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Canadian Journal of Cardiology

Sustained Performance of a “Physicianless” System of Automated Prehospital STEMI Diagnosis and Catheterization Laboratory Activation

Published:October 20, 2016DOI:https://doi.org/10.1016/j.cjca.2016.10.013

      Abstract

      Background

      Treatment times for primary percutaneous coronary intervention frequently exceed the recommended maximum delay. Automated “physicianless” systems of prehospital cardiac catheterization laboratory (CCL) activation show promise, but have been met with resistance over concerns regarding the potential for false positive and inappropriate activations (IAs).

      Methods

      From 2010 to 2015, first responders performed electrocardiograms (ECGs) in the field for all patients with a complaint of chest pain or dyspnea. An automated machine diagnosis of “acute myocardial infarction” resulted in immediate CCL activation and direct transfer without transmission or human reinterpretation of the ECG prior to patient arrival. Any activation resulting from a nondiagnostic ECG (no ST-elevation) was deemed an IA, whereas activations resulting from ECG's compatible with ST-elevation myocardial infarction but without angiographic evidence of a coronary event were deemed false positive. In 2012, the referral algorithm was modified to exclude supraventricular tachycardia and left bundle branch block.

      Results

      There were 155 activations in the early cohort (2010-2012; prior to algorithm modification) and 313 in the late cohort (2012-2015). Algorithm modification resulted in a 42% relative decrease in the rate of IAs (12% vs 7%; P < 0.01) without a significant effect on treatment delay.

      Conclusions

      A combination of prehospital automated ST-elevation myocardial infarction diagnosis and “physicianless” CCL activation is safe and effective in improving treatment delay and these results are sustainable over time. The performance of the referral algorithm in terms of IA and false positive is at least on par with systems that ensure real-time human oversight.

      Résumé

      Contexte

      Le délai d’intervention coronarienne percutanée (ICP) primaire dépasse souvent le délai maximal recommandé pour ce type d’intervention. Les systèmes d’activation de laboratoire de cathétérisme cardiaque (LCC) préhospitalier « sans médecin » semblent prometteurs, mais font face à la résistance du milieu médical qui craint la possibilité de « faux positifs » et d’activation inappropriée (AI).

      Méthodes

      Entre 2010 et 2015, les premiers répondants ont effectué un électrocardiogramme (ECG) préhospitalier à tous les patients se plaignant de douleurs thoraciques ou de dyspnée. Un diagnostic automatisé d'« infarctus aigu du myocarde » entraînait immédiatement l'activation du LCC et le transfert direct du patient sans transmission de message ou relecture de l'ECG par un humain. Toute activation consécutive à un ECG ne permettant pas d'établir un diagnostic (sans sus-décalage du segment ST) était considérée être une AI, tandis qu'une activation résultant d'un ECG indiquant possiblement un infarctus du myocarde avec sus-décalage du segment ST, mais sans preuve angiographique d'événement coronarien, était considérée être un « faux positif ». En 2012, l'algorithme de référence a éé modifié pour exclure la tachycardie supraventriculaire et le bloc de branche bilatéral.

      Résultats

      Il y a eu 155 activations dans la première cohorte (2010-2012; avant la modification de l'algorithme) et 313 dans la dernière cohorte (2012-2015). La modification de l’algorithme susmentionnée a entraîné une diminution relative du taux d’AI de l’ordre 42 % (12 % vs 7 %; p < 0,01), sans pour autant qu’il y ait d’incidence significative sur le délai d’intervention.

      Conclusions

      Il a été déterminé que la combinaison du diagnostic préhospitalier automatisé d’infarctus du myocarde avec sus-décalage du segment ST et d’activation de LCC « sans médecin » constituait un moyen à la fois sûr et efficace d’améliorer le délai d’intervention chez les patients, les résultats obtenus ayant été durables au fil du temps. En ce qui concerne les AI et les « faux positifs », le rendement du système automatisé a été considéré au moins équivalent à celui des modalités d’intervention avec surveillance humaine.
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