Objective-To exane the prognostic significance and role in risk stratification of the biochemical marker troponin T in patients admitted with unstable angina.Design-Single centre, blinded, prospective study ofpatients admitted with chest pain.Setting

The presence of admission troponin T in patients with myocardial infarction defines a subgroup, particularly those with ST-segment elevation, at increased risk of subsequent cardiac events and identifies a group that may benefit from alternative early management strategies.

The diagnostic performance of a new enzyme linked immunosorbent assay for the cardiac structural protein troponin T in the differential diagnosis of ischaemic cardiac damage was assessed. A well documented set of patients admitted to the coronary care unit of a district general hospital were studied. At a cutoff value of 0·2μ/L, troponin T measurements 12–24 h after admission or 12–16 to 24–48 h from onset of chest pain showed an overall efficiency of 97 · 6% for diagnosis of proven myocardial infarction. Troponin T was not detectable in patients when ischaemic heart disease could be excluded but was present in four patients with angina. Detectable troponin T in these angina patients was associated with subsequent cardiac events.

1. Cardiac troponin T is a recently developed serological marker used as a sensitive diagnostic tool for early myocardial damage in 'at risk' human patients. 2. Serum troponin T values were measured in young 30-d-old broilers with ascites and in healthy age-matched flockmates. 3. The data showed a significant increase (P < 0.001) in troponin T values in ascitic broilers compared with control birds. A similar increase in the arterial pressure index in ascitic birds indicated a good positive correlation at this age. 4. The results suggest that this new assay cross-reacts with chicken cardiac troponin T antigen and that it may be an important indicator of myocardial cell damage for use in future genetic selection programmes in the combat against ascites.

SUMMARY. We have compared measurement of cardiac troponin T by enzyme linked immunosorbent assay with creatine kinase MB isoenzyme (CK-MB) concentration measurement in 219 Royal Marine commandos with no evidence of cardiovascular disease who have elevated creatine kinase (CK) produced by arduous physical training. CK was elevated up to 22.6 times and CK-MB mass up to 6.6 times the upper reference limit. Only two commandos had detectable cardiac troponin T, with neither exceeding the upper reference limit of 0.2 /lg/L. At decision thresholds optimized for diagnosis of acute myocardial infarction in previous published work, 58.3070 of the total CK activity, 13.8% of the CK-MB concentration/CK activity ratio and 1.6% of CK-MB concentration measurements showed elevated values but no elevations in cardiac troponin T occurred. Cardiac troponin T is currently the investigation of choice for the differential diagnosis of patients with an elevated CK due to skeletal muscle trauma to exclude myocardial damage. Additional key phrases: CK-MB mass; myocardial infarction; cardiac enzymes; relative index; skeletal muscle traumaThe differential diagnosis in patients presenting with chest pain where there may be skeletal muscle trauma creates a problem for the laboratory. A range of approaches have been suggested including creatine kinase (CK) isoenzyme separation, creatine kinase MB (CK-MB) isoenzyme/total CK activity ratio, 1 CK-MB concentration measurement and CK-MB mass/total CK activity ratio.? We have compared the diagnostic performance of proposed strategies for the differentiation of skeletal and cardiac muscle damage with measurement of cardiac troponin T (cTnT) in the situation of extreme elevation of CK due to arduous physical training. METHODSRoyal Marine recruits were studied during commando training. All had been pre-screened Correspondence: Dr P 0 Collinson. 450by full physical examination and electrocardiography both at entry, following basic training and during the training programme. None had any cardiac symptoms at any time.Two hundred and nineteen men were examined, age range 18 to 26 years, median 20.8 years, in four troops (training cohorts). Serial blood samples were obtained from individuals during training at I, 12, 19, 24 and 29 weeks. Serum was separated and stored at -70 DC prior to estimation for aspartate transaminase activity (AST), CK activity, CK-MB concentration and cTnT.AST and CK were measured on all samples. Samples for further study were selected from those periods of training corresponding to maximal physical exertion. One hundred and twenty-nine samples were selected at week 24 and 106 at week 29. On week 29 samples were taken following one of the final qualification assignments. This comprised a 30 mile route march, in full webbing, carrying a 40lb (18 kg) pack,

This study provides the first evidence in man of a significant role for lipoprotein(a) in unstable angina. The correlation between lipoprotein(a) concentration and cardiac Troponin T concentration suggests that lipoprotein(a) may be significantly involved in the early failure of plaque rupture stabilization.

Troponin T is a cardiac-specific protein forming part of the contractile apparatus of striated muscle, and in humans it is a new, sensitive and highly specific indicator of early myocardial damage in 'at risk' patients. Serum troponin T values were investigated in 7-day-old hypoxia- and hyperoxia-treated and 10-day-old ascitic and debilitated commercial broiler chicks. The results showed that there was a significant increase in troponin T values in the hypoxic chicks (P< 0.05) compared with their normoxic flockmates. There was also a small, but insignificant rise in the troponin T values of the hyperoxia-treated chicks. The results confirm previous studies that myocardial damage in these young chicks is associated with hypoxia and that the injury caused permits the measurement of troponin T released from the cardiomyocytes. Significant increases in troponin T were also measured in 10-day-old ascitic (P < 0.05) and debilitated (P < 0.02) broiler chicks compared with age-matched control broilers. In both age-groups of birds, the arterial pressure index, a measurement of right ventricular hypertrophy caused by chronic pulmonary hypertension, was similar with the respective control values and yet the troponin T concentrations were significantly different. These results demonstrate the importance of this assay in young broiler chickens as a marker of early myocardial damage in these birds. It is proposed that this assay for troponin T could be a valuable prognostic tool in future genetic selection programmes to reduce the degree of susceptibility to hypoxia and with it the incidence of ascites in young broilers.

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