Heart Attack and Acute Coronary Syndrome

Description

Alternative Names

Treatment

Patients with heart disease or those with risk factors should seek emergency medical help immediately if they have any signs or symptoms of an attack. Early treatment is critical for recovery.

When a patient arrives at the hospital with a possible heart attack the patient is given an electrocardiogram within 10 minutes and put on constant monitoring. Blood and other tests are taken to determine the condition.

Treatment options will depend on whether the patient has angina, acute coronary syndromes, or a full-blown heart attack.

Patients who are diagnosed with acute coronary syndrome (ACS) may be at risk for a full-flown heart attack. ACS refers to either unstable angina or NSTEMI (non ST-segment elevation myocardial infarction). Unstable angina is potentially serious and chest pain is persistent, but blood tests do not show markers for heart attack. With NSTEMI, the blood tests suggest a developing heart attack, but most likely, injury in the arteries is less serious than with a full-blown heart attack.

Physicians use a patient's medical history, a number of tests, and the presence of a certain factors to help predict which ACS patients are most at risk for developing a more serious condition. Of note, the degree of chest pain itself is not necessarily useful for determining the actual damage in the heart.

Depending on how severe the condition is, the patient is then given either medical treatments or more invasive approaches, such as angioplasty. Some experts believe that, even if patients with ACS are only given drug therapy, they should still be transferred to centers equipped for angioplasty.

Immediate Treatments to Support the Patient

Early supportive treatments are similar for both ACS and heart attack patients.

Oxygen. Oxygen is almost always administered right away, usually through a tube that enters through the nose. The patient is given aspirin if one was not taken at home.

Transfusions. A 2001 study suggested that giving transfusions to elderly heart attack patients with even mild anemia improved short-term survival rates.

Medications for Relieving Symptoms.

• Nitroglycerin. Most heart attack patients will usually receive nitroglycerin, usually under the tongue. Nitroglycerin decreases blood pressure and dilates the blood vessels around the heart, increasing blood flow. Nitroglycerin may be given intravenously in certain cases (e.g., those with recurrent angina, congestive heart failure, or high blood pressure). There is some evidence suggesting that intravenous administration may help reduce long-term heart muscle changes that can occur after a heart attack. (Patients with very low blood pressure or severely slow heart rate will not receive nitroglycerin.)
• Morphine. Morphine not only relieves pain and reduces anxiety but it also dilates blood vessels, thereby aiding the circulation of blood and oxygen to the heart. Morphine can decrease blood pressure and slow down the heart. In certain patients where such conditions can worsen their heart attacks, other drugs such as meperidine (Demerol) or nalbuphine (Nubain) may be used.

Anti-Clotting Medications. Appropriate anti-clotting medications are started immediately in all patients.

• Aspirin is given immediately unless the patient had taken aspirin before entering the hospital. It is continued afterward indefinitely.
• Clopidogrel (a more potent anti-platelet agent) is usually added and continued for one to nine months afterward. It is sometimes used in place of aspirin.
• Heparin is generally administered to moderate to high-risk patients. Low-molecular weight heparin (LMWH), such as enoxaparin, is now recommended over standard heparin.
• Glycoprotein IIb/IIIa inhibitors, most often tirofiban, are added for patients undergoing angioplasty. Some studies also suggest that they might be beneficial in some nonsurgical patients with ACS, notably NSTEMI (non ST-segment elevation myocardial infarction).

Opening the Arteries: Thrombolytic Drugs or Emergency Angioplasty (PTCA)

After a heart attack, clots form in the injured artery within four to six hours in 90% of heart attack victims. Opening a clotted artery as quickly as possible is the best approach to improving survival.

The standard medical and surgical solutions for opening arteries are the following.

• Angioplasty, also called percutaneous transluminal coronary angioplasty (PTCA), is the major surgical procedure for opening the arteries.
• Thrombolytics are known as blood-clot-busting drugs and are the standard medications used to open the arteries. They are administered as soon as possible in centers where angioplasty is not available or in patients who are not good candidates for angioplasty.

