'Time is muscle' : still the primary consideration when thrombolytics are used in MI Early trials with thrombolytics showed that intracoronary streptokinase significantly prolonged survival after myocardial infarction, compared with placebo, However, cardiac catheterisation facilities are nOt available for most patients, treatment is delayed until arteriography is performed and haemorrhagic complications are more likely with this route of administration, Intravenous streptokinase has since been shown to produce significant survival benefits, especially in patients treated early, Salvage of myocardium and preservation of left ventricular function is presumed to be the mechanism by which mortality is reduced , However, improved left ventricular function has only been demonstrated in a few studies, Plasminogen activator is clot-specific and therefore causes less systemic lysis, It has been shown to produce higher reperfusion rates than streptokinase in 2 multicentre studies, Haemorrhagic complications of thrombolysis can be minimised if aggressive anticoagulation is avoided and a venous catheter left in .place (instead of multiple venipuncture), In practice, plasminogen activator is not associated with significantly fewer bleeding complications than streptokinase. Anaphylactic reactions and hypotension are possible with streptokinase but do not occur with plasminogen activator, Patients treated with thrombolytics have an increased risk of reinfarction, The occurrence of early reocclusion is dependent upon the severity of any residual stenosis; this may be reduced by angioplasty imd it is interesting to note that a recent study has shown that elective angioplasty at 7-10 days is as effective as emergency angioplasty, Patients therefore do not require immediate arteriography and it is possible that a method of identifying candidates for angioplasty on the basis of clinical criteria and non·invasive tests may be developed. Genentech has spent $280 million (Canadian) on the development of a recombinant plasminogen activator and each 100mg treatment will cost $2900, Although a cost-benefit study has shown plasminogen activator to be superior to streptokinase in large and moderate-sized infarcts, the results may not be applicable in all countries, Cost calculations must take into account the relative costs of plasminogen activator and streptokinase (the study assumed a five-fold difference) and the strategy of managing reocclusion , 4 INPHARMA · 4 June 1988 Strategies for the use of thrombolytics and the subsequent management of patients are 'arbitrary and arguable' , Minimising the delay before treatment is more important than the choice of thrombolytic agent. Waters DO, Wiseman A Canadian Medical Association Journal 138 598· 601,1 Apr 1988 "" 0156 · 2703/88/0604 ·0004/0$0100/0 © ADIS Press

‘Time is muscle’: still the primary consideration when thrombolytics are used in MI

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'Time is muscle' : still the primary consideration when thrombolytics are used in MI

Early trials with thrombolytics showed that intracoronary streptokinase significantly prolonged survival after myocardial infarction, compared with placebo, However, cardiac catheterisation facilities are nOt available for most patients, treatment is delayed until arteriography is performed and haemorrhagic complications are more likely with this route of administration, Intravenous streptokinase has since been shown to produce significant survival benefits, especially in patients treated early, Salvage of myocardium and preservation of left ventricular function is presumed to be the mechanism by which mortality is reduced , However, improved left ventricular function has only been demonstrated in a few studies, Plasminogen activator is clot-specific and therefore causes less systemic lysis, It has been shown to produce higher reperfusion rates than streptokinase in 2 multicentre studies,

Haemorrhagic complications of thrombolysis can be minimised if aggressive anticoagulation is avoided and a venous catheter left in .place (instead of multiple venipuncture), In practice, plasminogen activator is not associated with significantly fewer bleeding complications than streptokinase. Anaphylactic reactions and hypotension are possible with streptokinase but do not occur with plasminogen activator,

Patients treated with thrombolytics have an increased risk of reinfarction, The occurrence of early reocclusion is dependent upon the severity of any residual stenosis; this may be reduced by angioplasty imd it is interesting to note that a recent study has shown that elective angioplasty at 7-10 days is as effective as emergency angioplasty, Patients therefore do not require immediate arteriography and it is possible that a method of identifying candidates for angioplasty on the basis of clinical criteria and non·invasive tests may be developed.

Genentech has spent $280 million (Canadian) on the development of a recombinant plasminogen activator and each 100mg treatment will cost $2900, Although a cost-benefit study has shown plasminogen activator to be superior to streptokinase in large and moderate-sized infarcts, the results may not be applicable in all countries, Cost calculations must take into account the relative costs of plasminogen activator and streptokinase (the study assumed a five-fold difference) and the strategy of managing reocclusion ,

4 INPHARMA · 4 June 1988

Strategies for the use of thrombolytics and the subsequent management of patients are 'arbitrary and arguable' , Minimising the delay before treatment is more important than the choice of thrombolytic agent. Waters DO, Wiseman A Canadian Medical Association Journal 138 598· 601,1 Apr 1988 ""

0156·2703/88/0604·0004/0$0100/0 © ADIS Press