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A Pharmacist's Guide to Atrial Fibrillation Atrial fibrillation (AF) is characterized by disorganized atrial depolarization from multiple reentrant circuits in the atria, resulting in a loss of atrial contraction. The atrial rate is usually about 400 -700 beats per minute, but the atrioventricular (AV) junction will not conduct all of these impulses to the ventricle. Consequently, the ventricular response is irregularly irregular and is usually about 100-160 beats per minute. Patients with AF may have symptoms such as palpitations, shortness of breath, fatigue, lightheadedness, syncope, and symptoms of congestive heart failure. Systemic embolization, particularly stroke, is a serious complication of AF. The risk of an embolic event is also high with conversion to sinus rhythm 0-20/0). Controlling Ventricular Response When a rapid ventricular response is associated with hemodynamic compromise or severe heart failure (e.g., in pulmonary edema), immediate direct-current cardioversion (DCC) is warranted. When ventricular response is rapid, with no severe hemodynamic compromise, agents that block the AV node should be used initially. The goals of therapy are to decrease the resting ventricular rate to 80 -100 beats per minute and to improve symptoms. Traditionally, intravenous (IV) digoxin has been the mainstay of therapy; however, its onset is slow (i.e. , hours), and, used alone, it is ineffective in some patients (e.g. , those with high adrenergic states). Alternatively, agents with a faster onset, such as N calcium-channel blockers (verapamil
Contributing authors: Ashesh j. Gandhi, PharmD, and j erry 1. Bauman, PharmD, FCCP, Departments of Pharmacy Practice and Medicine, Section of Cardiology, Un iversity of Illinois at Chicago.
This program was developed by
~
and
~5~P
and is supported by an educational grant from
3M Pharmaceuticals
or diltiazem) or beta-blockers (esmolol or metoproloD may be used. These agents can then be given orally w ith or without digoxin, depending on the ventricular resp onse. Cardioversion/Anticoagulation After pharmacologic control of ventricular rate has been achieved, patients with AF may be given elective cardioversion either pharmacologically (e.g., with oral quinidine or IV procainamide) or electrically (i.e ., through DCC). The current guidelines of the American College of Chest Physicians recommend that patients with AF of more than two days duration should be given anticoagulation therapy before elective cardioversion. Warfarin should be started at least three weeks before cardioversion, with a goal international normalized ratio (INR) of 2 to 3, and continued for four weeks after sinus rhythm has been achieved. The guidelines also recommend long-term anticoagulation therapy (INR of 2 to 3) as primary prevention of stroke in all patients with paroxysmal or chronic AF, except in patients with lone AF who are less than 60 years old. Patients who have been successfully cardioverted also need long-term anticoagulation therapy. In some patients with no risk factors for stroke, recent studies imply that aspirin may be just as effective as anticoagulants in preventing stroke, and with a lower risk of hemorrhagic side effects. Antiarrhythmic Therapy Some patients w ith recurrences of AF may benefit from long-term antiarrhythmic prophylactic therapy. Traditionally, the type IA agents, quinidine, procainamide, and disopyramide, have been used for long-term prevention of AF. However, several studies have implied that long-term quinidine therapy may be associated with an increase in mortality (presumably caused by proarrhythmia). These studies are controversial and require larger prospective trials. Other useful agents are the type IC agents, such as flecainide and propafenone, and the type III agents, such as amiodarone and sotalol. Chronic use of these agents has also been
questioned following the Cardiac Arrhythmia Suppression Trial (CAST), in which an increased incidence of mortality (again presumably secondary to proarrhythmia) was associated with use of these agents for suppression of frequent ventricular ectopy in patients w ho have experienced myocardial infarction. However, type IC agents can effectively prevent recurrences of AF, and the risk of proarrhythmia is low so long as patients do not have structural heart disease (particularly coronary artery disease) or poor left ventricular function. Sotalol, propafenone, and amiodarone lack approval from the Food and Drug Administratio n for treating AF, but they are commonly prescribed for this indication. Several trials have shown that low-dose amiodarone (200 mg once daily) is effective in preventing recurrences of AF and maintaining sinus rhythm. Major organ toxicity associated w ith low-dose amiodarone appears to be infrequent, but pulmonary, hepatic, and thyroid functions should be assessed at base line and every six months thereafter. Sotalol should be initiated cautiously w ith close monitoring of the heart rhythm because torsades de pointes is a relatively common adverse effect w ith its use. Generally, prophylactic antiarrhythmic agents are used for symptomatic recurrences of AF. Type IA agents are prescribed most frequently, if no contraindications exist. When patients develop intolerable adverse effects w ith type IA agents, then type IC agents may be used, but only in the absence of organic heart disease. In the presence of heart disease, type III agents may be used but with close monitoring and adequate follow-up. Alternatively, some patients may not be candidates for antiarrhythmic therapy or for cardioversion (e.g., those with AF of long duration, extensive organic heart disease, or intolerance to antiarrhythmiC drugs). These patients are forced to remain in AF and are given only medications that can control the ventricular rate, such as AV nodal blocking agents and long-term oral anticoagulants.
