P2748The PROTROPICS feasibility: prognostic value of elevated troponins in critical illness

Abstract

Background: Troponins are sensitive and specific markers of cardiac injury, most commonly used in clinical practice for the diagnosis of myocardial infarction (MI). Critically ill patients frequently have elevated troponins. Whether fulfilling criteria for MI or not, observational evidence to date shows that elevated troponins in critical illness are associated with an increased risk of death when adjusted for other confounding factors. Purpose(s): We aimed to assess the feasibility of a large study to ascertain the prognostic value of troponin elevations on hospital mortality in critically ill patients. Method(s): We recruited patients in 4 academic medical and surgical intensive care units (ICUs) in Canada. All patients admitted to participating ICUs during the 1 month enrolment period were eligible. We excluded cardiac surgical patients and patients who were admitted and either died or were discharged within 12 hours. Using a deferred consent model, while the patients were in the ICU, we obtained high sensitivity troponin T and ECGs daily for 1 week, every other day for 3 weeks and then weekly for 2 months. Clinicians were blinded to the study troponins and ECGs. Data on the patients' symptoms, medications, laboratory results, and clinical events were also collected. We defined MI using the third universal definition. ECG adjudicators were blinded to the troponin measurements. Patients were followed until hospital discharge, death or for a maximum of 3 months. Result(s): We screened 304 admissions; 282 patients were eligible. Full consent was provided by 81% of patients/substitute decision makers and 12% consented to the use of collected data but declined further participation. Overall, 99 (38%) suffered an MI, 31 (12%) had an isolated troponin elevation, and 132 (50%) had no troponin elevation. The crude hospital mortality rate was 9% in those without a troponin elevation, but 29% with an isolated troponin elevation (RR 3.0, 95% confidence interval [CI] 1.1 to 7.6) and 29% with an MI (RR 3.1, 95% CI 1.5 to 6.3). In a logistic regression model that adjusted for APACHE II score and vasopressor use, MI was not associated with an increase in hospital mortality (aOR 2.1, 95% CI 0.9 to 5.1, p=0.09); isolated troponin elevation also was not associated with hospital mortality (aOR 2.3, 95% CI 0.7 to 7.9, p=0.2). Conclusion(s): Troponin elevations and troponin elevations meeting MI criteria are frequent during critical illness and these patients are at higher risk of mortality compared to patients who do not have a troponin elevation. Whether the association of troponin elevation with death in the ICU is independent of other prognostic factors remains uncertain. This pilot study has established the feasibility of conducting a large-scale investigation addressing this issue.