Conventional Treatment of Heart Attack

A heart attack is a medical emergency that demands immediate attention. The faster an individual is treated in the acute phase of a heart attack, the greater the ability to prevent further complications. As time passes, the risk of damage to the heart muscle increases. If an individual thinks they are having a heart attack based on the symptoms described, call 911 emergency immediately. Not seeking medical attention can cause serious damage to the heart muscle and even death.

First line treatment: After a heart attack victim is brought to the hospital, oxygen will be started, 160 - 325 milligrams of aspirin will be given immediately, nitroglycerin (which dilates blood vessels and allows more oxygen to the tissue) will be given under the tongue or intravenously (in the veins), and analgesia (usually morphine) will be given intravenously. In many areas, first responders can be trained to administer these prior to arrival at the hospital.

Thrombolytic therapy: Thrombolytic therapy, also known as clot busting, is indicated for the treatment of ST segment elevation myocardial infarction (STEMI). Clot busting is used if the drug can be administered within 12 hours of the onset of symptoms, the patient is eligible based on exclusion criteria, and primary percutaneous coronary intervention (PCI) is not immediately available. The effectiveness of thombolytic therapy is highest in the first two hours after a heart attack. Twelve hours after a heart attack, the risk associated with thrombolytic therapy, such as bleeding and stroke, outweighs any benefit. Because irreversible injury to the heart muscle occurs within two to four hours of the heart attack due to a lack of blood flow and oxygen, there is a limited window of time available for reperfusion to work.

Thrombolytic drugs are not used for the treatment of unstable angina, NSTEMI, and for the treatment of individuals with evidence of cardiogenic shock (primary failure of the ventricles of the heart to function effectively).

Currently available thrombolytic agents include streptokinase, urokinase, and tissue plasminogen activator (tPA or Alteplase ®). More recently, thrombolytic agents similar in structure to tPA such as reteplase (Retavase ®) and tenecteplase (TNKase ®) have been used. These newer agents are easier to administer than tPA. However, all these agents are very expensive. If tPA and related agents are used, other anticoagulation (blood thinning) with heparin or low molecular weight heparin is needed to keep the coronary artery open. Because urokinase and streptokinase have anticoagulant activity, heparin use is less necessary when using these thrombolytic agents.

Thrombolytic therapy is not always successful, and has a 10 - 20% failure rate. If the thrombolytic agent fails to open the infarct-related coronary artery, the patient is then either treated with anticoagulants or percutaneous coronary intervention (PCI) is then performed. Complications, particularly bleeding, are significantly higher with rescue PCI than with primary PCI due to the increase bleeding associated with the thrombolytic agent.

Percutaneous coronary intervention (PCI): The use of percutaneous coronary intervention as a therapy to stop a myocardial infarction (heart attack) is known as primary PCI. The goal of primary PCI is to open the artery as soon as possible, preferably within 90 minutes of the individual coming to the hospital. This time is referred to as the door-to-balloon time. Few hospitals can provide PCI within the 90 minute interval. The current guidelines in the United States restrict primary PCI to hospitals with available emergency bypass surgery as a backup, but this is not the case in other parts of the world. Primary PCI involves performing a coronary angiogram (injection of dye and then an X-ray to look at the blood vessels) to determine the location of the blocked vessel, followed by balloon angioplasty (the mechanical widening of a narrowed or totally obstructed blood vessel) and frequently deployment of a stent (an expandable wire mesh that is placed in a blocked coronary artery and opened - sometimes contains anticoagulant drugs). While the use of stents does not improve the short term outcomes in primary PCI, the use of stents is widespread because of the decreased rates of procedures to treat restenosis (re-clogging) compared to balloon angioplasty. Other therapies used during primary PCI include intravenous heparin, aspirin, or clopidogrel (Plavix ®).

