ATRIAL FIBRILLATION MANAGEMENT

Ralph GHORAYEB

2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation

http://www.uptodate.com/contents/management-of-new-onset-atrial-fibrillation

http://www.uptodate.com/contents/atrial-fibrillation-cardioversion-to-sinus-rhythm

Ferri's Clinical Advisor 2015

EKG

CLASSIFICATION

Multiple classification schemes have been used in the past to characterize AF. The current classification scheme (divided into three major types) used by the ACC/AHA guideline committee is as follows:

Paroxysmal AF—more than one episode of AF that terminate spontaneously within 7 days (most episodes last less than 24 hr)

Persistent AF—episodes of AF that last longer than 7 days and may require either pharmacologic or electrical intervention to terminate

Permanent AF—AF that has persisted for longer than 1 yr, either because cardioversion has failed or because cardioversion has not been attempted

CLASSIFICATION

• In addition to the previous AF categories, which are mainly defined by episode timing and termination, the ACC/AHA/ESC guidelines describe additional AF categories in terms of other characteristics of the patient:

• Lone atrial fibrillation (LAF)—generally refers to AF in younger patients (<60 yr old) who have normal echocardiographic findings

• Nonvalvular AF—absence of rheumatic mitral valve disease, a prosthetic heart valve, or mitral valve repair

• Secondary AF—occurs in the setting of a primary condition that may be the cause of the AF, such as acute myocardial infarction, cardiac surgery, pericarditis, myocarditis, hyperthyroidism, pulmonary embolism, pneumonia, or other acute disease. It is considered separately because AF is less likely to recur once the precipitating condition has resolved.

ACUTE MANAGEMENT

MANAGEMENT

The first step in management is to determine whether the patient is stable or not…

-Look for any hemodynamic instability such as hypotension

-Is the patient responsive?

-Are there any mental status changes?

-are symptoms persistent and unbearable?

INITIAL MANAGEMENT DECISION

afib UnstableUrgent

Cardiovert

Stable

Rate vs rhythm Control

Anticoagulate**

URGENT MANAGEMENT

Three circumstances for which urgent or emergent cardioversion may be needed include:

●Active ischemia (symptomatic [eg, angina] or electrocardiographic evidence).

●Evidence of organ hypoperfusion (eg, cold clammy skin, confusion, acute kidney injury).

●Severe manifestations of heart failure (eg, pulmonary edema)

URGENT MANAGEMENT

Some patients’ clinical condition may improve quickly with urgent rate control while others need to have sinus rhythm restored immediately.

Clinical judgement is needed to determine whether rate control should be tried or whether to proceed directly to cardioversion

Of equal importance is recognition that cardioversion in patients who have been in AF for 48 hours or longer, or of unknown duration, is associated with an increased risk of stroke and should not be performed in the absence of performing transesophageal echocardiography to screen for thrombus or at least three weeks of anticoagulation, unless the patient is critically ill and no alternatives to cardioversion are available

In a patient with any of these indications for urgent cardioversion, and no alternative treatment options and/or failure to respond to rate control, the need for restoration of normal sinus rhythm takes precedence over the need for protection from thromboembolic risk. (benefit outweighs the risk (5-7%))

Intravenous anticoagulation with heparin or administration of a newer oral anticoagulant (eg, dabigatran, apixaban, or rivaroxaban) should be started, but it should not cause a delay in emergent cardioversion.

STABLE PATIENTS

STABLE PATIENT

•Perform a complete history and physical examination, including an attempt to obtain old records that might contain information about prior supraventricular arrhythmias. The history is particularly helpful in the decision to pursue a rate or a rhythm control strategy

•Risk factors for AF, as well as disease associations, may be identified. Old records should be searched for evidence of a prior episode of AF or other atrial tachyarrhythmias.

•Identify associated comorbidities that may place a patient at risk of stroke or bleeding.

•A 12-lead electrocardiogram (ECG) should be performed to verify the diagnosis of AF and assure that ongoing ischemia is not present on the ECG. Old records should be searched for evidence of a prior episode of AF or other atrial tachyarrhythmias.

•Order laboratory tests including electrolytes, cardiac markers of ischemia/infarction, and thyroid stimulating hormone, in an attempt to identify an underlying cause.

STABLE PATIENT

●Start a ventricular rate slowing drug for patients in whom this is indicated.

● For patients with a rapid ventricular response, who manifest symptoms or signs of hypoperfusion, rate control (or cardioversion) may be needed urgently.

●Determine the need for anticoagulant therapy based on an assessment of stroke and bleeding risks.

●Discuss with the patient the cause (if known), prognosis, and natural history of AF.

●Consult a cardiologist or electrophysiologist (if needed).

●Schedule follow-up.

