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[Cardiac troponin I in unstable angina]
P Musso1, A Vernocchi, A Crippa
1Divisione di Cardiologia, Ospedale Civile, Ivrea, Torino.
Insights
Cardiac troponin I (cTn-I) is a specific marker for myocardial necrosis. This study found no cTn-I in patients with unstable angina, indicating it is not a prognostic marker for major coronary events in this population.
Area of Science:
- Cardiology
- Biomarkers
- Clinical Pathology
Context:
- Unstable angina presents a high risk for myocardial infarction and sudden death.
- Elevated cardiac enzymes and proteins are associated with unstable angina, signaling potential major coronary events.
- Cardiac troponin I (cTn-I) is a highly specific marker for myocardial cellular necrosis.
Purpose:
- To assess the presence of cTn-I in patients with unstable angina but without signs of myocardial necrosis.
- To evaluate the utility of cTn-I as a prognostic marker for major coronary events in unstable angina patients in the short and medium term.
Summary:
- A prospective study of 33 unstable angina patients (excluding acute myocardial infarction) found no detectable cTn-I in blood samples at admission or during the initial 48 hours.
- During a two-month follow-up, two patients died from myocardial infarction, nine underwent revascularization surgery, and five had angioplasty.
- No cTn-I was detected in any patient, including one who experienced myocardial infarction during hospitalization.
Impact:
- Cardiac troponin I (cTn-I) is confirmed as a sensitive and specific indicator of myocardial necrosis.
- The study concludes that cTn-I is not present in patients with unstable angina and therefore has no role in predicting major coronary events in this patient group.
Background:
Unstable angina implies high risk of myocardial infarction and sudden death. Increased levels of cytoplasmatic enzymes and proteins (creatine phosphokinase, MB creatine phosphokinase troponin T, etc.) were described in unstable angina, providing information about incoming major coronary events. Cardiac troponin I (cTn-I) is a structural protein inhibiting the actinomyosine ATPase; it is only found in myocardial cells. Serum titration of cTn-I has been recently introduced into clinical practice as a sensitive and specific marker of myocardial cellular necrosis.
Objectives:
The aim of our prospective study was to assess the presence of cTn-I in blood samples of patients with unstable angina and no signs of myocardial necrosis. Furthermore we intended to test the possible use of cTn-I in unstable angina as a prognostic marker of major coronary events on short and middle term.
Methods:
We studied 33 consecutive patients admitted to our CCU for unstable angina. According to unstable angina Braunwald's classification, 6 patients were included in the first class, 4 patients in the second class and 23 patients in the third class. We excluded patients with acute or recent myocardial infarction. Blood samples of all patients were obtained at the time of CCU admission and every eight hours in the first and second day. Serum cTn-I titration was performed with the sandwich immunoenzymometric method, recently introduced by Diagnostic Pasteur. Two months follow-up was carried out in order to survey major coronary events and revascularization procedures, either angioplasty or coronary artery bypass surgery.
Results:
No patients with unstable angina exhibited cTn-I in their blood samples; accordingly, cTn-I was not found in the first blood sample of a patient who underwent myocardial infarction during hospitalization. During the follow-up 2 patients died of myocardial infarction, 9 patients had surgical revascularization and 5 patients angioplasty.
Conclusions:
CTn-I is a sensitive and specific marker of myocardial necrosis. It is not found in patients with unstable angina; therefore it has no role as a prognostic marker of major coronary events.