Heart Attack and Acute Coronary Syndrome

Description

Alternative Names

Other Treatments

In addition to thrombolytics, a number of agents are now available for use during a heart attack and for treating acute coronary syndrome. Some of these and other medications are also important for preventing either a first or a second heart attack.

Aspirin and Other Anti-Clotting Agents

Anti-clotting agents that inhibit or break up blood clots are used at every stage of heart disease. They are generally either anti-platelet agents or anticoagulants. Investigators are also studying combinations of anti-clotting agents, which may be useful in patients with severe heart disease. All anti-clotting therapies carry the risk of bleeding, which can lead to dangerous situations, including stroke.

Anti-platelet Drugs. These agents prevent formation of blood platelets. Platelets are very small disc-shaped blood cells that are important for blood-clotting.

• Aspirin. Aspirin is an antiplatelet agent. It is the most common anti-clotting drug and nearly anyone with heart disease is advised to take it daily in low dose.
• Glycoprotein IIb/IIIa Inhibitors. These potent blood-thinning agents include abciximab (ReoPro, Centocor), eptifibatide (Integrilin), tirofiban (Aggrastat), and lamifiban. They are administered intravenously in the hospital and are being used with angioplasty and stent placement. They are proving to be helpful for ACS patients with NSTEMI (non ST-segment elevation myocardial infarction) .
• Thienopyrindines. Clopidogrel (Plavix) and ticlopidine (Ticlid) are potent oral platelet inhibitors.

Anticoagulants. Anticoagulants help thin blood and include the following:

• Heparin. Standard, or unfractionated, heparin. Low-molecular weight heparin (LMWH), which include Enoxaparin (Lovenox), dalteparin (Fragmin), tinzaparin (Innohep).
• Warfarin (Coumadin).
• Direct thrombin inhibitors. They include argatroban (Novastan), danaproid (Orgaran), and lepirudin (Refludan)

How Anti-Clotting Agents Are Used in Heart Attack Patients. Unlike the thrombolytic (clot-busting) agents, which are used to break up blood clots during a heart attack, anti-clotting agents are used to prevent blood clots from forming in the first place. Such agents then may be used along with thrombolytics, immediately after a heart attack, and also as on-going maintenance to prevent a heart attack.

• The physician usually gives the patient heparin or aspirin, either alone or in combination with thrombolytic therapy. Aspirin should be given immediately, and heparin is usually started during or at the end of the thrombolytic infusion.
• Other agents, such as glycoprotein IIb/IIIa receptor antagonists, are being tested in combination with thrombolytic agents.

All these drugs pose a risk for bleeding.

Beta-Blockers

Beta-blockers reduce the oxygen demand of the heart by slowing the heart rate and lowering pressure in the arteries. They are now well known for reducing deaths from heart disease. They include propranolol (Inderal), carvedilol (Coreg), bisoprolol (Zebeta), acebutolol (Sectral), atenolol (Tenormin), labetalol (Normodyne, Trandate), metoprolol (Lopressor, Toprol-XL), and esmolol (Brevibloc).

Administration During a Heart Attack. Intravenous administration of beta-blockers (metoprolol or esmolol) within the first few hours of a heart attack can reduce the destruction of heart tissue. Evidence strongly supports a lower incidence of complications and better survival rates after a heart attack in patients who had been treated with a beta-blocker. In spite of this evidence, beta blockers are greatly underutilized. In one major New York center, for example, 72% of patients who could have benefited from them were not given these important agents after a heart attack.

Prevention After a Heart Attack. Beta-blockers are also important after a heart attack in preventing another heart attack. In fact, among elderly heart attack patients, those who do not use these agents afterward have a much poorer outcome.

Side Effects. Side effect include the following:

Some beta-blockers lower HDL cholesterol (the beneficial cholesterol) by about 10%. The effect is most marked in smokers. Fatigue and lethargy are the most common neurologic side effects. Some people experience vivid dreams and nightmares, depression, and memory loss. Exercise capacity may be reduced. Dizziness and lightheadedness, especially when getting up from a lying down position.

Other side effects may include cold extremities, asthma, decreased heart function, gastrointestinal problems (e.g., heartburn, gas, diarrhea, or constipation), and sexual dysfunction.

Because they can narrow bronchial airways and constrict blood vessels, patients with asthma, emphysema, and chronic bronchitis should avoid them whenever possible. They should not be used by patients with severe heart failure or severe AV block.

If side effects occur, the patient should call a physician, but it is extremely important not to stop the drug abruptly. Angina, heart attack, and even sudden death have occurred in patients who discontinued treatment without gradual withdrawal.

