Prognostic ability of cystatin C and homocysteine plasma levels for long-term outcomes in very old acute myocardial infarction patients

BACKGROUND AND AIMS: This study sought to evaluate the prognostic powers of combined use of cystatin C (Cys C) and homocysteine (Hcy) at predicting adverse events of patients >80 years old with acute myocardial infarction (AMI). PATIENTS AND METHODS: The analysis involved 753 patients >80 years old undergoing coronary angiography for chest pain in China from January 2006 to December 2012. Kaplan–Meier method was used for survival and major adverse cardiac events (MACE) rates. Multivariate Cox regression was performed to identify mortality predictors. Receiver operating characteristic curve analysis was performed to predict the cutoff values of Cys C and Hcy for all-cause mortality. RESULTS: The duration of follow-up was 40–116 months (median, 63 months; interquartile range, 51–74 months). The long-term survival and event-free survival rates of AMI patients were significantly lower than those of unstable angina pectoris patients (P<0.05), and were significantly different according to the tertile concentration of Cys C of AMI patients (P<0.01). Cys C and Hcy were independent risk factors for long-term all-cause mortality (odds ratio [OR] =3.72 [2.27–6.09]; OR =1.59 [1.04–2.61]) and MACE (OR =2.83 [1.82–4.40]; OR =1.09 [1.04–1.21]) of AMI patients. The predictive cutoff value of Cys C was 1.815 mg/L (82.8%, 86.4%) and that of Hcy was 15.06 μmol/L (84.4%, 83.1%) in AMI patients. Combined use of both biomarker’s cutoff values further increased the sensitivity and specificity of all-cause mortality. CONCLUSION: Cys C is a strong independent predictor of long-term all-cause death and MACE in very old AMI patients. The combined use of Cys C and Hcy further improves the predictive accuracy.