Studies of ambulance patients with ischemic heart disease. 11. Selection of patients for ambulance telemetry.

One hundred eighty-two of 1,928 patients (9.4 per cent) transported by ambulance during a six-month period in Baltimore had ECGs transmitted. Review of the remaining 1,746 records by two cardiologists indicated that an additional 113 patients should have had their ECGs transmitted because of life-threatening conditions. Of patients with acute ischemic heart disease, 47 had ECG monitoring and 24 did not. There were 22 per cent more Killip 111/1V patients with a 19 per cent higher mortality at three months among the "non-transmitted" patients as compared to the "transmitted" patients, controlling for all other relevant variables. Critical presentations inappropriately affect ambulance staffs' selection of patients for monitoring.