Converting Atrial Fibrillation to NSR

Pills or Electrical Thrills

Peter Holzberger MD

www.mediclicks.net

Background

• Atrial fibrillation is the most common sustained arrhythmia

• Affects 2 million Americans• 6% over the age of 65 experience it• Responsible for 15% strokes

– Benjamin E: Epidemiology of Atrial Fibrillation. In Falk RH, Podrid PJ, eds:Atrial Fibrillation: Mechanisms and Management. 2nd Ed, Lippincott-Raven Press, New York 1997, pp.1-22.

Symptoms

• Inappropriate heart rate response

• Irregular rate

• Loss of atrial systolic function

• Thromboembolism

Choices for Immediate Treatment

• Anticoagulation and Rate Control

• Or

• Conversion to NSR

NSR-Pills Or Electrical Thrills

• Pills– Placebo– Single Dose Antiarrhythmic Treatment– Ibutilide

• Electrical Thrills– Traditional External Cardioversion– Double External Cardioversion– Biphasic Cardioversion

Choices

• 40 yr old healthy female with 6 hrs of palpitations. First time ever.

• Found in atrial fib. Rate slowed with IV lopressor, and patient feels much better.

• ED evaluation entirely normal

• Next step is ?

Choices

• A) DC Cardioversion

• B) P.O. Propafenone

• C) Discharge on p.o. lopressor and revaluate next day

• D) Admit for further workup and treatment

Predictors of Conversion to NSR

• Duration of atrial fib– <24 hrs spontaneous conversion in up to 66%

• Underlying cardiac function

• Underlying cardiac disease

• Age

Pills - Placebo

• Conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm: The effect of no treatment and high-dose amiodarone. A randomized, placebo controlled study – 100 patients PAF (<48 hrs)– IV Amiodarone (3 gms) vs. IV Placebo

– Cotter et al,.Eur Heart J Dec 1999; 20(24):1833-42

Placebo

– Cotter et al,.Eur Heart J Dec 1999; 20(24):1833-42

92

64

0102030405060708090

100

24 hrs

IV amiodaroneIV Placebo

Conversion (%)

P=0.0017

Choices

• 45 yr old on Coumadin for recent DVT presents with several day history of palpitations.

• INR has been therapeutic for several months

• Rate is controlled but still feels poorly• Evaluation entirely unremarkable• What next?

Choices

• A) DC Cardioversion

• B) P.O. Propafenone

• C) Discharge on p.o. lopressor and revaluate next day

• D) Admit for further workup and treatment

Pills - Single Dose Rx

– Boriani et al, Pacing Clin Electrophys Nov 1998; Vol.21 Part II, 2470-74

Single Dose

• 417 patients with AF < 8 days• Randomized to

– Placebo– IV Amiodarone 5mg/kg bolus followed by 1.8

gms/24hrs– IV Propafenone– PO Propafenone 600 mg– PO Flecainide 300 mg

– Boriani et al, Pacing Clin Electrophys Nov 1998; Vol.21 Part II, 2470-74

Single Dose

– Boriani et al, Pacing Clin Electrophys Nov 1998; Vol.21 Part II, 2470-2474

0

20

40

60

80

100

SR≤1 hr SR≤3hr SR≤8hr

PlaceboIV AmioIV PropPO PropPO Flec

Choices

• 45 yr old female with several week history of worsening SOB, no palpitations

• Exam reveals, mild CHF, A fib rate 140, Echo EF 35%-global hypo

• What next?

Choices

• A) DC cardioversion

• B) p.o. Propafenone

• C) Discharge on p.o. lopressor and revaluate next day

• D) Admit for further workup and treatment

Anticoagulation Prior to Conversion to NSR

• At least 3 weeks Therapeutic INR >2.0• Unless arrhythmia is less than 48 hours in duration

– Even then heparin has been advocated in high embolic risk patients

• Mitral stenosis, CHF, previous emboli

– Chest. Sixth ACCP Consensus Conference on Antithrombotic Therapy Vol. 119(1) Suppl. Jan 2001 194S-206S

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TEE Prior to Conversion to NSR

