In 2004, Elizabeth Taylor was diagnosed with heart failure. She died from the disease seven years later at age 79.

Around 6.2 million Americans currently share that diagnosis — and some 870,000 more are diagnosed with heart failure each year.

Heart failure — which is the inability of the heart to pump blood well enough to consistently supply the body with adequate flow — is a long-term condition that can damage vital organs. It often develops slowly as a result of atherosclerosis, heart attack, diabetes, high blood pressure, obesity, deposits of an abnormal protein (amyloid) in heart tissue, or heart valve disease. Symptoms include shortness of breath, difficulty breathing when lying down, swollen feet/ankles/legs or stomach, and fatigue.

In its earliest stages, heart failure is treated with a combination of regular exercise, LDL cholesterol and blood pressure medications, and abstaining from alcohol, tobacco, and recreational drugs.

As the disease progresses, it may be necessary for the patient to have a pacemaker or cardiac defibrillator implanted.

But according to a new American Heart Association statement, up to 30% of people diagnosed with heart failure take dangerous or ineffective supplements and herbs.

Blue cohosh, for example, can cause a rapid heartbeat and elevate blood pressure. Lily of the valley — if taken with a common heart failure medication, digoxin — can cause an irregular heartbeat, confusion, and low potassium levels.

Thiamine (vitamin B1), vitamin E, and hawthorn are often used but have no proven benefits.

If you have heart failure, ask your cardiologist about the safety of supplements and herbs before you take them.