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Chest pain patients in Sweden’s emergency departments are routinely evaluated using the high-sensitivity troponin T assay, which is just beginning to be in widespread use in the United States.
A large-scale registry study published in the Journal of the American College of Cardiology looked at the experience there and what it might mean as more EDs bring the test online.
Earlier this year, the U.S. Food and Drug Administration granted 510(k) clearance for Roche’s Elecsys Troponin T Gen 5 STAT (TnT Gen 5 STAT) blood test for patients with a suspected heart attack. The company’s fifth-generation blood test uses two monoclonal antibodies against cardiac troponin T to pick up the marker of myocardial damage with a turnaround time of nine minutes. Interestingly, although it is the same test referred to as “high-sensitivity” in trials outside the United States, the company was urged by the FDA to call it “next-generation” in this country.
The Swedish study led by researchers at Karolinska Institutet suggests that, overall, fewer patients diagnosed with “unspecified chest pain” suffered acute myocardial infarction (AMI) or died after being sent home under the new protocol.
To rule out myocardial infarction, EDs have traditionally ordered an ECG and testing for the cardiac biomarkers troponin T or I. Emerging as an option is the new and more sensitive assay, which has been introduced at Swedish hospitals.
To discover if high-sensitivity troponin T is associated with a lower incidence of cardiovascular events, the researchers conducted a large-scale registry study of 65,000 patients with unspecified chest pain who had been discharged from 16 Swedish emergency clinics between 2006 and 2013.
Results indicate that the risk of suffering a serious cardiovascular event within 30 days of returning home was much lower in patients discharged from an emergency clinic with the new protocol as compared with the old one. The percentage of those with subsequent AMI, death, or unplanned revascularization declined from 0.9% to 0.6%.
“Our results are of interest to other countries such as the USA, which is about to change its methods,” explained Per Svensson, MD, PhD, associate professor and senior lecturer at Karolinska Institutet’s Department of Medicine in Solna.
Among patients admitted to the hospital for unspecified chest pain diagnosis, however, the study found that the risk of suffering serious events increased, from 3.4% to 7.2%, after the change in evaluation method.
“We may conclude from the results of our study that examination using high-sensitivity troponin is associated with fewer serious cardiac events and an improvement in risk profile for patients released from emergency clinics with unspecified chest pain,” Svensson pointed out. “The opposite was observed in patients sent home after admission to hospital, which suggests that high-risk patients are identified and hospitalized more frequently. We therefore conclude that high-sensitivity troponin has helped to improve the evaluation of emergency patients with unspecified chest pain.”