Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services Duke Internal Medicine Residency Curriculum Atrial

Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services

Duke Internal Medicine Residency Curriculum

Atrial Fibrillation

Allen Atchley, MDJohn Petersen, MDRichard Vest, MD



Learning Objective

• Review of Definitions• Epidemiology• Initial Evaluation• Treatment of Stable Disease• Treatment of Rapid Ventricular Response• Anticoagulation• Quiz



Definitions

• Paroxysmal (self terminating): AF with episodes that last less than 7 days and may be recurrent

• Persistent: AF which fails to self terminate and lasts for longer than seven days, but can be terminated by cardioversion

• Permanent: >1yr and cardioversion has failed or not been attempted

• Lone (15-30% of AF): AF in individuals without structural heart disease



Epidemiology

• Almost always occurs in setting of structural heart disease

• In Cross-Sectional ATRIA study of 1.9million 1

– 1% with AF– 70% of whom > 65 years old– More in men (1.1%) then women (0.8%)

• With longer length of life, prevalence of AF will increase– 2.3 Million Americans now, 5.6 million in year

2050

1. Go AS, et al. JAMA 2001; 285:2370-5.



Risk Factors

• Underlying heart disease: which leads to atrial enlargement, elevation in atrial pressure or infiltration or inflammation of the atria

• In structurally normal hearts it is suggested that PACs may trigger AF, with 89-94% of ectopic foci from near the pulmonary veins 1

• CHD: especially if prior MI and heart failure. Only 2-5% of patients with new onset AF had concurrent MI. 2,3 Only 0.6% of patients with stable CAD had AF 4

• Rheumatic Heart Disease: 16-70% with AF, depending on number and type of valvular disorders

• Congenital Heart Disease• PE• COPD

1. Haissaguerre M, et al. NEJM 1998; 339;659-66. 2. Zimetabum pJ et al. JACC 2000; 36: 1223-7. 3. Friedman HZ et al. Am J Cardiol 1987 59: 866-9.

4. Cameron A, et al. Am J Cardiol 1988; 61:714-17.



Risk Factors (Continued)

• Pericarditis• Myocarditis• OSA• BMI > 30kg/m2

• Hyperthyroidism (8.3% of patients will develop AF), seen in both symptomatic and subclinical disease 1

• Cardiac Surgery: 30-40% of CABG patients, and 37-50% of valve surgery patients

• Inflammation (defined by elevated CRP) 2

• Supraventricular tachyarrhythmias with spontaneous conversion

• Alcohol: Binge drinking• Medications: theophylline, adenosine, digitalis

1. Frost L, et al. Arch Intern Med 2004; 164:1675-8. 2. Aviles RJ, et al Circulation 2003; 108:3006-10.



Initial Evaluation

• History (to define pattern of symptoms, onset date, frequency, duration of AF, and precipitating causes)

• ECG (to confirm diagnosis)• Echocardiogram (to review for structural

abnormalities)• TSH (if elevated, then fT4, T3)• Evaluate for CAD if symptoms suggestive of

unstable atherosclerotic disease.



Treatment of Stable Atrial Fibrillation

• Restoration of sinus rhythm is considered if the patient has symptoms, progressive cardiomyopathy, or in attempts to “limit risk of embolism”

• Direct Current CardioVersion (DCCV) for the stable/ asymptomatic patient– DCCV is successful up to 80% of the time– DCCV for the stable patient should be carried out with

conscious sedation and available airway/ACLS support



Treatment

– Prior to DCCV, If a fib duration < 48 hours • Start IV heparin gtt and proceed to DCCV• Consider long term anticoagulation for high risk of

recurrent disease. underlying structural disease, or high risk for CVA

– If a fib duration > 48 hours or unknown• Start IV heparin drip

– TEE to rule out atrial thrombus then DCCV, or– Rx anticoagulation with coumadin for 3-4

weeks, then DCCV– Anticoagulation should be continued for at least 3-4

weeks after DCCV (risk of CVA still high AFTER cardioversion!)




