Peripheral Arterial Disease and Cardiovascular Risk

Abstract

Peripheral arterial disease (PAD) refers to the obstruction of large arteries of the body. The prevalence of PAD in the general population is estimated to be around 12% to 14% and increases up to 20% of those over 70 years old. It is of interest that 70% to 80% of affected individuals are asymptomatic and only a minority requires revascularization or amputation. Major risk factors for PAD are smoking, physical inactivity, dyslipidemias, hypertension, diabetes, and, consequently, the metabolic syndrome (MetS); PAD affects approximately 30% of people with diabetes mellitus. Since the early 1990s, studies revealed the association between PAD and mortality from cardiovascular disease (CVD). For example, Criqui et al evaluated the association of large-vessel PAD with mortality rates from CVD and reported that the relative risk of dying among patients with large-vessel PAD when compared to those with no largevessel disease was 3.1-fold higher (95% confidence interval [CI] 1.9-4.9) for all-cause mortality and 5.9-fold higher (95% CI 3.0-11.4) for CVD mortality. Diet has long been investigated in relation to CVD risk and its major risk factors, like dyslipidemia, hypertension, diabetes, and the MetS. A recent systematic search of the literature based on 15 relevant observational studies that evaluated the direct effect of diet on CVD risk reported that the attributable risk of an unhealthy dietary pattern varies from 9% to 37%; moreover, the authors observed that the inclusion of diet component in CVD risk scores may increase the accuracy of the models and better identify people at high risk. The Mediterranean diet is one of the most known and studied dietary patterns in relation to human health. It was described in the late 1960s by Ancel Keys in the Seven Countries Study. This traditional dietary pattern is characterized by daily consumption of olive oil, fruits and vegetables, nonrefined grains and dairy products as well as weekly consumption of fish and poultry, potatoes, olives, nuts and legumes, and monthly consumption of red meat. Another major characteristic of this dietary pattern is the moderate consumption of alcohol, mainly wine (1-2 glasses/d), usually with meals. However, it should be acknowledged that although the dietary patterns that prevail in the wider Mediterranean region share many common characteristics, the macronutrient distribution varies from area to area. Nevertheless, studies from the Mediterranean region as well as from other parts of the world strongly support the cardioprotective role of this dietary pattern, mainly through its beneficial role on cardiometabolic markers. At this point it is important to mention that the Mediterranean diet may exert its positive influence on human health and CVD particularly due to its antioxidant and anti-inflammatory effects. Despite the large body of evidence regarding Mediterranean diet and CVD mortality and morbidity, the role of this traditional dietary pattern on risk of PAD has been rarely studied. Very recently, Ruiz-Canela et al, in a randomized trial conducted from October 2003 and December 2010 in Spain, assessed the association between Mediterranean diet and the occurrence of symptomatic PAD in 7477 participants with type 2 diabetes mellitus or at least 3 cardiovascular risk factors, aged 55 to 80 years and without clinical PAD or baseline CVD. Participants were randomized to the following groups: a Mediterranean diet supplemented with extra virgin olive oil, a Mediterranean diet supplemented with nuts, or counseling on a low-fat diet (control group). All participants received a comprehensive dietary educational program on a quarterly basis. Both Mediterranean diet intervention groups were associated with lower risk of PAD compared to the control group. A mechanistic hypothesis of the beneficial effect of Mediterranean diet on PAD may be due its pleiotropic beneficial effects on endothelial function, arterial blood pressure, lipids, and glucose