Impact of Cardiovascular–Kidney–Metabolic Syndrome Staging on Myocardial Infarction Outcomes: A Retrospective Analysis of 2.7 Million Patients

<b>Background</b>: Cardiovascular-kidney-metabolic (CKM) syndrome, recently defined by the American Heart Association, encompasses the interplay between obesity, diabetes, chronic kidney disease, and cardiovascular disease. This study aimed to investigate the impact of CKM syndrome severity on outcomes in patients with acute myocardial infarction (AMI). <b>Methods</b>: A retrospective analysis was conducted using the National Inpatient Sample database from 2016 to 2019. Adult patients hospitalized with AMI were stratified into CKM Stages 0-4 based on ICD-10 codes. Multivariable logistic regression models were used to examine associations between CKM stages and in-hospital procedures and outcomes. <b>Results</b>: The study analyzed 2,768,154 AMI cases. Advanced CKM stages were associated with older age and a higher proportion of males. Patients with severe CKM were more likely to undergo invasive procedures. Coronary angiography showed the strongest association in CKM Stage 4A (aOR: 6.86, 95% CI: 6.73-6.99, <i>p</i>-value < 0.001) and Stage 4B (aOR: 3.87, 95% CI: 3.80-3.95, <i>p</i>-value < 0.001). Similarly, the likelihood of PCI was highest in Stage 4A (aOR: 5.93, 95% CI: 5.79-6.08, <i>p</i>-value < 0.001) and Stage 4B (aOR: 4.14, 95% CI: 4.04-4.24, <i>p</i>-value < 0.001). Notably, patients with CKM Stage 0 demonstrated higher odds of adverse outcomes compared to other stages. <b>Conclusions</b>: This study reveals a complex relationship between CKM syndrome severity and AMI outcomes. Patients with advanced CKM stages were more likely to undergo invasive procedures, and those without CKM risk factors unexpectedly showed worse outcomes. Among Stages 1-4B, no consistently graded association emerged between the CKM stage and adverse outcomes. These findings warrant further investigation into underlying mechanisms and long-term prognosis.