The association of anaemia and high-sensitivity cardiac troponin and its effect on diagnosing myocardial infarction

Aims: Anaemia is common in patients with acute myocardial infarction (MI). We investigated the association of high-sensitivity cardiac troponin (hs-cTn) and haemoglobin (Hb) and the influence of anaemia on the performance of diagnostic protocols for suspected MI.

Methods and results: Patients with suspected MI were consecutively enrolled at a tertiary centre. Final diagnoses were independently adjudicated by two cardiologists. Performance measures of hs-cTn-based algorithms were compared for anaemic and non-anaemic patients (Hb <12 g/dL in women and <13 g/dL in men). The influence of anaemia on survival (median follow-up 1.7 years) was investigated using multivariable cox-regression analysis and the association of Hb and hs-cTn by multivariable linear regression analysis. Overall, 2223 patients were included, of whom 415 (18.7%) had anaemia. In anaemic patients, the incidence of MI was similar; however, chronic myocardial injury was significantly more prevalent (20.1% vs. 48.2%). The negative predictive value to rule-out MI was similar for both algorithms and all assays in patients with anaemia, although the positive predictive value to rule-in MI was partly reduced for the 0/3-h algorithm. Fewer anaemic patients were triaged after 1 h. Anaemia was an independent predictor of death. Adjusted for patient characteristics, Hb was significantly associated with hs-cTn. By providing a point-based tool, the Hb-associated hs-cTn concentration and thus chronic myocardial injury may be predicted.

Conclusion: Anaemia partly affects the rule-in, but not the rule-out of MI in hs-cTn-based diagnostic protocols. Hs-cTn concentrations and thus chronic myocardial injury may be predicted by clinical variables and Hb.

Trial registration: clinicaltrials.gov (NCT02355457 and NCT03227159).