• Stable patients with refractory or persistent a fib

– Rate control with anticoagulation • Control ventricular response with beta-blocker, CCB, or digoxin• Chronic anticoagulation with coumadin (INR 2-3) vs. ASA

(discussed more extensively later)• AFFIRM trial- no difference in survival or CVA rates with rate

control vs. aggressive rhythm control and anticoagulation

– Consider Rx with antiarrythmic therapy +/- reattempt DCCV

– Rate of “chemical cardioversion” with antiarrythmic Rx is approximately 50% (highly dependent upon agent used)

– Anticoagulation for chemical cardioversion is the same as with DCCV




• Stable patients with refractory or persistent a fib

– Consider referral to EP for catheter based a fib ablation

– Treatment with catheter ablation of the pulmonary veins is a rapidly advancing/growing procedure

– Occassionally, catheter based ablation of the AV node with subsequent pacemaker placement is needed

– Rarely, referral for surgical pulmonary vein ablation (Maze procedure) +/- atrial appendage removal is considered



Rapid Ventricular Response (RVR)

• Occurs when patients have atrial fibrillation and elevated heart rate

• RVR can cause:– Hemodynamic instability– Unwanted symptoms (palpitations, dizziness, fatigue)– Tachycardia-mediated cardiomyopathy

• RVR is common in new-onset a. fib– Typical ventricular rate in untreated a. fib is 90-170

• A. fib patient previously well rate controlled, consider:– Medical non-adherance– Hyperthyroidism– Cardiac ischemia– Hypercholinergic states (bleeding, infection)



Treatment of RVR

• Hemodynamic instability– DCCV is treatment of choice for tachycardia with

hemodynamic instability (ACLS guidelines)

• IV rate-control agents are often preferred agents1

– Potential toxicities are hypotension and heart block– Diltiazem 5-15mg IV over 2-7min (ACC Class I Rec.)– Metoprolol 5mg IV over 2 min (ACC Class I Rec.)– Digoxin 0.25mg IV, up to 1.5mg (ACC Class IIb Rec.)

• Rhythm control agents often require help from Cardiology– Amiodarone, Dofetilide, Sotalol– Can be used when BB & CCB would cause hypotension

1. Fuster V, Ryden LE, et. al; ACC/AHA/ ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary. Journal of the American College of Cardiology. 2001;38:4:1231-1265.



Atrial Fibrillation and Risk of CVA

• Clinical characteristics of a. fib and frequently seen co-morbidities place patients at increased risk of CVA– Dilated atria with reduced left atrial blood flow– Valvular heart disease (especially mitral stenosis)

• Additional clinical characteristics increase risk of CVA– Older age– Female sex– HTN– Diabetes– History of TIA/CVA– Left ventricular dysfunction

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How Much of a Risk of CVA?

• Incidence of CVA is associated with age and number of clinical characteristics

• Study of 27,202 patients with new diagnosis of a. fib1

– Age 50-59: 1.3%/year incidence of CVA– Age 60-69: 2.2%/year incidence of CVA– Age 70-79: 4.2%/year incidence of CVA– Age 80-89: 5.1%/year incidence of CVA

• Risk scores have been published to quantitate risk of CVA considering age and clinical characteristics

1. Frost L, Engholm G, Johnsen S, et al. Incident Stroke after Discharge fro the Hospital with a Diagnosis of Atrial Fibrillation. American Journal of Medicine 2000;108:36.



Framingham Heart Study A. fib Risk Score1

• 868 patients with new-onset a. fib, 705 not treated with warfarin• 5-year risk of CVA correlated with age and clinical features

1. Wang TJ, Massaro JM, Levy D, et al. A Risk Score for Predicting Stroke or Death in Individuals With New-Onset Atrial Fibrillation in the Community. JAMA 2003;290:1049.



CHADS2 Risk Score: 11,526 Patients with Nonvalvular A fib1,2

• Low risk=0 points• Intermediate risk=1-2 points• High risk=3 points

1. UpToDate.com ® 2. Gage BF, Waterman AD, Shannon W. Validation o Clinical Classification Schemes for Predicting Stroke. JAMA 2001;285:2864.



