Management of Atrial Fibrillation Talal Moukabary,
MD,
Mario D. Gonzalez,
MD*
KEYWORDS Atrial fibrillation Ventricular rate Sinus rhythm Thromboembolism Catheter ablation Antiarrhythmic drugs KEY POINTS Management of atrial fibrillation includes the management of its risk factors and the underlying cardiac disease, prevention of thromboembolism, control of ventricular rate during atrial fibrillation, and restoration and maintenance of sinus rhythm. Prevention of thromboembolism should always be individualized to each patient. Control of ventricular rate during atrial fibrillation is essential for all patients. Restoration and maintenance of sinus rhythm are done through antiarrhythmic drug therapy, cardioversion, and catheter or surgical ablation.
INTRODUCTION
Atrial fibrillation (AF) is a very common clinical problem affecting more than 2.3 million US adults.1 This high prevalence is expected to rise over time because of increasing risk factors (age, obesity, hypertension, and so forth).1 About 35% of patients who are older than 80 years have AF.2 This high prevalence is also associated with high cost because AF represents about 1% of overall health care spending.3 MANAGEMENT OF ATRIAL FIBRILLATION
The management of AF involves multiple facets: (1) management of underlying disease if present and the management of AF risk factors, (2) prevention of thromboembolism, (3) control of the ventricular rate during AF (rate control), and (4) restoration and maintenance of normal sinus rhythm (rhythm control). MANAGEMENT OF THE UNDERLYING DISEASE AND RISK FACTORS
Management includes the treatment of modifiable predisposing or exacerbating factors including hypertension, obesity, heart failure, sleep apnea, and hyperthyroidism.
Clinical Electrophysiology, Penn State Heart and Vascular Institute, Milton S. Hershey Medical Center, Penn State University, 500 University Drive, Hershey, PA 17033, USA * Corresponding author. E-mail address: [email protected] Med Clin N Am 99 (2015) 781–794 http://dx.doi.org/10.1016/j.mcna.2015.02.007 medical.theclinics.com 0025-7125/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
782
Moukabary & Gonzalez
PREVENTION OF THROMBOEMBOLISM
Thromboembolism and stroke can have lethal or devastating consequences. This issue needs to be addressed in every patient with appropriate measures taken. The first step is assessment of the risk of thromboembolism. This risk is used to individualize the recommended therapy, and is based on clinical characteristics and not on whether AF is paroxysmal or persistent and regardless of whether or not AF is symptomatic.2 The following recommendations regarding anticoagulation for stroke and thromboembolism prevention are made in patients who have no contraindication for such therapy. Patients who have mechanical heart valves should be anticoagulated with warfarin.2 Target international normalized ratio is 2 to 3 or 2.5 to 3.5 depending on valve type and location.4 Patients who have nonvalvular AF should be assessed using the CHA2DS2-VASc scoring system (Table 1).5 Patients who have a CHA2DS2-VASc score of 2 or more should be considered for anticoagulation for stroke and thromboembolism prevention. This can be performed using warfarin therapy or with use of a direct thrombin or factor Xa inhibitor (dabigatran, rivaroxaban, or apixaban). Renal function is a major factor in choosing an agent for anticoagulation for stroke and thromboembolism prevention. Patients with end-stage renal disease are usually anticoagulated with warfarin. Patients who have a CHA2DS2-VASc score of 1 may be treated with aspirin or warfarin or a direct thrombin or factor Xa inhibitor (dabigatran, rivaroxaban, or apixaban).2 In patients who have a CHA2DS2-VASc score of zero it is reasonable not to use antithrombotic drug therapy. Aspirin is usually prescribed as 325 mg by mouth daily, which is the dose that was used in the Stroke Prevention in Atrial Fibrillation trial.6 This is the only study that showed benefit for aspirin alone in stroke prevention in patients with AF.2 Before prescribing aspirin, it is important to review the result of the Apixaban Versus Acetylsalicylic Acid to Prevent Strokes study,7 which compared apixaban with aspirin in patients for whom vitamin K antagonist therapy was unsuitable. The study was prematurely terminated given the superiority of apixaban over aspirin in preventing stroke or systemic embolism, even though apixaban and aspirin had similar risk of major bleeding.7 When selecting the anticoagulant type and its dose it is critical to assess renal function and assess possible drug interactions. For an overview of the newer oral anticoagulants see Table 2.
