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), and time 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 and verbally report clinical assessment and ECG 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 and ED 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 and reperfusion within 90 minutes of arrival. Parametric and nonparametric statistics are used for analysis.

Results: During the study period, there were 164 STEMI patients transported by EMS; mean age was 66.1 years, and 56% were male. Of these, 93 (56.7%) had an EMS ECG and 31 (33%) had AMI team activation before ED arrival. Mean time to laboratory for all patients was 49.8 +/- 34.4 minutes and time 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) and received 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) and reperfusion (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 and reperfusion.