The risk factors of coronary artery calcification (that is, the accumulation of calcified plaques seen on computed tomography) include: established risk factors of heart disease, such as male, older age, glucose intolerance, smoking, dyslipidemia (lipoprotein metabolic diseases, including hypercholesterolemia), hypertension, obesity, elevated inflammatory markers and low education level. Recent data show that the quantity and quality of sleep are related to several such risk factors.
First, coronary atherosclerosis and calcification
A large number of studies show that the degree of coronary artery stenosis shown by coronary angiography is not linearly related to the occurrence of future coronary heart disease events, but is more likely to be related to the lesion of coronary artery wall, that is, the stability of coronary atherosclerotic plaques. Unstable plaque rupture or even rupture, leading to acute coronary syndrome.
Atherosclerotic calcification can occur in young people in their twenties. Further research shows that this disease in young people is the accumulation of crystalline calcium in lipid corpuscles of lipid nuclei. Calcium deposition is more common and serious in the elderly population. In most progressive diseases, when mineralization is dominant, it means that lipid components are precipitated and fibrous tissue is increased.
The role of mineralization in the pathogenesis and outcome of coronary atherosclerotic plaque is unclear. Some studies suggest that the occurrence of coronary artery calcification may change the mechanical properties of atherosclerotic plaques, and the affected myocardium can be protected by strengthening the fragile and easy-to-rupture atherosclerotic plaques. When coronary artery calcification occurs in a large area, the possibility of vascular rupture is small, but in the early and middle stages of calcification, the vulnerability of plaque increases obviously.
Although calcification always appears in the local coronary artery stenosis area, it also means coronary thrombosis syndrome and coronary artery dissection after angioplasty. Some studies believe that mild or moderate stenosis plaques are more likely to rupture and lead to coronary syndrome.
Hangartner et al. conducted pathological experiments on the hearts of 54 patients with stable angina pectoris, showing that > 50% of coronary artery lesions have narrow diameters, of which 48% are caused by centripetal fibrous (hard) plaques, 28% by fatty (soft) plaques, 12% by eccentric fibrous plaques, and 12% by eccentric fatty plaques. 44% of the plaques causing 30% ~ 50% stenosis are eccentric, often a series of highly stenosis lesions. Most patients are a mixture of all plaque forms in different proportions, but in a boat, 2/3 are fibrous and 1/3 are lipid-rich plaques. These observations show a significant contradiction, that is, the wider the calcification range of coronary artery, the greater the possibility of coronary events. Calcification can be found in some mild or moderate stenosis plaques. Some people think that this form of lesion is more likely to rupture and lead to coronary syndrome, while others think that calcified plaque itself is not easy to rupture. More precisely, the existence of calcified plaque means that it is more likely to be related to fatty plaque and unstable plaque.
196 1 year, blankenhorn et al. observed that coronary artery calcification only occurred in atherosclerosis. Some later studies also support this view. According to the summary data, the incidence of atherosclerotic plaque is 50% in the population aged 20-29 and increases to 80% in the population aged 30-39. The incidence of calcification is 50% in the 40-49 age group, 80% in the 60-69 age group and only 30% in the 60-69 age group. In patients with symptomatic coronary heart disease aged 30-39, the incidence of calcification is 72% and the incidence of stenosis is 60%.
Some autopsy data show that the percentage of coronary artery stenosis is moderately related to calcification. Mautner et al. observed that 54% of the 75% stenotic coronary artery segments showed coronary artery calcification on EBCT, while only 465,438+0% ~ 75%, 26% ~ 50% and 65,438+0% ~ 25% stenotic lesions were found. In a word, compared with stenosis (368), more calcified sites are accompanied by non-stenosis (632). In addition, at least 93% of 75% coronary arteries with 1 vascular stenosis showed calcification, while stenosis
Animal and clinical studies have also found that atherosclerosis is related to calcification, but their pathological processes are completely different. C 1air et al. observed that the calcified components on the arterial wall increased during the process of atherosclerosis degeneration. Young et al. comparatively observed coronary atherosclerosis and calcification, and found that calcification mostly occurred at the proximal end of the left anterior descending branch, and the distal end was relatively rare, which was obviously different from the distribution of atherosclerotic lesions.
Second, coronary artery calcification and clinical prognosis
Clinical research shows that the progression of coronary atherosclerosis is a powerful independent predictor of future coronary heart disease events. Margolis et al studied 800 patients with angina pectoris. It was found that the 5-year survival rate of patients with calcification and symptoms by traditional X-ray examination was 58%, and that of patients without calcification was 87%. Therefore, the prognostic significance of coronary artery calcification seems to have nothing to do with age, sex and coronary angiography. In addition, coronary artery calcification is also independent of exercise test and left ventricular ejection fraction. Detrano et al.' s research also shows that coronary artery calcification revealed by traditional X-ray examination is helpful to identify the increased risk of cardiac events in asymptomatic high-risk patients during 1 year. Naito et al. followed up 24 1 elderly patients for 4 years, and found that 4.9% of 82 patients with coronary artery calcification had myocardial infarction, while none of 59 patients without coronary artery calcification had myocardial infarction, but there was no significant difference in total mortality between the two groups.
Third, different views on coronary artery calcification.
Some review documents point out that calcium deposition in atherosclerosis is obviously related to the severity of the disease and poor prognosis, so coronary artery calcification is considered as a "bad" phenomenon. However, some clinical and biomechanical studies show that calcium deposition often reduces the vulnerability of plaque rupture, so coronary calcification seems to be a "good" sign. Objective evaluation should consider that coronary artery calcification has two functions at the same time. Calcium deposition indicates the existence of atherosclerotic lesions. Generally speaking, the more serious the calcium deposition, the wider the scope of atherosclerotic lesions. A group of atherosclerotic lesions, especially unstable lesions, are easy to cause coronary heart disease. However, unstable lesions may not calcify, while stable lesions are more likely to calcify.
It is considered that coronary artery calcification is a "bad" phenomenon because the number of calcified plaques roughly reflects the sum of atherosclerotic areas in coronary artery branches. However, the factors that determine the prognosis of coronary artery are not only the number of atherosclerosis, but also the possibility that each plaque is easy to rupture. In a sense, calcification may mean a protective effect.