Atrial FibrillationAssessment and Management in the ED

Joseph R. Cline MD FACEPAssociate Professor (CHS)Section of Emergency MedicineUniversity of Wisconsin School of Medicine and Public Health

Atrial FibrillationObjectivesReview prevalence and associated and confounding conditionsReview clinical assessment and categorizationReview management strategy Discuss classification of antiarrhythmics and the use in AFDiscuss thromboembolic risk in AF

In a cross-sectional study of almost 1.9 million men and women, the prevalence of atrial fibrillation increases with age, ranging from 0.1 for those less than 55 years of age to over 9 percent in those 85 years of age. At all ages, the prevalence is higher in men than women. Data from Go, AS, Hylek, EM, Phillips, K, et al, JAMA 2001; 285:2370. Atrial Fibrillation -- Prevalence --

Atrial Fibrillation-- Incidence and Prevalence --Overall prevalence = 0.4% of U.S. populationFrom 1996-2001, primary hospital discharge diagnosis of Atrial fibrillation increased by 34% Most common arrhythmia in the ED setting: 1 3% of ED visits overallPrevalence: age < 55 yrs < 0.1% > 55 yrs = 5% > 80 yrs > 9% Life-time risk = 25% for age > 40 yrs (M or F)Accounts for 15% of all strokesAF increases risk of stroke 5 X

Atrial Fibrillation-- Classification --Paroxysmal AF duration less than 7 days and may be recurrentPersistent AF fails to self-terminate; duration greater than 7 days; can be terminated by cardioversionPermanent AF duration more than 1 year; cardioversion either failed or has not been attemptedLone AF paroxysmal, persistent, or permanent AF without structural heart disease

Atrial Fibrillation -- Prevalence in associated diseases --Hypertension increased relative risk of only 1.42; however prevalence of hypertension accounts for the high associationCAD AF is transient in 6-10% of MI patients; however it is almost never in isolation to other ECG findings of ACS (Zimetbaum et al. Incidence and predictors of myocardial infarction among patients with atrial fibrillation. J Am Coll Cardiol 2000; 36;1223)Incidence in chronic, stable CHD is 0.6%Valvular heart diseaseHigh prevalence with Rheumatic heart diseaseMS + MR 52%MS alone 29%MR alone - 16%AS alone 1%Degenerative MR incidence 5% per year

Atrial Fibrillation-- Prevalence in associated diseases, cont. --Heart Failure 10-30%Pulmonary embolism 10-14 % (rarely the only sign or symptom)Hyperthyroidism low TSH in 5.4%; clinical hyperthyroidism present in 1%COPDPost cardiac surgeryPericarditisObstructive sleep apnea ( for patients with AF and OSA, incidence of AF recurrence is 2X for those not treated with CPAP)Congenital heart diseasePeripartum cardiomyopathyHoliday Heart

Atrial Fibrillation-- Pathogenesis --Underlying heart disease of any cause that is complicated by: heart failure atrial enlargement elevated atrial pressure inflammation or infiltration of the atriaEchocardiographic risk factors increased left ventricular wall thickness left atrial diameter > 4 cm reduced left ventricular fractional shorteningTriggering event majority related to atrial premature beat minority related to atrial flutter or atrial tachycardia

Atrial Fibrillation-- History and Physical Exam --Define symptomsDefine pattern ParoxysmalPersistentRecurrentPermanentOnset or date of discoveryFrequency and duration of episodesPrecipitating causes and modes of termination

Atrial Fibrillation-- History --SymptomsPalpitations, weakness, dizziness, reduced exercise capacity, dyspneaAngina, CHF symptoms, syncope (hypotension) relate to underlying heart diseaseUp to 90% of episodes are asymptomatic with approximately 20% of such episodes longer than 48 hrs90% of AF patients have recurrent episodes

Atrial Fibrillation-- Exam --ABCsVital signsRate / BP to assess perfusion and guide decision for urgent / emergent ECVAssess for signs of CHFHeart tones: variable intensity of S1 is diagnostic of atrial fibrillation