WORKUP

Laboratory Tests

• Thyroid-stimulating hormone, free T 4

• Serum electrolytes

• Toxicity screen

• CBC count (looking for anemia, infection)

• Cardiac enzymes—CK and/or troponin level (to investigate cardiomyopathies or myocarditis and myocardial infarction)

• BNP (to evaluate for CHF)

• D-dimer/CT scan of chest PE protocol (if the patient has risk factors to merit a pulmonary embolism workup)

RATE VS RHYTHM CONTROL

Rate Control vs Rhythm Control

**no clear survival benefit in rate vs rhythm control**

RATE CONTROL

For most patients with new onset atrial fibrillation (AF) and who are in AF at the time of presentation, rate control will precede any attempt to restore sinus rhythm; the principal exception is patients who are hemodynamically unstable

In patients with mild to moderate symptoms, slowing the rate often results in significant improvement or even resolution of symptoms.

RATE CONTROL

We believe that attempting to get the rate below 85 beats per minute at rest is reasonable in symptomatic patients.

For patients who continue with unacceptable symptoms at this goal, an attempt should be made to see if a lower rate goal lessens symptoms.

For asymptomatic patients with permanent AF, a more lenient rate control goal of <110 beats/min may be reasonable

RATE CONTROL

Agents:

Beta Blocker: Metoprolol and Propranolol,bisoprolol (ICU=esmolol gtt)

Non-dihydropyridine CA blockers: verapamil & Diltiazem (ICU=diltiazem gtt)

Digoxin

DRUG SELECTION

The drug selected and the route of administration (oral versus intravenous) are dictated by the clinical presentation:

•Beta blockers or verapamil or diltiazem are the preferred to digoxin in the absence of heart failure (HF).

•Intravenous or oral amiodarone may help control rate when the other drugs are ineffective or cannot be given.

•Digoxin is the preferred drug only in patients with AF due to HF.

Digoxin can also be used in patients who cannot take or who respond inadequately to beta blockers or calcium channel blockers. The effect of digoxin is additive to both of these drugs.

DRUG SELECTION

The choice among a beta blocker, diltiazem, and verapamil is frequently based upon physician and patient preference, although it may be influenced by other medical problems that are present.

As an example, beta blockers are particularly useful when the ventricular response increases to inappropriately high rates during exercise, after an acute myocardial infarction, and when exercise-induced angina pectoris is also present.

Intravenous beta blockade is more effective than intravenous calcium channel blockade for rate control , especially after cardiac surgery.

If there is a question about tolerance of the beta blocker, a drug with a short half-life would be recommended.

On the other hand, a calcium channel blocker is preferred in patients with chronic obstructive pulmonary disease and asthma.

RHYTHM CONTROL

RESTORATION OF SINUS RHYTHM• In patients with recent onset atrial fibrillation (AF), who are hemodynamically stable (with only mild to moderate symptoms) and whose rate has been controlled (as discussed above), a decision needs to be made regarding the restoration of sinus rhythm.

•We believe that most patients with symptomatic new onset AF and most patients with apparently asymptomatic AF should have at least one attempt at cardioversion (either electrical or chemical) to sinus rhythm.

RESTORATION OF SINUS RHYTHM Circumstances in which it is reasonable to not attempt cardioversion in a patient with new onset AF include:

●Patients who are completely asymptomatic, particularly those who are very elderly (>80 years) with multiple comorbidities, where risks of undergoing cardioversionand/or pharmacologic rhythm control may outweigh the benefits of restoring sinus rhythm.

REASONS TO NOT CARDIOVERT ●Low likelihood of successful cardioversion or maintenance of SR after cardioversion:

•AF has been present continuously for more than one year

•The left atrium is markedly enlarged (atrial dimension >5.0 cm; atrial volume >40 mL/m2) 

•Patients who had recurrence while taking adequate doses of appropriate antiarrhythmic drug therapy and have recently undergone cardioversion. Drug refractory patients may have successful conversion to SR but are less likely to maintain SR long term.

•Cardioversion with long-term maintenance of SR is likely to be unsuccessful if the underlying cause (eg, thyrotoxicosis, pericarditis, and mitral valve disease) for the AF has not been corrected prior to cardioversion.

TIMING

•There is a low risk of systemic embolization if the duration of the arrhythmia is 24 to 48 hours or less and there are no cardiac abnormalities (particularly mitral valve disease or significant left ventricular enlargement due to a cardiomyopathy) on transthoracic echocardiography.

• Most patients with new onset AF of longer than 48 hours duration should have cardioversion postponed until:

Three weeks of anticoagulation has been achieved

Or

A transesophageal has been performed and shows no left atrial appendage clots

ELECTRICAL VERSUS PHARMACOLOGIC CARDIOVERSION1.  The choice of electrical or pharmacologic cardioversion depends

upon the comfort of the clinician to use one or the other approach.

