LETTER TO THE EDITOR
Prehospital thrombolytic therapy for ST-segment elevation myocardial infarction
John S. Geddes, MD, FRCP, FACC
Section of Cardiology,Health Sciences Centre,700 William Avenue,Winnipeg, MB R3E 0Z3,Canada
geddesjs{at}cc.umanitoba.ca
The results of the ER-TIMI (Thrombolysis in Myocardial Infarction) 19 trial (1) provide yet another building block in the case for prehospital administration of thrombolytic agents to patients presenting with acute ST-segment elevation myocardial infarction (MI). These results reflect as accurately as possible the contemporary impact on time to administration (32-min decrease), and they come at a point when there is increasing focus on the use of percutaneous coronary intervention (PCI) as an alternative to thrombolysis (2). Despite the modest impact on timing, I strongly agree with the statement by Morrow et al. (1) that, with the necessary supportive infrastructure in the prehospital situation, there is little reason to delay thrombolytic treatment.
Now that the practical difficulties related to initiating medically supervised thrombolytic therapy during the prehospital phase have receded, the question focuses on which patients to treat before transport. The 12-h time window adopted for this study seems unsuitable for day-to-day practice. Eligible patients seen within the first hour or so with conspicuous electrocardiographic (ECG) evidence of myocardial injury clearly have most to gain from immediate thrombolytic treatment. For them a saving of under 30 min may be crucial, and even if short transport and door-to-drug times are anticipated, administration of a thrombolytic agent in the field would seem imperative. In contrast, those with a symptom duration in excess of 4 h and less dramatic ECG findings have less to gain and, in places where medical triage of calls from paramedics could be a limiting factor, resources might be conserved by waiting until after a short transit time to the hospital.
Because reperfusion during the early hours after onset is critical for the salvage of meaningful quantities of myocardium and because it is inconceivable that timely PCI can be implemented universally, I believe that facilities for prehospital administration of thrombolytic therapy should now be made widely available, at least for patients who seek help quickly. In countries where the ambulances are staffed by physicians this practice was generally adopted early in the thrombolytic era. Today it is highly inappropriate that patients seen early in areas served by paramedic systems should be deprived of a time-critical treatment, even for half an hour, because of a difference in medical organization. If availability of thrombolytic agents in paramedic vehicles becomes the rule rather than the exception there will be the opportunity to provide treatment at a time when much more of the myocardial "horse" is still in the "stable," resulting in substantial benefit to patients.
The initial concept of prehospital coronary care envisaged patients coming under the umbrella of intensive care when the ambulance arrived: following appropriate stabilization, transport to the hospital without potentially harmful "haste or fuss" could take place (3). Widespread adoption of thrombolysis initiated by supervised paramedics would bring the implementation of this valid concept fully up to date.
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References
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- Morrow DA, Antman EM, Sayah A, et al. Evaluation of the time saved by prehospital initiation of reteplase for ST-elevation myocardial infarction. J Am Coll Cardiol. 2002;40:71–77[Abstract/Free Full Text]
- Andersen HR. DANAMI-2: the Danish multicenter randomized trial of thrombolytic therapy versus acute coronary angioplasty in acute myocardial infarction. J Am Coll Cardiol. 2002;40:16–17
- Pantridge JF, Geddes JS. A mobile intensive-care unit in the management of myocardial infarction. Lancet. 1967;ii:271–273
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