Atrial Fibrillation-- ECG --Verification of diagnosisirregularly irregularNo discernable P wavesIdentify associated findings or complicationsMILVHBundle branch blockPre-excitation

Atrial Fibrillation-- ECG --Aeschmann beats aberrently conducted beats following a shorter R-R interval than the previous R-R interval

Atrial Fibrillation-- Chest X-ray --Identify heart size, vasculatureAssess for additional complicating diseasesCOPDPneumonia

Atrial Fibrillation-- Lab --Standard electrolytes assess for hypokalemiaTSH and free T4 For all cases of new onset Atrial fibrillationPatients with low TSH and normal free T4 have subclinical hyperthyroidismINRMost patients with AF will need anticoagulationPatients currently anticoagulated need confirmation of theraputic level

Atrial Fibrillation-- Management and Disposition --Which category?Recent onset AFRecurrent paroxysmal AFRecurrent persistent AFPermanent (Chronic) AFand patient condition, determinesWhich primary optionRate controlUrgent cardioversionDelayed cardioversionRhythm control / maintenance if convertedSystemic embolization prevention

Atrial Fibrillation-- Management and Disposition --

Elective cardioversion in the EDduration clearly identified less than 48 hrsNo reversible causelow risk of intra-cardiac thrombus formation

Atrial Fibrillation-- ED Cardioversion in the stable patient --Burton, John H. et al. Electrical cardioversion of ED patients with Atrial Fibrillation. Annals of Emergency Medicine 2004;44: 22-30

Retrospective, consecutive cohort42 months, Oct 1998 March 2002 4 institutions3,688 AF encounters

Excluded: Cardioversion for unstable patientshypotension, dyspnea, ischemic chest pain, alteredconsciousness, CHF, acute MINo standardized protocol at any of the study sites388 stable AF encounters(10.5%)Mean age = 61 +/- 13 yrs332 successful (86%)56 unsuccessful (14%)91% discharged55% discharged9% admitted45% admitted

Atrial Fibrillation-- Management and Disposition --

Urgent or Emergent cardioversion in the ED

What are the indications?What are the contraindications?

Atrial Fibrillation-- Management and Disposition --Urgent cardioversion Restoration of sinus rhythm takes precedence over mitigation of thromboembolic riskIndicated if any of the following is present:Active ischemiaSignificant hypotension where LV dysfunction (systolic or diastolic) or valvular disease is a factorSevere CHF Pre-excitation syndrome (eg WPW)

Relative Contraindications to urgent cardioversionDuration of episode > 48hrs or uncertain durationAssociated mitral valve disease, cardiomyopathy or CHF (known EF < 50%)Prior history of thromboembolic event

Atrial Fibrillation-- Management and Disposition --Rate control indicated if starting Class 1a or 1c antiarrhythmic drug due to possible recurrence with Atrial flutter with 1:1 conductionNecessary for prevention of tachycaria-induced left venticular dysfunction

Agents for rate controlBeta blockersIV therapy: Metoprolol, EsmololOral therapy: AtenololCalcium channel blockersDiltiazemVerapamilDigoxinUseful only in CHF patients or as second/third line agent

Atrial Fibrillation-- Antiarrhythmic agents --

Fast Channel (Na+)Action PotentialPurkinje fibersSlow Channel (Ca++) Action PotentialSinus / A-V Nodes0123420Myocardial Cellular ElectrophysiologyClass 1 antiarrhythmics-Slowing of conductance-Phase 0 is determined by Na+ channel-Slowing of conduction velocity and decreased excitabilityClass 4 antiarrhythmics-Slowing of AV nodal conductance-Phase 0 is determined by Ca++ channel-Slowing of conduction velocity in sinus and AV nodes

