Atrial fibrillation cardioversion

Conversion of atrial fibrillation and flutter In a crossover, placebo-controlled study in 16 patients with recent onset atrial fibrillation, cardioversion was achieved in two of six patients who received dofetilide 8 micrograms/kg and in two of nine who received 12 micrograms/kg (41). None cardioverted with placebo. However, the average duration of atrial fibrillation was 35 days in those who cardioverted with dofetilide and 83 days in those who did not. The authors concluded that dofetilide had only limited effect in cardioverting atrial fibrillation of moderate duration. 

Expert opinion is a source, frequently elicited by survey, that is used to obtain information where no or few data are available. For example, in our experience with a multicountry evaluation of health care resource utilization in atrial fibrillation, very few country-specific published data were available on this subject. Thus the decision-analytic model was supplemented with data from a physician expert panel survey to determine initial management approach (rate control vs. cardioversion) first-, second-, and third-line agents doses and durations of therapy type and frequency of studies that would be performed to initiate and monitor therapy type and frequency of adverse events, by body system and the resources used to manage them place of treatment and adverse consequences of lack of atrial fibrillation control and cost of these consequences, for example, stroke, congestive heart failure. This method may also be used in testing the robustness of the analysis [30]. 

Duration of atrial fibrillation/atrial flutter >48 h or unknown, o Electrical or chemical cardioversion in a patient without adequate anticoagulation may cause embolization of atrial thrombi. 

Atrial flutter cardioversion o Same as atrial fibrillation... 

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

Electrical cardioversion It may be desirable to reduce the dose of digoxin for 1 to 2 days prior to electrical cardioversion of atrial fibrillation to avoid the induction of ventricular arrhythmias, but physicians must consider the consequences of increasing the ventricular response if digoxin is withdrawn. If digitalis toxicity is suspected, delay elective cardioversion. If it is not prudent to delay cardioversion, select the lowest possible energy level to avoid provoking ventricular arrhythmias. Lab test abnormalities Periodically assess serum electrolytes and renal function (serum creatinine concentrations) the frequency of assessments will depend on the clinical setting. 

Kieny JR, Sacrez A, Facello A, et al. Increase in radionuclide left ventricular ejection fraction after cardioversion of chronic atrial fibrillation in idiopathic dilated cardiomyopathy. Eur. Heart J. 1992 13 1290-5. 

Ibutilide is approved for the chemical cardioversion of recent-onset atrial fibrillation and atrial flutter. Ibutilide appears to be more effective in terminating atrial flutter than atrial fibrillation. It can also lower the defibrilla-... 

Supraventricular tachycardia is the major arrhythmia indication for verapamil. Adenosine or verapamil are preferred over older treatments (propranolol, digoxin, edrophonium, vasoconstrictor agents, and cardioversion) for termination. Verapamil can also reduce the ventricular rate in atrial fibrillation and flutter. It only rarely converts atrial flutter and fibrillation to sinus rhythm. Verapamil is occasionally useful in ventricular arrhythmias. However, intravenous verapamil in a patient with sustained ventricular tachycardia can cause hemodynamic collapse. 

Treatment of atrial fibrillation is initiated to relieve patient symptoms and prevent the complications of thromboembolism and tachycardia-induced heart failure, the result of prolonged uncontrolled heart rates. The initial treatment objective is control of the ventricular response. This is usually achieved by use of a calcium channel-blocking drug alone or in combination with a 13-adrenergic blocker. Digoxin may be of value in the presence of heart failure. A second objective is a restoration and maintenance of normal sinus rhythm. Several studies show that rate control (maintenance of ventricular rate in the range of 60-80 bpm) has a better benefit-to-risk outcome than rhythm control (conversion to normal sinus rhythm) in the long-term health of patients with atrial fibrillation. If rhythm control is deemed desirable, sinus rhythm is usually restored by DC cardioversion in the USA in... 

Marcus GM, Sung RJ. Antiarrhythmic agents in facilitating electrical cardioversion of atrial fibrillation and promoting maintenance of sinus rhythm. Cardiology. 2001 95 1-8. 

NPV = negative predictive value PPV = positive predictive value ACS = acute coronary syndrome PTCA = percutaneous transluminal coronary angioplasty PCI = percutaneous coronary intervention DCCV = direct-current cardioversion A fib = atrial fibrillation NA = not applicable. 

Roy D, Quiles J, Sinha M, et al. Effect of direct-current cardioversion on ischemia modified albumin levels in patients with atrial fibrillation. Am J Cardiol 2004 93 366-368. 

McNamara RL, et al. Management of atrial fibrillation review of the evidence for the role of pharmacologic therapy, electrical cardioversion, and echocardiography. Ann Intern Med 2003 139(12) 1018-1033. 

Arnold AZ, et al. Role of prophylactic anticoagulation for direct current cardioversion in patients with atrial fibrillation or atrial flutter. J Am Coll Cardiol 1992 19(4) 851-855. 

Reisinger J, et al, Flecainide versus ibutilide for immediate cardioversion of atrial fibrillation of recent onset, Eur Heart J 2004 25(l 5) 13 I 8-1324,... 

Madrid AH, et al. Comparison of flecainide and procainamide in cardioversion of atrial fibrillation. Eur Heart J 1993 ... 

Khan IA. Single oral loading dose of propafenone for pharmacological cardioversion of recent-onset atrial fibrillation. J Am Coll Cardiol 2001 37(2)542-547. 

Bianconi L, et al. Effects of oral propafenone administration before electrical cardioversion of chronic atrial fibrillation a placebo-controlled study. J Am Coll Cardiol 1996 28(3) 700-706. 