2. For first episodes, electrical cardioversion is preferred.

3. In some patients, antiarrhythmic drugs are administered prior to cardioversion to increase the chance of successful reversion and to prevent early, intermediate, and late recurrence.

4. For patients with paroxysmal episodes of AF, drug therapy is preferred if they will have sinus rhythm maintained with long-term antiarrhythmic drug therapy, and as patients with paroxysmal AF will likely convert anyway with or without electrical cardioversion.

ELECTRICAL VERSUS PHARMACOLOGIC CARDIOVERSION • In the acute setting, pharmacologic cardioversion (e.g., ibutilide, dofetilide) is less commonly used than electrical cardioversion.

•A major disadvantage with pharmacologic cardioversion is the risk of development of ventricular tachycardia and other serious arrhythmias, especially due to acute prolongation of the QT interval.

ELECTRICAL CARDIOVERSION ●Synchronized DC cardioversion should be performed while the patient is under the influence of procedural sedation and is having blood pressure, heart rate, oxygen saturation, and CO2 capnography monitored.

Generally, cardioversion should be done in a situation where airway equipment and airway expertise are present.

PHARMACOLOGIC CARDIOVERSION As mentioned before, some patients have antiarrhythmic drugs started before direct current (DC) cardioversion

Rarely, an attempt at cardioversion with an antiarrhythmic drug alone can be appropriate, such as those for whom the risk of anesthesia is high.

Flecainide, propafenone, ibutilide, dofetilide, and, to a lesser degree, amiodarone all have efficacy for pharmacologic conversion of atrial fibrillation (AF).

Of these, we prefer flecainide or propafenone unless the duration of AF is greater than seven days, in which case dofetilide, or, to a lesser degree, amiodarone or ibutilide have some role for medical conversion.

None of these drugs is as efficacious as DC cardioversion.

PHARMACOLOGIC CARDIOVERSION Flecainide — Flecainide is a very effective antiarrhythmic drug for the pharmacologic conversion of a patient with AF of short (<24 hours)).

Flecainide should not be used in patients with structural heart disease, particularly those with left ventricular systolic dysfunction and in those with coronary artery disease.

PHARMACOLOGIC CARDIOVERSION Propafenone — Propafenone is significantly more effective in paroxysmal as opposed to persistent AF, with rates likely approaching those seen with flecainide 

As with flecainide, we do not suggest using propafenone in patients with structural heart disease, particularly those with left ventricular systolic dysfunction and those with coronary artery disease.

PHARMACOLOGIC CARDIOVERSION Amiodarone — Cardioversion with either intravenous or oral amiodarone is not particularly effective and occurs several hours later than with flecainide, propafenone,ibutilide, and vernakalant

Intravenous amiodarone may be more effective in converting AF after it has been given for hours and days.

Oral amiodarone requires long-term loading and is effective in converting about 25 percent of patients with persistent AF to sinus rhythm after six weeks of loading.

Thus, we do not recommend it solely for the purpose of cardioversion.

It is not approved by the United States Food and Drug Administration for the treatment of AF.

PHARMACOLOGIC CARDIOVERSION However, amiodarone may occasionally have value before cardioversion in patients who will receive the drug long term for maintenance and may be considered as adjunctive therapy to increase the likelihood of successful cardioversion in patients who are known to be refractory to electrical cardioversion or in those in whom there is a concern about early relapse.

PHARMACOLOGIC CARDIOVERSION Vernakalant — Vernakalant is a relatively new antiarrhythmic drug that has not been as extensively studied as all of the above agents.

It is available in Europe in intravenous forms for the rapid conversion (50 percent conversion within 10 minutes) of recent-onset AF (≤7 days duration for patients not undergoing surgery, and ≤3 days duration for post-cardiac surgery patients) to sinus rhythm

ANTICOAGULATION

ANTICOAGULATION 

 Most patients with new onset atrial fibrillation (AF) will revert to sinus rhythm spontaneously or undergo an attempt at cardioversion.

●For patients with AF of more than 48 hours (or unknown) duration, we recommend at least three weeks of oral anticoagulation prior to cardioversion, and four weeks or more of anticoagulation following cardioversion.

For patients in whom more urgent restoration of sinus rhythm is desirable for a variety of reasons (including hemodynamic compromised symptoms, difficult rate control, or patient convenience), an alternative strategy is to perform a transesophageal echocardiogram prior to cardioversion to rule out left atrial thrombi and proceed to cardioversion if no thrombi are detected (anticoagulate for at least four weeks after cardioversion).

ANTICOAGULATION

Anticoagulant therapy should be continued for at least 1 mo after cardioversion to minimize the incidence of adverse thromboembolic events. It can be stopped after 1 mo as long as AF has not recurred.

