[Evaluation of a rapid qualitative test for cardiac troponin T in clinical diagnosis of patients with acute coronary syndrome]

[Acute coronary syndrome in the prehospital phase]

Cardiovascular diseases are the number one cause of death in Germany. In 2002 about 70,000 people died of acute myocardial infarction (AMI) and of these 37% died before arrival at hospital which underlines the relevance of adequate prehospital care. The generic term acute coronary syndrome (ACS) was introduced because a single pathomechanism accounts for the different forms and comprises unstable angina pectoris (iAP), non-ST-elevation myocardial infarction (NSTEMI), ST-elevation myocardial infarction (STEMI) and sudden cardiac death (SCD). Characteristic features are retrosternal pain, vegetative symptoms and radiation of pain into the adjoining regions. Further differentiation can only be achieved by the 12-lead ECG, as cardiac-specific enzymes do not play a role in prehospital decisions. Prehospital delays should be avoided, history and physical examination should be brief but focused, vital parameters should be assessed and monitored. Basic treatment for ACS should comprise inhalative oxygen, nitrates, morphine, aspirin and beta-blockers. If STEMI is diagnosed, patients with symptoms <12 h should undergo fibrinolytic therapy unless there is primary percutaneous coronary intervention (PCI) available within 90 min or if contraindicated. Heparin should be given to patients with STEMI depending on the choice of fibrinolytic agent, it otherwise results in a higher risk of bleeding, but in patients with iAP or NSTEMI it reduces mortality. All patients must be accompanied by the emergency physician during transportation and should be brought to a hospital with primary PCI, especially those with complicated ACS. Treatment of complications depends largely on the type, persistence and severity.

The prognostic value of troponin in patients with non-ST elevation acute coronary syndromes: a meta-analysis

OBJECTIVES

This study was designed to compare the prognostic value of an abnormal troponin level derived from studies of patients with non-ST elevation acute coronary syndromes (ACS).

BACKGROUND

Risk stratification for patients with suspected ACS is important for determining need for hospitalization and intensity of treatment.

METHODS

We identified clinical trials and cohort studies of consecutive patients with suspected ACS without ST-elevation from 1966 through 1999. We excluded studies limited to patients with acute myocardial infarction and studies not reporting mortality or troponin results.

RESULTS

Seven clinical trials and 19 cohort studies reported data for 5,360 patients with a troponin T test and 6,603 with a troponin I test. Patients with positive troponin (I or T) had significantly higher mortality than those with a negative test (5.2% vs. 1.6%, odds ratio [OR] 3.1). Cohort studies demonstrated a greater difference in mortality between patients with a positive versus negative troponin I (8.4% vs. 0.7%, OR 8.5) than clinical trials (4.8% if positive, 2.1% if negative, OR 2.6, p = 0.01). Prognostic value of a positive troponin T was also slightly greater for cohort studies (11.6% mortality if positive, 1.7% if negative, OR 5.1) than for clinical trials (3.8% if positive, 1.3% if negative, OR 3.0, p = 0.2)

CONCLUSIONS

In patients with non-ST elevation ACS, the short-term odds of death are increased three- to eightfold for patients with an abnormal troponin test. Data from clinical trials suggest a lower prognostic value for troponin than do data from cohort studies.

Analytical and clinical performance of an improved qualitative troponin T rapid test in laboratories and critical care units

OBJECTIVE

To evaluate the performance of a visual troponin T rapid test in the hands of nontraditionally trained personnel of 2 critical care units in comparison to 3 laboratories.

METHODS

Method comparisons of the troponin T rapid test versus cardiac troponin T enzyme-linked immunosorbent assay were performed with 804 samples from 510 patients with suspected acute coronary syndromes. Cross-reactivity with skeletal troponin T was studied up to 5000 microg/L.

RESULTS

Laboratories and critical care units obtained comparable results in the analytical cutoff of the test (0.11 and 0. 10 microg/L) and in the diagnostic sensitivities in the detection of acute myocardial infarction (96% and 93% after 8 hours) and of high-risk patients with unstable angina pectoris (100% and 100%). Different percentages of false-positive results (0.2% and 3%) were found, which may reflect different objectives and strategies in these hospital units. The cross-reactivity with skeletal troponin T was less than 0.01%.

CONCLUSIONS

The troponin T rapid test gives reliable results not only when used by laboratory personnel experienced in the execution of analytical methods, but also in the hands of nurses and physicians working in clinical units outside the laboratory.