Statins and Other Cholesterol and Lipid-Lower Agents

In 2002, The National Cholesterol Education Program's Adult Treatment Panel issued its latest recommendations. The results of these guidelines would increase the number of Americans taking LDL-lowering agents from 15 million to 36 million, with significant increases occurring in people under 45 and over 65 years old and among men in all age groups. A number of agents are available for lowering cholesterol and other dangerous fat molecules (lipids). They include the following:

• Statins are now the standard agents for most people who require LDL-lowering therapy. Bile-acid binding resins or niacin may be considered. (Another LDL-lowering agent, probucol, is usually limited to people with genetic disorders that cause severely high cholesterol levels.) If LDL-goals are not achieved, combinations of a statin with a bile-acid resin such ezetimibe (Zetia) or niacin should be considered.
• Fibrates or niacin are beneficial for people who need to lower triglycerides and increase HDL.

[For more detailed information on other cholesterol-lowering agents and cholesterol in general see the Well-Connected Report, Cholesterol, Other Lipids, and Lipoproteins.]

Statins. Statins inhibit the liver enzyme HMG-CoA reductase, which is used in the manufacturing of cholesterol. They are the most effective drugs for the treatment of high cholesterol, and, according to a 2003 major analysis of over 200 studies, they reduce risk for heart events by 60% and stroke by 17%.

Two studies in 2002 and 2003, however, muddied these positive findings. In one, lowering moderately-high LDL cholesterol levels with a statin did not improve survival rates among high-risk patients. Some experts believe that statin treatment was not aggressive enough in this study. In the other 2003 study, however, cholesterol levels--whether high or low--had no effect on mortality rates among heart attack survivors over 65. More research is needed on these findings.

Still, most experts estimate a 25% or more reduction in mortality rates when patients take statins after a heart attack. They may even become important agents for many people at risk for heart disease who have normal cholesterol levels or below. In fact, the benefits of statins may go beyond simply improving cholesterol levels.

Statins include lovastatin (Mevacor), simvastatin (Zocor), and pravastatin (Pravachol). These are the most studied statins and have proven effectiveness and good safety record. Newer synthetic statins including fluvastatin (Lescol), atorvastatin (Lipitor), and rosuvastatin (Crestor) are proving to be very beneficial.

In many studies the side effects reported by statin users were nearly the same as those taking placebos (inactive agents). Those reported include gastrointestinal discomfort, headaches, skin rashes, muscle aches, sexual dysfunction, drowsiness, dizziness, nausea, constipation, and peripheral neuropathy (numbness or tingling in the hands and feet).

The primary safety concern with statins has involved an uncommon condition called myopathy, which can cause muscle damage and in some cases, muscle and joint pain. Severe cases of myopathy warrant discontinuation. Patients should tell their physicians about any unusual muscle discomfort or weakness and if their urine becomes brown-colored.

Statins also can effect the liver, particularly at higher doses, so periodic liver function tests should be administered.

Angiotensin Converting Enzyme Inhibitors

Angiotensin converting enzyme (ACE) inhibitors are important agents after a heart attack, particularly in patients at risk for heart failure. Taking an ACE inhibitor at the onset of a heart attack may, in fact, reduce the damage. These agents are commonly used to treat hypertension and are recommended as first-line treatment for people with diabetes and kidney damage, for some heart attack survivors, and for patients with heart failure.

ACE inhibitors include captopril (Capoten), ramipril (Altace), enalapril (Vasotec), quinapril (Accupril), benazepril (Lotensin), perindopril (Aceon), and lisinopril (Prinivil, Zestril).

Side Effects. Side effects of ACE inhibitors are uncommon but may include an irritating cough, excessive drops in blood pressure, and allergic reactions. Of great concern is research suggesting that aspirin interferes with ACE inhibitors (and other so-called NSAIDs) and increases the risk for heart failure in patients taking ACE inhibitors. An encouraging 2003 analysis, however, reported that ACE inhibitors still significantly reduced risks for adverse heart events, including hospitalizations for heart failure, regardless of whether or not the patients were also taking aspirin.

Magnesium

Magnesium has blood-thinning properties and may help open blood vessels. It is important to correct any magnesium deficiencies in heart attack patients (such as those who were on diuretics). For certain patients who cannot be given thrombolytic therapy, intravenous magnesium has been investigated. The most recent evidence suggests, however, that it offers no significant benefits for patients with heart attack.

Infection-Fighting Agents

Flu Shots. One study reported that influenza vaccinations might protect heart attack patients against another attack during flu season. And a 2002 study reported that flu shots given to patients who had angioplasty were associated with a significantly lower risk for death from heart events.

Antibiotics. Researchers have been investigating antibiotics for treating patients with heart disease and past infection of Chlamydia pneumoniae or H. pylori. Results have been mixed. In one large 2002 study, patients with heart attack or ACS were treated with amoxicillin or azithromycin, two common antibiotics, for a week. A year later they had a 40% lower risk for adverse heart events than those not given antibiotics--regardless of whether they had evidence of infection. Other small studies have also been positive. Some experts believe the protection from of antibiotics may be due to inflammatory effects--rather than anti-bacterial. Of note, some studies have found no protection for the heart from antibiotics.