Desai, Milind Y.

Introduction: In the randomized VALOR-HCM study of symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM), mavacamten reduced the need for septal reduction therapy at 16 weeks. The current sub-study sought to assess the impact of mavacamten on systolic anterior motion (SAM) of the mitral valve and associated mitral regurgitation (MR). Methods: Patients on maximally-tolerated medical therapy referred for septal reduction therapy were randomized 1:1 to mavacamten or placebo. Echocardiographic assessment was performed by an independent, blinded core laboratory. SAM was assessed as none, mild (anterior leaflet >/= 1 cm from the septum), moderate (anterior leaflets <1cm from the septum), and severe (anterior leaflet in contact with septum). MR was assessed according to ASE guidelines. Results: Among 112 enrolled patients, 23.2% (n=27) had at least moderate (2+) MR. Most (92.9%, n=104) had at least moderate resting SAM, of whom 55.4% (n = 62) had severe SAM. At 16 weeks, 53.7% of patients treated with mavacamten had at least one level improvement in resting SAM compared to 21.6% of patients treated with placebo ( p = 0.001), and 35.2% had at least a two level improvement in SAM compared with 11.8% of placebo patients ( p = 0.007)(Figure 1A). Similarly, patients treated with mavacamten had an improvement of -36.0 + 28.8 mmHg in resting left ventricular outflow tract gradient at week 16 compared to -1.5 + 26.5 mmHg with placebo (<0.001). At week 16, 48.1% of patients treated with mavacamten had at least a one grade improvement in MR, and 23.1% had at least a two grade improvement compared to 12.2% and 6.1% of patients treated with placebo ( p <0.001 and 0.025, respectively)(Figure 1B). Conclusions: In highly symptomatic patients with oHCM, treatment with mavacamten reduced resting SAM with an improvement in associated MR.

Introduction: In the randomized VALOR-HCM study of symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM), mavacamten reduced the need for septal reduction therapy at 16 weeks. Because mavacamten is a cardiac myosin inhibitor that may improve ventricular compliance, this sub-study hypothesized that mavacamten would favorably impact diastolic function. Methods: Symptomatic patients on maximally-tolerated medical therapy referred for septal reduction therapy were randomized 1:1 to mavacamten or placebo. Echocardiographic assessment was performed by an independent, blinded core laboratory. Diastolic grade was determined according to ASE guidelines. Between-group comparisons were made from baseline to week 16. Results: Among 112 enrolled patients, baseline left atrial volume index (LAVi) was similar (Table). At 16 weeks, mavacamten treatment resulted in a significant reduction in LAVi (-5.2 vs -0.5 with placebo, p = .003). Similarly, although lateral E/e’ and septal E/e’ were comparable at baseline, patients treated with mavacamten demonstrated a significant reduction at week 16 (lateral E/e’: -3.5 vs 0.7, p <0.001; septal E/e’: -3.3 vs 0.7, p < 0.001)(Table). Patients treated with mavacamten were also more likely to improve their diastolic dysfunction grade (31.4% vs 12.8%, p = 0.032) (Figure). Conclusions: After only 16 weeks of therapy, in a highly symptomatic oHCM population with echocardiographic-guided drug titration, mavacamten improved measures of diastolic function.

Background: In the randomized phase 3 VALOR-HCM study (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) of patients with obstructive hypertrophic cardiomyopathy, mavacamten reduced the need for septal reduction therapy. Because mavacamten improves ventricular compliance, this sub-study examined the effects of treatment with this cardiac myosin inhibitor on diastolic function. Methods: Symptomatic obstructive hypertrophic cardiomyopathy patients on maximally tolerated medical therapy referred for septal reduction therapy were randomized 1:1 to mavacamten or placebo. At baseline and week 16, a resting and stress echocardiogram was performed with interpretation by a core laboratory. In this exploratory substudy, the principal end point was the change in parameters used to define the grade of diastolic function in patients treated with mavacamten and placebo. A related objective was to assess the proportion of patients with an improvement in diastolic function grade. A secondary aim was to assess for correlation between diastolic function parameters and the secondary end points from VALOR-HCM: New York Heart Association class, quality of life, and cardiac biomarkers. Results: Diastolic dysfunction grade was evaluable in 98 patients at baseline and week 16. Among patients treated with mavacamten, 29.4% (15 of 51) demonstrated improvement in diastolic function grade compared with 12.8% (6 of 47) patients with placebo ( P =0.05). Average E/e’ ratio decreased significantly in patients treated with mavacamten (−3.4±5.3) compared with placebo (0.57±3.5; P <0.001). Indexed left atrial volumes (mL/m 2 ) also decreased significantly in patients who received mavacamten (−5.2±7.8) compared with placebo (−0.51±8.1; P =0.005). After adjustment for change in left ventricular outflow tract gradient and mitral regurgitation, mavacamten was significantly associated with a decrease in average E/e’ ratio and indexed left atrial volumes. Change in average E/e’ ratio was significantly correlated with the secondary end points from VALOR-HCM. Conclusions: In this exploratory substudy, after 16 weeks of therapy, mavacamten improved diastolic function, and this change correlated with improvement in clinical and biomarker end points. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04349072.

Background: Septal reduction therapy (SRT) in patients with intractable symptoms from obstructive hypertrophic cardiomyopathy (oHCM) is associated with variable morbidity and mortality. The VALOR-HCM trial (A Study to Evaluate Mavacamten in Adults with Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) examined the effect of mavacamten on the need for SRT through week 32 in oHCM. Methods: A double-blind randomized placebo-controlled multicenter trial at 19 US sites included patients with oHCM on maximal tolerated medical therapy referred for SRT with left ventricular outflow tract gradient ≥50 mm Hg at rest or provocation (enrollment, July 2020–October 2021). The group initially randomized to mavacamten continued the drug for 32 weeks, and the placebo group crossed over to dose-blinded mavacamten from week 16 to week 32. Dose titrations were based on investigator-blinded echocardiographic assessment of left ventricular outflow tract gradient and left ventricular ejection fraction. The principal end point was the proportion of patients proceeding with SRT or remaining guideline eligible at 32 weeks in both treatment groups. Results: From the 112 randomized patients with oHCM, 108 (mean age, 60.3 years; 50% men; 94% in New York Heart Association class III/IV) qualified for week 32 evaluation (56 in the original mavacamten group and 52 in the placebo cross-over group). After 32 weeks, 6 of 56 patients (10.7%) in the original mavacamten group and 7 of 52 patients (13.5%) in the placebo cross-over group met SRT guideline criteria or elected to undergo SRT. After 32 weeks, a sustained reduction in resting left ventricular outflow tract gradient (−33.0 mm Hg [95% CI, −41.1 to −24.9]) and Valsalva left ventricular outflow tract gradient (−43.0 mm Hg [95% CI, −52.1 to −33.9]) was observed in the original mavacamten group. A similar reduction in resting (−33.7 mm Hg [95% CI, −42.2 to −25.2]) and Valsalva (−52.9 mm Hg [95% CI, −63.2 to −42.6]) gradients was quantified in the cross-over group after 16 weeks of mavacamten. After 32 weeks, improvement by ≥1 New York Heart Association class was observed in 48 of 53 patients (90.6%) in the original mavacamten group and 35 of 50 patients (70%) after 16 weeks in the cross-over group. Conclusions: In severely symptomatic patients with oHCM, 32 weeks of mavacamten treatment showed sustained reduction in the proportion proceeding to SRT or remaining guideline eligible, with similar effects observed in patients who crossed over from placebo after 16 weeks. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04349072.