Can a Multi-marker Strategy Improve Risk Stratification and Expedite Discharge in Unstable Angina? A Comparison With High Sensitive Troponin T

Chest pain accounts for up to 1% of visits to GPs in England, about 700000 visits (5%) to emergency departments and up to 25% of emergency admissions to hospitals. Recent epidemiological studies indicate a substantial and increasing rate of admissions with chest pain even as admissions with acute myocardial infarction are falling. From 1986 to 2000 the rate of admissions for chest pain in Scottish hospitals more than doubled. Further work by the same group indicates that admission to hospital with angina, excluding those coded for acute coronary syndrome or acute myocardial infarction, is associated with a 30 day mortality of 1.5%. Other studies have identified a sizable event rate in patients who have been 'troponin negative'. This increasing phenomenon places great strain on the NHS and indeed any health provider. Any form of testing that adds significant incremental value to established tests and that can effectively rule out myocardial ischaemia and moreover demonstrate good medium and long-term outcome could potentially benefit both patients and the NHS delivery of healthcare.

Brain Natriuretic Peptide Biochemical markers of left ventricular wall stress or ischaemia could enhance the diagnostic accuracy of exercise tolerance tests. These have been used successfully for the detection of left ventricular dysfunction, heart failure and in the risk stratification of acute coronary syndromes.

Biomarkers of acute stress

Growth Differentiation Factor -15 Transforming growth Factor constitute a superfamily of cytokines that exert prominent actions in adult haemostasis and adaptation by regulating cell survival, proliferation and differentiation. GDF-15 is a distant member of the TGF-B superfamily. In animal models it is induced in response to ischaemia-reperfusion injury, pressure overload and heart failure possibly via pro-inflammatory cytokine and oxidative stress dependent signalling pathways. There is both evidence of an adverse outcome in patients with an elevated GDF-15 level in highly selected trials with NSTEMI as well as the non-selected chest pain population. This latter analysis was a post-hoc one and there are no prospective studies in an unselected chest pain population evaluating GDF-15.

Heart Type Fatty Acid Binding Protein (HFABP)- Direct evidence of myocardial ischaemia HFAP is a low molecular weight protein that is involved in the intracellular uptake and buffering of free fatty acids in the myocardium. It has been shown to be a sensitive and early marker of myocardial infarction providing direct evidence of myocardial ischaemia as well as myocyte necrosis unlike HSCRP and BNP. This is intuitive given its small molecular size and consequently its propensity to be leaked from the porous membranes of ischaemic myocardial cells. In the study by Kilcullen et al even Tn negative patients were well stratified by HFABP.