-- Antiarrythmic Agent ClassificationVaughn-Williams Classification (Journal of Clinical Pharmacology, 1984)Class 1- depression of Na+conductance during phase 0; slowed conduction velocity and decreased excitability1a: moderate depression of Na+ conductance in resting and depolarized tissue; depression of K+ currents and prolongation of repolarizationQuinidine, Procainamide, Disopyramide1b: depression of Na+ conductance in depolarized fibers only;Lidocaine, Tocainide, Phenytoin1c: marked depression in Na+ conduction; no effect on repolarizationEncainide, Flecainide, PropafenoneClass 2- -adrenergic receptor blockersAtenolol, MetoprololClass 3- prolongation of action potential duration by varied effectsBretylium, Sotolol, Amiodarone, Ibutilide, DofetilideClass 4- depression of Ca+-dependent slow channelsDiltiazem, Verapamil

Atrial Fibrillation-- Management and Disposition --Delayed cardioversionAF duration of 48 hours or duration unknownAssociated mitral valve disease, cardiomyopathy or CHFPrior history of thromboembolic event

Anticoagulate with a goal INR of 2.0 to 3.0 for at least three weeks before and four weeks after either electrical or pharmacologic cardioversion.

Atrial Fibrillation-- Management and Disposition for Delayed ECV --Strategy 1 (Conventional)Oral anticoagulation with WarfarinTarget INR 2.0 3.0No antiarrythmicsRate control as needed hospitalization usually necessary if rate control needed MetoprololDiltiazemDigoxin (useful only in presence of CHF)Scheduled ECV after minimum of 3 weeks of anticoagulation4 weeks of anticoagulation after ECV

Strategy 2 Indicationrecent onset but > 48 hrs useful for hospitalized patients (rate control, associated complications) and stable patients for which earlier timing is usefulPatients with increased risk of hemorrhage with anticoagulationScreening Transesophageal echocardiography (TEE) No anticoagulationNo antiarrhythmicsRate control as neededECV if no thrombi seen

Atrial Fibrillation -- Indications for hospitalization --For the treatment of an associated medical problem, which is often the reason for the arrhythmia For elderly patients who are more safely treated for AF in hospital For patients with underlying heart disease who have hemodynamic consequences from the AF or who are at risk for a complication resulting from therapy of the arrhythmia

Atrial Fibrillation-- Rate control alone vs rhythm control--Rhythm control strategyAdvantages: Better exertional capacityImproved cardiac function for CHF patientsMitigation of other arrhythmic related symptoms (eg palpitations)Disadvantages: frequent recurrences of AF 50% of patient recurr in 3-6 months repeated need for electrical cardioversion; adverse effects of prophylactic antiarrhythmic drugs including life-threatening events related to proarrhythmic effectsNo clear benefit of either approach for patients over 65 years of age; trend for increased mortality in rhythm control (AFFIRM trial, NEJM 2002, > 4,000 patients)Rate control with anticoagulation is acceptable in patients 65 yrs or greaterStrategy is weighed for acutely symptomatic patient with new onset of Atrial fibrillation, particularly if < 65 yrs

Atrial Fibrillation-- Rate control alone vs rhythm control --VanGelder, et al, A Comparison of Rate Control and Rhythm Control in Patients with Recurrent Persistent Atrial Fibrillation, NEJM 2002;347:1834-40

522 Patients with persistent AF after previous electrical cardioversion Mean age 68 +/- 8 Mean duration of AF diagnosis 315 dMean duration of presenting episode 32 dNo history of heart disease 21%Primary Endpoints: DeathCHF TE event BleedingPacersevere drug adverse eventPrimary endpoint:Rhythm control = 23%Rate control = 17%Follow up period of at least 2 yrsRhythm controlRate controlEntry: ECV + Sotolol1st recurrence: ECV + Flecanide or Propafenone2nd recurrence: Amiodarone load +ECV + Amiodarone main.Target HR < 100Digoxin, Diltiazem, blocker alone orIn combinationAll patients anticoagulated: could be discontinued ifIn NSR 4 weeks after ECV

Atrial Fibrillation-- Rate control alone vs rhythm control --VanGelder, et al, A Comparison of Rate Control and Rhythm Control in Patients with Recurrent Persistent Atrial Fibrillation, NEJM 2002;347:1834-40