Some studies suggest that a combination of early administration of a thrombolytic followed by angioplasty may have significant benefits for many patients, but such an approach is not routine.

The best candidates for either thrombolytic therapy or angioplasty are the following:

• Adults younger than 75 years old with elevated ST segments or indications of bundle branch block (an ECG reading showing an interruption in the electrical pathway within the heart).
• Symptoms occurred within 12 hours.

Specific Candidates for Emergency Angioplasty. If it is available, most patients--both men and women--who meet the criteria for either thrombolytic drugs or angioplasty would do better with angioplasty (although only in centers equipped to do this procedure). In fact, in a 2002 study, survival rates at one year were better in women who had had angioplasty than in men. Of concern, however, was another 2002 study reporting that angioplasty rates were 7% lower in women than in men. African Americans--both men and women--were also less likely to be given angioplasty than Caucasian men. These groups are slightly more likely to refuse the procedure than Caucasian men, but this does not explain the wide discrepancy. The reasons for these lower rates require investigation.

Other specific candidates who might be good candidates for angioplasty include the following:

• Elderly patients--even those over 75-- who meet the criteria for both approaches tend to do better with angioplasty than thrombolytic therapy.
• Patients with diabetes who meet the criteria for both approaches.
• Patients under age 75 who go into shock and when angioplasty can be performed within 18 hours of shock. (There is no advantage for patients over 75 who are in shock.)
• There is some evidence to suggest that patients with heart failure may do better with angioplasty than with thrombolytics, but more studies are needed to determine this.

As with thrombolytic treatments, angioplasty is most effective when performed within 12 hours of symptoms, and the sooner the better. Unfortunately not all communities have centers experienced in the procedure. The experience of the medical center's staff is critical for optimal benefits, and not all surgeons are experienced in angioplasty. However, the procedure is becoming increasingly available and overall mortality rates are improving over time with angioplasty. Patients or their families should be sure their surgeon has performed at least 75 of these procedures and that the medical center has performed at least 200.

Specific Candidates or Non-Candidates for Thrombolytics. People who meet the criteria for either thrombolytics or angioplasty may benefit from thrombolytic drugs even if they have certain high-risk conditions that include diabetes, systolic blood pressure less than 180 mm Hg, any heart rate, or a history of heart attack.

A number of studies report that women do worse after thrombolytic therapy. Evidence indicates, however, that they are generally older with more serious medical conditions when they seek treatment. One study also reported that women were given these drugs an average of 14 minutes later than men were. Women on thrombolytic therapy still do better than those not given these drugs. The bottom line is that thrombolytic therapy is life saving, and appropriate candidates, regardless of age or gender, should not be denied this therapy.

The use of thrombolytics in the following patients should be avoided or used with great caution:

• People older than 75. A 2000 study suggested that their risk of death was 38% higher than patients in their age group who were not given therapy. A higher risk exists in such older patients even if they are otherwise healthy.
• Patients with elevated ST segments whose symptoms have continued beyond 12 hours.
• Pregnant women.
• People who have experienced recent trauma (especially head injury) or invasive surgery.
• People with active peptic ulcers.
• Patients who have been given prolonged CPR.
• Current users of anticoagulants

Thrombolytics should not be used in the following patients:

• Patients who have experienced any recent major bleeding.
• Patients with depressed ST segments.
• Patients with a history of stroke. (Selected patients whose strokes occurred far in the past may be able to benefit from these drugs, but more research is needed to confirm this.)
• Patients with uncontrolled high blood pressure.

