[Role of lipid lowering therapy in patients with peripheral arterial occlusive disease].

BACKGROUND

Peripheral arterial occlusive disease (PAOD) is common in older age. PAOD is associated with an increased risk of vascular events (e. g. myocardial infarction or stroke). Therefore, the prevention and treatment of PAOD is important, especially at a time when the elderly population is increasing. There is an association between lipid abnormalities and the risk of developing PAOD. However, it is not yet definitively established if early intervention with lipid lowering drugs prevents the development of PAOD and improves outcome.

RESULTS OF STUDIES

In a 5-year follow-up study, in which hypercholesterolemia was treated by partial ileal bypass (POSCH study), the incidence of claudication was reduced to 19% (n = 126) in the surgical treatment group vs. 33.6% (n = 119) in the control group (p < 0.01). Direct imaging of peripheral atherosclerosis was not performed and a partial ileal bypass operation is followed by considerable changes in nutrition. A 2-year follow-up study of 153 patients with femoral atherosclerosis treated with colestipol-niacin demonstrated a decreased progression of angiographically assessed femoral atherosclerosis (p < 0.02). A subgroup analysis of the Scandinavian Simvastatin Survival Study (n = 4,444) reported worsening symptoms in 3.6% in the placebo group as compared to 2.3% in the simvastatin group (p = 0.008). In an open trial lipid-lowering therapy with statins did not improve functional outcomes including 6 minutes walking distance and 4 minutes walking velocity in 392 men and women with an ankle-brachial-index (ABI) < 0.90. A summary performance score combined performance in walking speed, standing balance, and time for five repeated chair rises into an ordinal score ranging from 0 to 12 (12 = best) was improved (p < 0.001). A randomized placebo controlled prospective study with simvastatin including 43 patients in each group demonstrated an improved painfree and total walking distance as well as an increased ABI after 6 months. A second placebo controlled study investigated the effect of 10 mg and 80 mg atorvastatin in 354 patients after 12 months. Painfree walking time was only improved by 80 mg atorvastatin, maximum walking time and ABI remained unchanged. A questionnaire regarding physical activity showed improved results already for 10 mg atorvastatin, whereas quality of life did not change. Pathomechanistic explanations, such as regression of peripheral atherosclerosis, were not described.

CONCLUSION

All in all the association between the progression of PAOD and lipid abnormalities is surprisingly inconclusive and the effects of lipid-lowering are not defined. Well designed long-term studies assessing primary and secondary prevention of PAOD with defined endpoints, such as amputation rate or number of vascular interventions are missing. The mechanisms improving physical activity whithout affecting PAOD outcome have to be investigated.