Clinical application of biomarkers in obstructive hypertrophic cardiomyopathy: insights from SEQUOIA-HCM

Abstract Background Multiple studies show that circulating cardiac biomarkers, N-terminal pro-B type natriuretic peptide (NT-proBNP) and high sensitivity cardiac troponin I (hs-cTnI) are associated with key pathophysiological processes and clinical outcomes in obstructive hypertrophic cardiomyopathy (oHCM). Herein we describe the impact of aficamten on cardiac biomarkers in SEQUOIA-HCM (NCT05186818). Purpose In this pre-specified analysis, we describe associations between baseline NT-proBNP and hs-cTnI concentrations and assess the relationship between changes after treatment with aficamten and trial endpoints. Methods Patients with oHCM in NYHA Class II-III, were randomized 1:1 to 24 weeks of daily aficamten (5–20 mg, n=142) or placebo (n=140). Aficamten dose was adjusted to achieve Valsalva left ventricular outflow tract gradient (LVOT-G) <30 mmHg while maintaining left ventricular ejection fraction (LVEF) ≥50%. Peak oxygen consumption (pVO2) was measured by cardiopulmonary exercise testing at baseline and week 24. Cardiac biomarkers were measured at baseline, each dose titration (weeks 2, 4, and 6), every 4 weeks during treatment and after 4 weeks drug washout. Multivariable regression analysis was used to identify significant predictors of baseline biomarker values. Joint modeling and mediation analysis was used to determine how much of the treatment effect was indirectly mediated by NT-proBNP and hs-cTnI. Results In 282 symptomatic oHCM patients (mean age 59 years, 41% female), the median (IQR) NT-proBNP was 788 ng/L (346, 1699) and hs-cTnI was 12 ng/L (9, 27). At baseline, LVOT-G modestly correlated with NT-proBNP, rho = 0.26 (p<0.001) but not hs-cTnI, rho = 0.06 (p=0.36). Predictors of baseline biomarker values are summarized in Table 1. Compared to placebo, aficamten treatment was associated with an early relative reduction from baseline at week 8 in NT-proBNP (-79% (95% CI -83%, -76%, p<0.001) and in hs-cTnI -41% (-49%, -32%), p<0.001. This magnitude of change persisted to week 24 with biomarker return to baseline after aficamten washout (Figure 1). The mediation analysis suggested that NT-proBNP reduction over the 24-week treatment period reflected 101% (41%, 195%) of aficamten’s effect on pVO2. In contrast hs-cTnI reduction reflected 3% (-18%, 30%) of aficamten’s effect on pVO2. Conclusions Concentrations of NT-proBNP and hs-cTnI are associated with clinically relevant echocardiographic variables in oHCM. Compared with placebo, aficamten treatment markedly reduced plasma NT-proBNP and hs-cTnI concentrations, evident from week 2 and persisting until the end of treatment. NT-proBNP reduction may link LVOT-G with reduced exercise capacity in oHCM. These data support the use of biomarkers as a tool for managing patients with oHCM in order to monitor response to aficamten therapy.Effect of aficamten on biomarkersPredictors of baseline biomarkers