**6. Discussion**

190 Lipoproteins – Role in Health and Diseases

small sample size) (Table 8,9,10).

20-40

increased low density lipoprotein cholesterol level.

**TC** 

**LDL** 

**HDL** 

**Risk factor OR (95%CI) p value** 

>5,2 mmol/l 0,926(0,568-1,510) 0 5,2-7 mmol/l 0,844(0,484-1,470) 0,548 7,1-9 mmol/l 1,050(0,366-3,017) 0,928 > 9 mmol/l 1,540(0,450-5,272) 0,491

> 3 mmol/l 0,755(0,458-1,246) 0,008 3-5 mmol/l 0,722(0,421-1,239) 0,238 5,1-6 mmol/l 1,014(0,233-1,239) 0,985 > 6 mmol/l 0,892(0,207-3,852) 0,879

< 1,0 for males; < 1,2 mmol/l for females 2,303(1,483-3,577) 0

It was noticed, that a decrease in high density lipoprotein cholesterol – is an important and reliable cardiovascular mortality risk factor in middle-aged patients (40-60 years). For the 41-50 years patients the mortality risk increases nearly 5 times when high density lipoprotein cholesterol level declines less than 1,0 mmol/l for men, and less than 1,2 mmol/l for women (4,985, 95%CI 1,230-20,196, p<0,05). In the 51-60 year group the risk of death increases 2,5 times with a similar levels of high density lipoprotein cholesterol significantly (2,572, 95%CI 1,094-6,106, p< 0,05) and with a total cholesterol more than 5,2 mmol/l insignificantly (1,073, 95%CI 0,462-2,495, p=0,87). A similar trend for the high density lipoprotein cholesterol was evaluated for the elderly patients, without significance (due to

**Years OR (95%CI) p value**

41-50 0,591(0,147-2,383) 0,46 51-60 0,610(0,238-1,564) 0,303 61-70 0,581(0,258-1,312) 0,191 71-80 0,771(0,395-1,504) 0,445 >80 0,421(0,088-2,012) 0,279

**Table 8.** Cardiovascular one year mortality rate depending on age groups for the patients with

TC – total cholesterol, LDL- low density lipoprotein cholesterol, HDL – high density lipoprotein cholesterol **Table 7.** Cardiovascular one year mortality rate for males depending on lipoproteins level.

> In the last decade, lack of evidence on low density lipoprotein cholesterol and high density lipoprotein cholesterol in the pathogenesis of coronary heart disease have appeared. Mostly long-term outcomes were evaluated by the previous studies on lipoprotein disorder. We decided to estimate impact of the dyslipoproteinemia to the one year survival. It is proved by another studies, that patients with very low high density lipoprotein cholesterol have much higher risk of severe cardiovascular event or cardiovascular death comparing with patients with normal high density lipoprotein cholesterol level. Lower high density lipoprotein cholesterol values are associated with a higher great cardiovascular events risk and a greater burden of atherosclerosis, even among the patients with reduced low density lipoprotein cholesterol level [33,40,41]. In another side, very low low density lipoprotein cholesterol level is a significant prognostic factor, improved survival for the patient with acute coronary syndrome and may be a target for the treatment. In this study first and foremost we found that reduced high density lipoprotein cholesterol are highly prevalent in a large cohort of the patients with coronary artery disease and tend to be associated with a significantly higher cardiovascular mortality risk. More than a half of the patients in our study had decreased high density lipoprotein cholesterol, and therefore the higher cardiovascular events and mortality risk, especially for the patients with stable angina. These data are similar to another studies [40]. Results from another studies showed that the prevalence of the elevated low density lipoprotein cholesterol increases with age [17]. By data from our

study it is not only the problem for the eldery patients. The prevalence of the impaired low density lipoprotein cholesterol by the gender was similar both for men and women and it was high for the patients with established coronary artery disease, taking notice that elevated low density lipoprotein cholesterol can be managed and controlled successfully with lifestyle changes, medications or a combination both of them. We have found that decreased high density lipoprotein cholesterol level is a significant independent risk factor for cardiovascular one year mortality. Interestingly, in another similar studies reduced high density lipoprotein cholesterol more often were found in young men. In our study 90% of females with coronary artery disease had a decreased high density lipoprotein cholesterol level. Also, insufficient high density lipoprotein cholesterol level more often have been found in eldery people. Although high density lipoprotein cholesterol less than 1,3 mmol/l for women has been widely considered as a cardiovascular risk factor, in the present study we selected a cutoff point of less than 1,2 mmol/l as a lowest high density lipoprotein cholesterol value that allowed us to identify those females at risk of cardiovascular one year mortality. It have been evaluated that about 20% of participants of our study had reduced high density lipoprotein cholesterol with elevated low density lipoprotein cholesterol level together. So, it is let to suspect, that one year cardiovascular mortality risk for them have to be much higher. There are a lot of evidence, that decreased high density lipoprotein cholesterol significantly increases cardiovascular mortality risk in stable patients. Also, there are some studies, showed that reduced high density lipoprotein cholesterol is associated with a higher risk of adverse outcomes [40]. Some reports on lipoproteins did not evaluated cardiovascular mortality due to acute or chronic ischaemic syndrome. Comparing acute coronary syndrome and chronic coronary artery disease patients we have been evaluated the more important role of total cholesterol and low density lipoprotein cholesterol on cardiovascular one year mortality for acute patients, though not significant. In contrast, high density lipoprotein cholesterol was strong independent risk factor both for acute (not significant) and chronic patients. Suprisingly, total cholesterol more than 5,2 mmol/l and low density lipoprotein cholesterol more than 3,0 mmol/l reduced one year mortality risk both for acute and chronic patients significantly. Additionally, the previous studies showed the increased mortality rate due to elevated low density lipoprotein cholsterol, have not comprehensively evaluated the impact of different low density lipoprotein cholesterol and high density lipoprotein cholesterol lipoproteins levels on cardiovascular mortality. Lehto and al. evaluated, that among 35-64 years females with acute myocardial infarction total cholesterol more that 8 mmol/l significantly increases reccurence cardiovascular disease risk [42]. It was a reason to search an impact of different levels of low density lipoprotein cholesterol and total cholesterol on cardiovascular mortality risk for men and women. Our hypothesis was confirmed, as it became clear, that one year cardiovascular mortality risk sharply rises when signally increased total cholesterol more than 9 mmol/l and low density lipoprotein cholesterol more than 6 mmol/l, especially in women. The future major research need to evaluate a different lipoprotein and total cholesterol levels impact in cardiovascular mortality, not only in short term, but in long-term outcomes as well. It seems, the highest levels of lipids, that could be attributed to hereditary dyslipoproteinemia, may be very important predicting cardiovascular mortality rates and reducing a cardiovascular death risk. As it was find earlier, high density lipoprotein cholesterol more predictive for middle-aged men. Similarly, our study evaluated the more important role of decreased high density lipoprotein cholesterol, especially for 51-60 years men with the chronic coronary artery disease for one year cardiovascular mortality.