Glycoprotein IIb/IIIa inhibitors: Glycoprotein IIb/IIIa receptors on platelets (cells of the clotting system) bind to fibrinogen in the final common pathway of platelet aggregation. Antagonists (opposing) to glycoprotein IIb/IIIa receptors are potent inhibitors of platelet aggregation, and drugs include abciximab (ReoPro ®), eptifibatide (Integrilin ®), and tirofiban (Aggrastat ®). The use of intravenous (IV) glycoprotein IIb/IIIa inhibitors during PCI and in patients with heart attack or acute coronary syndromes has been reported to reduce death and re-infarction (re-blockage). Side effects include an increase in bleeding.

Angiotensin converting enzyme inhibitors (ACE inhibitors): Oral angiotensin converting enzyme inhibitors (ACEI, such as lisinopril (Prinivil ®, Zestril ®)) dilate blood vessels and increase oxygen to the heart and are recommended in heart attack patients within the first 24 hours of symptom onset, if the individual can tolerate these drugs. Contra-indications to ACEI use include hypotension (low blood pressure) and declining kidney function with ACEI use. The use of an ACEI four to six weeks after a heart attack is recommended for patients with congestive heart failure, left ventricular dysfunction, hypertension (high blood pressure), or diabetes.

Coronary artery bypass graft surgery (CABG): Coronary artery bypass graft (CABG) surgery bypasses one or more blocked blood vessels by a blood vessel graft to restore normal blood flow to the heart. These grafts usually come from the patient's own arteries and veins located in the chest, leg, or arm. The graft goes around the clogged artery to create new pathways for oxygen-rich blood to flow to the heart. Some problems associated with CABG include a heart attack (occurs in 5% of patients), stroke (occurs in 5%, with the risk greatest in those over 70 years old), blood clots, death (occurs in 1-2% of individuals), and sternal wound infection (occurs in 1-4%). Infection is most often associated with obesity, diabetes, or having had a previous CABG. In about 30% of patients, "post-pericardiotomy syndrome" can occur anywhere from a few days to six months after surgery. The symptoms of this syndrome are fever and chest pain. This condition can be treated with medications. The incision in the chest or the graft site (if the graft was from the leg or arm) can be itchy, sore, numb, or bruised. Some individuals report memory loss and loss of mental clarity or "fuzzy thinking" following CABG.

Sometimes surgeons can perform open heart surgery without using a bypass pump and while the heart is beating (off-pump bypass surgery). The procedure causes fewer side effects than the standard procedure, but it is not practical in all situations. If just the front or right coronary arteries need bypass, a surgeon may replace the blocked artery with an artery from the chest via a small keyhole incision, without opening the chest, to detour the blockage (minimally invasive coronary bypass (MINI-CABS)). This procedure also decreases the many problems associated with conventional coronary artery bypass surgery.

Monitoring for arrhythmias: After a heart attack, monitoring for life-threatening arrhythmias (irregular heart beat) or conduction disturbances is performed in a coronary care unit in the hospital. The patient will be given a type of drug called an antiarrhythmic agent (such as amlodipine (Norvasc ®) or diltiazem (Cardizem ®)) if arrhythmias are found.

Rehabilitation: Cardiac rehabilitation is a medically supervised program to help heart patients recover quickly and improve their overall physical and mental functioning. Cardiac rehabilitation is performed to optimize function and quality of life in those afflicted with a heart disease. This can be with the help of a physician, or in the form of a cardiac rehabilitation program. Physical exercise may have beneficial effects on cholesterol, blood pressure, weight, and stress and is an important part of rehabilitation after a heart attack. An exercise program will be given to the patient by their health care provider. Some individuals are afraid to have sex after a heart attack. Most people can resume sexual activities after three to four weeks. The amount of activity needs to be determined by the patient's healthcare provider.

Secondary prevention: The risk of a recurrent myocardial infarction decreases with blood pressure management and lifestyle changes, including stopping smoking, regular exercise, a sensible diet (more fresh fruits and vegetables and a decrease in red meats, junk food, saturated and trans fats), and limitation of alcohol intake (no more than two drinks daily). Medications including nitrates, antiplatelet drugs (aspirin), beta blockers, angiotensin converting enzyme inhibitors (ACEI), and statins are used commonly after a heart attack.

