The PROTROPIC feasibility study: prognostic value of elevated troponins in critical illness

Elevated cardiac troponin concentrations in people with critical illness are associated with an increased risk of death. We aimed to assess the feasibility of a larger study to ascertain the utility of cardiac troponin as a prognostic tool for mortality in critically ill patients.

Patients admitted to participating intensive care units during the one-month enrolment period were eligible. We excluded cardiac surgical patients and patients who were admitted and either died or were discharged within 12 hr. In enrolled patients, we measured high-sensitivity cardiac troponin I (hs-cTnI) and obtained electrocardiograms to ascertain the incidence of myocardial infarction (MI) and isolated troponin elevation. Our feasibility objectives were to measure recruitment rate, the proportion of patients who consented under a deferred consent model, and time required for data collection and study procedures.

Over a four-week enrolment period, 280 patients were enrolled using a deferred consent model. We obtained subsequent consent from 81% of patients. Study procedures and data collection required 1.7 hr per participant. Overall, 86 (38%) suffered a MI, 23 (10%) had an isolated hs-cTnI elevation, and 117 (52%) had no hs-cTnI elevation. The crude hospital mortality rate was 10% without an hs-cTnI elevation, 29% with an isolated hs-cTnl elevation (relative risk [RR]) 2.2; 95% confidence interval [CI], 1.0 to 6.0) and 29% with an MI (RR, 2.6; 95% CI, 1.4 to 5.1).

Myocardial injury with elevated hs-cTnI concentrations and MIs occur frequently during critical illness. This pilot study has established the feasibility of conducting a large-scale investigation addressing this issue.