Diagnosis and risk stratification of patients with anginal pain and non-diagnostic electrocardiograms

Patients with acute chest pain suggestive of myocardial ischaemia, and norm al or non-diagnostic electrocardiograms, form a difficult subgroup for diag nosis and early risk stratification. We prospectively evaluated the role of troponin T (cTnT), troponin I (cTnI), CKMB mass and myoglobin, in the diag nosis and risk stratification of 214 patients with acute chest pain of less than or equal to 24 h and non-diagnostic or normal ECGs admitted directly to the Cardiac Unit of the Royal Victoria Hospital Belfast from the Mobile Coronary Care Unit or the Accident/ Emergency Department. This was a single -centre prospective study, and follow-up (3 months) was complete for all pa tients. Blood was assessed for quantitative cTnT, cTnI, CKMB mass and myogl obin, and qualitative cTnT on admission and at 12 h. Diagnosis of index eve nt and incidence of new cardiac events (death, non-fatal myocardial infarct ion, revascularization, or readmission for unstable angina) over 3 months w ere assessed. Based on standard criteria, myocardial infarction occurred in 37/214 (17%), and unstable angina in 72/214 (34%). At 12 h from admission, cardiac troponins had higher sensitivity for the diagnosis of acute corona ry syndromes (myocardial infarction and unstable angina) than conventional markers (cTnI 48%, cTnT 38%, CKMB mass 30% or myoglobin 27%). At 3 months, a new cardiac event had occurred in 42/214 (20%). Significantly higher even t rates occurred when any of the biochemical markers was elevated, but the statistical significance was highest for patients with elevated cTnI (p<0.0 001). Whilst gender; history of ischaemic heart disease (IHD), stress test response, cTnT, cTnI, CKMB mass and myoglobin were univariate predictors, c TnI at 12 h and stress test response were the only two independent signific ant predictors for a subsequent cardiac event at 3 months. Raised cTnI at 1 2 h after admission had the highest sensitivity for the diagnosis of acute coronary syndromes, and was independently associated with a 2-3 times incre ased risk of future cardiac events within 3 months among patients with acut e chest pain suggestive of myocardial ischaemia hut with normal or non-diag nostic ECGs.