Trends in clinical outcomes and survival following prehospital thrombolytic therapy given by ambulance clinicians for ST-elevation myocardial infarction in rural sub-arctic Norway.

Abstract

Prehospital thrombolytic therapy given by ambulance emergency medical services to patients with acute ST-segment elevation myocardial infarction (STEMI) may produce earlier reperfusion than percutaneous coronary intervention. Clinical results from prehospital thrombolytic therapy in rural areas are scarce. We studied outcomes during 11 years of a prehospital thrombolytic therapy system in rural sub-arctic Norway. Ambulance personnel gave protocol basic treatment and transmitted electrocardiograms to hospital physicians who made the decision for prehospital thrombolytic therapy. The study was divided into three time periods; 2000-2003, 2004-2007 and 2008-2011. A total of 385 STEMI patients received prehospital thrombolytic therapy, median patient age was 61.2 years, and 77% were men. Time saved by prehospital reperfusion therapy was 131 minutes. The proportion who got prehospital thrombolytic therapy within 2 hours of symptom onset increased from 21% in 2000-2003 to 39% in 2008-2011 ( P=0.003). The proportion who underwent coronary angiography or percutaneous coronary intervention within 24 hours of first medical contact increased from 56.4% to 95.4% ( P<0.001). Post-STEMI systolic heart failure decreased from 19.4% to 8.1% ( P=0.02), while 1-year mortality fell, non-significantly, by 50% over time to reach 5.6%. Thirteen patients suffered acute out-of-hospital cardiac arrest; all were successfully defibrillated. Ten patients had major bleeding events (2.6%). A decentralised prehospital thrombolytic therapy system based on ambulance personnel, telemetry and centralised 7/24 invasive diagnosis and treatment service, combined with system maturation over time, was associated with earlier reperfusion, improved clinical outcomes and better survival. Prehospital thrombolytic therapy is a feasible and safe intervention used in rural settings with long evacuation lines to percutaneous coronary intervention facilities.