Diagnostic accuracy of prehospital capillary high-sensitivity cardiac troponin I in patients with acute chest pain: the prospective multicenter VALIDATE study

BACKGROUND: High-sensitivity cardiac troponin I (hs-cTnI) plays a central role in the diagnosis and management of non-ST-elevation myocardial infarction (NSTEMI), including rule-out and rule-in strategies in the emergency department. Extending hs-cTnI testing to the prehospital setting could accelerate patient orientation and clinical decision-making, but the diagnostic performance of prehospital capillary hs-cTnI remains insufficiently studied. OBJECTIVE: The study aimed to evaluate the diagnostic performance of prehospital capillary hs-cTnI for the diagnosis of NSTEMI at hospital discharge. DESIGN: The study is a prospective multicenter diagnostic accuracy study with blinded index test results. SETTINGS AND PARTICIPANTS: Four French emergency medical service systems with 10 mobile intensive care units. Adult patients presenting with acute chest pain were included. INDEX TEST: Prehospital hs-cTnI measurement using a point-of-care device (Atellica VTLi) on capillary samples. Treating clinicians were blinded to hs-cTnI results. OUTCOME MEASURES AND ANALYSIS: The primary outcome was the diagnostic performance of capillary hs-cTnI for the diagnosis of NSTEMI at hospital discharge. Diagnostic performance was assessed using the area under the receiver operating characteristic curve with 95% confidence intervals (CIs). Clinically relevant thresholds were defined a priori based on predefined safety criteria. MAIN RESULTS: Among 659 patients included in the primary analysis, 71 (10.8%) had NSTEMI. Prehospital capillary hs-cTnI demonstrated good diagnostic performance [area under the curve (AUC) = 0.83, 95% CI = 0.78-0.88]. A rule-out threshold of <2.2 ng/L, evaluated according to prespecified performance criteria, identified 7.1% of patients, with a negative predictive value of 1.00 (95% CI = 0.92-1.00). A rule-in threshold of >43.6 ng/L identified 6.5% of patients, with a positive predictive value of 0.65 (95% CI = 0.51-0.79). In the predefined sensitivity analysis, venous hs-cTnI showed similar diagnostic performance (AUC = 0.84, 95% CI = 0.79-0.89). CONCLUSION: Prehospital capillary hs-cTnI showed good diagnostic performance for NSTEMI, although feasibility in routine practice was challenged by unavailable or uninterpretable measurements. Further external validation is warranted before implementation in prehospital diagnostic pathways.