Clinical Utility of Rapid Test and Quantitative Measurement of T Troponin for Risk Stratification of Patients with Unstable Angina

pp 27-35

Abstract

Objectives

The purposes of this work were to: 1) compare the utility of the rapid assay (TRap) vs. quantitative measurement of T troponin (TnT) inpatients with unstable angina in relation to death/myocardial infarction during hospitalization and at 30-day follow-up, and 2) compare sensitivity, specificity, positive and negative predictive values.

Materials and methods

One hundred and seventeen patients (60% male, 40% female) were prospectively enrolled. TRap andTnT measurement were carried out at 4 and 6 hrs after admission, respectively. A value ?0.1 ng/ml was considered abnormal. During hospitalization, 8 patients (6.8%) undergone events and 16 patients(13.6%) developed them after 30-day period.

Results

TnT >_ 0.1ng/ml was detected in 51 patients (43.6%).TRap was positive in17 (14.5%). In patients with positive and negative TRap the event incidence during hospitalization was 23.5% and 4% respectively (p = 0.01OR= 7.3 CI = 1.3-2.0) and during follow-up 35% and10%respectively (p = 0.001OR= 4.9CI = 1.3-1.9). TnT values were positively related to AMI/death as it rate was 15.7% (TnT in-creased values) vs. 0% (TnT normal values) (p =0.0009) during hospitalization. The corresponding rates 30 days after were 25.5% vs. 4.5% respectively(p = 0.002 OR = 7.21 CI = 1.7-20).

                 _{Sensitivity Specificity(+) Predictive value (-) Predictive value}

_{Events     TropT   TnT  TropT TnT          TropT  TnT           TropT       TnT}

_{Hospita       50     100   88.1     60.6          23.5    15.7           96            100}

_lization

_{Follow-up  37.5    81.3   89      62.4           35.3     25.5          89.1        95.5}

In a multivariate analysis, T troponin turned outto be the only independent marker of death/AMI at 30 days irrespectively the method employed. Obtaines values were TRap (OR 4.9 p= 0.009 CI =1.49-16.1) or TnT (OR 7.18; p = 0.003; IC = 1.9-26.8), however TnT (OR 7.18 p = 0.003 CI = 1.9-26.8). ROC curve analysis showed not statistical differences between TnT and TRap.

Conclusion

T troponin elevation, detected as a positive result in the TRap or TnT>_ 0.1 ng/ml within 6 hours after admission is the only independent risk marker for infarction/death within the first month after discharge. TnT measurement showed more sensitivity, less specificity and higher negative predictive value compared to TRap but both tests were comparable for risk stratification in patients with unstable angina.