WASHINGTON — Patients presenting to the ED with an undetectable level of high-sensitivity cardiac troponin T and whose electrocardiogram shows no sign of ischemia have a minimal risk for MI or death within 30 days and can be safely discharged, according to research presented here.
In a study of 14,636 patients (mean age, 47 years; 53% women) who reported to a Swedish ED with chest pain from 2010 to 2012, researchers examined patients’ blood levels of high-sensitivity cardiac troponin T. The goal of the study was to evaluate if an undetectable high-sensitivity cardiac troponin T level (<5 ng/L) and an ECG without signs of ischemia can rule out MI in the ED, researcher Martin Holzmann, MD, PhD, said in a press conference at the American College of Cardiology Scientific Sessions.
Of the patients studied, 61% had an initial high-sensitivity cardiac troponin T <5 ng/L, 21% had 5 to 14 ng/L and 18% had >14 ng/L.
MI incidence very low
The primary outcome was fatal or nonfatal MI within 30 days. During follow-up, 0.44% of the 8,907 patients with an undetectable high-sensitivity cardiac troponin T were diagnosed with MI, of whom 0.17% showed no signs of ischemia on ECG. According to the researchers, this means that only one in 594 patients who seek medical attention for chest pain, but have no signs of heart damage on an ECG and undetectable levels of high-sensitivity cardiac troponin, are actually at immediate risk for MI.
The negative predictive value in patients with undetectable high-sensitivity cardiac troponin T was 99.8% for MI and 100% for death within 30 days, Holzmann said. This relationship held true regardless of the patients’ risk factors for MI or how long they had experienced symptoms, he said.
In patients with undetectable high-sensitivity cardiac troponin T, there were 2 deaths within 30 days. At 1 year follow-up, there were 38 deaths, of which 32 were caused by cancer and two by CV, Holzmann said.
“We believe that up to 20% to 25% of all admissions to the hospital because of chest pain may be prevented using our simple strategy,” Holzmann said.
Clinical implications include avoidance of unnecessary admissions, potential reduction of overcrowding of the ED and saving time for the patient and doctor, he said.
The results were published simultaneously in the Journal of the American College of Cardiology by Nadia Bandstein, MD, Holzmann and two other colleagues, all from the department of emergency medicine at Karolinska University Hospital and Karolinska Institute, Sweden.
According to the researchers, this is the first large study to specifically examine the use of high-sensitivity cardiac troponin T to predict MI risk.
Current guidelines recommend that high-sensitivity cardiac troponin T be analyzed at least 3 hours after the onset of chest pain. Holzmann said these findings suggest that only one measure of the biomarker needs to be taken, and may allow some patients to be discharged directly from the ED. – by Katie Kalvaitis and Erik Swain
For more information:
Bandstein N. Late-Breaking Clinical Trials III. Presented at: American College of Cardiology Scientific Sessions; March 29-31, 2014; Washington, D.C.
Bandstein N. J Am Coll Cardiol. 2014;doi:10.1016/j.jacc.2014.03.017.
Disclosure: Bandstein and Holzmann report no relevant financial disclosures.