A simple strategy improves prehospital electrocardiogram utilization and hospital treatment for patients with acute coronary syndrome (from the ST SMART Study)

Abstract

Although the American Heart Association recommends a prehospital electrocardiogram (ECG) be recorded for all patients who access the emergency medical system with symptoms of acute coronary syndrome (ACS), widespread use of prehospital ECG has not been achieved in the United States. A 5-year prospective randomized clinical trial was conducted in a predominately rural county in northern California to test a simple strategy for acquiring and transmitting prehospital ECGs that involved minimal paramedic training and decision making. A 12-lead ECG was synthesized from 5 electrodes and continuous ST-segment monitoring was performed with ST-event ECGs automatically transmitted to the destination hospital emergency department. Patients randomized to the experimental group had their ECGs printed out in the emergency department with an audible voice alarm, whereas control patients had an ECG after hospital arrival, as was the standard of care in the county. The result was that nearly 3/4 (74%) of 4,219 patients with symptoms of ACS over the 4-year study enrollment period had a prehospital ECG. Mean time from 911 call to first ECG was 20 minutes in those with a prehospital ECG versus 79 minutes in those without a prehospital ECG (p <0.0001). Mean paramedic scene time in patients with a prehospital ECG was just 2 minutes longer than in those without a prehospital ECG (95% confidence interval 1.2 to 3.6, p <0.001). Patients with non-ST-elevation myocardial infarction or unstable angina pectoris had a faster time to first intravenous drug and there was a suggested trend for a faster door-to-balloon time and lower risk of mortality in patients with ST-elevation myocardial infarction. In conclusion, increased paramedic use of prehospital ECGs and decreased hospital treatment times for ACS are feasible with a simple approach tailored to characteristics of a local geographic region.

Figure 1

Lead configuration for synthesized 12-lead electrocardiogram used in the ST SMART trial. A standard 5-electrode patient cable was used in which the right arm (RA), left arm (LA), and right leg (RL) electrodes were placed in the usual Mason-Likar torso positions. The left leg (LL) electrode was placed in the sixth intercostal space at the left midclavicular line; the chest (C) electrode was placed in the fourth intercostal space midway between the left midclavicular line and the left sternal border. Paramedics used 2 familiar landmarks to locate the left leg and chest electrodes. Namely the left leg electrode was placed at a level just below the xiphoid process (landmark used for finding chest compression site in cardiopulmonary resuscitation) and the chest electrode was placed on an imaginary line between the left leg electrode and the suprasternal notch (used with permission from Drew et al).

Figure 2

Enrollment summary for ST SMART study.