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Quantitative and qualitative effects of intracoronary streptokinase in unstable angina and non-Q wave infarction
Insights
Intracoronary streptokinase showed limited effectiveness in treating unstable angina and non-Q wave infarction, with no significant changes in artery stenosis. Some patients even experienced worsening, suggesting limited utility for this thrombolytic therapy.
Area of Science:
- Cardiology
- Interventional Cardiology
- Thrombolytic Therapy
Background:
- Thrombolytic therapy is effective for totally occluded arteries in acute myocardial infarction.
- Coronary thrombus is implicated in unstable angina and non-Q wave infarction pathophysiology.
- Limited data exists on intracoronary streptokinase use in these syndromes.
Purpose of the Study:
- To evaluate the efficacy of intracoronary streptokinase in patients with unstable angina or recent non-Q wave infarction.
- To assess changes in coronary artery lesions after streptokinase infusion.
- To determine the utility of this therapy in specific acute coronary syndromes.
Main Methods:
- 36 patients with unstable angina or non-Q wave infarction received intracoronary streptokinase (100,000-300,000 IU).
- Coronary lesions were analyzed qualitatively (magnification) and quantitatively (digital subtraction) before and after therapy.
- 18 patients underwent restudy 3-10 days later during angioplasty.
Main Results:
- Pre-treatment: 67% of arteries had eccentric, irregular lesions; average diameter stenosis was 83.8%.
- Post-treatment: No significant changes in lesion morphology or stenosis (diameter 82.9%).
- Restudy showed no significant quantitative or qualitative improvements; 2 patients deteriorated.
Conclusions:
- Intracoronary streptokinase appears to have limited utility for unstable angina or non-Q wave infarction with <100% occlusion.
- Thrombus may be organized, infusions too late, or absent, limiting efficacy.
- Further research is needed on longer infusions or alternative thrombolytic agents.
Abstract:
Thrombolytic therapy has been shown to be effective in reopening totally occluded arteries in acute myocardial infarction. Coronary thrombus is also believed to play a role in the pathophysiology of unstable angina and non-Q wave infarction. However, few patients with these two acute coronary syndromes have been treated with intracoronary streptokinase. Therefore, 100,000 to 300,000 IU (mean 177,000 +/- 80,000 IU) of intracoronary streptokinase was infused into 36 consecutive catheterized patients who either presented with an acute episode of unstable angina or had had a recent non-Q wave infarction and in whom a less than 100% occluded ischemia-producing artery could be identified. Qualitative techniques utilizing vessel magnification and quantitative analysis with digital subtraction were performed on the ischemia-producing coronary lesion before and immediately after streptokinase therapy and 3 to 10 days later in 18 patients who were restudied at the time of transluminal coronary angioplasty. Before streptokinase treatment, 24 (67%) of 36 ischemia-producing arteries contained eccentric, irregular lesions. The percent diameter stenosis and percent area stenosis in all ischemia-producing arteries averaged 83.8 +/- 8.3% and 94.8 +/- 3.3%, respectively. After streptokinase treatment there were 23 arteries (64%) with eccentric irregular lesions. The percent diameter stenosis and percent area stenosis in all ischemia-producing arteries were similar to pre-streptokinase values (82.9 +/- 5.9% and 93.8 +/- 4.0%, respectively). At restudy, there were also no significant changes in any quantitative or qualitative variable. Five individual patients showed a significant reduction in percent stenosis after streptokinase. This improvement was independent of duration of symptoms, use of heparin before angiography, streptokinase dose or reduction of fibrinogen levels post-streptokinase. Two additional patients deteriorated clinically and developed total occlusion of the ischemia-producing artery within 12 hours of streptokinase infusion. These data suggest that intracoronary streptokinase may be of limited utility in either unstable angina or recent non-Q wave infarction with a less than 100% occluded ischemia-producing artery. In these syndromes, thrombus may be organized or short infusions may be given too late to be effective. In some cases, thrombus may even be absent. Whether longer infusion of streptokinase or other thrombolytic agents will be of benefit remains to be determined.