Abstract 4367632: Perioperative NT-proBNP Change Predicts Adverse Outcomes After Septal Myectomy: A Nonlinear U-Shaped Association in Obstructive Hypertrophic Cardiomyopathy

Background: Although there have been some studies on the preoperative N-terminal pro-B-type natriuretic peptide (NT-proBNP), the prognostic significance of perioperative changes in NT-proBNP (ΔLn(NT-proBNP)) after septal myectomy for obstructive hypertrophic cardiomyopathy (OHCM) remains unestablished. Hypothesis: Nonlinear patterns of perioperative NT-proBNP variation predict long-term clinical outcomes. Methods: We analyzed 1,533 consecutive OHCM patients (2012–2020) with paired NT-proBNP measurements (preoperative and pre-discharge), and the patients were categorized into Decreased (n=511), Stable (n=511), and Increased (n=511) according to ΔLn(NT-proBNP). Composite endpoint included: composite of cardiovascular death, heart failure, reoperation, ICD implantation, stroke, and rehospitalization. Multivariable Cox regression (adjusted for age, atrial fibrillation, aortic clamp time, ICU time) and restricted cubic splines (RCS) assessed associations between NT-proBNP (preoperative, postoperative, Δ) and outcomes. Model Performance analysis and subgroup analysis were conducted to evaluate the models. Results: Over a median follow-up of 3.34 years, 24 deaths (11 cardiovascular) and 251 composite endpoint events occurred. RCS analysis revealed distinct patterns: postoperative NT-proBNP exhibited a significant linear association with increased composite endpoint risk (Poverall=0.010), while ΔNT-proBNP demonstrated a robust inverted U-shaped relationship with the composite endpoint (Pnonlinear=0.007,Poverall=0.025), indicating highest risk with mild postoperative increases. Multivariable Cox analysis confirmed postoperative NT-proBNP (HR 1.210(1.051–1.393), p=0.008) and the nonlinearity of ΔNT-proBNP(HR 0.840(0.721~0.978) for quadratic term, p=0.024) as independent predictors of the composite endpoint after adjusting for the traditional clinical variables(age, Atrial fibrillation, Aortic clamp time, ICU time). Incorporating postoperative NT-proBNP and ΔNT-proBNP nonlinearity enhanced model discrimination and reclassification beyond base model (NRI=0.117,p=0.040; IDI=0.007; p=0.033). Subgroup analysis confirmed the robustness of NT-proBNP in the vast majority of subgroups and demonstrated a stronger predictive effect in NYHA III/IV. Conclusions: Perioperative NT-proBNP change exhibits an inverted U-shaped nonlinear association with adverse outcomes post-myectomy, providing critical incremental prognostic value for risk stratification in OHCM.