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The severity of coronary atherosclerosis at sites of plaque rupture with occlusive thrombosis
1Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California 90048.
Insights
Atherosclerotic plaque rupture leading to acute myocardial infarction occurs at severely narrowed coronary arteries (mean 91% stenosis). This study suggests plaque rupture is unlikely to cause fatal heart attacks in cases of mild to moderate coronary stenosis.
Area of Science:
- Cardiovascular Pathology
- Interventional Cardiology
Background:
- Acute myocardial infarction (AMI) is frequently caused by atherosclerotic plaque rupture with thrombosis.
- Understanding the severity of atherosclerosis at the rupture site is crucial for elucidating AMI mechanisms.
Purpose of the Study:
- To quantify the degree of coronary artery stenosis at the site of plaque rupture in patients who died of AMI.
- To investigate the relationship between plaque severity and fatal AMI.
Main Methods:
- Histologic examination of 184 coronary arteries from 162 autopsy patients who died of AMI.
- Planimetric measurement of artery, plaque, thrombus, and luminal cross-sectional areas at the rupture site.
- Calculation of the percentage of stenosis due to plaque.
Main Results:
- Plaque rupture with thrombosis occurred at sites of severe coronary artery stenosis, averaging 91%.
- Stenosis levels ranged from 67% to 99% at the rupture site across different coronary arteries.
- The severity of stenosis was consistently high, regardless of the specific coronary artery affected.
Conclusions:
- Plaque rupture leading to fatal AMI occurs predominantly at severely stenosed coronary arteries.
- Plaque rupture is unlikely to be the primary cause of AMI in individuals with mild to moderate coronary stenosis.
Abstract:
Atherosclerotic plaque rupture with superimposed thrombosis is recognized as the lesion causing greater than 90% of acute myocardial infarctions. To determine the severity of atherosclerosis at the site of plaque rupture, 184 coronary arteries from autopsies of 162 patients who died of acute myocardial infarction were studied. There were 102 men, 72 +/- 10 years old (mean +/- SD), and 60 women, 75 +/- 8 years old. All arteries were dissected from the heart, fixed, decalcified, cut at 2 to 3 mm intervals and processed routinely for histologic examination. A planimeter was used to measure artery, plaque, thrombus and luminal cross-sectional area at the site of plaque rupture with thrombosis in sections projected at x13.8 magnification. At the site of atherosclerotic plaque rupture with superimposed thrombosis, the degree of stenosis due to plaque was: 90 +/- 7% for the right (n = 67), 91 +/- 6% for the left anterior descending (n = 79) and 91 +/- 6% for the left circumflex (n = 38) coronary arteries. Plaque rupture in fatal acute myocardial infarction occurs at sites of severe narrowing (mean 91%, range 67% to 99%). Thus, plaque rupture with thrombosis is unlikely to cause the fatal acute myocardial infarction in patients with mild to moderate coronary stenosis.