Point-of-care assessment of platelet reactivity in the emergency department may facilitate rapid rule-out of acute coronary syndromes: a prospective cohort pilot feasibility study.
OBJECTIVE
Accurate, efficient and cost-effective disposition of patients presenting to emergency departments (EDs) with symptoms suggestive of acute coronary syndromes (ACS) is a growing priority. Platelet activation is an early feature in the pathogenesis of ACS; thus, we sought to obtain an insight into whether point-of-care testing of platelet function: (1) may assist in the rule-out of ACS; (2) may provide additional predictive value in identifying patients with non-cardiac symptoms versus ACS-positive patients and (3) is logistically feasible in the ED.


METHODS
Prospective cohort feasibility study.


METHODS
Two urban tertiary care sites, one located in the USA and the second in Argentina.


METHODS
509 adult patients presenting with symptoms of ACS.


METHODS
Platelet reactivity was quantified using the Platelet Function Analyzer-100, with closure time (seconds required for blood, aspirated under high shear, to occlude a 150 µm aperture) serving as the primary endpoint. Closure times were categorised as 'normal' or 'prolonged', defined objectively as the 90th centile of the distribution for all participants enrolled in the study. Diagnosis of ACS was made using the standard criteria. The use of antiplatelet agents was not an exclusion criterion.


RESULTS
Closure times for the study population ranged from 47 to 300 s, with a 90th centile value of 138 s. The proportion of patients with closure times ≥138 s was significantly higher in patients with non-cardiac symptoms (41/330; 12.4%) versus the ACS-positive cohort (2/105 (1.9%); p=0.0006). The specificity of 'prolonged' closure times (≥138 s) for a diagnosis of non-cardiac symptoms was 98.1%, with a positive predictive value of 95.4%. Multivariate analysis revealed that the closure time provided incremental, independent predictive value in the rule-out of ACS.


CONCLUSIONS
Point-of-care assessment of platelet reactivity is feasible in the ED and may facilitate the rapid rule-out of ACS in patients with prolonged closure times.
Department of Emergency Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Chad E
CE
Darling
Javier A
JA
Sala Mercado
Walter
W
Quiroga-Castro
Gabriel F
GF
Tecco
Felix R
FR
Zelaya
Eduardo C
EC
Conci
Jose P
JP
Sala
Craig S
CS
Smith
Alan D
AD
Michelson
Peter
P
Whittaker
Robert D
RD
Welch
Karin
K
Przyklenk
D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis*; D015331:Cohort Studies; D004636:Emergency Service, Hospital; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015539:Platelet Activation; D019095:Point-of-Care Systems; D011446:Prospective Studies; D013997:Time Factors
Acute coronary Syndromes; Emergency Department:; Platelet