One Troponin Test to Identify Low-Risk Patients Fast

May 18, 2012

May 18, 2012 (Updated May 21, 2012) (Christchurch, New Zealand) — A simple strategy of measuring just contemporary central-laboratory troponin I within two hours of presentation as the sole biomarker in conjunction with ECG and the TIMI risk score can identify a large group of chest-pain patients who are at low risk of cardiac events and are suitable for safe early discharge from the ER, a new study suggests [1].

"As the components required for this strategy are already widely available, rapid uptake of this accelerated diagnostic protocol is possible by most hospitals with the potential for immediate health service benefit," the authors conclude.

The study was published online May 9, 2012 in the Journal of the American College of Cardiology, by a group led by Dr Martin Than (Christchurch Hospital, New Zealand).

They tested this protocol on a group of 1975 patients presenting to the ER with chest pain. The accelerated protocol classified 392 patients (20%) as low risk, only one of whom (0.25%) had a cardiac event within the next 30 days. This translates into a sensitivity of 99.7% and a negative predictive value of 99.7%.

Than commented to heartwire : "There haven't been many papers on combining clinical risk stratification with a troponin test. There is a lot of interest in the high-sensitivity troponin test for identifying a low-risk population, but this is not available in many places yet. While we are waiting for this test to come through, we have come up with an approach than can be used here and now."

He noted that at present guidelines recommend two troponin tests for chest-pain patients in the ER, six to 12 hours apart. "So patients are normally admitted overnight. Our approach allows 20% of patients to leave fairly quickly. They will still need outpatient follow-up within the next few days, but we can be pretty sure they are not having an MI and don't need immediate hospitalization."

The authors note that patients with chest pain account for approximately 10% of ER presentations and 25% of hospital admissions, yet up to 85% do not have a final diagnosis of ACS. "Prolonged assessment contributes to duplication of work, high costs, and emergency-department overcrowding," they write.

"This study also demonstrates that central-laboratory troponin assays currently in use have sufficient sensitivity at an early time point to negate the need for additional biomarkers (such as myoglobin and creatine kinase-MB)," they add.

Than said that his team is now investigating variations on this accelerated protocol that would include a different clinical risk score or the high-sensitivity troponin test that may identify more people (maybe up to 50%) who can be sent home early.

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