Approximately 70% of individuals with diabetes mellitus will die of myocardial infarction or sudden death, due in large part to the high prevalence of subclinical and clinical atherosclerosis. Thus, for all practical purposes, coronary artery disease is a coronary atherosclerosis, and a major priority in the care of diabetic patients. Intervention studies have demonstrated the efficacy of lowering blood pressure in reducing the long-term risk of stroke, CAD and CVD events in general, and the available evidence indicates that the benefits of antihypertensive therapy now extend to patients with co-existing PAD or at high risk for the disease. However, beyond these general recommendations for hypertensive patients, the approach to the patient with combined hypertension and PAD or at risk for the disease should logically differ than for patients with hypertension alone, based on some unique aspects of the pathophysiology of hypertensive atherosclerosis. In this context, considering these unique aspects and the possibility of reducing the risk of hypertensive atherosclerosis to a greater extent in patients with PAD or at risk for the disease, suggestions for a management strategy aimed at prevention of CAS will be offered. This strategy assumes tight control of blood pressure, for the related efforts to assess the existence of hypertension and tight control of blood pressure for the management of a specific PAD-related lesion, have yet to be incorporated in current recommendations for patients with PAD. Suggestions will be made for further research to test the validity of this strategy, with use of surrogate and hard outcomes.
Understanding Peripheral Arterial Disease (PAD)
The walls of blood vessels are composed of smooth muscle and a layer of endothelium supported by connective tissue. The function of the blood vessels is to transport blood and its contents throughout the body. The force exerted by the blood on the vessel wall is known as blood pressure. Blood pressure is highest in the aorta and large arteries and lowest in the arterioles and veins. Peripheral arterial disease (PAD) is a condition in which atherosclerotic plaques have narrowed or occluded the arteries to a point where perfusion of the tissues distal to the lesion is inadequate. This occurs most commonly in the lower extremities but can also affect the arms. PAD is a marker for more widespread atherosclerotic disease and is associated with an increased risk of myocardial infarction and stroke. High blood pressure has been closely linked with an increased risk and progression of PAD. In hypertensive patients, it is important to screen for PAD so that specific treatment to lower the risk of progression of atherosclerosis in the peripheral arteries and methods to reduce cardiovascular risk can be implemented.
Understanding Hypertension
The management of raised BP is at least as important as lowering raised lipids in patients with PAD. Observational data suggest that lowering BP in PAD is associated with a lower risk of progression of the disease. Although this has not been tested in a randomized controlled trial, a number of these have shown benefit on cardiovascular outcomes with ACE-inhibitors and angiotensin receptor blockers (ARBs) compared with placebo. These drugs are recommended as first-line treatment in all patients with PAD and hypertension to reduce cardiovascular mortality and morbidity, and the same BP targets in hypertensive patients without PAD should be adopted (>130/80 mmHg). This target may be revised in the future as a result of the results from the SPRINT trial. High-dose statins have also been shown to have beneficial effects on reducing BP and cardiovascular outcomes, and are likely to have a role in the treatment of hypertensive patients with PAD. Lifestyle modification, including weight loss, reduction in sodium intake and increased regular exercise, with dietary approaches to stop hypertension (DASH), as for the treatment of all hypertensive patients, should be encouraged in PAD patients with hypertension.
Hypertension is the leading risk factor and is highly prevalent in patients with PAD, reported in 50-92% of patients. Hypertension is associated with increased cardiovascular morbidity and mortality, and in patients with PAD, mortality is increased threefold when hypertension is present. The macrovascular effects of raised BP lead to accelerated atherosclerosis, an effect that is at least partly independent of other risk factors. Hypertension causes endothelial damage and dysfunction, and a prothrombotic and proinflammatory state, which in turn lead to atherosclerosis. It has also been shown to cause a faster rate of progression of PAD.
Managing Dual Risks of PAD and Hypertension
There is common agreement on therapeutic lifestyle changes for both PAD and hypertension. The American Heart Association has published diet and lifestyle recommendations for reducing the risk of cardiovascular disease in healthy people and in people with various health problems. These diet and lifestyle recommendations are based on a thorough review of a large body of scientific literature. AHA diet and lifestyle goals and strategies are outlined in Table VII. The AHA recommendations aim to reduce cardiovascular risk factors, such as hypertension, dyslipidemia, and insulin resistance, as well as to prevent and treat known cardiovascular diseases. Because the AHA recommendations are general and far-reaching, it is possible for patients to become confused or even discouraged when they try to apply these recommendations to specific health problems, such as PAD and hypertension. Therefore, it is important for clinicians to help each patient develop a prioritized plan for lifestyle changes, with clear short-term and long-term goals. In helping the patient develop a plan for lifestyle changes, the clinician should make use of diet and lifestyle recommendations from the AHA and also provide additional guidance specific to management of PAD and comorbid hypertension.