Factors related to lack of risk reduction with rhythm control strategy

Tachycardia induced cardiomyopathy and heart failure also are likely reduced with rate control (incidence of CHF similar inthe two arms of the study)

Patients with risk factors for stroke are still at risk for stroke evenwhen sinus rhythm is maintained (17% of the thromboembolicevents occurred after cessation of anticoagulant therapy and in5 of 6 cases the patient was in sinus rhythm at the time of the event)

Senescent conduction disease is occasionally unmasked by rhythm control strategy

Atrial Fibrillation-- Maintenance of Sinus Rhythm after Chemical or Electrical Cardioversion --Canadian Trial of Atrial Fibrillation InvestigatorsRoy, et al Amiodarone to Prevent Recurrence of Atrial Fibrillation, NEJM, 2000;342:913-920403 patients; 19 centers201 Amiodarone202 Propafenone ; Sotolol101 Propafenone101 SotololMean 16 month follow-up35% recurrence for Amiodarone63% recurrence for Propafenone or Sotolol

Atrial Fibrillation-General Management Principles--- Pharmacologic Cardioversion --Semi urgent (hospitalization or Obs Unit)Class 1c used only if no pre-existant heart diseasemonitoring for rapid conducting At. FlutterFlecainide Propafenone Class 3monitoring for QT prolongation; TorsadeDofetilideIbutilideOut-patient / Ambulatory scenarioClass 1c Pill-in-the-PocketFlecainidePropafenoneUsed only when demonstrated effective under as in-patientMust have AV nodal blockade with blockade or Ca++ channel blocker to prevent 1:1 AV conduction if Atrial flutter occursClass 1c Extended dosingAmiodarone particularly with patients with pre-existing heart disease

Atrial Fibrillation-General Management Principles--- Maintenance of Sinus Rhythm after Chemical or Electrical Cardioversion ACC / AHA / ESC anticoagulation recommendations

Atrial Fibrillation-General Management Principles-

Assessment of Thromboembolic Risk

Atrial Fibrillation-- Risk for Thromboembolism --Go, AS, Hylek, EM, Chang, Y, et al, JAMA 2003

Risk assessment CHADS2CHF any history (1)Hypertension prior history (1)Age > 75 (1)Diabetes mellitus (1)Stroke, TIA or systemic embolic event (2)

Atrial Fibrillation-- Risk for Thromboembolism --Risk assessment CHADS2Go, AS, Hylek, EM, Chang, Y, et al, JAMA 2003 Score (risk) Event rate (% / yr)Warfarin Without Warfarin NNT0 (low)0.250.494171 (interm)0.721.521252 (interm)1.272.50 813 (high)2.25.27 334 (high)2.356.02 275,6 (high)4.66.88

Atrial Fibrillation-- Prevention of Thromboembolism --ACC / AHA / ESC anticoagulation recommendations

Age < 60 + heart disease but no other risks: AspirinAge 60 75 with no risks:AspirinAge 65 75 with heart disease or DM: WarfarinWomen > 75:WarfarinMen > 75: Warfarin or AspirinAge > 65 with CHF:WarfarinEF < 35% + HypertensionWarfarin

Atrial Fibrillation-- Summary

Patients with new onset atrial fibrillation of less than 48 hrs duration, who have normal ventricular function, no known mitral valvular disease and no history of thromboembolic event can be considered for cardioversion in the EDUp to 90% of atrial fibrillation episodes are asymptomatic with approximately 20% of such episodes longer than 48 hrs (Select your cardioversion cases carefully!)If the episode is greater than 48hrs, rate control, anticoagulate and refer for delayed cardioversionTSH and free T4 are essential in the evaluation of initial onsetAF is transient in 6-10% of MI patients; however it is almost never in isolation to other ECG findings of ACSCHAD2 scheme is extremely helpful in assessing thromboembolic risk and need for anticoagulationIn patients greater than age 65, rhythm control strategy is very appropriateAF is transient in 6-10% of MI patients; however it is almost never in isolation to other ECG findings of ACS