Emergency department crowding and thrombolysis delays in acute myocardial infarction

We estimate the effect of emergency department (ED) crowding on door-to-needle time for patients given intravenous thrombolysis for suspected acute myocardial infarction. This was a retrospective observational study of patients thrombolyzed in the ED for suspected acute myocardial infarction in 1998 to 2000 in 25 community and teaching hospital EDs in Ontario. EDs located close together and sharing a common ambulance diversion system were grouped into networks consisting of 2 to 5 hospitals each. At patient registration in an ED, the ambulance diversion status of all EDs in the network was determined. Network crowding was calculated as the percentage of EDs that were diverting ambulances on patient registration, categorized as none (0%), moderate (60 minutes) were 1.32 (95% confidence interval [CI] 0.98 to 1.79) and 1.40 (95% CI 1.12 to 1.75), respectively, for high network crowding compared with none, and 1.21 (95% CI 0.89 to 1.63) and 1.06 (95% CI 0.86 to 1.29), respectively, for moderate crowding compared with none. In multivariate analyses, moderate and high crowding conditions were associated with increased median door-to-needle time (3.0 minutes [95% CI 0.1 to 6.0] and 5.8 minutes [95% CI 2.7 to 9.0], respectively). ED crowding is associated with increased door-to-needle times for patients with suspected acute myocardial infarction and may represent a barrier to improving cardiac care in EDs.