Most of the participants in the study had moderate heart failure, defined by breathlessness and fatigue after walking up one flight of stairs, or severe heart failure, characterized by similar symptoms while walking less than one block on level ground. Fourteen patients, seven in each drug group, were unable to continue treatment due to adverse side effects.
Beta-blocker drugs work on the body's sympathetic nervous system, which pours hormones like adrenaline into the bloodstream in response to stress. In response to high levels of these hormones, the heart beats faster and has to work harder. CHF patients have high levels of these stress-related hormones, a sort of chronic panic mode. By blocking that response, beta-blockers make the heart beat more efficiently.
"Years ago, we were all taught in medical school to never use beta-blockers in heart failure because the initial dose makes the condition worse. Now we know that if treatment is initiated very slowly and the dosage is gradually increased, the majority of stable heart failure patients can tolerate the drug," says Kukin. Stable patients are those who are not hospitalized, do not have fluid congestion and have a systolic blood pressure above 85 mmHg.
The two drugs had parallel benefits. "However, we only can start a beta-blocker with very low dosages. Carvedilol is the only one available in very low doses," he says.
In their study, the researchers had a pharmacist crush metoprolol tablets and repackage the powder in capsules to obtain low-enough doses for initiating therapy.
Because metoprolol is an older medication and now generic, the manufacturer ha
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Contact: Carole Bullock
caroleb@heart.org
214-706-1279
American Heart Association
24-May-1999