Prognostic Value of Age-Adjusted D-Dimer Cutoff Thresholds in Patients with Acute Coronary Syndrome Treated by Percutaneous Coronary Intervention

BACKGROUND: Associations between D-dimer and outcomes of patients with acute coronary syndrome (ACS) remain controversial. Using age-adjusted D-dimer cutoff thresholds improve the diagnostic accuracy for thrombotic diseases. This study aimed to investigate the prognostic value of age-adjusted D-dimer in ACS patients treated by percutaneous coronary intervention (PCI). METHODS: A total of 3972 consecutive patients with ACS treated by PCI were retrospectively recruited. The basal age-adjusted D-dimer threshold was 500 ng/mL and was calculated as age × 10 in patients older than 50 years. Cox regression was used for outcome analysis. C-index, net reclassification index (NRI), and integrated discrimination improvement (IDI) were calculated to assess the additional prognostic value of age-adjusted D-dimer when combined with established clinical risk factors. The primary outcome was all-cause death. RESULTS: During a median follow-up of 720 days, a total of 225 deaths occurred. High D-dimer level, as defined by age-adjusted thresholds, was an independent predictor for all-cause death (hazard ratio [HR]: 1.75, 95% confidence interval [CI]: 1.32–2.31, P < 0.001), cardiac death (HR: 1.84, 95% CI: 1.30–2.60, P = 0.001), and MACE (HR: 1.48, 95% CI: 1.19–1.83, P < 0.001). Sensitivity and subgroup analysis showed that high D-dimer levels were constantly associated with worse outcomes across common risk factors and comorbidities. Besides, age-adjusted elevation of D-dimer significantly improved the risk predictions for all-cause death when added to the model of established risk factors (C-index: 0.846 vs 0.838, Δ C-index: 0.008, 95% CI: 0.001–0.015, P(difference) = 0.027; NRI: 0.645, 95% CI: 0.464–0.826, P < 0.001; IDI: 0.008, 95% CI: 0.001–0.017, P = 0.048). CONCLUSION: In ACS patients treated by PCI, age-adjusted elevation of D-dimer was an independent predictor for adverse outcomes and improved the risk predictions for long-term mortality.