Pre-hospital ECG and Acute Coronary Syndrome
Search Strategy: Initially utilizing a PUBMED Clinical Queries search, you have difficulty narrowing your findings down to a reasonable number with either a sensitive or a specific search strategy. Therefore, you decide to combine searches so you search PUBMED for “emergency medical services” (54905 citations), “acute myocardial infarction” (47826 citations), “electrocardiogram” (142,937 citations), and “systematic review” (19478 citations). When you combine all four of these searches, you obtain 7 citations, the fourth being Ioannidis’ article. You subsequently do a Web of Science citation search on Ioannidis’ article and yield Brainard and Morrison’s work. Your final article is selected after reviewing the references of the other three articles.
You are the newly appointed EMS Director for your community hospital which serves a two-hundred square mile geographic vicinity in central Missouri. Never one to start a new job quietly, you are of course presented with a controversy during your first week.
A 50 year old male recently presented to your ED with chest pain which awakened him from sleep at 4AM. He lives on the outskirts of your tiny community with a 40-minute ground transport time in good weather and you have no local air transportation options available. Although he waited an hour after awakening from sleep with chest pain before calling 911, EMS was able to arrive at his home, evaluate him and transport him to your ED within 2 hours of symptom onset. His evaluation subsequently revealed an ST-segment elevation acute myocardial infarction and he received appropriate reperfusion therapy. Your Interventional Cardiologists approaches you the next day to request pre-hospital EKG’s from your EMS system. Uncertain of the evidence to support pre-hospital EKG’s, you decide to review the literature before committing your EMS providers.
First years: Effect of Ambulance 12-lead ECG Recording on Times to Hospital Reperfusion in Acute Myocardial Infarction, Med J Australia 2000; 172: 81-84.
Second years: Accuracy and Clinical Effect of Out-of-Hospital Electrocardiography in the Diagnosis of Acute Cardiac Ischemia: A Meta-Analysis. Annals EM 2001; 37: 461-470.
Third years: The Prehospital 12-Lead Electrocardiogram’s Effect on Time to Initiation of Reperfusion Therapy: A Systematic Review and Meta-Analysis of Existing Literature. Am J EM 2005; 23: 351-356.
Fourth years: Prehospital 12-Lead Electrocardiography Impact on Acute Myocardial Infarction Treatment Times and Mortality: A Systematic Review. Acad EM 2006; 13: 84-89.
Article 1: Effect of Ambulance 12-Lead ECG Recording on Times to Hospital Reperfusion in AMI, Med J Australia 2000; 172: 81-84
Article 2: Accuracy and Clinical Effect of Out-of-Hospital Electrocardiography in the Diagnosis of Acute Cardiac Ischemia: A Meta-Analysis, Annals EM 2001; 37: 461-470
Article 3: The Prehospital 12-lead Electrocardiogram’s Effect on Time to Initiation of Reperfusion Therapy: A Systematic Review and Meta-Analysis of Existing Literature, Am J EM 2005; 23: 351-356
Article 4: Prehospital 12-lead Electrocardiography Impact on Acute Myocardial Infarction Treatment Times and Mortality: A Systematic Review, Acad EM 2006; 13: 84-89
Several small studies of heterogeneous design demonstrate no significant transport delays and a probable reduction in door-to-needle times by using pre-hospital ECG for AMI in both rural and urban settings of 20-30 minutes. Acknowledging the accepted view that “time is myocardium” and the limited impact of health care providers on presentation delays, maximizing efficiency by concurrently activating the cardiac catheterization team while transportation is occurring is logical. Future trials should assess the impact of pre-hospital ECG on cost-effectiveness and patient-important outcomes such as cardiovascular mortality, post-MI functional status, and adverse outcomes from appropriate and inappropriate use of in-hospital reperfusion based upon the electrocardiograms in a variety of pre-hospital systems.