase, PubMed, Scopus, and Web of Science databases from inception until March 05, 2023. Results: After screening 349 studies, our final analysis included 5 studies with 843 obstructive HCM patients and an average follow-up of 27.2 weeks. A fixed effects model was used to calculate risk ratios (RRs). Our meta-analysis revealed a significant improvement in NYHA functional class from baseline in patients on mavacamten compared to placebo [RR, 4.59 (95% CI: 2.94-7.16), p&lt;0.00001]. Mavacamten use in obstructive HCM patients also resulted in significantly lower rates of septal reduction therapy (SRT) or patients who were guideline-eligible for SRT versus placebo [RR, 0.29 (95% CI: 0.22-0.39), p&lt;0.00001]. There was no significant effect of mavacamten use on the Kansas City Cardiomyopathy Questionnaire (KCCQ) score (p = 0.22). Also, no significant difference was observed in the occurrence of ≥1 serious adverse event (p = 0.77), atrial fibrillation (p = 0.98), and non-sustained ventricular tachycardia (p = 0.44) between mavacamten and placebo group. Conclusions: A substantial improvement in NYHA functional class without any serious adverse events, and a significant reduction in the number of patients requiring SRT, makes mavacamten a promising drug for obstructive HCM.

Aficamten: A Breakthrough Therapy for Symptomatic Obstructive Hypertrophic Cardiomyopathy.

Aficamten is a novel cardiac myosin inhibitor that has demonstrated its ability to safely lower left ventricular outflow tract (LVOT) gradients and improve heart failure symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM). Based on the REDWOOD-HCMopen label extension (OLE) study, participants receiving aficamten had significantly reduced resting and Valsalva LVOT gradient within 2 weeks after initiating treatment, with ongoing improvements over 24 weeks, and recent evidence suggests effects can sustain up to 48 weeks. While beta-blockers, calcium channel blockers, and disopyramide have shown some benefits in managing HCM, they have limited direct impact on the underlying disease process in patients with obstructive HCM. Aficamten achieves its therapeutic effect by reducing hypercontractility and improving diastolic function in obstructive HCM. Mavacamten was the first cardiac myosin inhibitor approved for symptomatic obstructive HCM. However, aficamten has a shorter human half-life (t1/2) and fewer drug-drug interactions, making it a preferable treatment option. This review evaluates the long-term clinical value and safety of aficamten in patients with obstructive HCM based on available data from completed and ongoing clinical trials. Additionally, the molecular basis of sarcomere-targeted therapy in reducing LVOT gradients is explored, and its potential in managing obstructive HCM is discussed.

Effects of septal myectomy on left atrial and left ventricular function in obstructive hypertrophic cardiomyopathy.

Mechanical function of the left atrium (LA) and the left ventricle (LV) has been demonstrated to be a prognostic factor in patients with hypertrophic cardiomyopathy (HCM). We explore whether myocardial mechanical function can be improved by septal reduction therapy in symptomatic obstructive HCM. Among 65 patients who underwent septal myectomy for symptomatic obstructive HCM from 2006 to 2022, 44 were analysed after excluding those who underwent simultaneous valve repair or replacement or maze operation. LA and LV functional variables including LA strain and LV global longitudinal strain were evaluated by two-dimensional and speckle-tracking echocardiography and compared before and 1year after surgery. After septal myectomy, LA volume index (58.1±18.3 vs. 45.3±14.6mL/m2 , P=0.001) decreased significantly. As LV end-systolic dimension increased after surgery, the LV ejection fraction decreased (73.8±6.7 vs. 62.9±8.3%, P<0.001). LA strain (24.4±9.3 vs. 30.5±13.6%, P=0.004) improved after septal myectomy, but LV global longitudinal strain deteriorated (-12.6±3.6 vs. -11.6±4.3%, P=0.033), mainly related to worsening non-septal longitudinal strain (-14.4±4.3 vs. -10.9±8.4%, P=0.005). As haemodynamic loads due to LV outflow tract obstruction was relieved through surgical septal reduction therapy in patients with symptomatic obstructive HCM, there was a significant reduction in LA volume and restoration of LA mechanical dysfunction. However, LV mechanical dysfunction deteriorated even after surgical septal reduction therapy.

The Efficacy of Cardiac Myosin Inhibitors Versus Placebo in Patients with Symptomatic Hypertrophic Cardiomyopathy

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Clinical features of hypertrophic cardiomyopathy depending on the hereditary factor

The objective was to study the clinical features of symptomatic hypertrophic cardiomyopathy (HCM) depending on the form (familial / non-familial), the age of onset and the presence of arterial hypertension (AH).Methods and materials. During 6 years, we examined 250 HCM patients, 100 patients with symptomatic HCM aged from 18 to 86 years were included in the study. Results. Patients with the clinical manifestations onset at a young age more often had a familial form of the disease, an autosomal dominant type of inheritance, an asymmetric HCM with reverse curve interventricular septal morphology. On the contrary, patients with the clinical manifestations onset at the age of ≥45 years had non-familial form of the disease and asymmetric HCM with basal interventricular septal hypertrophy. The young HCM patients with associated AH more often were obese, had CHF of III–IV functional class (NYHA), larger anteroposterior left atrial diameter than patients without AH and more often needed interventricular septal reduction. HCM patients and associated AH with the disease onset at the age of ≥45 years significantly more often had angina syndrome. Absolute indications for interventricular septal reduction in HCM patients with the disease onset ≥45 years of age were determined only for HCM patients and associated AH. At the same time, 50 % of HCM+AH patients both at a young age and in the older group, had obesity. Conclusions. The interventricular septal morphology differs significantly depending on the age of clinical manifestations onset. Co-existing AH and obesity are predictors of the progressive HCM course and an increase in the proportion of patients with absolute indications for interventricular septal reductions regardless of the age of clinical manifestations onset.

