Flecainide

TWO COMMON HEART TREATMENTS FOUND HARMFUL

Two long-accepted treatments for heart patients, one used during heart attacks and the other to treat irregular heart beats, have recently been found harmful and sometimes fatal.

Injecting sodium bicarbonate (baking soda) has been routine treatment for heart attack since the 1920s. A recently published study in the American Journal of Medicine (July 1989) was the first controlled research showing adverse effects in humans, Commenting on the results, the principal investigator Allen I1. Arieff, M.D. stated: "People who survived cardiac arrest probably did so despite the bicarbonate."

The alkaline. sodium bicarbonate was thought to counter the accumulation of ltactic acid in the blood that poisons the body. During a heart attack, the liver's normal ability to break down lactic acid is impaired, causing an upset of the body's delicate acid/ alkaline balance.

Dr. Arieff, professor of medicine at University of California at San Francisco and chief of geriatric research, Veterans' Administration Medical Center, previously co-authored a study that found bicarbonate given to animals actually made heart and liver function worse, causing a rise in lactic acidlevels (Science, 15 February 1985). This is the opposite of the desired effect.

The study was comprised of people with severe heart disease who were about to undergo diagnostic cardiac catheterization. Half the people were given sodium bicarbonate by vein and the other half were given a small amount of saline (salt) solution as a placebo. None of those getting placebo showed any adverse effects. However, all five of those given bicarbonate were observed to have reduced coronary blood flow, decreased oxygen use, and increased lactic acid levels.

While the adverse effects of bicarbonate disappeared within two hours, Arieff pointed out that the hearts of people with severe disease are working as hard as possible to supply a normal amount of oxygen during a cardiac emergency and "bicarbonate might push them over the brink."

PRESCRIPTION HEART DRUGS CAUSE MORE HARM THAN GOOD

One death and two life-threatening adverse reactions to flecainide (brand name: Tambocor), a drug commonly prescribed for heart rhythm disorders were reported in Annals of Internal Medicine (15 July 89). While it was already known that antiarrhythmic drugs, such as flecainide, can cause or worsen the very problem they are treating, it was thought to be of serious risk only for people with a particular potentially fatal type of fast heart beat known as ventricular tachycardia. The new reactions involved people being treated for a different irregular heartbeat known as atrial fibrillation, which is chronic but not usually fatal. The drug caused ventricular fibrillation in two men who survived and one woman who did not.

This report comes several months after the National Institutes of Health announced it was dropping flecainide and a similar drug encainide (brand name: Enkaid) from its ongoing multicenter Cardiac Arrhythmia Suppression Trial (CAST). The drugs were dropped because they were discovered to be causing heart attacks and deaths (The New, York Times, 26 April 1989).

The CAST study was designed to confirm the usefulness (compared to a placebo, or sugar pill) of flecainide and encainide in reducing the incidence of repeat heart attacks and death. Instead, a higher number of deaths and heart attacks was found in the drug-treated people, as compared with their untreated counterparts. This surprising finding (both drugs have been widely prescribed for years) was discovered by the study's safety monitoring committee. (Doctors in the field did not know which drug participants were taking because the study was double-blind and they did not have access to the data that was available to the monitors.)

Experts were quoted in the press as being stunned when the serious and fatal effects were discovered. The drugs were approved for use in mild and moderate heartbeat irregularities, but this was the first long-term , large-scale test of their ability to prevent death. (Approval for treatment of mild and moderate arrhythmia was based on much smaller and shorterterm investigations.)

The FDA has since required the manufacturers to revise the physician/pharmacist labeling of the two drugs to specify that they should be used only for "lifethreatening" arrhythmias. In an editorial accompanying the Annals article, Mark E. Josephson, M.D., cardiologist and professor of medicine at the Hospital of University of Pennsylvania cautions that "In treating arrhythmias, one must always remember the Eleventh Commandment, 'Thou must not make the treatment

COPYRIGHT 1989 Center for Medical Consumers, Inc.
COPYRIGHT 2004 Gale Group