Abstract:

Objective ·To investigate the predictive value of the combination of preoperative D-dimer levels and the N-terminal pro-B-type natriuretic peptide (NT-proBNP) ratio for early major adverse cardiovascular events (MACE) following the modified extended Morrow procedure in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods ·Patients with HOCM who underwent the modified extended Morrow procedure in the First Hospital of Lanzhou University between January 2015 and June 2025 were enrolled. Baseline data and perioperative data were collected for all patients. Baseline data included demographic indicators, symptoms and functional status, medical history, preoperative levels of blood biomarkers (D-dimer and NT-proBNP, with the latter calculated as an age- and sex-adjusted ratio), and preoperative echocardiographic parameters. The primary outcome was MACE within 30 days postoperatively. Four predictive models were constructed using Logistic regression: a model based on clinical baseline variables, a model combining clinical baseline variables with the NT-proBNP ratio, a model combining clinical baseline variables with D-dimer levels, and a model combining clinical baseline variables with two biomarkers (the ratio of NT-proBNP and the levels of D-dimer). Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Calibration accuracy, prediction accuracy, and clinical applicability were assessed using calibration curves, the Brier score, and decision curve analysis (DCA). Risk stratification of patients was performed using the optimal cut-off values for the NT-proBNP ratio and D-dimer, and perioperative risks and clinical outcomes were compared. Results ·Among the 83 patients included in the final analysis, 21 (25.30%) experienced MACE within 30 days postoperatively. The combined dual-biomarker model demonstrated the best predictive performance, with an AUC of 0.935, superior to the model based on clinical baseline variables and to any model combining clinical baseline variables with a single biomarker. Compared to the clinical baseline variable model, the combined dual-biomarker model showed an NRI of 1.390 and an IDI of 0.366 (both P<0.001). It also exhibited the best calibration (Hosmer-Lemeshow test P=0.767, Brier score 0.080), and DCA indicated the highest net benefit across a wide range of threshold probabilities. Patients were stratified into three groups (“dual-low”, “single-high”, and “dual-high”) based on the optimal cut-off values of the NT-proBNP ratio and D-dimer, revealing a significant risk gradient in MACE incidence. Furthermore, patients in the “dual-high” group had a more complex perioperative course, with significantly longer cardiopulmonary bypass time, aortic cross-clamp time, postoperative mechanical ventilation time, and postoperative hospital stay compared to those in the “dual-low” group (all P<0.05). Conclusion ·The preoperative combination of an age- and sex-adjusted NT-proBNP ratio and D-dimer levels can be used to construct an efficient and robust risk prediction model for early postoperative MACE. This strategy demonstrates excellent performance in discrimination, calibration, and clinical applicability, effectively identifying patients at extremely high risk and providing an objective basis for individualised perioperative management.

Key words: hypertrophic obstructive cardiomyopathy (HOCM), D-dimer, N-terminal pro-B-type natriuretic peptide (NT-proBNP), modified extended Morrow procedure, major adverse cardiovascular event (MACE)