Cardiac troponin-I predicts long-term mortality in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease patients are at increased risk for mortality, particularly from cardiovascular conditions. Acute exacerbation increases heart burden and may lead to release of troponin I. This study investigates the long-term prognostic value of elevated troponin I detected during acute exacerbation of chronic obstructive pulmonary disease. The records of 182 patients with acute exacerbation in whom troponin I levels were sampled during their hospitalization were reviewed retrospectively. Receiver operator curve was used to determine the cut-off level for troponin I that discriminated survivors and non-survivors, and predictors for all-cause mortality were tested in a multivariate analysis. The results showed that, during a mean observation time of 50.1 +/- 45.6 months, 66 (36.3%) patients died, providing 1, and 3-year survival rates of 84%, and 54%, respectively. Troponin I levels were significantly higher in non-survivors compared with survivors, mean troponin I +/- SD in microg x L(-1): 1.35 +/- 3.17 vs. 0.53 +/- 2.08, respectively, p = 0.0033. ROC curve analysis identified troponin I > 0.03 microg x L(-1) as the optimal cut-off level for prediction of mortality. Kaplan-Meier survival analysis revealed that the probability of survival was significantly lower in patients with troponin I > 0.03 microg x L(-1) (log-rank test p = 0.0058). On multivariate analysis, only ischemic heart disease (HR = 2.335, p = 0.0017) and troponin I level (HR = 1.31541, p = 0.2513) were independent predictors of mortality. In conclusion, it was found that a mildly elevated troponin I level measured in patients with chronic obstructive pulmonary disease during acute exacerbation is a strong independent predictor of mortality following discharge.