Coronary Artery Disease
Prognostic Role of Troponin T Versus Troponin I in Unstable Angina Pectoris for Cardiac Events With Meta-Analysis Comparing Published Studies

https://doi.org/10.1016/S0002-9149(98)00200-8Get rights and content

Abstract

Controversy exists as to the clinical roles and relative specificities of cardiac troponin T or I in patients with unstable angina pectoris (UAP). We measured troponin T and I levels on admission in 123 patients with UAP. Of the 107 patients with normal creatine kinase during the first 24 hours, troponin T and I were elevated in 14 and 13 patients, respectively. At 30 days, 5 of 14 patients (36%) with elevated troponin T and 3 of 93 patients (3.2%) with normal troponin T had acute myocardial infarction (odds ratio [OR], 16.7; 95% confidence interval [CI] 3.4 to 81.5; p <0.001). Of 13 patients with elevated troponin I, 5 patients (39%) and 3 of 94 patients (3.2%) with normal troponin I had acute myocardial infarction (odds ratio, 21.7; 95% CI 4.3 to 110; p <0.001). No deaths occurred within 30 days. Both markers demonstrated equivalent sensitivity (63%) and specificities (troponin T: 91%; troponin I: 92%) for myocardial infarction. Meta-analysis of 12 published troponin T and 9 troponin I studies in patients with UAP produced risk ratios of 4.2 (95% CI 2.7 to 6.4, p <0.001) for troponin I compared with 2.7 (95% CI 2.1 to 3.4, p <0.001) for troponin T. Comparison of the sensitivities and specificities of both markers using summary receiver operating characteristic curves showed no significant difference in their abilities to predict acute myocardial infarction and cardiac death. Troponin T and I show similar prognostic significance for acute myocardial infarction or death in the same patients with UAP. The 2 markers are equally sensitive and specific, as confirmed by meta-analysis, and this supports a role in risk stratification.

Section snippets

Patient population

We prospectively screened 123 consecutive patients presenting to the Hartford Hospital emergency department with chest pain suspected to be due to myocardial ischemia. To ensure appropriate enrollment, only patients with UAP (new onset, severe or accelerated angina, subacute angina at rest, or acute angina at rest) were screened. Patients diagnosed with acute myocardial infarction as defined by World Health Organization21 electrocardiographic and enzymatic criteria within 24 hours of enrollment

Direct comparison of troponin T and troponin I in the same patients with UAP

Comparison of baseline demographic and clinical variables between patients with normal and elevated troponin T or I revealed that patients with elevated serum markers were significantly older (p <0.05 for troponin T and p <0.01 for troponin I), and had lower ejection fractions (p <0.01 for troponin T and troponin I). The mean admission troponin T and I levels were 0.3 ± 1.1 μg/L and 2.0 ± 7.2 μg/L, respectively. Table IIdepicts relative risk for acute myocardial infarction and cardiac death

Discussion

Our direct comparison of troponin T and I in patients with UAP shows that these markers independently predict acute myocardial infarction and cardiac death to a significant extent when increased above normal limits. Both markers demonstrated equal moderate sensitivity (63%) and high specificities (troponin T: 91% vs troponin I: 92%). Meta-analysis of 12 clinical trials of troponin T in 2,847 patients with UAP with a median follow-up duration of 30 days (range 4 to 1,095) produced a 2.7-fold

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