Anticoagulation for Prevention of Thromboembolism

• Aspirin and warfarin are used to prevent thromboembolism– Both can cause serious adverse events such as intracranial

hemorrhage and GI bleed

• The risk of hemorrhage must be weighed against the risk of thromboembolism in choosing the correct therapy

• Each patient with atrial fibrillation has a specific risk of thromboembolism considering age and co-morbidities



Anticoagulation for Prevention of Thromboembolism

• ASA therapy is estimated to reduce CVA risk by 22-32%1,2, or absolute yearly risk reduction of 1.5%– Efficacy was found to vary with magnitude of risk– ASA benefit is particularly noted in patients 65-75 years old

with no other risk factors

• Warfarin therapy is estimated to reduce CVA risk by 62-69%1,2, or absolute yearly risk reduction of 2.7-3.1%

• Rate of increase in major bleeding in patients with atrial fibrillation treated with warfarin versus ASA is 0.9 events per 100 patient-years

1. Hart RG, et al. Antithrombotic therapy to prevent stroke in patients with atrial fibrillation: a meta-analysis. Ann Intern Med 1999;131:493. 2. McNamara RL, et al. Management of atrial fibrillation: review of the evidence for the role of pharmacologic therapy, electrical cardioversion, and echocardiography. Ann Intern Med 2003;139:1018.



So, what to do? ACC/AHA Recommendations1

1. Fuster V, Ryden LE, et. al; ACC/AHA/ ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary. Journal of the American College of Cardiology. 2001;38:4:1231-1265.



Anticoagulation in Patients with Rhythm Control

• Should patients in NSR as a result of antiarrhythmics receive anticoagulation?

• Patients in RACE and AFFIRM trials received anticoagulation despite choice for rate or rhythm control– Incidence of CVA was similar in each group– Patients are hypothesized to have episodes of a. fib which

are not felt or observed

• Evidence is not clear, but most experts discourage a change in anticoagulation criteria for patients receiving rhythm control



Wafarin: Underused and Underanticoagulated

• Decision for anticoagulation must be personalized to each patient and family– Patients must be able to take doses appropriately and come

for adequate and regular INR monitoring

• Despite current guidelines, warfarin is far underused in patients with a. fib– ATRIA study1: anticoagulation observed in only 53% of

13,428 ambulatory patients with a. fib and no contraindication to anticoagulation

• INR is often sub or supra-therapeutic in patient cohorts, seen in 26-39%2

1. Go AS, et al. Warfarin use among ambulatory patients with nonvalvular atrial fibrillations: The ATRIA study. Ann Intern Med 1999;131:927. 2. SPAF III Study. Lancet 1996;348:633.



Anticoagulation Summary

• Risk for thromboembolism depends on patient age and co-morbidities

• Risk scores and clinical guidelines have been published to help guide choice of treatment

• Warfarin is underused in patients with atrial fibrillation and INRs are often not in therapeutic range



Quiz Time



Question 1

• In patients presenting with new onset AF, how often is there a concurrent diagnosis of myocardial infarction?

• A: < 1%• B: 2-5%• C: 10-15%• D: 25-33%• E: 45-50%



Answer to Question 1

• Answer: B, 2-5%

• Active ischemia is associated with new onset atrial fibrillation. However, other signs or symptoms of unstable atherosclerotic disease are usually present at time of presentation.



Question 2

• All of the following are risk factors for AF except?

• A: Subclinical hyperthyroidism• B: Obesity• C: Elevated CRP• D: Caffeine intake• E: Obstructive sleep apnea




• D, caffeine intake

• Subclinical hyperthroidism, obesity, elevated CRP, and obstructive sleep apnea are all established risk factors for incident AF. While a relationship exist between caffeine and arrhythmogenesis, there is no established risk of new onset AF in the doses of caffeine consumed by humans.



Question 3

• A 72yo male comes to clinic for establishment of primary care. He has atrial fibrillation and receives rate control with a beta-blocker. He has mitral valve prolapse but no other significant past medical history. To reduce his risk of thromboembolism, you recommend:

• A: Warfarin therapy with a goal INR of 2.0-3.0• B: Warfarin therapy with a goal INR of 2.5-3.5• C: ASA 81mg daily• D: ASA 325mg daily• E: No therapy. Warfarin is “rat poison,” and ASA is

worthless.




