High "sarcopenia index" reduce all-cause mortality in patients with acute myocardial infarction.

<p><em>BACKGROUND</em>The product of serum creatinine and cystatin C-based estimated glomerular filtration rate (hereinafter referred to as "Cr × eGFRcys"), serving as the formula for the Sarcopenia Index (SI), could be regarded as a representative marker for sarcopenia. However, no studies have investigated whether Cr × eGFRcys can predict all-cause mortality in elderly patients with acute myocardial infraction (AMI).</p><p><em>AIM</em>To investigate the association between Cr × eGFRcys and all-cause mortality risk in elderly AMI patients.</p><p><em>METHODS</em>We conducted a retrospective cohort analysis of 500 elderly (≥65 years) AMI patients.

Participants were stratified into high and low Cr × eGFRcys groups using the optimal cut-off determined by receiver operating characteristic (ROC) analysis, with all-cause mortality as the primary endpoint. Kaplan-Meier (hereinafter referred to as "K-M") survival curves assessed survival differences (log-rank test).

Multivariable Cox proportional hazards models evaluated the independent association of Cr × eGFRcys (as continuous, categorical, or per-standard deviation increase) with mortality. The added predictive value beyond conventional risk factors was assessed through C-statistics, continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI).</p><p><em>RESULT</em>Survival analysis revealed significantly better outcomes in the high Cr × eGFRcys group compared to the low group (log-rank p < 0.0001).

Inclusion of Cr × eGFRcys significantly enhanced the predictive accuracy of the baseline risk model for all-cause mortality: NRI = 0.43 (95 % CI: 0.17-0.61, p < 0.01), IDI = 0.04 (95 % CI: 0.01-0.08, p = 0.02), and C-index = 0.93 (95 % CI: 0.90-0.96), all with p < 0.05.</p><p><em>CONCLUSION</em>Cr × eGFRcys was significantly associated with all-cause mortality, and the optimal cut-off value for predicting all-cause mortality was 53.56, suggesting that Cr × eGFRcys may serve as a valid marker of all-cause mortality in elderly patients with AMI.</p>