Low Troponin Concentrations May Reduce Hospital Admissions for Patients With Low-Risk MI

Identifying patients with low plasma troponin concentrations could reduce hospital admissions for patients with chest pain by up to two-thirds, according to research published in The Lancet.

Many patients admitted to the hospital with chest pains are suitable for direct discharge. However, there is currently no procedure to rule out acute coronary syndrome (ACS) when they initially arrive, and although most patients do not have ACS, the number of hospital admissions continues to increase. 

Anoop Shah, MD, of the British Heart Foundation Centre for Cardiovascular Science and colleagues, conducted a study that included 6304 patients with suspected ACS. The study was broken into a deviation cohort of 4870 patients from 4 secondary and tertiary hospitals in Scotland, and 2 independent validation cohorts of 1061 patients.

Researchers measured plasma troponin concentrations using a high-sensitivity cardiac troponin I assay called ARCHITECT_STAT. The clinicians tested all patients for troponin at presentation, and again at 6 and 12 hours.

Patients with evidence of myocardial necrosis, who had a troponin concentration >99^th percentile, were classified with either type 1 or type 2 myocardial infarction (MI). Patients with type 1 MI had myocardial necrosis at an isolated presentation with ACS, and type 2 patients had symptoms of myocardial ischaemia due to increased oxygen demand and myocardial necrosis.

The results showed that 16% of the patients in the derivation cohort had type 1 MI, and 4% had type 2. One percent had a recurrence of MI, and 2% had cardiac deaths at 30 days. Sixty-one percent of patients who did not have MI at presentation had troponin concentrations <5 ng/L with a negative predictive value of 99.6%. The negative predictive value was consistent among all demographics.

“At this threshold,” the authors wrote, “almost two-thirds of patients with suspected ACS could have been discharged with very few cardiac events. Indeed, implementation of this threshold could double the number of patients discharged directly from the emergency department.”

In the 2 validation cohorts, troponin concentrations were <5 ng/L in 56% of patients with a negative predictive value of 99.4%. Patients with a lower troponin concentration had a lower risk of MI and cardiac death after 1 year than those with troponin concentrations >5 ng/L.

The authors concluded that this method could be implemented across multiple healthcare settings and reduce admissions by up to two-thirds, but additional research is required to determine the implications of this method in clinical practice.

Reference

1. Shah A, Anand A, Sandoval Y et al. High-Sensitivity Cardiac Troponin I at Presentation in Patients with Suspected Acute Coronary Syndrome: A Cohort Study. The Lancet. 2015; Oct 8. doi: 10.1016/S0140-6736(15)00449-3.