Oral H, et al, Facilitating transthoracic cardioversion of atrial fibrillation with ibutilide pretreatment. N Engl J Med 1999 340(24) 1849-1854. 

For effectual rhythm control, the first action is often to restore NSR acutely with a nonsurgical intervention called a cardioversion, by which the patient s heart is reset through the use of electrical current strategically delivered to the heart via external electrode pads. When atrial fibrillation is changed to a normal sinus rhythm, the patient is said to have been converted. The cardioversion process has a good success rate for achieving conversion however, patients must be anesthetized for the procedure, and the AF often returns. 

Cardioversion is an option in patients with persistent atrial fibrillation and has an initial success rate of 70 - 90% in selected people. Success is more likely in recent-onset AF and in younger people. 

FIGURE 6-1. Algorithm for the treatment of atrial fibrillation (AF) and atrial flutter. °lf AF <48 hours, anticoagulation prior to cardioversion is unnecessary may consider transesophageal echocardiogram (TEE) if patient has risk factors for stroke. Ablation may be considered for patients who fail or do not tolerate one antiarrhythmic drug (AAD). Chronic antithrombotic therapy should be considered in all patients with AF and risk factors for stroke regardless of whether or not they remain in sinus rhythm. (BB, 8-blocker CCB, calcium channel blocker p.e., verapamil or diltiazem] DCC, direct-current cardioversion.)... 

Arruodarone is used in chronic ventricular arrhythmias in atrial fibrillation it both slows the ventricular response and may restore sinus rhythm it may be used to maintain sinus rhythm after cardioversion for atrial fibrillation or flutter. Amiodarone should no longer be used for the management of reentrant supraventricular tachycardias associated with the Wolff-Parkinson-White syndrome as radiofrequency ablation is preferable. 

An 86-year-old woman was given adenosine 12 mg intravenously for sustained supraventricular tachycardia, which terminated but was followed by atrial fibrillation and paroxysmal ventricular tachycardia (24). Cardioversion was unsuccessful, but normal sinus rhythm was obtained with procainamide. This followed an anteroseptal myocardial infarction. 

The use of oral amiodarone in preventing recurrence of atrial fibrillation, for preventing recurrence after cardioversion or for pharmacological cardioversion of atrial fibrillation, has been reviewed (18). There is insufficient evidence to support its use as a first-line drug for... 

In a meta-analysis of five randomized, placebo-controlled trials of intravenous amiodarone about 500-2200 mg over 24 hours in the treatment of recent-onset atrial fibrillation in 410 patients, the incidence of adverse events was 27% with amiodarone and 11% with placebo (28). Intravenous amiodarone was significantly more effective than placebo in producing cardioversion. The most common adverse effects of intravenous amiodarone were phlebitis, bradycardia, and hypotension most of these effects were not considered to be dose-limiting. 

Of 85 patients with persistent atrial fibrillation after balloon mitral valvotomy given amiodarone (600 mg/day for 2 weeks and 200 mg/day thereafter), 33 converted to sinus rhythm (29). Of the other 52 patients, who underwent DC cardioversion at 6 weeks, 41 converted to sinus rhythm. Six patients had adverse effects attributable to amiodarone. Five had mild gastrointestinal symptoms, such as abdominal discomfort and nausea. One developed hypothyroidism after 3 months, which resolved when the dosage of amiodarone was reduced to 100 mg/day. 

Kosior D, Karpinski G, Wretowski D, Stolaiz P, Stawicki S, Rabczenko D, Torbicki A, Opolski G. Sequential prophylactic antiarrhythmic therapy for maintenance of sinus rhythm after cardioversion of persistent atrial fibrillation—one year follow-up. Kardiol Pol 2002 56 361-7. 

The prodysrhythmic effects of antidysrhythmic drugs have been reviewed in discussions of the pharmacological conversion of atrial fibrillation (38) and the relative benefits of rate control in atrial fibrillation or maintaining sinus rhythm after cardioversion (39). 

Dofetilide has a small positive inotropic effect in animal hearts (15,33). In a double-blind, placebo-controlled study of oral dofetilide 125, 250, or 500 mg bd for the maintenance of sinus rhythm after cardioversion of sustained atrial fibrillation or flutter in 201 patients, there were small changes in echocardiographic measures of atrial contractility, but no changes in stroke volume or cardiac output (34). 

In a double-bhnd, placebo-controlled study in 325 patients with atrial fibrillation or flutter cardioversion, rates for dofetilide 125, 250, and 500 micrograms bd were 6.1, 9.8, and 30% respectively, compared with 1.2% with placebo (45). The probabihties of remaining in sinus rhythm at 1 year with dofetihde 125, 250, and 500 micrograms bd were 0.40, 0.37, and 0.58 respectively, and 0.25 for placebo. 

In a comparison of intravenous dofetihde (8 micrograms/kg n = 48), amiodarone (5mg/kg n=50), or placebo (n = 52) in converting atrial fibrillation or flutter to sinus rhythm in 150 patients, two patients given dofetilide had non-sustained ventricular tachycardias four had torsade de pointes, in one case requiring electrical cardioversion (53). 

DeCara JM, PoUak A, Dubrey S, Falk RH. Positive atrial inotropic effect of dofetilide after cardioversion of atrial fibrillation or flutter. Am J Cardiol 2000 86(6) 685-8. 

Sedgwick ML, Lip G, Rae AP, Cobbe SM. Chemical cardioversion of atrial fibrillation with intravenous dofetilide. Int J Cardiol 1995 49(2) 159-66. 

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