Table 1 CHA2DS2-VASc scoring system for assessing thromboembolic risk in patients with nonvalvular atrial fibrillation CHA2DS2-VASc Acronym
Score Points
Congestive heart failure
1
Hypertension
1
Age >75 y
2
Diabetes mellitus
1
Stroke/transient ischemic attack/thromboembolism
2
Vascular disease (prior myocardial infarction, peripheral vascular disease, aortic plaque)
1
Age 65–74 y
1
Sex category (ie, female sex)
1
Management of Atrial Fibrillation
Table 2 The newer oral anticoagulants Typical Dosea
Anticoagulant
Mechanism of Action
Dabigatran
Direct thrombin inhibitor
150 mg BID
Rivaroxaban
Direct factor Xa inhibitor
20 mg daily
Apixaban
Direct factor Xa inhibitor
5 or 2.5 mg BIDb
a
Typical dose for patients with normal renal function. Use apixaban 2.5 mg BID if any two patient characteristics present: creatinie 1.5 mg/dL, 80 y of age, body weight 60 kg. b
Nonpharmacologic therapy for stroke and thromboembolism prevention involves left atrial appendage occlusion and excision. Percutaneous left atrial appendage occlusion can be performed using such devices as the WATCHMAN (Boston Scientific, Marlborough, MA). This device was shown to be noninferior compared with warfarin in patients who cannot receive warfarin.8 Surgical excision of the left atrial appendage is usually performed for patients undergoing cardiac surgery for other indications.2 RATE CONTROL
Control of ventricular rate is an essential consideration in all patients with AF. Few patients do not need specific therapy for the control of ventricular rate during AF. This is usually related to an associated cardiac conduction system disease. This group of patients should be monitored because the progression of this conduction system disease may lead to symptomatic bradycardia. It is not uncommon to see patients who have rapid ventricular rate during AF along with bradycardia during sinus rhythm caused by associated sinus node dysfunction. This is usually termed “tachycardia-bradycardia syndrome.” However, the bradycardia that ensues after spontaneous or induced termination of AF may represent a transient functional sinus node dysfunction. If rhythm control of AF is not possible, some patients may require pacemaker therapy to avoid bradycardia and allow the use of rate control pharmacotherapy. The target ventricular rate during AF was traditionally defined as having an average heart rate at rest less than or equal to 80 beats per minute and a maximum heart rate during a 6-minute walk test less than or equal to 110 beats per minute, or an average heart rate during 24-hour ambulatory electrocardiographic Holter monitoring less than or equal to 100 beats per minute (with no heart rate >110% maximum predicted ageadjusted exercise heart rate). This comes from the AFFIRM trial that showed that the management of AF with the rhythm-control strategy offers no survival advantage over the rate-control strategy.9,10 More recent data show that a more lenient strategy rate control (resting heart rate 48 h
High
Minimum of 3 wka
Long term
Duration of Atrial Fibrillation
MD,
Mario D. Gonzalez,
MD*
KEYWORDS Atrial fibrillation Ventricular rate Sinus rhythm Thromboembolism Catheter ablation Antiarrhythmic drugs KEY POINTS Management of atrial fibrillation includes the management of its risk factors and the underlying cardiac disease, prevention of thromboembolism, control of ventricular rate during atrial fibrillation, and restoration and maintenance of sinus rhythm. Prevention of thromboembolism should always be individualized to each patient. Control of ventricular rate during atrial fibrillation is essential for all patients. Restoration and maintenance of sinus rhythm are done through antiarrhythmic drug therapy, cardioversion, and catheter or surgical ablation.
INTRODUCTION
Atrial fibrillation (AF) is a very common clinical problem affecting more than 2.3 million US adults.1 This high prevalence is expected to rise over time because of increasing risk factors (age, obesity, hypertension, and so forth).1 About 35% of patients who are older than 80 years have AF.2 This high prevalence is also associated with high cost because AF represents about 1% of overall health care spending.3 MANAGEMENT OF ATRIAL FIBRILLATION
The management of AF involves multiple facets: (1) management of underlying disease if present and the management of AF risk factors, (2) prevention of thromboembolism, (3) control of the ventricular rate during AF (rate control), and (4) restoration and maintenance of normal sinus rhythm (rhythm control). MANAGEMENT OF THE UNDERLYING DISEASE AND RISK FACTORS
Management includes the treatment of modifiable predisposing or exacerbating factors including hypertension, obesity, heart failure, sleep apnea, and hyperthyroidism.