Thrombus

Pills (sort of) -Ibutilide

Pills (sort of) -Ibutilide

Pills (sort of) -Ibutilide

Ibutilide

– Stambler et al, Circulation October 1996; Vol 94, No 7, 1613-21

Ibutilide

• 266 patients (3 hrs to 45 days)– 133 with atrial flutter– 133 with atrial fibrillation

• Randomized to– Placebo/Placebo– 1mg/0.5mg– 1mg/1mg

– Stambler et al, Circulation October 1996; Vol 94, No 7,1613-21

Ibutilide

– Stambler et al, Circulation October 1996; Vol 94, No 7,1613-21

Ibutilide

• Proarrhythmia– PMVT developed in 8.3%

• Sustained PMVT 1.7%

– MMVT developed in 4%

• QTc prolonged an average of 63 msec.• No hemodynamic effects

– Stambler et al, Circulation October 1996; Vol 94, No 7,1613-21

Ibutilide

• Contraindications– Hx of Torsades– QTc > 440– K< 4.0 mEq/L– Concomitant Type 1 or III drug– HR <60– Severe LV dysfunction (EF < 30%)

Ibutilide

• Key Points– Close monitoring during infusion

• For NSR, PMVT (3 beats), QTc >600msec, conduction or hemodynamic problems

– Monitor post infusion for at least 4 hours or until QTc returns to baseline

– (longer with hepatic dysfunction)

– Trained personnel, defibrillator, Code Cart and IV magnesium should be present

Pills Or Electrical Thrills

• Pills– Placebo– Single Dose Antiarrhythmic Treatment– Ibutilide

• Electrical Thrills– Traditional External Cardioversion– Double External Cardioversion– Biphasic Cardioversion

Electrical Thrills - DC

• Used for conversion of atrial fib by Dr Bernard Lown in the 1960’s – 94% of 456 cases of atrial fib

• Overall efficacy felt to be about 85%

• Use of high energy (360J) associated with skin burns and possible myocardial stunning

DC Cardioversion

• Efficacy dependent on– Paddle size and position– Transthoracic impedance– Energy Waveform– Underlying disease

Paddle Position

• Anterior/Posterior #1

Paddle Position

• Anterior/Posterior #2

Paddle Position

• Anterior/Anterior

Transthoracic Impedance

• Lowered by putting pressure on the anterior paddle during cardioversion

Electrical Thrills - Double DC

– Saliba et al, J Am Coll Cardiol 1999; Vol.34, No 7: 2031-34

Double External Cardioversion

• Double Shock

Double External Cardioversion

• 55 patients who had all failed conventional DC cardioversion

• 84% success rate– 9 patients received more than one 720J

• No complications

• Saliba et al, J Am Coll Cardiol 1999; Vol.34, No 7: 2031-34

Pills and Electrical Thrills

– Oral et al, NEJM 1999, Vol. 340 No24:1849-54

Ibutilide and DC Cardioversion

• 100 consecutive patients – 50 assigned conventional DC

– 50 pretreated with 1 mg Ibutilide

– Oral et al, NEJM 1999, Vol. 340 No24:1849-54

72

100

0102030405060708090

100

% Success

DC only

Ibutilide/DC

P<0.001

Ibutilide and DC Cardioversion

• 20% treated with Ibutilide converted without DC

• 14 patients who did not convert with DC alone were then pretreated with Ibutilide– None converted with drug alone– All converted with DC

• Oral et al, NEJM 1999, Vol. 340 No24:1849-54

Electrical Thrills

Damped Biphasic

Biphasic - AF

• 165 patients randomized to monophasic vs. biphasic shocks– Stepped approach

• Biphasic: 70,120,150,170• Monophasic:100,200,300,360

– Mittal et al, Circulation March 2000,Vol.101(11): 1282-87

Biphasic - AF

– Mittal et al, Circulation March 2000,Vol.101(11): 1282-87

Conclusion

• Prior to conversion:– A fib less than 48 hrs or,– Anticoagulation with an INR >2.0 for 3 weeks,

or– TEE showing no clot at time of conversion

• Pills work about 40% of the time• Electrical Thrills work about 90% of the

time

Conclusion

• Biphasic waveform is superior and desirable

• Ibutilide will have a role– unable to perform anesthesia– very effective for atrial flutter– facilitate DC cardioversion

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