Increased plasma level of lipoprotein(a) and homocysteine is a marker of increased cardiovascular risk

Introduction. Recent molecular research regards Lp(a) as the “third cholesterol” which should be treated in the same way like the total and LDL-cholesterol in reduction of total cardiovascular risk. Although early data on the relationship between elevated blood homocysteine concentrations and CAD and stroke have been somewhat inconsistent, hyperhomocystinemia has been suggested as an indicator of an increased risk of cardiovascular disease. In light of this, our study objective was to provide answers to the following questions: 1. Is serum Lp(a) concentration a risk factor for coronary artery disease in Croatian population; 2. What are the frequencies of various apo(a) isoforms in elevated serum Lp(a) concentrations; 3. Is there a relation between elevated serum homocysteine and Lp(a) concentration; 4. Investigate the relation of Lp(a) to other lipid disorders and other cardiovascular risk factors. Methods. This study was performed in Dubrava University Hospital in Zagreb, Croatia. 87 patients participated with no known preliminary coronary or peripheral vascular disease. The patient groups were stratified according to increased and normal Lp(a) levels measured from serum. Extensive medical history was obtained, blood biochemistry was evaluated and all patients underwent exercise stress testing. Results. In the group with increased concentration of Lp(a) in serum (> 0.30 g/L) there were 53 patients (average age 55 years, 32 males and 21 females), and normal concentration of Lp(a) in serum (< 0.30 g/L) was found in 34 patients (average age 52 years, 20 males and 14 females). The patients with increased Lp(a) levels were significantly older than the patients with normal Lp(a) levels (p = 0.020). The average concentration of Lp(a) in patients with negative exercise stress testing results was 0.38g/L, and in those with positive exercise stress testing results it was 0.51 g/L, with this difference among groups being significant (p = 0.049). The correlation of homocysteine and Lp(a) levels was statistically significant (r = 0.57, p < 0.01). Frequencies of phenotype Lp(a) were determined with the predominance of S4 phenotype (in 34 patients, 39.10%). Conclusions. Lp(a) concentration is a statistically significant risk factor for coronary artery disease. Homocysteine and Lp(a) seem to interact to increase the risk of CAD. No significant association was observed between Lp(a) levels and conventional risk factors for CAD