Prehospital 12-Lead ECG: Efficacy or Effectiveness?

Abstract

Introduction. Previous literature has documented that prehospital 12-lead electrocardiography (ECG) decreases the time to reperfusion in patients with an acute ST-segment elevation myocardial infarction (STEMI). Objective. To compare time to ECG, time to angioplasty suite (laboratory), andtime to reperfusion in emergency medical services (EMS) STEMI patients, who received care through three different processes. Methods. The setting was a large suburban community teaching hospital with emergency department (ED)-initiated single-page acute myocardial infarction (AMI) team activation for STEMI patients. The population was STEMI patients transported by EMS from January 2003 to October 2005. Not all EMS agencies had prehospital 12-lead ECG capability. Paramedics interpret andverbally report clinical assessment andECG findings via radio. The AMI team is activated at the discretion of the emergency physician 1) before patient arrival to the ED based on EMS assessment, 2) after ED evaluation with EMS ECG, or 3) after ED evaluation andED ECG. Time intervals were calculated from ED arrival. To assess the impact of interventions on performance targets, we also report the proportion of patients who arrived in laboratory within 60 minutes andreperfusion within 90 minutes of arrival. Parametric andnonparametric statistics are used for analysis. Results. During the study period, there were 164 STEMI patients transported by EMS; mean age was 66.1 years, and56% were male. Of these, 93 (56.7%) had an EMS ECG and31 (33%) had AMI team activation before ED arrival. Mean time to laboratory for all patients was 49.8 ± 34.4 minutes andtime to reperfusion was 93.2 +/− 34.5 min. Patients with prearrival activation were transported to laboratory sooner (mean, 24.3 vs. 53. 4 minutes; p < 0.001) andreceived reperfusion sooner than all other patients (mean, 70.4 vs. 96.3 minutes; p = 0.007). More prearrival activation patients met performance targets to laboratory (96.7% vs. 73.7%; p = 0.009) andreperfusion (85.2% vs. 51.0%; p = 0.003). There was no difference in time to laboratory or to reperfusion for patients who received EMS ECG but no prearrival activation compared with those who received EMS transport alone. Conclusions. A minority of patients with EMS ECGs had prearrival AMI team activation. EMS ECGs combined with systems that activate hospital resources, but not EMS ECGs alone, decrease time to laboratory andreperfusion.

Key words:

• emergency medical services
• acute myocardial infarction
• reperfusion
• ECG.