The statement will also be published in the January issue of Diabetes Care.
Diabetes is a major risk factor for heart disease. TZD agents rosiglitizone maleate (Avandia) and pioglitazone hydrochloride (Actos) help doctors manage patients' glucose (blood sugar) levels and may even modify other heart disease risk factors such as high blood pressure, high cholesterol and inflammation, said Richard W. Nesto, M.D., chair of the department of cardiovascular medicine at the Lahey Clinic in Burlington, Mass., and lead author of the joint statement.
"There is now widespread use of TZDs in a broad group of patients with type 2 diabetes. At the same time there have been reports of congestive heart failure associated with their use," Nesto said.
In some people, the drugs are associated with fluid retention known as edema, especially swelling of the feet. Edema may also be a hallmark of congestive heart failure.
"It is sometimes difficult to know whether such swelling is a benign side effect of the drugs or a more ominous sign of heart failure," Nesto said. "It is this common association that concerns both cardiologists and diabetologists."
The joint writing group examined existing studies to identify patients with diabetes who are at increased risk for congestive heart failure and may not be ideal candidates for the thiazolidinedione class of drugs. "This gives us a way to manage risk," Nesto said. It also helps physicians and patients balance potential risk against "an otherwise excellent class of drugs that can improve glycemic control."
The consensus statement recommends that people with advanced heart disease or severe congestive heart failure should avoid TZDs. Also, people who don't have symptoms of congestive heart failure but whose hearts have impaired pumping ability should only use TZDs if no other means of glucose control has worked. In these extreme cases the drugs should be started at low doses.
Diabetic patients with mild to moderate congestive heart failure can also use TZDs. But the joint statement cautions that the drugs should be used with a "start low, go slow" regimen. This same low-dose, careful monitoring approach should be followed for people who don't have heart disease, but who do have one or more risk factors for congestive heart failure.
Because diabetes is a risk factor for heart disease, many patients prescribed TZDs for glucose control could also have underlying heart disease, he said.
"But at this point we don't know the real risk because we don't know either the actual number of patients with diabetes who are taking a TZD and develop congestive heart failure, compared to the total number of patients who are taking a TZD," he said. "This risk is probably quite low, but without solid data that's just guesswork."
Risk factors for congestive heart failure include heart attack, a history of heart failure, high blood pressure, enlargement of the left ventricle, heart valve disease, age older than 70, long-standing diabetes, chronic renal failure or a history of edema. Insulin use is also an important consideration since TZDs are more likely to trigger edema in persons who use insulin.
The new statement also urges patients taking TZDs to report weight gain of more than 3 kilograms (6.6 pounds), sudden onset of edema in the feet, shortness of breath or fatigue. If congestive heart failure is diagnosed after a TZD is started, use of the drug should be reconsidered. "Dosage change and temporary or permanent discontinuance are the obvious options, but no one of these is preferred for all patients," the AHA/ADA statement advises.
Co-authors are David Bell, M.D.; Robert O. Bonow, M.D.; Vivian Fonseca, M.D.; Scott M. Grundy, M.D., Ph.D.; Edward S. Horton, M.D.; Martin Le Winter, M.D.; Daniel Porte, M.D.; Clay F. Semenkovich, M.D.; Sidney Smith, M.D.; Larry Young, M.D.; and Richard Kahn, Ph.D.