New ‘sensitive’ test may help diagnose heart attack within hours
Washington: A highly sensitive new test may soon enable quicker diagnosis of heart attack than is currently possible, a new study has suggested.
One of the most common reasons patients seek care in an emergency department is for acute chest pain.
“Early identification of individuals at high and intermediate risk for myocardial ischemia [insufficient blood flow to the heart muscle] is crucial because they benefit the most from early and aggressive treatment,” the researchers said.
“According to international consensus and task force definitions of myocardial infarction [(MI; heart attack], the diagnosis of MI is based mainly on an elevated cardiac troponin level exceeding the 99th percentile and demonstrating an increase or decrease over time,” they added.
Highly sensitive troponin assays have been developed recently that reliably assess troponin levels in more than 50 percent of the general population.
“The reliable detection of very low troponin concentrations using these new highly sensitive assays in the acute setting might pose a challenge in everyday clinical practice,” they said.
Till Keller, M.D., of the University Heart Center Hamburg, Germany, and colleagues evaluated the diagnostic performance of the newly developed highly sensitive troponin I (hsTnI) assay compared with a contemporary troponin I (cTnI) assay and their serial changes in the diagnosis of heart attack.
The study included a total of 1,818 patients with suspected acute coronary syndrome (condition such as heart attack or angina) who were enrolled at chest pain units in Germany from 2007 to 2008. Twelve biomarkers including hsTnI and cTnI were measured on admission and after 3 and 6 hours.
Of the patients in the study, 413 (22.7 percent) had a final discharge diagnosis of acute MI. 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 percent and negative predictive value (NPV) of 94.7 percent; hsTnI determined after 3 hours had a sensitivity of 98.2 percent with NPV of 99.4 percent.
Compared with hsTnI, the cTnI assay (using the 99th percentile as cutoff) had comparable sensitivity and NPV: 79.4 percent sensitivity and 94.0 percent NPV on admission, and 98.2 percent sensitivity and 99.4 percent NPV after 3 hours.
The study has been recently published in JAMA.