Biphasic shock waveform for cardioversion of atrial fibrillation in the emergency room

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Slide 1 : BIPHASIC SHOCK WAVEFORM for CARDIOVERSION of ATRIAL FIBRILLATION in the EMERGENCY ROOM Dante ANTONELLI, Alexander FELDMAN, Aziz DARAWSHE, Nahum A. FREEDBERG, Lilach MALETSKEY, Tiberio ROSENFELD   Dept. of Cardiology and Emergency Room, Ha Emek Medical Center 18101, Afula , Israel
Slide 2 : Introduction Transthoracic electrical cardioversion, traditionally monophasic shock waveform, has been the mainstay of therapy for AF since its introduction to the clinical practice about 30 years ago.
Slide 3 : Recent studies have demonstrated that biphasic shock are more successful than monophasic shock waveforms for terminating VF or AF; however data about their routine use for AF conversion to sinus rhythm in the ER are limited. The aim: of our study was to evaluate the efficacy and safety of biphasic shocks for conversion of AF to sinus rhythm in the ER.
Slide 4 : Methods Study Population… From September 2001 to October 2002 we prospectively evaluated consecutive patients presenting to the ER because of symptomatic AF, in whom external cardioversion was indicated.
Slide 5 : Study Population Patients with AF > 48 hours duration were anticoagulated with warfarin for > 3 weeks and achieved an international normalized ratio > 2.0; for AF known to be < 48 hours duration no prior anticoagulation protocol was required. An echocardiogram was performed in all the patients within 3 months of the cardioversion for the assessment of left atrial diameter and left ventricular ejection fraction. Methods
Slide 6 : Study Protocol… All patients underwent cardioversion via anterior- laterally positioned hand-held electrode paddles (i.e. right infraclavicular thoracic and apex area). Biphasic shocks were delivered by an Agilent M4735A Heartstream XL defibrillator, that contains circuitry to measure the patient’s impedance and to adjust the waveform accordingly, prior to delivery of each shock ( Smart Biphasic waveform). Methods
Slide 7 : Study Protocol Patients received sequential shocks of 50 J (only the first 31 patients), 100 J, 150 J and 200 J if necessary. Successful cardioversion was defined as the conversion of AF to sinus rhythm for 30 seconds after the shock. At the discretion of the physician on duty in the ER a single oral dose of 300 mg. of Propafenone was administered 1 hour before the electrical cardioversion. Methods
Slide 8 : Results Our study population included 111 patients. Patient clinical characteristics: Age (mean ± SD) 64 ± 13 years ( range 31-88 ) Male / Female (n) 56 / 55 Weight (mean ± SD) 84 ± 16 kg. IHD 35 (32%) Valvular Heart Disease 27 (24%) Hypertension 46 (41%) Sick Sinus Syndrome 5 (4%) Chronic Obstructive Lung Disease 13 (12%) Diabetes Mellitus 29 (26%)
Slide 9 : Left Atrial Diameter (mean ± SD) 45 ± 8 mm Left Ventricular Ejection Fraction (mean ± SD) 57± 14 % A F < 48 h duration ( n ) 73 (66 %) A F > 48 h duration ( n ) 38 (34 %) Lone Atrial Fibrillation ( n ) 8 (7%) Pretreatment with Propafenone ( n ) 55 (50%) Ventricular response of AF (mean ± SD) 121±+ 28 Transthoracic Impedance (mean ± SD) 81 ± 13 ohms Chronic therapy : Beta blockers ( n ) 42 (38 %) Calcium antagonists ( n ) 18 ( 19%) Digoxin ( n ) 4 (3.6 %) Antiarrhythmic drugs ( n ) 10 ( 9 %) Patient clinical characteristics:
Slide 10 : Cumulative shock success
Slide 11 : Electrical Cardioversion in our ER was used during the years 1966-2000 in 496 episods of AF utilizing Monophasic Waveform shocks . The standard used protocol was a first shock energy of 200 J, followed by 300 J and 360 J, if necessary. The cumulative success was 91% .
Slide 12 : Successful Unsuccessful p Weight ( Kg ) 84 ± 17 85 ± 15 ns Left atrial diameter ( mm ) 45 ± 8 44 ± 8 ns Left Ventricular EF ( % ) 55 ± 13 52 ± 17 ns Pretreatment with Propafenone ( %) 51 49 ns AF < 48 h duration 73% P = 0.62 AF > 48 h duration 61% Predictors for Successful Cardioversion
Slide 13 : Guidelines for the management of patients with Atrial Fibrillation using Electrical External Cardioversion The Working Group Report of The European Society of Cardiology Atrial Fibrillation : current knowledge and recommendations for management (S. Levy et al. Eur Heart J. 1998; 19,1294-1320) …”The recommended initial energy is 200 J as 75% or more patients are successfully cardioverted with this energy. Higher energies (360 J) are needed if a 200 J shock fails to restore sinus rhythm.”.
Slide 14 : ACC/AHA/ESC Practice Guidelines Management of patients with Atrial Fibrillation (V. Fuster et al. J Am Coll Cardiol 2001; 38:1266i-lxx.) …”an initial energy of 200 J or greater is recommended for electrical cardioversion of AF. Devices that deliver current with a biphasic waveform are available, and these appear to achieve cardioversion at lower energy levels than those using a monophasic waveform.”.
Slide 15 : R. Page et al. “ Biphasic versus Monophasic Shock Waveform for conversion of Atrial Fibrillation”. ( J Am Coll Cardiol 2002; 39: 1956-63) …”one could consider using 200J as the appropriate first choice; in fact, this may be appropriate for pts with AF > 1 year duration.” …”for AF < 48 hours duration, first shock of 100 J could be justified, as it results in 80% conversion.”.  
Slide 16 : Cumulative Cardioversion Success Shock energy Cumulative shock success
Slide 17 : Complications Asystole up to 25 s was observed in 1 patient (with SSS) and Oedema polmonum in another patient: in both patients 200 J were delivered. Hypotension was reported in 1 patient who received 2 shocks (100 J + 150 J). Mild erythema was observed in 9 patients (9.7%).  
Slide 18 : Conclusions Biphasic shock waveform is a safe and effective method for conversion of AF. 150 J shock appears to be appropriate as a first choice.
Slide 19 : HaEmek Medical Center Afula, Israel
Slide 20 : Comparison of Cardioversion Protocols

 


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