What to give
Currently, the choice of thrombolytic varies by country and
depends especially on the type of health care system and funding
in place. In many countries, in the absence of previous
administration the first line thrombolytic is SK (1.5 million units
in 100 mls 5% dextrose/0.9% NaCl over 30–60 minutes).
Alternatively, tPA is given as a 15mg bolus followed by 50mg
over 60 minutes, then 35mg over a further 30 minutes. Based on
the GUSTO study a case can be made for tPA in those presenting
very early (<4 hours with large anterior infarcts). NNeeww ppllaass--
mmiinnooggeenn aaccttiivvaattoorrsssuch as recombinant plasminogen activator (r-
PA) and prourokinase are currently the subject of a number of
clinical studies. RReetteeppllaassee ((rrPPAA)), is a nonglycosylated deletion
mutant of wild type tPA. It is the first member of the third gener-
ation thrombolytics, has a longer half life and is given as a double
bolus (10IU + 10IU). Equivalence trials comparing tPA and
reteplase have demonstrated no difference in outcome and
currently these two drugs are interchangeable, with decisions
about use being based on availability and price.^6 LLaannootteeppllaasseehas
been withdrawn prior to launch because of patent issues and
TTNNKK--ttPPAAis being trialled against tPA (ASSENT 2).^7 Bleeding
with this new agent was between 2.8% and 7.4% dependent on
dose (ASSENT 1).^8 Data suggest that there may be a role for
“rescue” angioplasty in patients who fail to show electrocardio-
graphic evidence of reperfusion.^9 However, results of randomised
trials addressing this issue are awaited.
RReeffeerreenncceess
1 Fibrinolytic Therapy Trialists (FTT) Collaborative Group. Indications
for fibrinolytic therapy in suspected acute myocardial infarction:
collaborative overview of early mortality and major morbidity from all
randomised trials of more than 1000 patients. Lancet1994; 334433 : 311–22.
2 Feldman M, Cryer B. Aspirin absorption rates and platelet inhibition
times with 325mg buffered aspirin tablets (chewed or swallowed
whole) and with buffered aspirin solution. Am J Cardiol1999; 8844 :
404–9.
3 LATE Study Group. Late assessment of thrombolytic efficiency (LATE)
study with alteplase 6–24 hours after onset of acute myocardial
infarction. Lancet1993; 334422 : 759–66.
4 The European Myocardial Infarction Project Group. Pre-hospital
thrombolytic therapy in patients with suspected acute myocardial
infarction. N Engl J Med1993; 332299 : 383–9.