BACKGROUND: The safety of the European Society of Cardiology (ESC) 0/1-h algorithm for rapid rule-out and rule-in of non-ST-segment elevation myocardial infarction (NSTEMI) using high-sensitivity cardiac troponin (hs-cTn) has been questioned.
OBJECTIVES: This study aimed to validate the diagnostic performance of the 0/1-h algorithm in a large multicenter study.
METHODS: The authors prospectively enrolled unselected patients in 6 countries presenting to the emergency department with symptoms suggestive of NSTEMI. Final diagnosis was centrally adjudicated by 2 independent cardiologists. Hs-cTnT and hs-cTnI blood concentrations were measured at presentation and after 1 h. Safety of rule-out was quantified by the negative predictive value (NPV) for NSTEMI, accuracy of rule-in by the positive predictive value (PPV), and overall efficacy by the proportion of patients triaged towards rule-out or rule-in within 1 h.
RESULTS: Prevalence of NSTEMI was 17%. Among 4,368 patients with serial hs-cTnT measurements available, safety of rule-out (NPV 99.8%, 2,488 of 2,493), accuracy of rule-in (PPV 74.5%, 572 of 768), and overall efficacy were high by assigning three-fourths of patients either to rule-out (57%, 2,493 to 4,368) or rule-in (18%, 768 to 4,368). Similarly, among 3,500 patients with serial hs-cTnI measurements, safety of rule-out (NPV 99.7%, 1,528 of 1,533), accuracy of rule-in (PPV 62.3%, 498 of 800), and overall efficacy were high by assigning more than two-thirds of patients either to rule-out (44%, 1,533 of 3,500) or rule-in (23%, 800 of 3,500). Excellent safety was confirmed in multiple subgroup analyses including patients presenting early (=3 h) after chest pain onset.
CONCLUSIONS: The ESC 0/1-h algorithm using hs-cTnT and hs-cTnI is very safe and effective in triaging patients with suspected NSTEMI. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE]; NCT00470587; and Biomarkers in Acute Cardiac Care [BACC]; NCT02355457).
This is a validation study of the European Society of Cardiologist 0/1-hour rule for NSTEMIs that uses cut-off values for troponin T and I at 0 and 1 hour after presentation. The study uses data from 2 other studies of chest pain patients. Using the rule, 57% and 44% of patients have NSTEMI ruled out, with a negative LR of 0.01 and 0.02, using troponin T and I, respectively. Mortality at 30 days for this “ruled out” group was 0.1% for either troponin assay. However, the accompanying editorial pointed out that it is uncertain how much this low mortality depended on the intensity of outpatient follow-up after discharge. Additionally, patients with atypical symptoms were not included, and the mean time from onset of symptoms until evaluation was 5 hours. Finally, a study using this algorithm in the emergency department did not perform as well. These limitations temper the enthusiasm for recommending this rule for actual use in clinical practice.
This validation study continues to support an accelerated diagnostic pathway for the evaluation of suspected ACS in the ED. The classification into three categories seems interesting, although 25% fall into the observation group where management is not entirely clear. Also uncertain is how robust the 0/1h algorithm is for patients arriving within 3 hours of symptom onset.