A Patient's Guide to Atrial Fibrillation What Is Atrial Fibrillation? The human heart is divided into two upper chambers, called the atria, and two lower chambers, called the ventricles. In the normal heart, electrical impulses originate from a tissue called the sinus node, which is located high in the right atrium. The atrioventricular (AV) node is a tissue that serves as a bridge or connection between the atria and ventricles. During normal sinus rhythm of the heart, electrical impulses travel from the sinus node to the atria, through the AV node, and into the ventricles. When the electrical impulse enters the ventricles, they simultaneously contract, allowing blood to flow to the brain and the rest of the body.
Atrial fibrillation is an abnormal heart rhythm during which the impulses do not originate from the sinus node but from the atrium. The impulses are fast, disorganized, and irregular, and so, the impulses that pass through the AV node and into the ventricles are also irregular. Thus, the heart rate is much faster than normal. In normal hearts, the ventricles beat about 60-80 times per minute, and in atrial fibrillation, the ventricles beat about 100-160 times per minute and sometimes faster. Because the ventricles beat at a faster rate than normal, the ventricles do not have time to contract completely and the blood flow to the rest of the body may be impaired. Symptoms Symptoms of atrial fibrillation are variable, and not all of them may be present. Symptoms include palpitations, shortness of breath, dizziness, and weakness. Some of these symptoms are not specific to atrial fibrillation and may be due to other types of abnormal heart rhythms or heart conditions. However, you should contact your doctor immediately if any of these symptoms occur. Failure to seek medical help c~n sometimes lead to serious consequences, such as stroke, heart attack, and heart failure. Treatment Many options are available for treating or controlling atrial fibrillation. Some of these options include methods to restore a normal rhythm.
If symptoms are not severe, medications can sometimes be given to slow down the heart rate. These medications do not necessarily convert the atrial fibrillation into a normal sinus rhythm, however; they work on the AV node and slow down the rate enough to improve the ventricles' ability to pump blood to the rest of the body. Some medications commonly used to slow down the heart rate are atenolol, digoxin, diltiazem, metoprolol, propranolol, and verapamil. Some of these medications are also used to lower blood pressure in patients with hypertension. Another method, called cardioversion, involves applying an electrical shock to the heart to reset the rhythm to normal, or giving medications through the vein to stop the abnormal rhythm. In either case, because of the risk of developing a stroke from the procedure, patients are often given blood thinners such as warfarin by mouth for three to four weeks before cardioversion and for four weeks after the procedure. In some patients, even after cardioversion, risk factors may be present for recurrence of atrial fibrillation. In these cases, medications known as antiarrhythmics must be given on a long-term basis to prevent recurrences. Some antiarrhythmic medications commonly used in atrial fibrillation are amiodarone, disopyramide, flecainide, procainamide, propafenone, quinidine, and sotalol. Atrial fibrillation is associated with a high incidence of blood clot formation (with or without cardioversion), which can lead to a stroke or blood clots in the lungs or legs. To prevent this, blood thinners such as warfarin are often given on a permanent basis. However, the risks and benefits of thinning the blood (anticoagulation therapy) must be assessed on an individual basis, and not every patient with atrial fibrillation is a candidate for anticoagulation therapy. Patients who cannot be given blood thinners may be prescribed aspirin, which can still prevent a stroke or blood clot formation.
Other treatment options include surgical procedures and ablation, which are usually used as a last resort when all other measures have failed. Compliance It is important to take your medications for atrial fibrillation as directed by your doctor and not to miss any doses. Discuss with both your doctor and pharmacist the medicines that have been prescribed for your atrial fibrillation, the type of response you should expect from them, and any adverse effects that you may experience. Missing doses of your medications can result in recurrence of fast heart rates, and symptoms may reappear. If you experience any more changes in your heart rate, such as extremely fast or slow heart beats, call your doctor. Extra doses of your medicine should not be taken without prior consultation with your doctor.
