The Effects of Cholesterol and Blood Pressure Treatments on Severity of Coronary Artery Disease

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The summary below is from the full report titled "Statin and ß-Blocker Therapy and the Initial Presentation of Coronary Heart Disease." It is in the 21 February 2006 issue of Annals of Internal Medicine (volume 144, pages 229-238). The authors are A.S. Go, C. Iribarren, M. Chandra, P.V. Lathon, S.P. Fortmann, T. Quertermous, and M.A. Hlatky, for the Atherosclerotic Disease, Vascular Function and Genetic Epidemiology (ADVANCE) Study.

What is the problem and what is known about it so far?

Coronary artery disease is plaque buildup in the walls of blood vessels that supply blood to the heart. It takes years to develop and may not cause problems unless extreme narrowing occurs or plaque ruptures. With extreme narrowing, blood flow to the heart becomes partially blocked. Partial blockage causes chest pain with activity that goes away at rest (stable exertional angina). This is less serious than plaque rupture, which triggers formation of a blood clot and causes blood flow to the heart to become totally blocked. Blockage causes heart muscle damage, also known as a heart attack (myocardial infarction), or sudden death. Risk factors for these events include high blood pressure, high cholesterol level, diabetes, and smoking. Treatments for these risk factors can prevent coronary artery disease. Whether the treatments have different effects on the chance of developing stable angina, heart attack, or sudden death is not known.

Why did the researchers do this particular study?

To see whether treatments to prevent coronary artery disease have different effects on the chance of developing stable angina, heart attack, or sudden death.

Who was studied?

4142 patients who received a diagnosis of stable angina, heart attack, or sudden death between 2001 and 2003. All patients had health insurance through an integrated health care delivery system in northern California.

How was the study done?

The researchers found which patients had stable angina and heart attack by reviewing medical records and talking to doctors. They also reviewed death records kept by California to find patients with sudden death. They then looked for differences in the numbers of patients with each type of disease who took blood pressure–lowering and cholesterol-lowering drugs.

What did the researchers find?

Of the 4142 patients, 468 had stable angina, 916 had heart attacks, and 2758 had sudden death. Patients with sudden death and heart attack were less likely than those with angina to be taking statins (a type of cholesterol-lowering drug) and beta-blockers (a type of blood pressure–lowering drug) when they developed symptoms. Patients taking statins and beta-blockers seemed to have a lower chance of developing a heart attack than of having stable angina.

What are the limitations of the study?

The findings might be explained by many factors that the researchers could not measure, such as aspirin use. They also might not apply generally, because all patients had health insurance and had full access to doctors and hospitals.

What are the implications of the study?

Treatments to prevent coronary artery disease seem to have different effects on the chance of developing stable angina, heart attack, or sudden death. Statin and beta-blocker use may stabilize the disease and may protect patients from developing more severe forms, such as heart attacks.