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Abstract
The projects in this thesis aimed to examine the applications of the high-sensitivity troponin T (hs-TnT) assay in three different
clinical settings. In particular the following uses of hs-TnT measurement were examined: 1) Whether post-percutaneous coronary
intervention (PCI) TnT elevation occurs in patients undergoing same day discharge (SDD) after elective PCI, and if so, its
significance needs assessment; 2) Whether hs-TnT elevations occur after exercise stress testing (EST), and if so, the time course
and clinical significance need clarification; and 3) the utilisation of hs-TnT assay in disposition and outcomes of patients presenting
to the emergency department (ED) with symptoms suggestive of an acute coronary syndrome (ACS).
Discharging patients on the same day of elective PCI reduces costs of overnight hospitalisation and increasing patient‘s
satisfaction, in part due to avoiding cancelations due to a lack of beds for overnight stay. However, post-PCI TnT elevations, which
have been reported in ~80% of patients following elective PCI, are associated with increased rates of late death and/or myocardial
infarction (MI). Thus in these patients we examined the safety and efficacy of SDD with respect to late outcomes. Among 303
patients, rates of death/MI were comparable between those who underwent SDD and those who stayed overnight. Also, ≥5-fold
elevation of post-PCI hs-TnT levels did not appear to confer incremental short and long-term risk, though to confirm this
observation, trials in a much larger population would be needed.
While extreme physical activity may lead to significant elevations in cardiac biomarkers levels, elevations of Hs-TnT levels
after EST and their clinical significance among healthy individuals are uncertain. Among 105 healthy individuals, 12% developed
post-EST hs-TnT levels >14ng/L when their baseline levels were ≤14ng/L. These troponin elevations were first detected at 90
minutes, but at least three hours post-EST was needed to exclude an hs-TnT elevation. At a median follow up of 13 months, no
adverse events were recorded. The role of post-EST hs-TnT elevation in risk stratification of both asymptomatic (and symptomatic)
individuals needs to be assessed in future randomised clinical trials.
The counterpoint to the excellent sensitivity and negative predictive value of hs-TnT is reduced specificity. This put a lot of
challenge to establish a rapid way to rule-out ACS and to appropriately admit/discharge patients who present to ED with symptoms
suggestive of ACS. The majority of >1200 unselected consecutive patients attending ED in whom hs-TnT levels were elevated did
not have an ACS. Indeed, patients with non-cardiac causes of hs-TnT elevations have worse prognosis.