In recent years clinical troponin assays have become increasingly sensitive, however whether this translates into improved clinical outcomes for patients with suspected acute coronary syndromes (ACS) has not previously been examined.  Mills et al. investigated whether the introduction a new, high-sensitivity, troponin assay led to an improvement in patient outcomes.

Consecutive patients admitted with suspected ACS to the Royal Infirmary of Edinburgh, Edinburgh, Scotland, were investigated.  The authors examined the outcomes of patients admitted both before (n = 1038; February 1-July 31, 2008, during the validation phase) and after (n = 1054; February 1-July 31, 2009, during the implementation phase) the threshold of detection for myocardial necrosis was lowered from 0.20 to 0.05 ng/mL with a new sensitive troponin I assay.  Patients were stratified into 3 groups (<0.05 ng/mL, 0.05-0.19 ng/mL, and >0.20 ng/mL). During the validation phase, only concentrations above the original diagnostic threshold of 0.20 ng/mL were reported to clinicians.  The main outcome measure was event-free survival (recurrent MI and death) at 1 year.

During the validation phase, 39% of patients with plasma troponin concentrations of 0.05 to 0.19 ng/mL died or had a recurrent MI at 1 year, compared with 7% of patients with troponin concentrations of less than 0.05 ng/mL (P<.001) and 24% of patients with troponin concentrations of 0.20 ng/ mL or more (P = .007). Subsequently, lowering the diagnostic threshold to 0.05 ng/mL (the implementation phase) was associated with a lower risk of death and recurrent MI (from 39% to 21%) in patients with troponin concentrations of 0.05 to 0.19 ng/mL (odds ratio, 0.42; 95% confidence interval, 0.24-0.84; P=.01).

Conclusions:

In this study, the lowering of the threshold for detection of troponin I in patients with suspected ACS identified a group of patients at high risk for MI and death, and was subsequently associated with significant reductions in morbidity and mortality.

• Mills NL, Churchhouse AMD, Lee KK et al.  Implementation of a Sensitive Troponin I Assay and Risk of Recurrent Myocardial Infarction and Death in Patients With Suspected Acute Coronary Syndrome.  JAMA. 2011;305(12):1210-1216.