Beta-blockers extend life years after heart attack
Beta-blockers have many benefits for the heart, including treating high blood pressure (hypertension), relieving angina (chest pain from coronary heart disease), preventing additional heart attacks, and improving cardiac function in some cases of congestive heart failure. This class of drugs is also useful in correcting irregular disturbances in the rhythm of heartbeats (arrhythmias). Beta-blockers prevent the interaction of epinephrine (adrenaline) and its cousin neurotransmitters with so-called beta-receptors on cells throughout the body. In the case of the cardiovascular system, beta-receptors when activated primarily cause the heart to beat quicker and more forcefully. Blocking them, therefore, reduces the workload of the heart.
Past studies suggest that beta-blockers can reduce mortality by 25% to 40% in patients with certain kinds of heart failure, and cut sudden cardiac death up to 50% in patients with a recent heart attack. A new study in the October 29, 2002 issue of Circulation took previous research one step further and looked at whether beta-blockers could prevent recurrent heart attacks and death in patients at high risk for sudden death from irregular heartbeats.
About the Study
Researchers from the Brown Medical School (Providence, RI), Duke Clinical Research Institute (Durham, NC), and a number of other medical institutions studied 2096 men and women between the ages of 57 and 72 who participated in the Multicenter UnSustained Tachycardia Trial (MUSTT). This study enrolled patients at 85 sites in the United States and Canada over a six-year period, and was originally designed to test the effectiveness of a specialized type of antiarrhythmic therapy to reduce total mortality, cardiac arrest, and death due to arrhythmias in high-risk patients.
For this study patients were included if they had conditions placing them at increased risk of sudden cardiac death: a previous heart attack, at least some degree of heart failure and a serious type of intermittent heartbeat irregularity— nonsustained ventricular tachyarrhythmias (VT) —that did not produce symptoms. Subjects were randomly assigned to receive beta-blocker therapy or placebo. The patients’ physicians were allowed to select the type of beta-blocker therapy their patients would receive.
Among other things, the researchers measured deaths caused by heartbeat irregularities, non-fatal cardiac arrests, and death from all causes—comparing those who received beta-blockers to those who did not.
After adjusting for the age, sex and race of the subjects along with numerous factors affecting the condition of their hearts, the researchers found that those taking beta-blockers had 15% to 38% less risk of dying compared with those not taking these drugs. The death rates for beta-blocker patients were 16% at two years and 34% at five years, significantly lower than the death rates of 27% at two years and 50% at five years for patients not receiving beta-blockers. Beta-blocker therapy, however, did not significantly decrease the risk of cardiac arrest or death from heartbeat irregularities, though there was a trend toward this type of benefit.
Although these results suggest that beta-blockers may be beneficial for preventing death after a heart attack, there are a number of important limitations to this study. First, because the referring physicians decided which beta-blocker therapy to prescribe, researchers could not determine if certain beta-blockers are better than others. Second, the researchers did not adjust for a variety of other factors like medications, physical activity, body mass index, or marital status, which some investigators have found can influence cardiovascular health. Third, the effects of beta-blockers in patients who received other pharmacological antiarrhythmic therapy may also be obscured because several of these drugs possess some beta-blocker activity. Finally, since the researchers studied only high-risk patients who had had a previous heart attack, the findings do not necessarily apply to other patients at risk for serious arrhythmias who have never had a heart attack.
How Does This Affect You?
This study highlights the significant protective effect of beta-blocker therapy following a heart attack. While not all patients are medically eligible for this treatment, many who could safely use beta-blockers do not. If you are a heart attack survivor and are not taking a beta-blocker, you may wish to discuss the issue with your physician if you haven’t already.
In addition to beta-blocker therapy, the American Heart Association also recommends the following general guidelines for managing your health after a heart attack.
- If you smoke, quit.
Eat a heart-healthy diet that is:
- Low in saturated fat and cholesterol
- Rich in whole grains, fruits and vegetables
- Exercise regularly (under your doctor’s close supervision)
- Lose weight if overweight or obese.
- Take your medications as ordered.
Drink alcohol only in moderation.
- One or fewer alcoholic beverages per day for women
- Two or fewer alcoholic beverages per day for men
American College of Cardiology
American Heart Association
National Heart, Lung, and Blood Institute
Ellison KE, Hafley GE, Hickey K, et al. Effect of ß-blocking therapy on outcome in the Multicenter UnSustained Tachycardia Trial (MUSTT). Circulation. 2002;106:2694-2699.
Last reviewed Oct 31, 2002 by ]]>Richard Glickman-Simon, MD]]>
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