Predictors and prognostic value of myocardial injury following stent implantation

Background: Troponin I concentrations are frequently elevated following percutaneous coronary intervention (PCI) even in procedures without complications and are considered, by some, as predictive of long-term morbidity and mortality. We assessed whether post-PCI troponin I concentrations bore any relationship to clinical, angiographic and in-laboratory minor adverse events indicative of myocardial injury and evaluated, in follow-up, whether these levels are useful as a predictive markers of adverse events. Methods: Patients (n=147) who were scheduled for PCI for stent placement were prospectively studied. In-laboratory events recorded were protracted chest pain, electrocardiographic changes, slow flows, dissections and lateral branch affectation. Troponin I and creatinine kinase MB fraction (CK-MB) mass were measured at baseline and post-procedure. Mean clinical follow-up was for 10.4±3.6 months. Results: During PCI, at least one adverse event occurred in 34% of patients and, in 38% of them, there was an elevation of troponin I as compared to 5.1% of those patients without any adverse event (relative risk=7.4; P<0.001). Elevation of troponin I concentrations occurred in 16.3% of all patients, 79.2% associated with an AE. CK-MB was elevated in 15.6% of patients. On multivariate analysis, protracted chest pain, lateral branch involvement and slow flow remained statistically significant in relation to post-procedure elevations of troponin I concentrations. Clinical follow-up showed a poorer prognosis in patients who had had elevated troponin I concentrations. Conclusions: In-laboratory adverse event predict elevated post-procedure troponin I concentrations which are associated with myocardial injury. These elevations, in turn, predict poorer medium-term clinical outcomes.