Elevated Red Blood Cell Distribution Width Predicts Mortality and Major Adverse Cardiovascular Events After Acute Myocardial Infarction: A Large Propensity Score-Matched Cohort Study

<b>Background</b>: Red blood cell distribution width (RDW) is an accessible prognostic biomarker in cardiovascular disease, but its independent association with clinical outcomes in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) remains incompletely characterized, particularly regarding its prognostic value independent of anemia status. <b>Methods</b>: Using the TriNetX US Collaborative Network (70 healthcare organizations; >105 million patients), we identified 84,811 adult AMI patients who underwent PCI between January 2019 and December 2023 and had RDW measured on the index date. Patients were stratified by RDW ≥ 13.5% (high) versus <13.5% (low) and matched 1:1 using propensity scores based on 38 baseline characteristics. The primary outcome was 1-year all-cause mortality, assessed using a 30-day landmark approach. Secondary outcomes included major adverse cardiovascular events (MACE), heart failure, cardiogenic shock, recurrent AMI, cerebrovascular accident, ventricular tachycardia/fibrillation, and cardiac arrhythmia. <b>Results</b>: After matching (32,010 pairs), high RDW was significantly associated with increased 1-year all-cause mortality (HR 1.77, 95% CI 1.62-1.93, <i>p</i> < 0.001). High RDW was also associated with greater risks of MACE (HR 1.12), heart failure (HR 1.24), cardiogenic shock (HR 1.26), recurrent AMI (HR 1.11), cerebrovascular accident (HR 1.16), and cardiac arrhythmia (HR 1.14; all <i>p</i> < 0.01). Findings remained consistent across serial sensitivity analyses and subgroup analyses. Among non-anemic patients, high RDW remained strongly associated with mortality (HR 1.67, 95% CI 1.50-1.85, <i>p</i> < 0.001). <b>Conclusions</b>: Elevated RDW at the time of AMI is independently associated with mortality and adverse cardiovascular outcomes after PCI, including among non-anemic patients. RDW may serve as a readily available tool to support early risk stratification in this population.