If warfarin has been prescribed for thinning your blood, keep the following information in mind:
• Warfarin must be taken daily in the doses prescribed. • Alcohol intake must be limited because alcohol may alter the effects of warfarin. • Aspirin and aspirin-containing products should be strictly avoided unless you are specifically told to take them by your doctor. Acetaminophen can be used instead for aches and pains. • Consult your physician or pharmacist before taking vitamins, especially vitamin K. • Your diet should not be changed drastically. • Any uncontrolled bleeding or bruising should be reported to your doctor at once. • It is important that you keep medical appointments to check how thin your blood is. Your blood is checked with a blood test called the PT/ INR. This test enables the doctor or pharmacist to determine if you need a higher or lower dose of warfarin, based on the rate at which your blood clots. • Tell every doctor, pharmacist, or dentist who is treating you that you are taking warfarin.
Contributing authors: Ashesh j. Gandhi, PharmD, and j erry 1. Bauman, PharmD, FCCP, Departments of Pharmacy Practice and Medicine, Section of Cardiology, Un iversity of Illinois at Chicago.
This program was developed by
~
and
~5~P
and is supported by an educational grant from
3M Pharmaceuticals
or diltiazem) or beta-blockers (esmolol or metoproloD may be used. These agents can then be given orally w ith or without digoxin, depending on the ventricular resp onse. Cardioversion/Anticoagulation After pharmacologic control of ventricular rate has been achieved, patients with AF may be given elective cardioversion either pharmacologically (e.g., with oral quinidine or IV procainamide) or electrically (i.e ., through DCC). The current guidelines of the American College of Chest Physicians recommend that patients with AF of more than two days duration should be given anticoagulation therapy before elective cardioversion. Warfarin should be started at least three weeks before cardioversion, with a goal international normalized ratio (INR) of 2 to 3, and continued for four weeks after sinus rhythm has been achieved. The guidelines also recommend long-term anticoagulation therapy (INR of 2 to 3) as primary prevention of stroke in all patients with paroxysmal or chronic AF, except in patients with lone AF who are less than 60 years old. Patients who have been successfully cardioverted also need long-term anticoagulation therapy. In some patients with no risk factors for stroke, recent studies imply that aspirin may be just as effective as anticoagulants in preventing stroke, and with a lower risk of hemorrhagic side effects. Antiarrhythmic Therapy Some patients w ith recurrences of AF may benefit from long-term antiarrhythmic prophylactic therapy. Traditionally, the type IA agents, quinidine, procainamide, and disopyramide, have been used for long-term prevention of AF. However, several studies have implied that long-term quinidine therapy may be associated with an increase in mortality (presumably caused by proarrhythmia). These studies are controversial and require larger prospective trials. Other useful agents are the type IC agents, such as flecainide and propafenone, and the type III agents, such as amiodarone and sotalol. Chronic use of these agents has also been
questioned following the Cardiac Arrhythmia Suppression Trial (CAST), in which an increased incidence of mortality (again presumably secondary to proarrhythmia) was associated with use of these agents for suppression of frequent ventricular ectopy in patients w ho have experienced myocardial infarction. However, type IC agents can effectively prevent recurrences of AF, and the risk of proarrhythmia is low so long as patients do not have structural heart disease (particularly coronary artery disease) or poor left ventricular function. Sotalol, propafenone, and amiodarone lack approval from the Food and Drug Administratio n for treating AF, but they are commonly prescribed for this indication. Several trials have shown that low-dose amiodarone (200 mg once daily) is effective in preventing recurrences of AF and maintaining sinus rhythm. Major organ toxicity associated w ith low-dose amiodarone appears to be infrequent, but pulmonary, hepatic, and thyroid functions should be assessed at base line and every six months thereafter. Sotalol should be initiated cautiously w ith close monitoring of the heart rhythm because torsades de pointes is a relatively common adverse effect w ith its use. Generally, prophylactic antiarrhythmic agents are used for symptomatic recurrences of AF. Type IA agents are prescribed most frequently, if no contraindications exist. When patients develop intolerable adverse effects w ith type IA agents, then type IC agents may be used, but only in the absence of organic heart disease. In the presence of heart disease, type III agents may be used but with close monitoring and adequate follow-up. Alternatively, some patients may not be candidates for antiarrhythmic therapy or for cardioversion (e.g., those with AF of long duration, extensive organic heart disease, or intolerance to antiarrhythmiC drugs). These patients are forced to remain in AF and are given only medications that can control the ventricular rate, such as AV nodal blocking agents and long-term oral anticoagulants.
