The impact of co-morbidities on peak troponin levels and mortality in acute myocardial infarction: A population based, nationwide study

Objectives: To characterize peak cardiac troponin levels, in patients presenting with acute myocardial infarction (AMI), according to their comorbid condition and determine the influence of peak troponin (cTn) levels on mortality. Methods: We included patients with the first admission for AMI in the United Kingdom. We used linear regression to estimate the association between eight common co-morbidities {diabetes mellitus(DM), previous angina, peripheral arterial disease(PAD), previous myocardial infarction(MI), chronic kidney disease(CKD), cerebrovascular disease(CVD), chronic heart failure(CHF), and chronic obstructive pulmonary disease(COPD)} and peak cTn. Peak cTn levels were adjusted for age, sex, smoking status and co-morbidities. Logistic regression and restricted cubic spline models were employed to investigate the association between peak cTn and 180-day mortality for each co-morbidity. Results: 330,367 patients with AMI were identified. Adjusted peak cTn levels were significantly higher in patients with CKD[adjusted % difference in peak cTnT for CKD=42%, 95%CI 13.1 to 78.4] and significantly lower for patients with COPD, previous angina, previous MI and CHF when compared to patients without the respective co-morbidities (reference group) [cTnI;COPD=-21.7%,95%CI -29.1 to -13.4;previous angina=-24.2%, 95%CI -29.6 to -8.3;previous MI=-13.5%, 95%CI -20.6 to -5.9;CHF=-28% 95%CI -37.2 to -17.6]. Risk of 180-day mortality in most of the co-morbidities did not change substantially after adjusting for peak cTn. In general, cTnI had a stronger association with mortality than cTnT. Conclusions: In this nationwide analyses of patients presenting with acute myocardial infarction, co-morbidities substantially influenced systemic concentrations of peak cTn. Comorbid illness is a significant predictor of mortality regardless of peak cTn levels and should be taken into consideration while interpreting cTn both as a diagnostic and prognostic biomarker.