ATRIAL FIBRILLATION
MANAGEMENT

MINI-LECTURE

OBJECTIVES

REVIEW INITIAL MANAGEMENT OF AFIB; MEDICAL VS CARDIOVERTINGMEDICAL MANAGEMENT: RATE VS RHYTHM CONTROLROLE OF ANTICOAGULATION

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?

Answer: Although this patient is symptomatic they are hemodynamically stable and mentating well. There appears to be no role for urgent cardioverting (such as unresponsive, change in mental status, hypotension) so the patient can be managed medically. We will now review how to manage this kind of patient.

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EKG

Here is an example/review of what an EKG may look like in the previous patient with afib. Atrial activity is rapid (>320 bpm) without any organized activity, and of various amplitudes. No discrete P waves are seen in this image. There is also irregularly irregular ventricular response which shows up as variable R-R intervals. The Ventricular response is usually 130-200.

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Demographics

Common; 2.2 million people in U.S.Male>FemalePrevalence increases with age Leading cause of embolic strokesAssociated with increased risk for heart failure and all cause mortality

But before we move to management here is a brief review of the demographics of afib and also the morbidity that it can pose in terms of CVA and heart failure.

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WORK-UP

H and PCXREKGEchoTFTsCMPTrop and EKG

Here is an example of some basic labs/imaging that should be ordered during the initial management.

H and P; makes sure to ask about symptoms and onset to help define the type of afib such as paroxysmal vs permanent vs new onset etc.

CXR: to look for any pulmonary cause such as PNA

EKG: to make define the rhythm and make sure this is truly afib and not another type of SVT

Echo: evaluate LA size, LV function, valves, pericardium or any other potential structual etiology. Also look for thrombi that could embolize. May need also a TEE especially if considering cardioversion to r/o clots.

TFTs: to r/o hyperthyridism as a cause

CMP: look for electrolyte abnormalities and replete goal K=4 and mg=2.

Trop and EKG: to r/o ischemia although usually unlikely 2/2 ischemia unless pt also has other ischemic sxs.

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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

Stable

afib

Unstable

Urgent Cardiovert

Ss

Rate vs rhythm Control

Anticoagulate**

-Urgent cardioversion W/ defibrillator: if hemodynamic instability, hypotension, angina, heart failure

-if cardioverting, ensure R-wave synchronization w electrical cardioversion to prevent R-on-T shock which can induce Vfib

-there is also a role in the management of recent or new onset afib for elective cardioverting when the patient is hemodynamically stable and one wishes to try to bring them out of the arrhythmia however the details of that are beyond the scope of this talk.

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RATE VS RHYTHM CONTROL

Rate Control vs Rhythm Control**no clear survival benefit in rate vs rhythm control**

IMPORTANT:Remember to remind people that there is no clear mortality or stroke reduction benefit in rate vs rhythm control. This could be because of premature d/c of anticoagulation and antiarrhythmic drugs in those who underwent rhythm control.

-asymptomatic patients with HR goal 40%

-in patients with symptoms despite rate control can consider rhythm control

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RATE CONTROL

Agents:

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

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

Digoxin

Goal: Rest 60-80 bpm and Activity 80-110

Here are some choices of medications for rate control.

-remind students that not all Ca channel blockers can be used (i.e amlodipine would not be a good choice)

-also on this slide is the goal HRs for rate control and meds should be titrated to reach these goals but must also watch blood pressure because all these meds can cause some hypotension to varying degrees.

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RATE CONTROL; Which Agent to choose?

AFIB

SBP

90-110

SBP 100 to 120

SBP >120

DIGOXIN

Load: 0.5mg IV6 hrs later; 0.25mg IV6 hrs later; 0.25 mg IV

Maintenance: 0.125 mg daily

B-Blocker

Initial: Metoprolol 5mg IVP q5min x3doses

Prn: metoprolol 5mg IV q6hr prn

Maintenance: Metoprolol 25 mg po BID (max 100mg BID)

Ca2+ Blockers

Initial and prn: Diltiazem 10mg IVP q6hrs

Maintenance: Diltiazem 30mg PO q6hs

Pick rate controlling agent based on systolic BP. Each of these agents will drop BP to varying degrees; CA blockers>B blockers>digoxin

Also this slide shows how we start an oral maintenance early on and in addition to using prn pushes because the goal is to get the patient on maintenance meds early on in order to adequately control the arrhythmia and not just chase the rate constantly with prn doses.

