Cardiac troponin T: An important predictor of late death and myocardial infarction following hip fracture: An eight-year prospective observational cohort study

Background: Cardiac troponin is an accurate marker of minimal myocardial injury and has been shown to predict adverse outcomes in various non-acute coronary disease settings. Patients with hip fracture (HF), an osteoporotic, mostly octogenarian population, are prone to sustain myocardial injury through both peri-fracture stress and subsequent surgery (osteosynthesis or hemiarthroplasty). Objective: To assess the frequency and magnitude of myocardial injury on admission and in-hospital (post-surgery) as measured by troponin T (TnT) and to evaluate the long-term prognostic value of TnT on cardiovascular morbidity and mortality. Methods: TnT levels were measured on admission (adTnT) and during hospital stay in 148 patients with HF and followed them prospectively until December 27, 2009. Each patient's highest TnT value was designated peak TnT. TnT >0.1 ng/ml levels were identified as elevated, using ROC analysis to predict death. Survival was assessed using Cox regression analysis. Results: The study population was 81.3 ± 8.2 years of age, 32 men. Elevated adTnT and peak TnT were observed in 34 (22.9%) and 51 (34.4%) of patients, respectively. On December 27, 2009, 112 (75.7%) patients had died. After controlling for age, serum on-admission creatinine and CHF, adTnT emerged as a significant independent predictor of death (HR = 1.07, 1.02-1.12 95% CI P = 0.01). Late myocardial infarction (MI) observed in 13 patients at 1,314 ± 659 days was predicted by peak TnT (HR = 1.3, CI 1.06-1.57, P = 0.027). Conclusions: Myocardial injury as evidenced by elevated TnT levels was observed in 1/3 of our patients with HF. TnT elevation, mostly observed on admission, reflected peri-fracture stress rather than surgery-related factors. Death and MI during the 8-year follow-up period were positively associated with magnitude of TnT levels during the 8-year follow-up period; Study contribution: We have demonstrated a continuous and graded association between increasing troponin levels on admission and risk of death. Previous studies have examined this association using a threshold effect. Additionally, the present study features a long follow-up time (8 years), suggesting that troponin levels on admission increase the risk of death over a prolonged period of time.