It is well known that high levels of cholesterol in the blood can lead to heart attacks and strokes by triggering the buildup of plaque in the arteries, which can then break off and lodge in the heart or elsewhere. New research has shown that cholesterol can also cause heart failure, which is characterized by the inability of that organ to pump enough blood to supply oxygen throughout the body.
Heart failure affects 5.7 million Americans, with medical costs this year totaling $37.2 billion. About three-quarters of all cases are caused by high blood pressure. It is marked by shortness of breath, swelling in the lower extremities resulting from fluid buildup, fatigue and difficulties in carrying out everyday tasks, confusion and memory loss, and heart palpitations.
The most common treatment for heart failure is a drug that lowers blood pressure. But trials of the family of cholesterol-lowering drugs called statins in the prevention of heart attacks indicated that they also reduced the incidence of heart failure. Some researchers, however, thought this reduction was simply a benefit from the reduction in heart attacks in those receiving the drugs. Most previous studies have been inconclusive because patients in them already had heart disease, which clouded any conclusions that might be drawn.
To investigate, a team led by Dr. Daniel Levy of the National Heart, Lung and Blood Institute went back to the massive Framingham Heart Study, a decades-long study of the residents of the eponymous Massachusetts community. They identified 6,860 participants, none of whom had heart disease when they were enrolled. The group had an average age of 44 at the beginning of the study, and 54% were women. They were followed for an average of 26 years.
The team reported today in Circulation: Journal of the American Heart Association that 680 of the participants had developed heart failure. That group included:
-- 12.8% of those with low levels of high-density lipoprotein (HDL), the so-called good cholesterol, but only 6.1% of those with desirable levels of HDL;
-- 13.8% of those with high levels of low-desnity lipoprotein, the so-called bad cholesterol, compared with only 7.9% of those with desirable levels of LDL.
When the team adjusted for age, sex, body weight, smoking, blood pressure, diabetes and other factors, they concluded that those with high levels of undesirable LDL had a 29% greater risk of suffering heart failure, while those with high levels of desirable HDL had a 40% decreased risk of heart failure. Even when they took heart attacks into account, the results showed a statistically significant risk of heart failure associated with high levels of cholesterol.
Because the study was not a clinical trial, Levy said, it should not alter how physicians prescribe cholesterol-lowering drugs. Beyond drugs, he added, the best ways to improve cholesterol levels include physical activity, stopping smoking, limiting alcohol consumption and eating a diet high in monounsaturated fats such as olive oil.
— Thomas H. Maugh II