Abstract P375: Envisioning an “Ideal State” for Hypertrophic Cardiomyopathy — Patients and Health Care Professionals Discuss Steps to Improve Guideline-Directed Diagnosis and Treatment

Introduction: Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease, affecting an estimated 1 in 500 adults in the U.S. Despite its prevalence, the condition is underdiagnosed because HCM symptoms are not widely recognized among patients and health care professionals. Previously, the American Heart Association (AHA) hosted two Roundtable Discussions on HCM. These discussions identified diagnosis challenges and education resource gaps, and highlighted updates to HCM scientific guidelines. Objective: Build on previous Roundtables to identify steps needed to achieve an “ideal state” for patients with HCM through a guided discussion with patients and multi-disciplinary health care professionals. Methods: The virtual Roundtable was facilitated using a semi-structured interview guide with HCM patients (n=3) and multi-disciplinary health care professionals (n=8). The discussion recording was transcribed, and inductive and deductive thematic analyses identified key themes. Results: Patients described an “ideal state” that included increased awareness and management of HCM among patients and health care professionals, a greater sense of empowerment and trust in health care systems, and improved connections with allied health, mental health, and peer support services. Health care professionals described an “ideal state” as increased awareness of and training in HCM and genetics at all levels of medical education, equitable and timely access to care and diagnosis, improved models of care, and scientific advancements to improve treatment and diagnosis. Health care professionals cited financial barriers to achieving this state, particularly the need to improve health care financing to facilitate HCM care coordination across departments and health systems. The role of technology and digital tools was also identified as key to achieving the “ideal state,” with health care professionals noting both promise and limitations in their ability to improve HCM diagnosis and treatment. Conclusions: Reaching an “ideal state” for diagnosing and treating HCM patients requires systematic changes at the patient, health care professional, and health care system levels. Addressing the steps outlined during this discussion could vastly improve treatment, outcomes, and quality of life for patients with HCM as well as support health care professionals as they provide timely, guideline-directed diagnosis and treatment.

The role of cardiac catheterization in solving the issue of surgical treatment of symptomatic hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an underdiagnosed genetic heart disease with a prevalence of 0.2–0.5 %. Although the prognosis of HCM is relatively favorable, the annual overall mortality is about 0.7 %. The most common complication of HCM is obstruction of the left ventricular outflow tract (LVOT). Careful diagnosis and timely identification of high-risk patients by confirming the presence and degree of obstruction of the left ventricular outflow tract may reduce morbidity and mortality due to timely and correctly selected treatment. One-third of patients with HCM have echocardiographically confirmed LVOT obstruction at rest, and another third may have LVOT obstruction with provocation. Our clinical case demonstrates the presence of a small group of patients with HCM, whose LVOT obstruction is underestimated by transthoracic echocardiography (TTE) neither at rest nor when using provocative tests (Valsalva tests, exercise), and its hemodynamic significance is revealed only with invasive hemodynamic catheterization of the heart. Below, we illustrate the utility of hemodynamic catheterization as an adjunctive tool to echocardiography to help establish the presence, magnitude, and location of obstruction in patients with HCM in the absence of such data on TTE. In case of a high degree of suspicion that LVOT obstruction is responsible for refractory symptoms, catheterization can establish the presence of a hemodynamically significant LVOT gradient and, accordingly, without deviating from clinical recommendations, to carry out optimal surgical treatment, in our case – septal alcohol ablation with subsequent elimination of symptoms and restoration of the patient’s endurance to physical exertion.

Clinical Outcomes, Resource Utilization, and Treatment Over the Disease Course of Symptomatic Obstructive Hypertrophic Cardiomyopathy in the United States

We sought to describe the clinical outcomes, resource utilization, and treatment options for patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) over the course of their disease. Adults with obstructive HCM who were symptomatic were identified from the IBM MarketScan Commercial and Medicare supplemental database (January 2009 to March 2019). The index date was the initial obstructive HCM diagnosis date. Patients were required to have ≥12-month continuous eligibility before and after the index date. Incidence rates (IRs) and cumulative risk of cardiovascular events, healthcare resource utilization, and pharmacotherapy were assessed after index and compared with matched controls. Among 4,617 eligible patients with obstructive HCM, 2,917 (63.2%, mean age 60, 47.2% women) were symptomatic at index date. The most common cardiovascular events were atrial fibrillation/flutter (IR:1.421 per person-year [PPY], heart failure (IR: 0.895 PPY), and dyspnea (IR:0.797 PPY). Patients incurred higher resource use with frequent tests and monitoring, hospitalizations (0.454 PPY), and emergency room visits (0.611 PPY). The use of pharmacotherapy increased from 61.2% in the 6-month preindex period to 83.9% in the 6-month postindex period and remained stable after diagnosis. These events ranged from 3 to over 60-fold higher compared with controls, with the largest difference observed in arrhythmic events. The majority of patients were symptomatic at the time of obstructive HCM diagnosis, resulting in significantly increased cardiovascular complications and frequent disease monitoring after diagnosis versus controls. In conclusion, healthcare resource utilization was substantial, and these findings suggest a higher clinical and economic burden over the disease course among patients with symptomatic obstructive HCM, despite current treatment.