Extremely elevated lipoprotein (a) as an independent risk factor for peripheral arterial disease in large patient cohort

Abstract

Background Elevated lipoprotein (a) [LP (a)] levels are an independent, genetic, and causal factor for cardiovascular disease and associated with myocardial infarction (MI). Although the association between circulating levels of lipoprotein(a) [Lp(a)] and risk of coronary artery disease (CAD) is well established, its role in risk of peripheral arterial disease (PAD) remains unclear. PAD affects over 236 million individuals and follows ischaemic heart disease (IHD) and cerebrovascular disease (CVD) as the third leading cause of atherosclerotic cardiovascular morbidity worldwide. LP (a) is genetically determined, stable throughout life and yet refractory to drug therapy. While 30 mg/dl is considered the upper normal value for LP (a) in central Europe, extremely high LP (a) levels (>150mg/dl) are rare in the general population. The aim of our study was to analyse the correlation between lipoprotein (a) [LP (a)] levels and an incidence of PAD in high-risk patients. Patients and methods We reviewed the LP (a) concentrations of 52.898 consecutive patients admitted to our cardiovascular center between January 2004 and December 2014. Of these, 579 patients had LP (a) levels above 150 mg/dl (mean 181.45±33.1mg/dl). In the control collective LP (a) was <30mg/dl (n=350). Other atherogenic risk factors in this group were HbA1c 6.58±1.65%, low density lipoprotein (LDL) 141.99±43.76 mg/dl, and body mass index 27.81±5.61. 54.40% were male, 26.07% were smokers, 93.2% had hypertension, and 24% had a family history of cardiovascular diseases. More than 82.6% were under statins. The mean glomerular filtration rate (GFR) was 69.13±24.8 ml/min [MDRD (Modification of Diet in Renal Disease)]. Results 45.00% (n=261) of the patients with LP (a) >150mg/dl had PAD. The prevalence of PAD in patients with LP (a) <30mg/dl in our control collective was 15.8%. (P- Value 0.001). Patients with LP (a) >150mg/dl had a significantly increased risk for PAD (Odds ratio 4.36, 95% CI 2.94–6.72, p: 0.001). 19.1% of patients were re-vascularized by percutaneous angioplasty (PTA) and 7.09% of patients had to undergo peripheral vascular bypass (PVB). Mean LP (a) level in patients with PAD was 182.6±31.61. Conclusion Elevated LP (a) levels above 150 mg/dl are associated with a significantly increased risk of PAD in our collective and it confirms our hypothesis. Over one fourth of these patients had severe PAD and requiring revascularization therapy. We need more prospective studies to confirm our findings. Funding Acknowledgement Type of funding source: None