(independament du CHADS score)

ANTICOAGULATION

●For patients with AF of less than 48 hours duration, our reviewers have differing approaches.

Some start unfractionated heparin, low molecular weight heparin, or a newer oral anticoagulant prior to cardioversion in all patients, while some proceed without anticoagulation in patients with AF of very short duration who have a low stroke risk profile.  

●For patients with a first episode of AF, our experts have differing approaches to the decision regarding long-term anticoagulation.

Most anticoagulate based on risk, as determined by the CHA2DS2-VASc score

However, some will not anticoagulate after a first episode, particularly if a reversible cause has been identified.

CHRONIC MANAGEMENT

RATE VS RHYTHM

Per the AFFIRM and RACE trials, either rate control or rhythm control strategies show no difference in composite cardiovascular end points of death, CHF, bleeding, drug side effects, or thromboembolism.

Both approaches have similar outcomes as long as appropriate anticoagulation is maintained based on the individual’s stroke risk.

RATE CONTROL

For patients without symptomatic AF, rate-control strategy with calcium channel blockers, beta-blockers, or digoxin is a reasonable option.

RACE 2 trial indicates that a lenient rate control strategy, with a target resting heart rate of <110 beats/min is non inferior for a composite primary end point that included CV death, heart-failure hospitalization, stroke, and other major events over a median 3-yr follow-up as compared to a strict control strategy, with a target resting heart rate of <80 beats/min and an exercise heart rate of <110 beats/min.

RHYTHM

• In patients with symptomatic AF, younger patients, or those with difficult to control heart rate, attempt should be made to maintain sinus rhythm with antiarrhythmic agents.

Options of antiarrhythmic agents include amiodarone, dronedarone, (paroxysmal atrial fibrillation only without heart failure), dofetilide, flecainide, propafenone (contraindicated with structural heart disease), procainamide, or sotalol.

Use of dronedarone should be avoided in patients with persistent and/or permanent atrial fibrillation due to worsened cardiovascular outcomes, especially in those with concomitant symptomatic heart failure 

ANTICOAGULATION

 The decision whether to pursue long-term anticoagulation must be made in light of the patient’s risk for a cardioembolic event versus risk for a bleeding event. The CHA2DS2-VASc has largely superseded the CHADS2 scoring system

CHA2DS2-VASC

C = congestive heart failure;

H = hypertension;

A = age (>75 years is 2 points);

D= diabetes;

S= stroke, transient ischemic attack, or thromboembolic disease (2 points);

V = vascular disease,

A = age 65-74 years; and

Sc = sex category, with females getting 1 extra point).

Patients with a CHA2DS2-VASc score of 0 are considered low risk, 1 to 2 are considered moderate risk, and >2 are considered high risk and would benefit from long-term anticoagulation (e.g., warfarin).

ANTICOAGULATION STRATEGY Anticoagulation with warfarin is generally not recommended in patients with CHADS-VASc score of >1 (other than for female), there is mounting evidence of benefit for anticoagulation.

Increasing amounts of evidence now show that aspirin likely does not protect a person from stroke in AF and has recently been dropped from the European Atrial Fibrillation guidelines.

Target INR for patients with a CHADS-VASc score of >2 is 2 to 3 and should be diligently monitored to avoid risk of stroke versus bleeding.

Patients with hypertrophic cardiomyopathy or thyrotoxicosis with AF also have a high risk of stroke and should be anticoagulated irrespective of their CHADS-VASc score.

COUMADIN

For CHAD2S2-VASc- score 2 or greater

Goal INR= 2 to 3

Must monitor INRs regularly

Can be dangerous if fall risk or bleeding risk high

DABIGATRAN

Direct Thrombin Inhibitor

RE-LY Trial showed superior to warfarin in preventing ischemic and hemorrhagic CVAs with reduced risk of life threatening bleeding but higher risk of GI bleeds

No lab monitoring*

No reversal agent available for major bleeding events

RIVAROXABAN

Oral factor Xa inhibitor

Seems to be equivalent in efficacy to warfarin for CVA prevention and no difference in major bleeding events

Demonstrates a reduction in intracranial hemorrhage

Note: risk of thrombotic events increased for 28 days after stopping drug so may need to bridge with another anticoagulant during this time.

CASE VIGNETTE

This is a 65 y/o M who presents to the ED with dizziness, shortness of breath, and palpitations which began approximately two hours ago when he was playing catch with his grandson. No syncope or chest pain.

On exam: He is afebrile with a BP=110/55, HR=110-162 bpm, and respiratory rate of 25. A&Ox4 w/ NAD. Cardiac exam reveals tachycardia with an irregularly irregular rhythm.

How would you approach the initial management of this patient?