Nitroglycerin: Sublingual (under the tongue, tablets or spray), oral, or topical (on the skin) nitrates are given to individuals after suffering a heart attack. Nitrates dilate (expand) blood vessels and allow more blood and oxygen to flow to heart tissue. When taken sublingually or intravenously, nitroglycerin works rapidly. Clinical trial data support the initial use of nitroglycerin for up to 48 hours in heart attack. There is little evidence that nitroglycerin provides substantive benefit as a long-term post-MI (after a heart attack) therapy except when severe pump dysfunction or residual ischemia (lack of blood flow and oxygen) is present. Nitrate tolerance (when nitrates no longer work as well) can be overcome either by increasing the dose or by providing a daily nitrate-free interval of 8 - 12 hours. Side effects include hypotension (low blood pressure) and headache.

Antiplatelet drug therapy: Antiplatelet drugs such as aspirin and/or clopidogrel (Plavix ®) should be continued to reduce the risk of plaque rupture and recurrent myocardial infarction. Aspirin is used for first-line treatment (meaning immediately) owing to its low cost and comparable efficacy (effectiveness), with clopidogrel reserved for patients intolerant of aspirin. The combination of clopidogrel and aspirin may further reduce risk of heart attack; however the risk of hemorrhage (bleeding) is increased. Side effects include many drug interactions and an increased risk of bleeding.

Beta blockers: Beta blocker therapy such as metoprolol (Lopressor ®, Toprol ®) or atenolol (Tenormin ®) should be started. These have been particularly beneficial in high-risk patients such as those with left ventricular dysfunction and/or continuing cardiac ischemia (lack of blood flow and oxygen). They also improve symptoms of cardiac ischemia (lack of oxygen and blood flow to the heart) in non-ST segment elevation (NSTEMI, a type of arrhythmia). Side effects associated with beta blockers include insomnia, loss of sexual drive, and tiredness (fatigue).

Angiotensin converting enzyme inhibitors (ACE inhibitors): ACE inhibitor therapy should be started 24 - 48 hours after a heart attack, particularly in patients with a history of heart attacks, diabetes mellitus, hypertension, anterior (front) location of infarct (blockage), and/or evidence of left ventricular dysfunction. ACE inhibitors reduce mortality, the development of heart failure, and decrease ventricular remodeling (changes in size and shape of heart valves) after the heart attack. Side effects of ACE inhibitors include hypotension (low blood pressure) and cough.

Statin drugs (HMG-CoA reductase inhibitors): Statins, such as atorvastatin (Lipitor ®) or lovastatin (Mevacor ®), help lower cholesterol levels and have been reported to reduce mortality and morbidity after a heart attack. Statin use may cause liver problems or muscle pain, and can deplete coenzyme Q10 (CoQ10) levels.

Other medications: The aldosterone antagonist agent eplerenone (Inspra ®) has been reported to further reduce risk of cardiovascular death after a heart attack in patients with heart failure and left ventricular dysfunction, when used in conjunction with standard therapies such as antiplatelet drugs and statins. Aldosterone is a hormone associated with sodium and potassium balance and fluid retention.

Fish oil: Omega-3 fatty acids, commonly found in cold water fish (such as salmon and halibut), have been reported to reduce death after a heart attack. However, further studies have not shown a clear-cut decrease in potentially fatal arrhythmias (irregular heart beat) due to omega-3 fatty acids. Fish oils may cause an increase in bleeding if taken with anti-platelet or anticoagulant medications.

Implantable cardiac defibrillators: Studies have found that Automatic Implantable Cardiac Defibrillators (AICD) in patients post-MI (after a heart attack) may be beneficial. A 31% risk reduction in all-cause mortality was found with the prophylactic (preventative) use of an AICD in patients post-MI with ejection fractions less than 30%. Cost therapy and benefits are weighed before a doctor uses this device.

Emerging therapies: Therapies in development for patients suffering from a heart attack include stem cell treatment and tissue engineering (growing healthy heart tissue).

Comments (0)