By George R. Aronoff, MD, FACP

Heart disease is the most frequent cause of death in dialysis patients. Although heart disease has decreased in the United States over the past 30 years, patients with chronic renal failure have not enjoyed the same reduction in the chances of having a heart attack or developing heart failure.

Hardening of the arteries is the most frequent cause of heart disease in dialysis patients. This process starts with fat deposits in the arteries and may begin at a young age, even in people without advanced kidney disease. Over time, the fat deposits contain calcium and form plaques that can block small arteries, like those in the heart. Many factors contribute to hardening of the arteries. This article will consider some of the risk factors for the development of hardening of the arteries and heart disease in patients with chronic renal failure. In addition, specific strategies for prevention will be presented.

Blood lipids or fats in the blood stream contribute to hardening of the arteries. Doctors frequently measure the total cholesterol as an indication of a patient's risk of developing heart disease. The total cholesterol is made up of LDL cholesterol, the so-called bad cholesterol, and HDL, the good cholesterol. Depending on how many other risk factors for heart disease a patient has, the target for total cholesterol may be as low as 200 mg/dl.

Lowering the total cholesterol and particularly, the bad cholesterol decreases the risk of heart disease. Patients with high cholesterol levels should consider changing their diet to avoid fatty foods and other foods high in cholesterol, like red meat. However, diet alone can only lower the cholesterol by a relatively small amount and many patients with high cholesterol will need to be on specific medications to lower their cholesterol levels.

Medications that lower cholesterol decrease the risk of heart disease and heart attacks. Although these medications are very effective, they may have side effects that need to be monitored. They can also interact with other medications that dialysis and transplant patients may be taking. Consequently, doctors follow blood tests closely in patients taking cholesterol-lowering drugs.

Triglycerides are also a kind of fat normally found in the blood stream. When triglyceride levels are abnormally increased, they may be a risk factor for hardening of the arteries. Decreasing the amount of sugar in the diet may lower triglyceride levels and there are medications, which are also effective for that purpose.

Homocysteine is a chemical normally found in the blood that is important in making proteins. Levels are elevated in patients with chronic renal disease and may be associated with hardening of the arteries. Homocysteine blood levels decrease when patients take large doses of folic acid and other B-vitamins. It is not known whether lowering homocysteine levels in this way decreases the risks of heart attacks and strokes.

High blood pressure is a well established risk factor for heart disease and strokes. Blood pressure is usually reported as two numbers, the systolic and the diastolic blood pressure. Both systolic and diastolic blood pressures increase the risk when they are increased, particularly in patients who smoke, have diabetes or abnormal cholesterol.

A blood pressure of 130/85 is normal and it is recommended for patients younger than 65. Achieving a normal blood pressure should be the goal of therapy. For patients over the age of 65, the risk of strokes is even higher than the risk of a heart attack and a blood pressure of 140/90 is suggested. Patients who have protein in their urine or decreased kidney function, but not on dialysis, may benefit from an even lower blood pressure of 125/75, which is thought to slow the rate of worsening kidney function.

There are several ways to lower blood pressure without taking medications. A low salt diet and careful attention to removing extra fluid on dialysis are effective. Many dialysis patients can have a normal blood pressure if they are able to achieve their "dry weight" on dialysis and do not gain more than four or five pounds between dialysis treatments. On the other hand, fluid overload can lead to heart failure and heart attacks.

Smoking is a dangerous risk factor for hardening of the arteries. Smoking decreases the good cholesterol, increases blood pressure, decreases the oxygen in the blood stream and makes it easier for blood to clot in the tiny blood vessels in the heart and brain. It can cause heart attacks and sudden death, particularly in patients who already have heart disease. Quitting smoking is an important way to decrease the risk of strokes and heart attacks.  Even among persons who have smoked heavily in the past, the risk of a heart attack can be cut in half regardless of how long or how much they have previously smoked.

Diabetes mellitus or sugar diabetes is an important cause of hardening of the arteries. Diabetes is a leading cause of blockage of the tiny blood vessels in the kidneys, heart, brain and eyes. Consequently, high blood sugar levels are associated with worsening kidney function, heart attacks, strokes and blindness. Diabetes in adults is often associated with being overweight. Weight loss through sensible diet and exercise decreases the risk of heart disease and may improve diabetes control. In order to achieve the best control of blood sugar, diabetics may take medications by mouth or insulin injections. Some diabetic medicines are not good for patients with kidney disease, because they can cause acid to accumulate in the blood stream. Doctors familiar with kidney patients will avoid using these medicines.

Individuals with kidney disease are at a high risk of developing hardening of the arteries resulting in heart attacks, heart failure and strokes. Multiple factors are involved. The table below shows multiple strategies to prevent hardening of the arteries. Much of what we believe to be true about prevention is known from patients with normal kidney function. We think these strategies will work in patients with kidney disease and those on dialysis or with transplants. However, much more research is needed to learn which factors are most important and which preventive measures are most effective.

Strategies to Lower the Risk of Heart Disease

CONTROL

• Cholesterol and Triglycerides
• Blood Pressure
• Blood Sugar

WEIGHT LOSS IF OVERWEIGHT

• Proper Diet
• Modest Exercise

Written by George R. Aronoff, MD, FACP. Dr. Aronoff is a Professor of Medicine & Pharmacology and Chief, Division of Nephrology at the University of Louisville. He is also a member of AAKP's Medical Advisory Board. 

This article originally appeared in aakpRENALIFE, Vol. 16, No. 5, March 2001.

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