Statin drugs may increase problems with breathing and exercise in people with one form of heart failure, a new study suggests. Researchers looked at medical records of 136 people. Most of them had diastolic heart failure. With this condition, the heart is stiff or does not relax fully between beats. The other patients had systolic heart failure. This means that the heart does not contract fully when it beats. Some people in both groups took a statin drug. These drugs reduce cholesterol and inflammation. Among people with diastolic heart failure, those who took statins had poorer lung function than those who did not. They also did only about half as much exercise. These effects were not seen among statin users with systolic heart failure. Muscle pain is a side effect for some people who take statins. Study results were presented November 3 at a medical conference, HealthDay News reported.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Chances are good that you're taking a statin. And if you aren't, chances are good that you will someday. That's because cholesterol-lowering statin drugs are among the most commonly prescribed of all medicines. These drugs include atorvastatin (Lipitor), simvastatin (Zocor) and others.

In 2008 alone, 200 million prescriptions were written for statins worldwide. They were valued at about $14 billion.

Why are these drugs so popular? There are at least three answers:

• They work well.
• They rarely cause serious side effects.
• They treat common conditions, including coronary artery disease and high cholesterol.

Other factors also have helped to make them popular. For example, in recent years expert guidelines have lowered the levels considered ideal for cholesterol. This has increased the number of people eligible for treatment. Marketing by the drugs' makers also has had a major effect.

While statins are generally quite safe, side effects may occur. These drugs occasionally cause muscle weakness, muscle pain or both. And they can sometimes damage the liver.

According to a new study, some people taking statins may have another side effect. The drugs may make diastolic heart failure worse.

With diastolic heart failure, the heart does not relax normally between beats. As a result, the heart cannot pump blood as effectively as it should. Common symptoms include shortness of breath, fatigue and a reduced capacity for exercise.

In this new study, people with diastolic heart failure taking a statin were compared with otherwise similar people not taking a statin. Those taking a statin were able to do 50% less exercise. Their lung function was reduced by 12%.

Researchers also looked at people with a different type of heart disease, called systolic heart failure. In this group, people who took statins actually had better exercise capacity and lung function.

These findings are not a reason for people to stop taking statin drugs. This new study was small. It included only 136 people. And the study was retrospective. That means researchers looked back at people who took statin drugs and compared them with people who did not.

This method of research sometimes leads to faulty conclusions. Perhaps people in the diastolic heart failure group had more lung disease or breathing problems before they started taking statins. In this case, the exercise limits and reduced lung function blamed on statins might not be related to the drugs. So the findings of this new study must be confirmed by other studies.

Still, the findings are worrisome. Patients and their doctors should be aware of this newly reported side effect.

What Changes Can I Make Now?

Medicines are prescribed for their benefits. But be aware that all medicines have the potential to cause problems. For statins, the most common side effects include:

• Muscle pain
• Nausea
• Diarrhea
• Constipation
• Rash

Keep in mind that statin drugs may interact with other medicines. So even if you've been taking a statin drug without problems, a newly prescribed medicine might provoke statin-related side effects. For example, taking a statin drug with certain antibiotics (such as erythromycin) can cause muscle weakness. Other drugs that can interact with statins include:

• Medicines for AIDS called protease inhibitors (such as ritonavir or nelfinavir)
• Clarithromycin
• Diltiazem
• Gemfibrozil
• Niacin
• Verapamil

If you take a statin drug, talk to your doctor about these interactions. Make sure to ask whether any newly prescribed drug is okay to take with those you already take, including statins.

If you've recently started taking a statin and notice problems with breathing or less stamina during exercise, talk to your doctor about this new study. He or she may suggest that you stop the statin or switch to another drug.

Finally, avoid the need for statin treatment if you can. Many people are able to control their cholesterol levels by improving their diet and getting regular exercise. Losing excess weight can allow some people who take statin drugs to stop them.

What Can I Expect Looking to the Future?

In the future, I believe we will rely on each person's genes to predict whether a drug will be helpful or likely to cause side effects. Until then, you can expect researchers to do more studies to confirm that statin drugs worsen diastolic heart failure. If this conclusion is confirmed, U.S. drug regulators may take action. For example, they may notify doctors or require prescriptions to carry new warnings.

Given the known benefits of statin drugs, it will be important to determine how big the risk is for people with diastolic heart failure. We also will want to know whether some statins cause less trouble than others. This information will allow patients and their doctors to make good decisions about whether taking a statin drug is a good idea.