Before undergoing quadruple heart bypass surgery to relieve blocked arteries, former President Clinton had been taking a daily statin drug to lower his cholesterol.
But when he lost weight and his cholesterol level dropped, Clinton stopped taking the medication.
"I think that's a terrible mistake," said Dr. Richard Stein of the American Heart Association. "When you stop refilling those pills, you're giving up that 30 [percent] to 40 percent reduction of having a heart attack that they provide you with."
Research shows that up to half of all people who start a cholesterol-lowering drug quit taking it within a year.
For some it's the cost of the medication; the pills can run as much as $3 a day. For others it's the side effects, such as severe muscle cramping.
But the most common reason may be psychological. Many people refuse to take a medication indefinitely for a problem they cannot see or feel.
"We are good for taking pills for sore throats or coughs because we have the symptoms," Stein said. "We are terrible for taking pills for high cholesterol, and these are perhaps the most important pills for us to take."
Drugs Do More Than Lower Cholesterol
Doctors emphasize that while drugs such as Lipitor, Pravachol and Zocor lower harmful cholesterol levels, they also have other benefits.
"Statin drugs also directly affect the inflammation on the plaques within the artery walls," said Dr. Christopher Cannon of Brigham & Women's Hospital in Boston. "That prevents them from breaking open and thus prevents heart attacks."
Research suggests that once patients stop taking statin drugs, the risk of a heart attack increases significantly within just two to three months.
Some cardiologists expect the former president, now that he's had bypass surgery, will have to take a much higher dose of a cholesterol-lowering drug for the rest of his life.
ABC News' John McKenzie filed this report for World News Tonight.