Diagnostic accuracy of high-sensitivity troponin I in an accelerated protocol to assess 30-day outcomes among chest pain patients in the emergency department.

Introduction: In Malaysia, acute coronary syndrome is the leading cause of hospitalisation. Identification of patients with low 30-day risk of major adverse cardiac event (MACE) may facilitate an early and safe discharge from overcrowding emergency departments (ED). This study aimed to determine the diagnostic accuracy of high-sensitivity-cardiac-troponin-I (hs-cTnI) for ruling out 30-day MACE among chest pain patients in ED.

Materials and methods: A prospective observational study using an Accelerated Diagnostic Protocol (ADP) which included Thrombolysis-in-Myocardial-Infarction (TIMI) score, electrocardiogram, and 0- and 3-hour hs-cTnI. TIMI = 0 and ≤1 was used in ADP-1 and ADP-2, respectively.

Results: 20 (10%) and 64 (32%) of 201 patients were low-risk, whereby none of whom developed MACE in ADP-1 and ADP-2, respectively. Using the overall hs-cTnI cut-off, ADP-1 had a Sensitivity (Sn) of 100% [95% Confidence Interval (CI)] (51.7 to 100), Specificity (Sp) of 10.2% (6.5 to 15.6), Negative Predictive Value (NPV) of 100% (80.0 to 100) and Positive Predictive Value (PPV) 3.3% (1.4 to 7.4). ADP-2 yielded a Sn of 100% (51.7 to 100), Sp of 32.8% (26.4 to 40.0), NPV of 100% (92.9 to 100) and PPV of 4.4% (1.8 to 9.7). Using gender-specific hs-cTnI cut-off, either that of Abbott or a Malaysian population, yielded similar diagnostic accuracy; except the former produced slightly higher Sp of 75.4% (68.7-81.1).

Conclusion: Using either the overall or gender-specific cut-offs, both protocols yielded 100% diagnostic accuracy for ruling out MACE which may enable a safe early discharge of up to 32% of chest pain patients in ED.