Among individuals with suspected acute coronary syndrome (ACS), hospital stays could be safely shortened with an implementation using high-sensitivity cardiac troponin T (hs-cTnT) levels below 5 ng/L as an early rule-out pathway for myocardial infarction (MI), according to a study published in BMJ Open Heart.

For the prospective single-center cohort study, researchers included 10,315 individuals treated consecutively (54% men; mean age 64 ±16 years) at Victoria Hospital in Kirkcaldy, Scotland, for suspected ACS. Among the patients, 64% were treated with standard care and 36% were treated after the implementation of an early rule-out pathway. The groups had similar sex and mean age. In the standard care group, MI was ruled out for hs-cTnT concentrations below 14 ng/L (99th centile) at symptom presentation and 6-12 hours following symptom onset. In the intervention group, MI was ruled out for hs-cTnT concentrations below 5 ng/L at symptom presentation and symptoms persisting at least 3 hours, or for hs-cTnT concentrations of at least 5 ng/L that persisted for 3 hours. Duration of stay and all-cause, 1-year mortality was compared between the groups using Student’s t-test, X2 test, and Mann-Whitney U test.

Following implementation of an early rule-out pathway, the duration of hospital stays shortened from 534 (IQR, 220-2279) minutes to 390 (IQR, 218-1910) minutes (P <.001). Among those with hs-cTnT concentrations <5 ng/L at symptom presentation, hospital stays shortened from 236 (IQR, 180-484) to 219 (IQR, 170-328) minutes (P <.001). All-cause mortality at 1 year occurred among 10.9% vs 10.4% of the standard vs intervention groups, respectively (odds ratio, 1.02; 95% CI, 0.88-1.18). No significant differences in cardiovascular death at 30 days or 1 year were observed between the groups.

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Limitations to this study included the use of a single study center; the use of a nonrandomized trial design; the potential for bias and/or misclassification; the inability to exclude those for whom troponin was requested for different clinical conditions, such as acute heart failure or pulmonary embolus; and the use of manufacturer-recommended hs-cTnT thresholds instead of USFDA-recommended thresholds.

“In patients with suspected [ACS], implementing an early rule-out pathway, using an hs-cTnT concentration of <5 ng/L at presentation for risk stratification, reduced the duration of stay in hospital without compromising safety,” the study authors noted. “Adopting such a strategy could have major benefits for patients and healthcare providers.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Sandeman D, Syed MBJ, Kimenai DM, et al. Implementation of an early rule-out pathway for myocardial infarction using a high-sensitivity cardiac troponin T assay. Open Heart. Published online November 25, 2021. doi:10.1136/openhrt-2021-001769.