[Some considerations on progression and regression of coronary arteriosclerosis based on histological studies of acute coronary thrombosis]. 
This study showed that studies of structural changes of arteriosclerotic coronary lesion and coronary flow in the stenotic segments are very important for understanding the progression and regression of coronary sclerosis.  In control groups of both sex over 50 years of age (544 males and 400 females), the frequency of stenosis of over 75% of 3 main coronary branches was approximately 20% in cases under 69 years of age and about 30% in cases over 70 years.  In cases of myocardial infarction over 50 years of age (157 males and 89 females), stenosis of over 90% was approximately 90% in te left anterior descending artery, 70-80% in the right coronary artery and 70% in the left circumflex artery and three vessels showing stenosis over 90% were found in half of the cases.  Of 70 coronary arterial lesions found in 67 cases of acute myocardial infarction, 48 were found in over 90% stenotic segments, 16 in over 75%, the rest in under 75%.  Hemorrhage in atheroma was found in 55 lesions, atheroma or thick intima without hemorrhage in 9, calcified focus in 3 and coronary embolism in 3.  Of 67 thrombi, 44 occlusive and 3 mural thrombi were found in over 90% stenotic segments, 13 and 2 in over 75% stenotic segments and 2 and one in segments and 2 and one in segments with under 75% stenosis, respectively.  Histological findings of coronary thrombi showed that in 45 of 65 thrombi, two zones of differing age of thrombus could be identified and the rest were fresh thrombi.(ABSTRACT TRUNCATED AT 250 WORDS)