Two-thirds of patients at very low risk for cardiac events can be safely discharged immediately from the hospital after identifying low plasma troponin concentrations at presentation, according to a cohort study of 6,304 patients with suspected acute coronary syndrome. Researchers found:

• In patients without myocardial infarction (MI) at presentation, troponin concentrations were <5 ng/L in 61% of patients.

• In patients without myocardial infarction at presentation, troponin concentrations <5 ng/L had a negative predictive value of 99.6% for the primary outcome.

• At 1 year, patients with troponin concentration of < 5 ng/L had a lower risk of MI and cardiac death than did those with a troponin concentration of ≥5 ng/L.

• Implementation could reduce hospital admissions.

Citation: Shah ASV, Anand A, Sandoval Y, et al. High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study. Lancet. [Published online ahead of print October 8, 2015]. doi: 10.1016/S0140-6736(15)00391-8.

Commentary: The ideal test would allow us to determine which patients with a possible diagnosis of acute coronary syndrome or MI could safely be sent home from the emergency room. While a negative predictive value of 99.6% is good, it does mean that approximately 1 patient out of 200 will be missed. Of the 12 patients missed using the criteria in this study, 5 had evidence of an MI on initial EKG and 2 in cardiac arrest on presentation. In using any criteria, it is important to apply those criteria in the context of all the information at hand for the patient who is being seen. —Neil Skolnik, MD