Troponin ratio and risk stratification in subjects with acute coronary syndrome undergoing percutaneous coronary intervention

Abstract

Background Cardiac enzyme release after percutaneous coronary intervention (PCI) seems to play a role in risk stratification. After PCI, CK-MB plasmatic concentrations three times above the upper level of normal (ULN) are currently the most used risk stratification parameters. We sought to assess whether peak cardiac troponin I (cTn-I) concentration/base concentration ratio (PBTR) may act as a predictor of major adverse cardiac events (MACEs) after PCI, regardless of cTn-I ULN. Methods We evaluated 326 consecutive patients with acute coronary syndrome (ACS) who underwent PCI. Baseline and post-PCI cTn-I values were evaluated over serial blood samples every 6h for at least 72h. Patients were further divided into four groups according to their PBTR values (< 1, 1–4, 4–10, > 10). MACEs were recorded over a 6-month follow-up period. Patients with primary PCI or unsuccessful PCI were excluded from the study. Results Higher values of PBTR significantly correlated with a worse prognosis at 6 months (< 1, 16.30% of MACEs; 1–4, 19.42%; 4–10, 24.39%; > 10, 35.63%; p < 0.05), both in Q-wave myocardial infarction (MI) and unstable angina (UA) subgroups. The correlation remained statistically significant, even considering subjects with peak cTn-I less than three times the ULN ( p < 0.05) and after correction for age, gender, risk factors, diagnosis (MI versus UA), and peak cTn-I levels in a multiple Cox' regression analysis (HR 1.62, p < 0.05). Conclusions PBTR is an independent predictor of MACEs after PCI in a 6-month follow-up period. This risk stratification tool may be useful to predict adverse events in PCI patients, even in the case of apparently non-elevated peak cTn-I concentrations.