Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations

Abstract

Background: Recent data suggest that older men with detectable cardiac troponin I (cTnI) concentrations that remain below the 99th percentile concentration cutoff are at increased risk for subsequent cardiovascular events. We designed this study to extend this observation by examining risk prediction in both men and women presenting to an emergency department with chest discomfort. Methods: We obtained data for all-cause mortality and hospital discharges associated with either acute myocardial infarction (AMI) or congestive heart failure (CHF) for up to 8 years after the initial presentation in 448 patients who originally presented in 1996 with acute coronary syndrome (ACS). We performed retrospective analysis for cTnI (AccuTnI™; Beckman Coulter) in frozen plasma samples based on the patients' reported time from onset of symptoms. Peak cTnI concentration was used for risk assessment. Results: Patients with cTnI concentrations >0.02 g/L (i.e., limit of detection), including those whose peak values remained below the 99th percentile (0.04 g/L), were at greater risk for death and AMI/CHF readmissions at 2, 5, and 8 years of follow-up compared with those with peak cTnI <0.02 g/L. All results were statistically significant (P <0.05) except for death within 2 years among patients with normal but detectable cTnI (0.02 to 0.03 g/L), relative to the group with values <0.02 g/L. Kaplan-Meier analyses indicated that both

The use of a cytokine panel to define the long-term risk stratification of heart failure/death in patients presenting with chest pain to the emergency department

“…The study population and its characteristics have been previously reported [2,7]. Briefly, after ethics approval in 1996, consecutive unique patients presenting to the emergency department with symptoms suggestive of ACS were recruited for a cardiac marker study.…”

“…After measurement by the cytokine array, the same EDTA plasma specimens were assayed for NT-proBNP with the Elecsys® 1010 Roche analyzer (interassay CV<7%). This patient cohort previously had cTnI measured (AccuTnI, Beckman Coulter) in heparin specimens in 2003 [7], and both NTproBNP and cTnI are stable during long-term storage [2,7]. As we had prior data suggesting that both NT-proBNP and cTnI add to the prognostic accuracy of risk prediction, we included these biomarkers in the hazard analysis models.…”

“…Health outcome were obtained by linkages to the Registered Persons Data Base (RPDB) for mortality outcomes and the Canadian Institute for Health Information Discharge Abstract Database (CIHI-DAD) for hospital discharges associated with HF [2,7]. Both the RPDB and CIHI-DAD (i.e., administrative databases) have been reported to be highly accurate in obtaining these endpoints [2,7].…”

“…Both the RPDB and CIHI-DAD (i.e., administrative databases) have been reported to be highly accurate in obtaining these endpoints [2,7]. Based on the death date and earliest subsequent readmission for HF, indicators were created to reflect whether or not an event (death or HF readmission) occurred within 8 years post presentation (patients who died without previous HF readmission, follow-up were censored at the date of death).…”

“…Kaplan-Meier curves were constructed to display time to an event (HF/death), with differences between groups assessed by the log rank test. The Cox proportional hazard model was used to compare time to an event for those with ≥three positive biomarkers (panel positive) versus those with fewer (panel negative), after adjusting for age (continuous variable), sex, history of HF, NTproBNP, and cTnI, the latter in accordance with previously published cutoffs: NTproBNP>183 ng/L in the 9 h specimen and cTnI peak categories (<0.02 μg/L as reference) [2,7]. Between-group comparisons of central tendency were based on the Wilcoxon signed rank test and the chi-square test was used to test differences between proportions.…”