PARIS – A new algorithm incorporating high-sensitivity cardiac troponin T values in patients with ST-segment elevation seems to differentiate between MI and cardiac but noncoronary disease in patients with acute chest pain.
The algorithm could help triage patients in the first hour of presentation so that those who need coronary angiographies get them quickly and unnecessary angiographies are minimized, Dr. Philip Haaf said in a press briefing at the annual congress of the European Society of Cardiology.
Troponins are increased in cardiovascular disorders including tachyarrhythmia, heart failure, hypertensive urgency or emergency, Takotsubo cardiomyopathy, and myocarditis in patients without a coronary obstruction. The introduction of high-sensitivity assays for cardiac troponins has allowed earlier diagnosis of acute MI in many patients.
But the assays also have caused "considerable confusion among treating physicians" because minor elevations in cardiac troponins can be seen in some patients who do not have a coronary obstruction but have tachyarrhythmia, hypertensive urgency, or heart failure, said Dr. Haaf of University Hospital Basel (Switzerland).
He and his associates analyzed data on the first 887 patients who presented to emergency departments with acute chest pain in the APACE (Advantageous Predictors of Acute Coronary Syndrome Evaluation) study. The ongoing, multicenter study has enrolled close to 2,000 patients so far, obtaining a meticulous patient history, ECG analysis, and measures of novel cardiac biomarkers from each. High-sensitivity cardiac troponin T (hs-cTnT) was measured at presentation and serially thereafter in a blinded fashion, and final diagnosis was adjudicated by two independent cardiologists.
They found that the initial hs-cTnT value and the absolute change in hs-cTnT value within the first hour helped differentiate MI from cardiac but noncoronary disease but that the relative change in hs-cTnT was less discriminatory. In a receiver operating characteristic analysis, using both the initial hs-cTnT and absolute change in the first hour provided an area under the curve of 0.94.
"This is all statistics. What we tried to do is translate these statistics into more clinically applicable terms," Dr. Haaf said.
Analyzing data on 127 patients with acute MI and 125 with cardiac, noncoronary disease, they found that in the 233 patients with ST-segment elevation on ECG, 98% of patients who had an MI had either presentation values for hs-cTnT above 0.028 mcg/L or an absolute change in hs-cTnT of at least 0.005 mcg/L in the first hour.
Changes in hs-cTnT after the first hour did not add much helpful information, he added.
This three-step algorithm – ST elevation, hs-cTnT value at presentation, and absolute change in hs-cTnT in the first hour – provided a positive predictive value of 79% and a "relatively high" negative predictive value of 98% in differentiating acute MI from cardiac, noncoronary disease, Dr. Haaf said.
The study was funded by the Swiss National Science Foundation, the Swiss Heart Foundation, Abbott, Roche, Nanosphere, Siemens, and University Hospital.
No disclosure information was reported.