Other Heart Supportive Agents

After a heart attack, the patient may need a number of different medications, depending on their risk factors for a future heart attack:

• Beta-blockers reduce the oxygen demand of the heart by slowing the heart rate and lowering arterial pressure. Intravenous administration of beta-blockers (metoprolol or esmolol) within the first few hours of a heart attack can reduce the destruction of heart tissue. Oral agents may be sufficient for some patients with unstable angina.
• Angiotensin converting enzyme (ACE) inhibitors should be given on the first day to all patients, unless there are medical reasons for not taking them.
• Calcium channel blockers may provide relief in patients with unstable angina whose symptoms do not respond to nitrates and beta blockers. They are also useful for patients with Prinzmetal's angina.
• Statins. Statins are important cholesterol lowering agents that are beneficial for heart attack patients and may have heart-protective properties that go beyond lowering cholesterol. Of interest, however, was a 2003 study suggesting that cholesterol levels--whether high or low--had no effect on mortality rates among heart attack survivors over 65. More research is needed.
• Atropine. Atropine may be given for a very low heart rate (bradycardia) or signs of atrioventricular (AV) block, in which electric conduction of nerve impulses to specialized muscles in the heart is slowed or interrupted.

Treatment for Patients in Shock or with Congestive Heart Failure

Severely ill patients, particularly those in shock (a dangerous condition that includes a drop in blood pressure and other abnormalities) or with congestive heart failure, will be monitored closely and stabilized. Oxygen is administered, and fluids are given or replaced when it is appropriate to either increase or reduce blood pressure. Such patients may be given dopamine, dobutamine, or both. Other treatments depend on the specific condition.

Heart failure. Intravenous furosemide may be administered. Patients may also be given nitrates, and ACE inhibitors, unless they have a severe drop in blood pressure or other conditions that preclude them. Clot-busting drugs or angioplasty may be appropriate and life-saving in many of these patients, although they are less likely to be given these treatments. (A 2003 study suggested that drugs may be more beneficial in this group, but more research is needed to confirm this.)

Shock. A procedure called intra-aortic balloon counterpulsation (IABP) is proving to help these patients when used in combination with thrombolytic therapy. IABP involves inserting a catheter containing a balloon, which is inflated and deflated within the artery to boost blood pressure. Left ventricular assist devices and early angioplasty might be considered.

Treatment of Arrhythmias

An arrhythmia is a deviation from the hearts normal beating pattern caused when the heart muscle is deprived of oxygen and is a dangerous side effect of a heart attack. A very fast or slow rhythmic heart rate often occurs in heart attack patients and is not usually a dangerous sign.

Premature beats or very fast arrhythmias called tachycardia, however, may be predictors of ventricular fibrillation. This is a lethal rhythm abnormality, in which the ventricles of the heart beat so rapidly that they do not actually contract but quiver ineffectually. The pumping action necessary to keep blood circulating is lost.

Preventing Ventricular Fibrillation. People who develop ventricular fibrillation do not always experience warning arrhythmias, and to date, there are no effective agents for preventing arrhythmias during a heart attack.

• Potassium and magnesium levels should be monitored and maintained.
• Intravenous beta-blockers followed by oral administration of the drugs may help prevent arrhythmias in certain patients.

Treating Ventricular Fibrillation.

• Defibrillators. Patients who develop ventricular arrhythmias are given electrical shocks with defibrillators to restore normal rhythms. Some studies suggest that implantable cardioverter-defibrillators may prevent further arrhythmias in heart attack survivors of these events who are at risk for further arrhythmias. At this time, however, their use is investigative in these patients.
• Antiarrhythmic Agents. Antiarrhythmic drugs include lidocaine, procainamide, or amiodarone. Amiodarone or another antiarrhythmic drug may be used afterward to prevent future events.

Managing Other Arrhythmias. People with an arrhythmia called atrial fibrillation have a higher risk for stroke after a heart attack and should be treated very aggressively. Other rhythm disturbances called bradyarrhythmias (very slow rhythm disturbances) frequently develop in association with a heart attack and may be treated with atropine or pacemakers.