• D: ASA 325mg daily

• According to the ACC/AHA guidelines for management of atrial fibrillation, a patient who is less than 75 years old with no risk factors (HTN, EF<35%, CHF, CAD, previous CVA or TIA, DM) should receive ASA 325mg daily. Mitral valve prolapse without mitral stenosis has not been shown to increase risk of thromboembolism. Patients with atrial fibrillation and mitral stenosis should receive warfarin with a goal INR of 2.5-3.5.



Question 4

• According to the ATRIA Study, what percentage of patients with atrial fibrillation who quality for anticoagulation are placed on warfarin?

• A: 15%• B: 27%• C: 45%• D: 53%• E: 66%




• D: 53%

• In the ATRIA study, only 53% of 13,428 ambulatory patients with a. fib and no contraindication to anticoagulation received warfarin. Additional studies have suggested that INRs are sub or supra-therapeutic in 26-39% of patients treated with warfarin.



Question 5

True or False

One advantage to the restoration of sinus rhythm in a patient with new onset atrial fibrillation, is that the patient will not require anticoagulation.




• False, if a patient has restoration of sinus rhythm from either electrical or pharmaceutical cardioversion it is suggested that all patients be continued on anticoagulation for at lease 3-4 weeks. It is thought that despite sinus rhythm there is a period of electrical mechanical disassociation following cardioversion and therefore risk of embolism continues. After 3-4 weeks there is still a risk of embolic disease if the patient has asymptomatic paroxysmal episodes of atrial fibrillation and the patient’s individual risk of embolism (i.e. age, structural heart disease) would need to be considered to define approprite anticoagulation.



References

• ATRIA: Go AS, Hylek EM, Phillips KA, Chang Y, Henault LE, Selby JV, Singer DE. Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagluation and Risk Factors in Atrial Fibrillation Study. JAMA 2001; 285:2370-5.

• Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Guiniou G, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. NEJM 1998; 339:659-66.

• Cameron A, Schwartz MJ, Kronmal RA, Kosinski AS. Prevalence and Significance of atrial fibrillation in coronary artery disease (CASS Registry). Am J Cardiol 1988; 61:714-17.

• Zimetabum PJ, Josephson ME, McDonald MJ, McClennen S, Korley V, et al. Incidenc and predictors of myocardial infarction among patients with atrial fibrillation. JACC 2000; 36: 1223-7.

• Friedman HZ, Weber-Bornstein N, Deboe SF, Mancini GB. Cardiac Care unit admission criteria for suspected acute myocardial infarction in new-onset atrial fibrillation. Am J Cardiol 1987 59: 866-9.

• Frost L, Vetergaard P, Mosekilde L. Hyperthyroidism and risk of atrial fibrillation or flutter: a population-based study. Arch Intern Med 2004; 164: 1675-8.

• Aviles RJ, Martin DO, et al. Inflammation as a risk factor for atrial fibrillation. Circulation 2003; 108: 3006-10.



References (Continued)

• Hart RG, et al. Antithrombotic therapy to prevent stroke in patients with atrial fibrillation: a meta-analysis. Ann Intern Med 1999;131:493.

• Frost L, Engholm G, Johnsen S, et al. Incident Stroke after Discharge fro the Hospital with a Diagnosis of Atrial Fibrillation. American Journal of Medicine 2000;108:36.

• Gage BF, Waterman AD, Shannon W. Validation o Clinical Classification Schemes for Predicting Stroke. JAMA 2001;285:2864.

• Fuster V, Ryden LE, et. al; ACC/AHA/ ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary. Journal of the American College of Cardiology. 2001;38:4:1231-1265.

• McNamara RL, et al. Management of atrial fibrillation: review of the evidence for the role of pharmacologic therapy, electrical cardioversion, and echocardiography. Ann Intern Med 2003;139:1018.

• Wang TJ, Massaro JM, Levy D, et al. A Risk Score for Predicting Stroke or Death in Individuals With New-Onset Atrial Fibrillation in the Community. JAMA 2003;290:1049.

• Go AS, et al. Warfarin use among ambulatory patients with nonvalvular atrial fibrillations: The ATRIA study. Ann Intern Med 1999;131:927.

• UptoDate On Line Version 14.1

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Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services Duke Internal Medicine Residency Curriculum Atrial