ALARRM: A laboratory approach for rapid risk-assessment for myocardial infarction

Current pathways using high-sensitivity cardiac troponin (hs-cTn) to rule in and rule out myocardial infarction (MI) are assay specific. This requires clinicians and laboratories to use the correct assay-specific cutoffs, deltas, and time between measurements for optimal decision making. To overcome these challenges, we developed a new common laboratory pathway (i.e., ALARRM: a laboratory approach for rapid risk-assessment for MI) to aid in early risk stratification for MI in the emergency department (ED) using the combined validated clinical chemistry score (CCS) and common change criteria (3C) algorithm. The objective of our study was to assess the diagnostic performance (sensitivity and specificity) and effectiveness (combination of rule out/low risk and rule in/high risk) of ALARRM.

The study cohort (n = 855) consisted of patients presenting to the ED with acute coronary syndrome symptoms and had two blood samples collected three hours apart for measurement of Abbott hs-cTnI, Ortho hs-cTnI, Roche hs-cTnT, glucose, and creatinine (for the estimated glomerular filtration rate (eGFR) calculation). We also assessed the European society of cardiology (ESC) single sample assay-specific cutoffs with both ALARRM and ESC criteria being assessed for index MI in the cohort.

The sensitivity for MI using ALARRM was 100 % for all three assays, however this was not the case for the ESC single cutoffs where the Ortho hs-cTnI assay missed 4 MIs. The specificities in patients with serial measurements with ALARRM were > 90 %, with the overall effectiveness for ALARRM being 61 % (95 %CI: 58 to 64) for Roche, 80 % (95 %CI: 77 to 82) for Abbott, and 89 % (95 %CI: 86 to 91) for Ortho.

The ALARRM pathway represents a highly efficacious and common approach using hs-cTn for early risk stratification for MI.