Dec. 7, 2000 -- A new study suggests doctors should be cautious about prescribing certain medications that lower high blood pressure. An analysis of nine different studies finds that one popular class of these drugs is less effective in preventing heart-related problems and may actually increase the risk of heart attacks and heart failure.
Doctors who conducted the analysis say there is no reason for patients taking these drugs, known as calcium-channel blockers, to be overly concerned. Rather, the study is meant to reiterate to doctors that these drugs should never be given as an initial treatment, or first-line therapy, for people with high blood pressure, says Marco Pahor, MD, author of the study appearing in this week's issue of The Lancet.
His study compared results from nine different blood pressure-lowering trials involving over 27,000 people. Patients in the trials received various drugs to lower their high blood pressure including calcium-channel blockers, ACE inhibitors, diuretics and beta blockers. The last two are older medications that doctors have used for years to effectively lower blood pressure.
Compared with people who took other drugs, people who took calcium-channel blockers to lower blood pressure had a 26% higher risk of heart attack, a 25% higher risk of heart failure, and a 10% higher risk of combined major heart disease.
"Doctors should limit the use of calcium-channel blockers unless other agents are not effective in lowering blood pressure or contraindicated for the patient because of side effects," says Pahor, professor of medicine and director of the Sticht Center on Aging at Wake Forest University School of Medicine in Winston-Salem, N.C.
Another study in the same issue of the journal finds that compared with ACE inhibitors, calcium-channel blockers increase the risk of heart disease by 19% and the risk of heart failure by 18%. That study included over 26,000 people with high blood pressure.
In an editorial that accompanies both of the studies, two experts from Tulane University School of Medicine in New Orleans, say the results are consistent with what a panel of experts said three years ago. At that time, the panel recommended giving only diuretics or beta blockers for the initial treatment of high blood pressure.
Jiang He, MD and Paul Whelton, MD, say these newer studies being reported this week "also provide support for the use of ACE inhibitors as initial choice of [blood-pressure-lowering] therapy. ACE inhibitors may be especially useful in patients who are at high risk of heart failure," they say. Some doctors favor combining ACE inhibitors with the older drugs and studies are in progress to determine how to best accomplish that goal.
All the experts say, however, that the new studies should not be interpreted to mean that calcium-channel blockers are not useful drugs or that they are harmful. In fact, Pahor's study found them to be just as effective as the other drugs at lowering blood pressure. But, he says the other drugs may have additional benefits that calcium-channel blockers don't have, which is why they should always be used first. Calcium-channel blockers also appear to be fairly effective at reducing the risk of stroke among people with high blood pressure, so he and Whelton say one scenario in which they could be used as the initial treatment might be in people with a very high risk of stroke but a low risk of heart disease.
Concerned patients taking calcium-channel blockers should talk with their doctors before stopping the use of calcium-channel blockers on their own.
"The risk of abruptly stopping a medication -- such as a calcium-channel blocker -- is greater than continuing it until patients can go talk with their doctor about a particular study and consider changing it to a different blood pressure agent," says Norman Feinsmith, MD, FACC, a cardiologist at the University of Pennsylvania in Philadelphia.