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Review of: Robert Swor, DO, Stacey Hegerberg, RN, Ann McHugh-McNally, et al: Prehospital 12-Lead ECG: Efficacy or Effectiveness? Prehospital Emergency Care. 2006. 10:374–377.
The Science
All patients transported to William Beaumont Hospital in Troy, Michigan, who received a prehospital 12-lead ECG were observed from January 2003 to October 2005 to assess the impact of the prehospital 12-lead on time to reperfusion in the cath lab. Patients were divided into three groups. Study patients were retrospectively classified in one of three groups based on when the acute myocardial infarction (AMI) team was activated: 1) activation before patient arrival to ED, based on EMS assessment and concurrence by online medical direction; 2) activation after physician ED evaluation and review of EMS ECG; or 3) activation after ED evaluation and ED ECG. Time intervals were calculated from ED arrival until 1) first ECG, 2) arrival in the cardiac catheterization suite (laboratory), and 3) time to mechanical reperfusion.
During the study period, there were 164 patients transported who were found to have acute ST segment myocardial infarction (STEMI). Of these, 93 (56.7 percent) had an EMS ECG of which 31(33 percent) and activation of the AMI team based on prehospital ECG interpretation which was provided over the radio to the ED physician. Patients who had AMI team activation based on the prehospital ECG consistently arrived at the cath lab and had reperfusion within the accepted guidelines. Their arrival to cath lab times and reperfusion were significantly better than those without pre-arrival AMI activation.
Their conclusion was that AMI team activation based on diagnostic prehospital ECG interpretation significantly shortens the time to cath lab arrival and reperfusion.
The Street
This study clearly demonstrated what all of us know: the sooner the AMI team is activated, the quicker our patients get coronary reperfusion. The goals in the emergency department are: 1) door to ECG less than 10 minutes; 2) door to cath lab within 60 minutes; and 3) door to reperfusion within 90 minutes.
In this study, the prehospital ECGs were interpreted by the transporting paramedics who then conveyed it to the ED physician over the radio. The ECGs were not faxed or sent to the ED by telemetry. Surprisingly, only a third of these interpretations resulted in AMI team activation prior to the patient s arrival in the ED. The remaining two thirds had AMI team activation after arrival at the ED and were seen by the ED physician. Why did the ED physician not activate the AMI team based on the prehospital 12-lead? Did they not trust the paramedic interpretation? Perhaps this study makes a good argument for sending the ECG to the ED by telemetry. Perhaps the ED physicians need to be more involved in the education of the paramedics so that they have more confidence in their interpretation.
Another astounding component to this study is that only 57 percent of STEMI patients even got a prehospital 12-lead. What is not reported is why. Did those patients not present signs or symptoms consistent with acute coronary syndrome? Were the transport times too short to do one? It would be helpful to know the reason why almost half of the STEMI patients did not receive a 12-lead ECG. Perhaps this might shed some light on why the ED physicians trusted only a third of the prehospital interpretations.
Regardless, this study represents another important substantiation of the value of prehospital 12-leads for improving the care of our patients suffering a myocardial infarction. Programs pursuing this must continuously evaluate its impact and examine ways to improve it.
