The diagnostic performance of newly developed highly sensitive troponin I (hsTnI) assay was compared with a contemporary troponin I (cTnI) assay and their serial changes in the diagnosis of heart attack.

Scientists at the University Heart Center (Hamburg, Germany) studied a cohort of 1,818 patients with suspected acute coronary syndrome, conditions such as heart attack or angina. The patients were enrolled in the study at chest pain units in Germany from 2007 to 2008. Twelve biomarkers including hsTnI and cTnI were measured on admission and six hours later. Heart attacks are clear in the public perception, and hospital admission for chest pains are one of the most common complaints. Highly sensitive troponin assays have been developed recently, and these tests can reliably assess troponin levels in more than 50% of the general population.

For the cTnI assay, the Architect STAT troponin I assay was used. The level of detection was 10 pg/mL, with a range of 0-50,000 pg/mL. The 99th percentile and the concentration with coefficient of variation of 10% is 32 pg/mL. The diagnostic threshold for myocardial infarction (MI) according to the World Health Organization's (Geneva, Switzerland) definition was given as 300 pg/mL by the manufacturer (Abbott Diagnostics, Abbott Park, IL, USA). The same manufacturer's prototype cardiac troponin I assay (Architect STAT High Sensitive Troponin) was used for hsTnI assay. For this assay, the level of detection is 3.4 pg/mL with a range, 0-50,000 pg/mL and the coefficient of variation is 10% at a concentration of 5.2 pg/mL.

For discrimination of acute MI, both hsTnI and cTnI were superior to the other evaluated diagnostic biomarkers. Using the 99th percentile cutoff, hsTnI on admission had a sensitivity of 82.3 % and negative predictive value (NPV) of 94.7%; hsTnI determined after three hours had a sensitivity of 98.2% with NPV of 99.4%. Compared with hsTnI, the cTnI assay, using the 99th percentile as cutoff had comparable sensitivity and NPV: 79.4% sensitivity and 94.0% NPV on admission, and 98.2% sensitivity and 99.4% NPV after three hours.

Till Keller, MD, a senior author of the study, concluded that "The shortcoming of conventional troponin assays with low sensitivity within the first hours after chest pain onset led to the evaluation of various so-called early biomarkers in the diagnosis of MI. In our study, the diagnostic information of hsTnI was superior to all other evaluated biomarkers alone." The study was published on December 28, 2011, in the Journal of the American Medical Association (JAMA).

Related Links:
University Heart Center
Abbott Diagnostics
World Health Organization