This article is more than 5 years old. Information may no longer be current.
Highly sensitive troponin I assay allowed earlier diagnosis of MI
Keller T. JAMA. 2011;306:2684-2693.
Click Here to Manage Email Alerts
The use of highly sensitive or contemporary troponin I assays may accelerate diagnosis of acute MI in patients with suspected acute coronary syndrome admitted to the ED with chest pain, according to recent data.
Researchers measured 12 biomarkers in patients with suspected ACS admitted to the chest pain units of three centers in Germany from 2007 to 2008. They used a prototype of a highly sensitive assay (Architect STAT High Sensitive Troponin, Abbott Diagnostics) and a less sensitive assay already used in clinical practice (Architect STAT, Abbott Diagnostics) to measure troponin I levels upon admission and at 3 and 6 hours after admission.
Of 1,818 patients included in the study, 22.7% received a diagnosis of acute MI. The highly sensitive (receiver operating characteristic [ROC] curve=0.96; 95% CI, 0.95-0.97) and contemporary (ROC=0.92; 95% CI, 0.9-0.94) assays appeared superior in identifying acute MI vs. the other biomarkers evaluated, such as those for ischemia, hemodynamic stress, inflammation, oxidative stress, angiogenesis, plaque instability and classic necrosis.
Study results showed that, using 99th percentile cutoff values, the highly sensitive troponin I assay had a sensitivity of 82.3% and a negative predictive value of 94.7% at admission. Similarly, the contemporary assay had a sensitivity of 79.4% and a negative predictive value of 94%. Sensitivity and negative value for both assays rose to 98.2% and 99.4% after 3 hours. Combining information from admission with the 3-hour serial change in troponin levels led to an increase in positive predictive value from 75.1% at admission to 95.8% at 3 hours for the highly sensitive assay and from 80.9% to 96.1% for the contemporary assay.
The researchers said the highly sensitive and contemporary troponin I assays yielded useful information.
“Acute chest pain is one of the most common reasons patients seek care in an ED,” they wrote. “Early identification of individuals at high and intermediate risk for myocardial ischemia is crucial because they benefit the most from early and aggressive treatment.”
Disclosure: Several researchers report a financial interest with Abbott Diagnostics.
|
|
The study by Keller and colleagues is typical of many in the literature that evaluate 'high-sensitivity' troponin assays and begin to provide the concept that these assays will be somewhat better, but not hugely better than contemporary assays in diagnosing acute MI when used at the appropriate cut off values (the 99th% upper reference limit). However, several issues should be understood by readers. First, the gold standard diagnosis was made using local assays. It is indicated that those assays — apparently by protocol — used a higher cut-off value than ideal. This exaggerates the differences that were found, ie, those using the lower cut-off value would be more sensitive even with the same assays. Second, issues related to the timing of ruling in and ruling out also relied on the less-sensitive metrics. What clinicians need to know is the optimal timing when one includes all of the patients diagnosed with the more sensitive approach whether using lower cut-off values or more sensitive assays. These more sensitive approaches will include additional patients who may or may not rule in or out in a longer time course. Third, the assay used has different normal ranges for men and for women. This apparently was not taken into account in the analysis. Finally, the same problem exists with the delta change calculations in regard to the population. However, in addition, there is progressive loss of sensitivity with increasing percentage changes and it is unclear which value maximizes overall accuracy. In addition, we might prefer to choose a more, rather than a less, sensitive approach.
All said, this is a novel highly sensitive or contemporary troponin I assay that seems to work well. This manuscript, despite the flaws it shares with so many other assessments of high sensitivity, begins to set the stage for the eventual use of these new assays.
– Allan S. Jaffe, MD
Cardiology
Today Editorial Board member
Disclosure: Dr. Jaffe has or does not consult for most of the major diagnostic companies.
 |
Follow CardiologyToday.com on Twitter. |