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Angioscopic evaluation of coronary-artery thrombi in acute coronary syndromes
K Mizuno1, K Satomura, A Miyamoto
1First Department of Internal Medicine, National Defense Medical College, Saitama, Japan.
Insights
Differences in coronary artery thrombi appearance between unstable angina and acute myocardial infarction may explain varying treatment responses. Reddish thrombi are common in myocardial infarction, while grayish-white thrombi are seen in unstable angina.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Thrombosis Research
Background:
- Atherosclerotic plaque disruption and thrombus formation are implicated in unstable angina and acute myocardial infarction.
- Thrombolytic therapy is effective for acute myocardial infarction but less so for unstable angina.
- Differences in coronary artery thrombus composition between these conditions were hypothesized.
Purpose of the Study:
- To investigate and compare the visual characteristics of coronary artery thrombi in patients with unstable angina and acute myocardial infarction.
- To explore potential reasons for the differential efficacy of thrombolytic therapy in these conditions.
Main Methods:
- Percutaneous transluminal coronary angioscopy was performed in 15 patients with unstable angina and 16 with acute myocardial infarction.
- Angioscopy was conducted within 48 hours (unstable angina) or 8 hours (acute myocardial infarction) of symptom onset.
- Coronary angiography was used to assess for occlusive thrombi.
Main Results:
- Coronary thrombi were detected in most patients (27/29).
- Grayish-white thrombi were frequent in unstable angina (71%), absent in acute myocardial infarction (P<0.01).
- Reddish thrombi were seen in all acute myocardial infarction cases with thrombi, but only 29% of unstable angina cases (P<0.01). Occlusive thrombi were common in acute myocardial infarction (81%) but absent in unstable angina (P<0.01).
Conclusions:
- Coronary artery thrombi are crucial in unstable angina and acute myocardial infarction pathogenesis.
- Distinct thrombus appearances (color, occlusion) suggest differences in composition, age, or blood flow.
- These visual differences may explain the varying effectiveness of thrombolytic therapy.
Background:
Disruption of an atherosclerotic plaque in a coronary artery followed by the formation of a thrombus is believed to be the cause of both unstable angina and acute myocardial infarction. Although thrombolytic therapy is efficacious in patients with acute myocardial infarction, for unknown reasons it is far less effective in patients with unstable angina. We postulated that there might be differences in the composition of the coronary-artery thrombi in unstable angina and acute myocardial infarction.
Methods:
To investigate the appearance of coronary-artery thrombi, we performed percutaneous transluminal coronary angioscopy in 15 patients with unstable angina and 16 with acute myocardial infarction. Angioscopy was performed within 48 hours after an episode of pain at rest in the patients with unstable angina and within 8 hours of onset in those with acute myocardial infarction.
Results:
Angioscopy revealed coronary thrombi in all but two patients (one in each group). Of the 29 patients with thrombi, those with unstable angina were frequently observed to have grayish-white thrombi (10 of 14, 71 percent), but none were seen in the 15 patients with acute myocardial infarction (P less than 0.01). By contrast, reddish thrombi were observed in all 15 patients with acute myocardial infarction who had thrombi, but in only 4 of the 14 patients with unstable angina and thrombi (P less than 0.01). As assessed by coronary angiography, occlusive thrombi occurred frequently in patients with acute myocardial infarction (13 of 16 patients) but were not seen in any of the 15 patients with unstable angina (P less than 0.01).
Conclusions:
Coronary-artery thrombi play an important part in the pathogenesis of unstable angina and acute myocardial infarction. However, the appearance of the thrombi is different in the two conditions, possibly reflecting differences in the composition of age of the thrombi or the presence or absence of blood flow in the artery. This difference may account for the contrasting results of thrombolytic therapy.