Background: Implementation of an early rule-out pathway for myocardial infarction using high-sensitivity cardiac troponin to risk stratify patients reduces length of stay and hospital admission. Whether gains are similar in low- and intermediate-risk patients and those discharged were correctly identified as being at lower risk of future cardiovascular events is uncertain.
Objectives: This study sought to evaluate the effectiveness and safety of risk stratification with high-sensitivity cardiac troponin in patients with suspected acute coronary syndrome stratified as low and intermediate risk.
Methods: In this secondary analysis of a stepped-wedge cluster-randomized controlled trial, we evaluated the effectiveness and safety of risk stratification with high-sensitivity cardiac troponin in 31,492 consecutive patients who presented with suspected acute coronary syndrome and identified as low (<5 ng/L) or intermediate (5 ng/L to 99th percentile) risk at presentation. The primary effectiveness outcome was length of hospital stay. The primary safety outcome was subsequent myocardial infarction or cardiac death at 1 year.
Results: Of 31,492 patients (59 ± 17 years, 45% women), 17,299 (54.9%) and 14,193 (45.1%) were low and intermediate risk, respectively. Following implementation, length of stay was reduced in low-risk (6.9 ± 3.2 vs 4.7 ± 2.8 hours: difference 2.2; 95% CI: 0.7-3.7 hours) and intermediate-risk (15.8 ± 4.7 vs 11.0 ± 4.9 hours: difference 4.8; 95% CI: 3.8-5.8 hours) patients (P < 0.001 for both). Discharge from the emergency department increased in low-risk (62% [4,962 of 7,941] vs 83% [7,747 of 9,358]; adjusted OR: 3.31; 95% CI: 3.06-3.57) and intermediate-risk (36% [2,445 of 6,759] vs 55% [4,095 of 7,434]; adjusted OR: 2.06; 95% CI: 1.92-2.21) patients. Following implementation, patients discharged were at lower risk of myocardial infarction or cardiac death at 1 year (1.5% [112 of 7,407] vs 1.0% [124 of 11,842]; adjusted HR [aHR]: 0.65; 95% CI: 0.50-0.86), whether stratified as low (0.6% vs 0.3%; aHR: 0.46; 95% CI: 0.26-0.83) or intermediate (3.4% vs 2.4%; aHR: 0.74; 95% CI: 0.55-0.99) risk at presentation.
Conclusions: Risk stratification with high-sensitivity cardiac troponin reduced length of stay and increased discharge from the emergency department in both low- and intermediate-risk patients with suspected acute coronary syndrome. Patients discharged from the emergency department were at lower risk of subsequent myocardial infarction or cardiac death at 1 year.
