Abstract 12993: Validated Staged Algorithm Using High-Sensitivity Assayed Cardiac Troponin I to Diagnose Non-ST-Segment Elevation Myocardial Infarction in Patients With Acute Chest Pain
Objective: Cardiac troponin testing is instrumental for the diagnosis of non-ST-segment elevation myocardial infarction (NSTEMI) in patients with acute chest pain. Various diagnostic algorithms incorporating relative or absolute changes (deltas) in high-sensitivity assayed cardiac troponin I (hs-cTnI) as well as different 99th percentile concentrations of a reference population have been tested to date. Since 99th percentiles depend strongly on gender, age, and health status, we derived a staged hs-cTnI algorithm independent of a 99th percentile to rule out/in NSTEMI in one cohort of chest-pain patients and validated it in another.
Methods: The CE-marked Architect STAT hs-cTnI assay (Abbott Diagnostics) was employed to measure hs-cTnI on admission (0h) and 3 hours later (3h) in a test population of 1407 German patients (pts; 61 ± 14 yrs, 910 men [65%], 217 NSTEMI [15.4%]) and a validation population of 674 Swiss pts (64 ± 15 yrs, 437 men [65%], 64 NSTEMI [9.5%]). The 99th percentile (from a 4000-subject reference population) was 21.7ng/l. With the aim of finding highest NPV to rule out NSTEMI and, subsequently, highest PPV in pts with positive rule-out findings to rule in NSTEMI, 99th percentile as well as arbitrary cutoff concentrations at 0h and 3h were tested for rule-out and relative as well as absolute deltas for rule-in.
Results: The rule-out criterion was hs-cTnI[3h] >50ng/l, the rule-in criterion was delta[hs-cTnI] ≥100ng/l. Pertinent results shown in the Table were independent of age and gender. NPV and SN as well as PPV and SP derived in the test cohort to rule out/in NSTEMI were confirmed in the validation cohort.
Conclusions: A 3-h cutoff concentration of 50ng/l enables NSTEMI rule-out with diagnostic certainty (NPV) and sensitivity (SN) close to 100%. An absolute delta of at least 100ng/l in pts with hs-cTnI[3h] >50ng/l enables NSTEMI rule-in with a diagnostic certainty exceeding 80%. Using hs-cTnI, a 99th percentile is not needed for confident NSTEMI diagnosis.
- © 2013 by American Heart Association, Inc.