Circadian fluctuations in the efficacy of thrombolysis with streptokinase

This study was designed to investigate possible diurnal fluctuations in the efficacy of thrombolysis with streptokinase and whether they follow the ci rcadian periodicity which has already been well documented for the time of onset of acute myocardial infarction, transient myocardial ischaemia, sudde n cardiac death, thrombotic stroke, and for the efficacy of thrombolysis wi th tissue-type plasminogen and urokinase. A total of 156 consecutive patien ts treated with streptokinase were studied retrospectively; success or fail ure of thrombolysis was determined according to accepted clinical and angio graphic criteria. A definite time peak for successful thrombolysis could be detected at the late afternoon and early evening hours; between 16.00 and 20.00 h, 30.2% of all successful thrombolysis cases were observed compared with 7.0% between 20.00 and 24.00 (p<0.05) or 10.5% between 00.00 and 04.00 (p<0.05). Between 16.00 and 20.00 h, 75.8% of treated patients had success ful thrombolysis compared to 15.2% of failed treatments and 9% equivocal re sults (p<0.001). Multiple regression analysis showed that the independent f actor with the major impact on successful reperfusion was the actual time o f thrombolysis (p=0.037), followed by the time delay from pain onset to str eptokinase administration (p=0.020), while age and gender had much lesser i mpact (p=0.328 and 0.215, respectively) and the individual risk factors eve n less. These findings may have several clinical implications; dose adjustm ent for the time of day may be required, with higher doses during morning h ours, or preference for primary coronary angioplasty in order to avoid the increase in bleeding complications related to higher doses of thrombolytic agents.