Pattern of plasma lipoprotein ( a ) in Sudanese patients with coronary artery disease

Coronary artery disease is one of the l wide. lipoprotein(a) [Lp (a)] is a cholesterol rich plasma lipoprotein Its structure and composition closely resembles low density lipoproteins (LDL). Elevated Lp (a) is the most common familial lipoprotein disorder in patients with premature Coronary Artery Disease (CAD). Objective: To study the pattern of plasma LP(a) levels in Sudanese patients who presented with coronary artery disease [CAD]. Material and Methods: This is a case control study. 30 patients randomly se admitted to the coronary care unit [C.C.U] in Elshaab Teaching Hospital with acute coronary syndrome in the period from April 2004 to July 2005 while 30 patients with non ischaemic cardiac problems admitted to the same ho randomly selected as a matched control group. Serum LP(a), cholesterol and low C) concentrations were determined using the conventional enzymatic colorimetric methods. Results: LP(a), cholesterol and LDL lev respectively]. Lp(a) is also high in patients blew 60years of age. High LP(a) correlates with high cholesterol, LDL and other risk factors. The role of Lp(a) as an independent 15 patients with no other risk factors had high LP(a) level. Conclusion: This study demonstrated significant Lp(a) level in patients with other risk factors of CAD [including cholesterol and LDL].


Introduction
Coronary artery disease [CAD] is one the leading causes of death for both men and women world wide 1 .CAD risk increases with age, obesity and certain diseases such as diabetes, hypertension, high serum cholesterol level, high level of low-density lipoprotein (LDL) in the blood and with certain social h smoking 2 .Inherited factors may also increase the likelihood of developing CAD 3 .
Lipoprotein a [Lp (a)] is a cholesterol rich plasma lipoprotein which was first identified as plasma antigen in 1963 by Berg 4 .Its structure and composition closely resemble low density lipoproteins (LDL).
The plasma concentration of Lp (a) is mostly genetically determined 5 .E is the most common familial lipoprotein disorder in patients with premature CAD 6 .Lp(a) are associated with significantly increased risk in subjects under 60 years but may be of less significance in the elderly patients 7 increases with age and in patients with renal insufficiency, nephritic syndrome and kidney transplantation 8 .However, in a brief study done in Sudan, the levels of lipoproteins were found to be relatively low/normal in patients with chronic renal diseases and that was attributed to diet and possibly genetic factors

Results
The age in group I ranged between 40 and 80 years while that of group II was between 41 and 78 yreas.Men represented 76% and 67% in y artery disease Group I showed significantly higher levels of the three biochemical markers (Lp (a), cholesterol and LDL) than group II (Table 2).Lp (a) was found to be more prevalent in patients with CAD than cholesterol and LDL [47% and 27% respectively], however there was a strong correlation between the high level of the three markers as 75% of the patients with high cholesterol and LDL has also high level of Lp(a) (Tables 2 and 3).

Table 3: The correlation between LP(a) and Cholestrol level
There was high prevalence of elevated Lp(a) levels in female gender (71%).It is also high in patients blew 60 years of age (70%) and in those with more than one risk factor (73%) [Tables 4 and 5].
The most prevalent risk factors were hypertension and diabetes while smoking is the least frequent one [

Discussion
Lp (a) level is genetically determined.The normal range of Lp (a) in human varies in different ethnic groups.The normal range in Caucasians is similar to that in Asians.However people of African descent have demonstrated normal range that are twice higher than Caucasians.Native American and Mexican populations have normal ranges that are half of the Caucasians populations 10 .
This study demonstrated significant high levels of Lp(a) in Sudanese patients with CAD and showed positive correlation between Lp(a) and the other risk factors (including high levels of Cholestrol and LDL) which is in keeping with the multi factorial etiology of CAD 11 70% of our patients who were <60years of age in the study group showed significant high levels of Lp(a).This fining may be consistent with the results of Kostner and other workers who reported that Lp(a) may be an important initiator and promoter, as well as an early marker for the premature CAD 11,12 .Significantly high levels of Lp(a) were seen in 5[71%] of the females compared to 9[39%] of males.
Our study demonstrated that 20% of the patients with CAD, who had no other risk factors had significantly high Lp(a) levels (table 4).It also showed that the prevalence of high Lp(a) in group I is more than that of cholesterol and LDL (table3).These findings may suggest a role for Lp(a) as an independent risk factor which keeps with the work of Sandkamp 12 .The same result was observed in the Framingham Offspring Study 7 However, these results contrast, the Physicians Health Study and Quebec Cardiovascular Study 13,14 .These differences in could be attributed to differences in sample collection, storage and type of Lp(a) assays.A recent metaanalysis 15 , including 27 published prospective studies (18 population-based and 9 with pre existing CAD) and involving 5436 cases with mean follow up of 10 years, demonstrated a moderate and independent association of Lp(a) and CAD.

Conclusion
This study suggests that Lp (a) level is significantly high in patients with CAD and those blew 60years of age.It is associated with other risk factors and correlates with Cholestrol and LDL levels.The sample size is rather small to suggest that it is an independent risk factor (although it was significantly high in 20% of the patients who had no other risk factor).
Further studies are needed to address the significance of Lp(a) in patients with CAD blew 60 years of age who has no other risk factors.

Table I :
Age and sex Distribution of the studY groups:

Table 2 :
The Biochemical Data In The Studied Group.

Table 5 :
The correlation between significant LP(a) levels and the different variables.

Table 6 :
: Number of patients in group 1 with traditional risk factors.