A Patient's Guide to Atrial Fibrillation What Is Atrial Fibrillation? The human heart is divided into two upper chambers, called the atria, and two lower chambers, called the ventricles. In the normal heart, electrical impulses originate from a tissue called the sinus node, which is located high in the right atrium. The atrioventricular (AV) node is a tissue that serves as a bridge or connection between the atria and ventricles. During normal sinus rhythm of the heart, electrical impulses travel from the sinus node to the atria, through the AV node, and into the ventricles. When the electrical impulse enters the ventricles, they simultaneously contract, allowing blood to flow to the brain and the rest of the body.
Atrial fibrillation is an abnormal heart rhythm during which the impulses do not originate from the sinus node but from the atrium. The impulses are fast, disorganized, and irregular, and so, the impulses that pass through the AV node and into the ventricles are also irregular. Thus, the heart rate is much faster than normal. In normal hearts, the ventricles beat about 60-80 times per minute, and in atrial fibrillation, the ventricles beat about 100-160 times per minute and sometimes faster. Because the ventricles beat at a faster rate than normal, the ventricles do not have time to contract completely and the blood flow to the rest of the body may be impaired. Symptoms Symptoms of atrial fibrillation are variable, and not all of them may be present. Symptoms include palpitations, shortness of breath, dizziness, and weakness. Some of these symptoms are not specific to atrial fibrillation and may be due to other types of abnormal heart rhythms or heart conditions. However, you should contact your doctor immediately if any of these symptoms occur. Failure to seek medical help c~n sometimes lead to serious consequences, such as stroke, heart attack, and heart failure. Treatment Many options are available for treating or controlling atrial fibrillation. Some of these options include methods to restore a normal rhythm.
If symptoms are not severe, medications can sometimes be given to slow down the heart rate. These medications do not necessarily convert the atrial fibrillation into a normal sinus rhythm, however; they work on the AV node and slow down the rate enough to improve the ventricles' ability to pump blood to the rest of the body. Some medications commonly used to slow down the heart rate are atenolol, digoxin, diltiazem, metoprolol, propranolol, and verapamil. Some of these medications are also used to lower blood pressure in patients with hypertension. Another method, called cardioversion, involves applying an electrical shock to the heart to reset the rhythm to normal, or giving medications through the vein to stop the abnormal rhythm. In either case, because of the risk of developing a stroke from the procedure, patients are often given blood thinners such as warfarin by mouth for three to four weeks before cardioversion and for four weeks after the procedure. In some patients, even after cardioversion, risk factors may be present for recurrence of atrial fibrillation. In these cases, medications known as antiarrhythmics must be given on a long-term basis to prevent recurrences. Some antiarrhythmic medications commonly used in atrial fibrillation are amiodarone, disopyramide, flecainide, procainamide, propafenone, quinidine, and sotalol. Atrial fibrillation is associated with a high incidence of blood clot formation (with or without cardioversion), which can lead to a stroke or blood clots in the lungs or legs. To prevent this, blood thinners such as warfarin are often given on a permanent basis. However, the risks and benefits of thinning the blood (anticoagulation therapy) must be assessed on an individual basis, and not every patient with atrial fibrillation is a candidate for anticoagulation therapy. Patients who cannot be given blood thinners may be prescribed aspirin, which can still prevent a stroke or blood clot formation.
Other treatment options include surgical procedures and ablation, which are usually used as a last resort when all other measures have failed. Compliance It is important to take your medications for atrial fibrillation as directed by your doctor and not to miss any doses. Discuss with both your doctor and pharmacist the medicines that have been prescribed for your atrial fibrillation, the type of response you should expect from them, and any adverse effects that you may experience. Missing doses of your medications can result in recurrence of fast heart rates, and symptoms may reappear. If you experience any more changes in your heart rate, such as extremely fast or slow heart beats, call your doctor. Extra doses of your medicine should not be taken without prior consultation with your doctor.
If warfarin has been prescribed for thinning your blood, keep the following information in mind:
• Warfarin must be taken daily in the doses prescribed. • Alcohol intake must be limited because alcohol may alter the effects of warfarin. • Aspirin and aspirin-containing products should be strictly avoided unless you are specifically told to take them by your doctor. Acetaminophen can be used instead for aches and pains. • Consult your physician or pharmacist before taking vitamins, especially vitamin K. • Your diet should not be changed drastically. • Any uncontrolled bleeding or bruising should be reported to your doctor at once. • It is important that you keep medical appointments to check how thin your blood is. Your blood is checked with a blood test called the PT/ INR. This test enables the doctor or pharmacist to determine if you need a higher or lower dose of warfarin, based on the rate at which your blood clots. • Tell every doctor, pharmacist, or dentist who is treating you that you are taking warfarin.