Despite remarkable gains in treatment over the last decade short-term mortality for those who survive to hospital with AT-elevation acute myocardial infarction (STEMI) remains high (5%-10%). Different studies have pointed out that reperfusion (intravenous fibrinolysis or percutaneous coronary interventions (PCI) and its timing are critical in decreasing STEMI patients' mortality. Studies of prehospital 12 lead electrocardiograms (12 lead PHECG) with advance emergency department (ED) notification suggest that there is a time to treatment advantage with this intervention. The use of 12 lead PHECG is not currently universal and part of standard treatment throughout the province. The purpose of the study is to follow STEMI study subjects during standard treatments and to compare the outcomes of subjects that received 12 lead PHECG with advanced ED notification in mixed rural/urban areas with outcomes of subjects treated in areas with only 3 lead PHECG monitoring and indirect ED notification. The investigators hypothesize that there will be a survival benefit for study subjects with 12 lead PHECG and advance ED notification in rural and urban environments through a reduction in door-to-reperfusion time and that 12 lead PHECG will be a cost-saving technology for the province of Ontario.

Many studies have established that reperfusion reduces mortality in ST-elevation acute myocardial infarction (STEMI) patients; the earlier reperfusion therapy is delivered, the greater the mortality reduction. Most STEMI patient in Ontario still do not receive reperfusion therapy within established target times of <30 minutes for fibrinolysis or <90 minutes for PCI. 12 lead PHECG with advance ED notification may have a time to treatment impact in STEMI patients. However studies, investigating this intervention were all small, largely urban trials, and were carried out with advanced care paramedics. In Ontario, many emergency medical services (EMS) systems cover large rural regions, and are frequently staffed by primary care paramedics with only basic life support training. Thus, the benefit of 12 lead PHECG in these settings is unclear. In addition, no study has assessed the cost-effectiveness of 12 lead PHECG compared to 3 lead PHECG.

Inclusion Criteria:

• Call 911 for assistance
• Are suspected by the paramedics of having ischemic chest pain for greater than 30 minutes but less than 6 hours
• Be greater than or equal to 18 years of age
• Experience chest pain that fails to completely respond to nitrates as per standard provincial chest pain protocol.

Exclusion Criteria:

• Subjects less than 18 years of age

This study will be conducted across Ontario. Selected regions representing approximately 17% of the population of Ontario and 6.4% of the popluation of Canada. Covering an area of 181426 per square kilometers with variable population densities from 2.5 to 234 person per square kilometers and representing rural, suburban, urban, and metropolis areas will be the catchment area for the study. A variety of EMS operators under the control of EMS Base Hospital programs will be involved in the data collection for this study. Patients presenting with suspected ischemic chest pain will be tracked as a part of the trial.