Clinical Electrophysiology, Penn State Heart and Vascular Institute, Milton S. Hershey Medical Center, Penn State University, 500 University Drive, Hershey, PA 17033, USA * Corresponding author. E-mail address: [email protected] Med Clin N Am 99 (2015) 781–794 http://dx.doi.org/10.1016/j.mcna.2015.02.007 medical.theclinics.com 0025-7125/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
782
Moukabary & Gonzalez
PREVENTION OF THROMBOEMBOLISM
Thromboembolism and stroke can have lethal or devastating consequences. This issue needs to be addressed in every patient with appropriate measures taken. The first step is assessment of the risk of thromboembolism. This risk is used to individualize the recommended therapy, and is based on clinical characteristics and not on whether AF is paroxysmal or persistent and regardless of whether or not AF is symptomatic.2 The following recommendations regarding anticoagulation for stroke and thromboembolism prevention are made in patients who have no contraindication for such therapy. Patients who have mechanical heart valves should be anticoagulated with warfarin.2 Target international normalized ratio is 2 to 3 or 2.5 to 3.5 depending on valve type and location.4 Patients who have nonvalvular AF should be assessed using the CHA2DS2-VASc scoring system (Table 1).5 Patients who have a CHA2DS2-VASc score of 2 or more should be considered for anticoagulation for stroke and thromboembolism prevention. This can be performed using warfarin therapy or with use of a direct thrombin or factor Xa inhibitor (dabigatran, rivaroxaban, or apixaban). Renal function is a major factor in choosing an agent for anticoagulation for stroke and thromboembolism prevention. Patients with end-stage renal disease are usually anticoagulated with warfarin. Patients who have a CHA2DS2-VASc score of 1 may be treated with aspirin or warfarin or a direct thrombin or factor Xa inhibitor (dabigatran, rivaroxaban, or apixaban).2 In patients who have a CHA2DS2-VASc score of zero it is reasonable not to use antithrombotic drug therapy. Aspirin is usually prescribed as 325 mg by mouth daily, which is the dose that was used in the Stroke Prevention in Atrial Fibrillation trial.6 This is the only study that showed benefit for aspirin alone in stroke prevention in patients with AF.2 Before prescribing aspirin, it is important to review the result of the Apixaban Versus Acetylsalicylic Acid to Prevent Strokes study,7 which compared apixaban with aspirin in patients for whom vitamin K antagonist therapy was unsuitable. The study was prematurely terminated given the superiority of apixaban over aspirin in preventing stroke or systemic embolism, even though apixaban and aspirin had similar risk of major bleeding.7 When selecting the anticoagulant type and its dose it is critical to assess renal function and assess possible drug interactions. For an overview of the newer oral anticoagulants see Table 2.
Table 1 CHA2DS2-VASc scoring system for assessing thromboembolic risk in patients with nonvalvular atrial fibrillation CHA2DS2-VASc Acronym
Score Points
Congestive heart failure
1
Hypertension
1
Age >75 y
2
Diabetes mellitus
1
Stroke/transient ischemic attack/thromboembolism
2
Vascular disease (prior myocardial infarction, peripheral vascular disease, aortic plaque)
1
Age 65–74 y
1
Sex category (ie, female sex)
1
Management of Atrial Fibrillation
Table 2 The newer oral anticoagulants Typical Dosea
Anticoagulant
Mechanism of Action
Dabigatran
Direct thrombin inhibitor
150 mg BID
Rivaroxaban
Direct factor Xa inhibitor
20 mg daily
Apixaban
Direct factor Xa inhibitor
5 or 2.5 mg BIDb
a
Typical dose for patients with normal renal function. Use apixaban 2.5 mg BID if any two patient characteristics present: creatinie 1.5 mg/dL, 80 y of age, body weight 60 kg. b
Nonpharmacologic therapy for stroke and thromboembolism prevention involves left atrial appendage occlusion and excision. Percutaneous left atrial appendage occlusion can be performed using such devices as the WATCHMAN (Boston Scientific, Marlborough, MA). This device was shown to be noninferior compared with warfarin in patients who cannot receive warfarin.8 Surgical excision of the left atrial appendage is usually performed for patients undergoing cardiac surgery for other indications.2 RATE CONTROL
Control of ventricular rate is an essential consideration in all patients with AF. Few patients do not need specific therapy for the control of ventricular rate during AF. This is usually related to an associated cardiac conduction system disease. This group of patients should be monitored because the progression of this conduction system disease may lead to symptomatic bradycardia. It is not uncommon to see patients who have rapid ventricular rate during AF along with bradycardia during sinus rhythm caused by associated sinus node dysfunction. This is usually termed “tachycardia-bradycardia syndrome.” However, the bradycardia that ensues after spontaneous or induced termination of AF may represent a transient functional sinus node dysfunction. If rhythm control of AF is not possible, some patients may require pacemaker therapy to avoid bradycardia and allow the use of rate control pharmacotherapy. The target ventricular rate during AF was traditionally defined as having an average heart rate at rest less than or equal to 80 beats per minute and a maximum heart rate during a 6-minute walk test less than or equal to 110 beats per minute, or an average heart rate during 24-hour ambulatory electrocardiographic Holter monitoring less than or equal to 100 beats per minute (with no heart rate >110% maximum predicted ageadjusted exercise heart rate). This comes from the AFFIRM trial that showed that the management of AF with the rhythm-control strategy offers no survival advantage over the rate-control strategy.9,10 More recent data show that a more lenient strategy rate control (resting heart rate 48 h
High
Minimum of 3 wka
Long term
Duration of Atrial Fibrillation
