LETTER TO THE EDITOR
Prehospital thrombolytic therapy for ST-elevation myocardial infarction: Reply
David A. Morrow, MD, MPH,
Elliott M. Antman, MD and
Eugene Braunwald, MD
TIMI Study Group, Cardiovascular Division, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, USA
dmorrow{at}rics.bwh.harvard.edu
We appreciate Dr. Geddes’ interest and comments on our report of the results of the ER-TIMI (Thrombolysis in Myocardial Infarction) 19 trial (1). We concur that it will be important for emergency medical systems implementing prehospital thrombolytic programs to develop carefully considered eligibility criteria, including evaluation of the time from symptom onset. However, the appropriate "time window" for consideration of prehospital thrombolysis may vary depending on characteristics of each emergency medical system, such as the typical transport times and other treatment options available. In systems where treatment with a fibrinolytic is the only option for timely reperfusion therapy and where field management times are long, we would be reluctant to deprive a patient presenting within 12 h of symptom onset without contraindications from receiving fibrinolytic as early as possible. The benefit of fibrinolysis within this time period has been established (2), and there is little reason to delay therapy once eligibility has been determined.
Certainly, the potential gains from prehospital fibrinolysis are less in patients presenting later in the course of acute myocardial infarction (AMI) (3). Thus, we agree that for patients activating the emergency medical response 6 to 12 h after symptom onset, other factors may be included in the decision whether to administer fibrinolytic prehospital. For example, in systems where the field management times are short (e.g., <20 min), patients with relative contraindications to fibrinolysis who are also presenting late may be served best by additional evaluation in the emergency department. Also, based on recent findings from the DANish multicenter randomized study on thrombolytic therapy versus acute coronary angioplasty in Acute Myocardial Infarction (DANAMI)-2 Trial (4), systems in which transfer for primary percutaneous coronary intervention is possible may wish to consider prehospital thrombolysis only for patients presenting very early after symptom onset. Such a strategy of deferring thrombolysis will hinge upon the expected door-to-balloon times for transferred patients.
Given the wide variation in each of these factors between emergency medical systems, it seems reasonable to tailor the details of a prehospital thrombolytic program to the system in which it will operate. In all cases, the decision whether to administer prehospital fibrinolytic should be made by the supervising physician on the basis of an integrated assessment of the clinical presentation, electrocardiogram, and treatment options available.
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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: results of the Early Retavase- (ER-TIMI) 19 trial. J Am Coll Cardiol. 2002;40:71–77[Abstract/Free Full Text]
- Fibrinolytic Therapy Trialists’ (FTT) Collaborative Group. Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Lancet. 1994;343:311–322[CrossRef][Medline]
- Boersma E, Maas AC, Deckers JW, Simoons ML. Early thrombolytic treatment in acute myocardial infarction: reappraisal of the golden hour. Lancet. 1996;348:771–775[CrossRef][Medline]
- Ferguson JJ. Highlights of the 51st Annual Scientific Sessions of the American College of Cardiology. Circulation. 2002;106:e24–30[Free Full Text]
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