Paramedic Triage Reduces Time to Balloon with No Extra Risk

By Charles Bankhead,
OTTAWA, Jan. 16 -- Patients with ST-segment myocardial infarction begin percutaneous intervention sooner when paramedics in the field triage them to appropriate hospitals, investigators here found.
Patients referred from the field in this city had a median door-to-balloon time of 69 minutes compared with 103 minutes for patients who needed interhospital transfer (P<0.001), Michel R. Le May, M.D., of the University of Ottawa, and colleagues reported in the Jan. 17 issue of the New England Journal of Medicine.
Door-to-balloon times of less than 90 minutes were achieved seven times more often among patients transferred from the field. Yet in-hospital, 30-day, and six-month mortality did not differ between patients referred from the field or from a hospital.
Primary percutaneous intervention is now considered the optimal reperfusion strategy for patients with STEMI, the authors wrote. Randomized trials comparing interhospital transfer and PCI versus fibrinolysis have shown that direct percutaneous intervention prevents 70 major cardiac events for every 1,000 patients treated.
Delays in treatment (either door to needle or door to balloon) increase the risk of death. For every 30-minute delay in door-to-balloon time, the relative risk of one-year mortality increases by 7.5%, according to 2004 research. As a result, efforts to shorten door-to-balloon times have been recommended.
In the Canadian study, Dr. Le May and colleagues reported findings from a study of university treatment of STEMI by direct percutaneous intervention, comparing field triage and referral by paramedics versus hospital triage and transfer. Advanced care paramedics received instruction in the evaluation of patients with chest pain, in addition to advanced training in cardiac life support received as part of their training and certification.
Patients who had symptom onset for 12 hours or less and had ST-segment elevation of at least 1 mm in two or more continuous limb ECG leads or at least 2 mm in two or more contiguous precordial leads were eligible for direct transfer from the field. Patients initially evaluated by primary care paramedics were excluded.
The study involved 344 consecutive STEMI patients referred for primary percutaneous intervention: 135 referred from the field and 209 from emergency departments. Primary percutaneous intervention was successfully performed in 93.6% of all patients. In addition to the shorter median door-to-balloon time associated with field referral, 79.7% of patients had door-to-balloon times of less than 90 minutes with direct referral by paramedics compared with 11.9% for interhospital transfer (P<0.001).
In-hospital mortality was 3% for patients referred by paramedics and 5.7% for patients transferred from emergency departments. The 30-day mortality was 4.4% with field referral and 5.7% with interhospital transfer. At six months, 6% of patients referred from the field had died, as had 7.7% of patients transferred from emergency rooms. None of the differences in mortality between the groups was statistically significant.
Dr. Le May disclosed grant support from Pfizer, sanofi-aventis, Bristol-Myers Squibb, Medtronic, Schering-Plough, and Hoffmann-La Roche.
Primary source: New England Journal of MedicineSource reference:Le May MR, et al "A citywide protocol for primary PCI in ST-segment elevation myocardial infarction" N Engl J Med 2008; 358: 231-240.