Relation of minor cardiac troponin I elevation to late cardiac events after uncomplicated elective successful percutaneous transluminal coronary angioplasty for angina pectoris

There is little information about the relation between mild cardiac troponin I (cTn-I) increase after coronary interventions and late outcome. We therefore focused on the long-term outcome and the clinical, morphologic, and procedural correlates of elevation of cTn-I compared with cardiac troponin T, creatine kinase (CK), CK-MB activity and mass, and myoglobin in 105 patients with successful elective percutaneous transluminal coronary angioplasty (PTCA) for stable or unstable angina. Patients with myocardial infarction and those with unstable angina who had a detectable increase in serum markers before PTCA were excluded. Markers were measured before and after the procedure and for 2 days. Patients were followed up to record recurrent angina, myocardial infarction, cardiac death, repeat PTCA, or elective coronary artery bypass graft surgery. Procedure success was achieved in all cases. Elevation in cTn-I (> or =0.1 microg/L) was observed in 23 of 105 patients (22%) (median peak: 0.25 microg/L); 18% had cardiac troponin T (cTn-T) release (> or = 0.1 microg/L, median peak 0.21); 11.4% CK-MB mass (> or =5 microg/L), and 7.6% myoglobin (> or =90 microg/L) release. Five and 2 patients had elevated CK and CK-MB activity, respectively. Fourteen of 18 patients with cTn-T elevation had a corresponding elevation in cTn-I (kappa 0.68; p = 0.001). Patients positive for cTn-I had more unstable angina (p = 0.042) and heparin before PTCA (p = 0.046), and had longest total time (p = 0.004) and single inflation (p = 0.01). By multivariate logistic regression, predictors of postprocedure cTnI elevation were maximum time of each inflation (odds ratio 9.2; p = 0.0012), type B lesions (odds ratio 6.6; p = 0.013), unstable angina (p = 0.041), and age > or =60 years (p = 0.032). Clinical follow-up was available in 103 patients (98%) (mean 19+/-10 months). Kaplan-Meier survival analysis showed that cTn-I elevation was not an important correlate of cardiac events (p = 0.34, by log-rank analysis). The incidence of recurrent angina, myocardial infarction, cardiac death, and repeat revascularization after 12 months was not different in patients positive or negative for cTn-I. We conclude that cTn-I elevation after successful PTCA is not associated with significantly worse late clinical outcome. Levels of cTn-I allow a much higher diagnostic accuracy in detecting minor myocardial injury after PTCA compared with other markers, but there is no association with periprocedural myocardial cell injury and late outcome when cTn-I and other markers are considered.

[Prognostic significance of early raised cardiac troponine I in unstable angina. Contribution to the identification of a high-risk sub-group]

The authors compared the clinical and angiographic characteristics of 44 patients with unstable angina according to cardiac Troponine I concentrations (TnIc) during early blood sampling and then tried to determine a threshold value to predic the occurrence of cardiac events during the hospital period and after 12 months. Tnlc, creatinine-kinase (CK), CK-MB activity and CK-MB mass were sampled over 48 hours. Forty-five per cent of patients had TnIc > or = 0.1 microgram/L; CK-MB activity and CK-MB mass were detected in 16 and 32% of patients. Age, gender, classification and recurrence of angina, previous cardiac history, risk factors, coronary angiographic appearances were comparable in patients with and without raised TnIc. No major cardiac events occurred during the hospital period in either group. The number of angioplasties and coronary bypass procedures was also comparable. At one year, the incidence of myocardial infarction (N = 4) and death (N = 5) was significantly different in patients with raised Tnlc (33% versus 0% in patients without increased TnIc). However, betablocker therapy was less prescribed in the group with the poorest outcomes and left ventricular dysfunction was also significantly more common in this group. Early elevation of Tnlc could contribute to the identification of a high risk subgroup of patients with unstable angina.

Release kinetics of serum cardiac troponin I in ischemic myocardial injury

OBJECTIVES

The study was undertaken to evaluate the release kinetics of cardiac troponin I (cTn-I) in ischemic myocardial injury.

DESIGN AND METHODS

The reference range for cTn-I was established by determination of cTn-I in sera and plasma obtained from 622 healthy volunteers (Group 1). cTn-I was compared to: (a) Creatine kinase (CK) MB mass and myoglobin in 12 patients with severe skeletal muscle damage (Group 2); (b) CK-MB activity in 48 patients with myocardial infarction (MI) receiving intravenous thrombolysis (Group 3) (in this group, an additional 43 patients with MI were analyzed separately to characterize cTn-I patterns in thrombolyzed and nonthrombolyzed populations): and in 44 patients with unstable angina (Group 4).

RESULTS

In Groups 1 and 2, no positive results (> or = 0.1 microgram/L) were obtained. In Group 3, the time-courses of cTn-I were mostly monophasic in form. A pathologic increase occurred earlier in cTn-I than in CK-MB activity (p = 0.0002); the period with increased cTn-I was longer (p = 0.001), the overall sensitivity of cTn-I (93.9%) was higher than that of CK-MB activity (p = 0.00001). cTn-I was more sensitive at admission (p = 0.0004). In additional patients, the cTn-I peak occurred and cTn-I disappeared significantly later in nonthrombolyzed than in the thrombolyzed group. In Group 4, positive tests results were detected in 45% of patients for cTn-I, 16% for CK-MB activity, and 32% for CK-MB mass.

CONCLUSIONS

The cTn-I assay appears to be ideally suited for the detection of ischemic myocardial injury in complex clinical situations because of its high specificity; cTn-I indicates myocardial tissue damage in patients with unstable angina and is superior to CK-MB activity and mass in this respect.

[Value of human cardiac troponin I determination in the diagnosis of acute myocardial infarction]

Immunoenzymatic assay (IEMA) of human cardiac Troponin I (TnI c) was used in patients admitted to the coronary care unit with acute myocardial infarction (AMI). TnI c was detected in all patients with AMI. The detection of TnI c was earlier after the onset of pain (4.5 +/- 2.3 hours) than that of CKMB activity (6.3 +/- 3.6 hours), p = 0.003. The kinetics of TnI c are usually monophasic and parallel to that of CKMB activity. The peak value occurs 12.2 +/- 4.6 hours and 15.8 +/- 9.0 hours after the onset of pain in patients treated by thrombolysis. The TnI c disappears from the plasma between 5 and 9 days after the onset of pain, later than CKMB activity (p = 0.0001). In 49 patients admitted for AMI treated by thrombolysis, the comparative sensitivities of TnI c (threshold: 0.1 ng/ml) and of CKMB activity (threshold: 15 IU/l; CK > or = 100 Ul/l) were, at the first sampling on admission, 61% and 22% respectively (p = 0.0002) (average interval from onset of pain to first blood sampling: 3.4 +/- 1.3 hours). TnI c was not detected in the plasma of 145 normal subjects nor in any of the 6 patients with severe muscular trauma or rhabdomyolosis (specificity: 100%). This IEMA is a specific and a sensitive method of diagnosing acute and subacute myocardial infarction. It is ideal for the detection of myocardial necrosis in complex clinical situations when the usual enzymatic markers may be ineffective.