Note: for digoxin if renal impairment cut doses in half.

Note: for metoprolol try to initially get rate under control with IVPs q5min x3 doses total but monitor BP while doing it. Start a PO maintenance dose also because by the time the PO kicks in the IV will wear off. Also titrate up the maintenance dose based on the amount of extra prn IVPs that are needed to control HR at goal.

Note: with dilatiazem start an initial IVP along with a maintenance PO because by the time the PO kicks in the IV will wear off. Titrate up the maintenance po dose based upon any extra prn IVPsthat are given to control rate. Once rate is stable and controlled at goal then convert short acting diltiazem into long acting daily dose.

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Rhythm Control

AGENT:

III: Amiodarone, Ibutilide, Dofetilide, Sotalol

IC: Flecainide, Propafenone

IA: Procainamide

Agent determined by comorbidities and adverse effects

Usually Consult cardiology before using these agents

This option is typically chosen when rate control cannot adequately control rate and symptoms.

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ANTICOAGULATION

Risk of stroke increases with valvular afibRisk of CVA=4.5% per year in nonvalvular afibRisk of CVA in recurrent paroxysmal afib=persistent afib=permanent afibAgents: ASA vs Coumadin vs Dabigatran vs Rivaroxaban

In addition to rate vs rhythm control we also need to place the patient on anticoagulation.

Remind students that choice of anticoagulation depends on patient specific risk factors such as GI bleeding, fall risk, ability to come to lab to check INR etc.

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ANTICOAGULATION; Which Agent to Choose?

CHADS2 SCORE

CHF: 1 point

HTN: 1 point

AGE >75: 1 point

DM: 1 point

Stroke or prior TIA: 2 points

Score:

0=ASA alone

1= either warfarin or ASA

2 or more= warfarin

We use the CHADS2 score to help identify patient specific risk factors for CVA and to help us choose the appropriate anticoagulation

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ASPRIRIN

CHADS2=0 or 181 mg to 325mg PO dailyLower risk for bleeding than warfarinNo need to check INRs etcLower risk of major bleeds in patients who are a fall risk

For CHADS2=1 can choose either asa or warfarin depending on patient specific risks

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Coumadin

For CHADS2 score 2 or greater and also 1 depending on patient and physician preferenceGoal INR= 2 to 3Must monitor INRs regularlyCan be dangerous if fall risk or bleeding risk high

Remind people that can reverse coumadin if need be with vitamin K and FFP

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ASA + Clopidogrel

If not a candidate for warfarin; this can reduce stroke risk greater than ASA aloneRisk for major bleeding increased

In patients who can take warfarin; warfarin is superior in CVA prevention than ASA+plavix

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Dabigatran

Direct Thrombin InhibitorAlternative to warfarin for CHADS2=1 or greater in those without valvular afibRE-LY Trial showed superior to warfarin in preventing ischemic and hemorrhagic CVAs with reduced risk of life threatening bleeding but higher risk of GI bleedsNo lab monitoring*No reversal agent available for major bleeding events

* No lab monitoring good in the sense that patients do not have to come regularly to get checked but bad in the sense that there is no way to monitor the true extent of the anticoagulation

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Rivaroxaban

Oral factor Xa inhibitorSeems to be equivalent in efficacy to warfarin for CVA prevention and no difference in major bleeding eventsDemonstrates 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.

SUMMARY

AFIB: very common arrhythmia and leading cause of embolic CVAsInitial Workup: H and P, trop, EKG, TSH, Echo, CXR, CMPManagement: First must determine if stable vs unstable (medically manage vs cardiovert immediately) For stable Afib: rate vs rhythm control (equal in efficacy). Start with rate control and if that fails try rhythm. Always remember to calculate CHADS2 score and anticoagulate for CVA ppx.

References

Uptodate.com; Topics: SVT, atrial fibrillation management, afib overviewSabatine, Marc S. Ed.; Pocket Medicine The Mass General Hospital Handbook of Internal Medicine 4th edition Lippincott Williams and Wilkins Philadelphia, PA 2008.MKSAP 16; Cardiology ACP 2012Maxine A. Papadakis, Stephen J. McPhee, Eds; CURRENT Diagnosis and Treatment; McGraw Hill Education 2012.Dan L. Longo, Anthony S. Fauci, Dennis L. Kasper, Stephen L. Hauser, J. Larry Jameson, Joseph Loscalzo, Eds. Harrison's Principles of Internal Medicine, Online. 18th ed. McGraw Hill 2012