Clinical Decision Rules and Point of Care Troponin Testing for the Diagnosis of Acute Myocardial Infarction in the Prehospital Setting

Abstract

Background Chest pain is one of the most common reasons for emergency 999 ambulance calls and the most common reason for emergency hospital admission. Diagnosing acute myocardial infarction (AMI) in a patient with chest pain in the prehospital settings by a paramedic is one of the most challenging tasks.

Aim I aimed to evaluate the diagnostic accuracy of clinical decision rules to be used in the prehospital setting to rule out AMI in patients with suspected cardiac chest pain, and to risk stratify the remaining patients.

Methods I derived the History and Electrocardiogram-only Manchester Acute Coronary Syndromes (HE-MACS) decision tool, then validated both the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision tool with a point of care troponin assay and the HE-MACS decision tool in the emergency department population. Also, I prospectively validated both HE-MACS and T-MACS in conjunction with a point of care troponin assay when used in the prehospital settings.

Result In the prehospital setting, HE-MACS ruled-out AMI in 2.5% of patients with chest pain and achieved a sensitivity of 100% (95% CI 95.3% to 100%) and a negative predictive value (NPV) of 100% (95% CI 76.8% to 100%). In addition, T-MACS ruled-out AMI in 29.3% of patient with chest pain and achieved a sensitivity of 95.9% (95% CI 86.0% to 99.5%) and a NPV of 98.2% (95% CI 93.6% to 99.8%).

Conclusion These findings suggest that both HE-MACS and T-MACS have shown great promise to be used in the prehospital setting. Both tools have effectively and safely risk stratified patients with suspected cardiac chest pain. We now require prospective evaluation of the clinical and cost-effectiveness of using the tools in practice prior to clinical implementation.