Rapid formation of left atrial appendage thrombus after unsuccessful cardioversion of atrial fibrillation

The acute effect of failed attempts of cardioversion on left atrial (LA) and left atrial appendage (LAA) functions are generally considered benign and no adverse effects have been reported. We report on a subject who had rapid formation of a fresh, mobile thrombus in the LAA despite unsuccessful cardioversion and therapeutic anticoagulation.     

Impact of biphasic electrical cardioversion of atrial fibrillation on early recurrent atrial fibrillation and shock efficacy

INTRODUCTION: Early recurrent atrial fibrillation (ERAF) after external cardioversion of atrial fibrillation (AF) occurs in 12% to 26% of patients. Whether biphasic cardioversion has an impact on the incidence of ERAF after cardioversion of AF is unclear. METHODS AND RESULTS: Consecutive patients (n = 216, mean age 66 years, 71% male, 88% with structural cardiovascular disease or hypertension) underwent cardioversion with a biphasic (Bi) or monophasic (Mo) shock waveform in randomized fashion. Energies used were 120-150-200-200 Ws (Bi) or 200-300-360-360 Ws (Mo). The two study groups (Bi vs Mo) did not differ with regard to age, sex, body mass index, underlying cardiovascular disease, left atrial diameter, left ventricular ejection fraction, duration of AF fibrillation, and antiarrhythmic drug therapy. Mean delivered energy was significantly lower in the Bi group (Bi: 186 +/- 143 Ws vs Mo: 324 +/- 227 Ws; P < 0.001). Overall incidence of ERAF (AF relapse within 1 minute after successful cardioversion) was 8.9% and showed no difference between the two groups (Bi: 8.1% vs Mo: 9.7%, P = NS). Cardioversion was successful in 95.4% of patients. The success rate was comparable in both groups (Bi: 94.3% vs Mo 96.8%; P = NS). First shock efficacy did not differ between Bi and Mo (76.4% vs 67.7%; P = NS). Mean number of shocks were 1.4 shocks per patient in both groups. CONCLUSION: Biphasic cardioversion allows comparable success rates with significantly lower energies. However, the incidence of ERAF is not influenced by biphasic cardioversion. With the energies used, biphasic and monophasic shock waveforms are comparable with regard to first shock and cumulative shock efficacy.     

Successful external cardioversion of atrial fibrillation in patients referred to an electrophysiologist for internal cardioversion.

BACKGROUND: Internal cardioversion of atrial fibrillation with direct current energy has become an increasingly employed technique for patients who fail external cardioversion. HYPOTHESIS: The purpose of this study was to determine whether internal cardioversion could be avoided by careful attention to cardioversion technique in a group of patients referred specifically for internal cardioversion after failed external cardioversion by community cardiologists. METHODS: We performed external cardioversion utilizing two operators applying significant pressure to the thorax with up to 360 J prior to the planned internal cardioversion in 20 patients referred for internal cardioversion after failed attempts at external cardioversion. RESULTS: Sixteen patients (80%) were successfully cardioverted and avoided the risk, inconvenience, and cost of internal cardioversion. CONCLUSION: External cardioversion with significant anterior paddle pressure by two operators can decrease the need for internal cardioversion in a significant portion of patients referred to electrophysiologists for internal cardioversion and should be considered prior to an invasive procedure.     

Transesophageal echocardiography-guided cardioversion of atrial fibrillation

Transesophageal echocardiography-guided anticoagulation management of patients with atrial fibrillation undergoing cardioversion has evolved over the past decade as a viable alternative to conventional anticoagulation management. Its use grew out of a need for a more predictable, dependable, and convenient approach to this difficult management dilemma, which has become increasingly prevalent in practice as an increasing number of patients present to clinics and hospitals with atrial fibrillation. In addition to its use in risk stratification of patients scheduled to undergo cardioversion, this management strategy allows for early cardioversion, which enables a minimal delay in proceeding from the diagnosis to the institution of therapy (electrical cardioversion). This review explores the evolution of the transesophageal echocardiography-guided strategy, the advantages and disadvantages of its use, and possible modifications to the strategy that would allow for a more convenient, practical, and more widely acceptable approach in the near future.     

Clinical value of left atrial appendage flow velocity for predicting of cardioversion success in patients with non-valvular atrial fibrillation.

BACKGROUND: Echocardiographic parameters for predicting cardioversion outcome in patients with non-valvular atrial fibrillation are not accurately defined. OBJECTIVE: To evaluate the role of left atrial appendage flow velocity detected by transoesophageal echocardiography for prediction of cardioversion outcome in patients with non-valvular atrial fibrillation enrolled in a prospective. multicentre, international study. METHODS: Four hundred and eight patients (257 males, mean age: 66 +/- 10 years) with non-valvular atrial fibrillation lasting more than 48 h but less than 1 year underwent transthoracic echocardiography and transoesophageal echocardiography before either electrical (n=324) or pharmacological (n=84) cardioversion. RESULTS: Cardioversion was successful in restoring sinus rhythm in 328 (80%) and unsuccessful in 80 patients (20%). Mean left atrial appendage peak emptying flow velocity was significantly higher in patients with successful than in those with unsuccessful cardioversion (32.4 +/- 17.7 vs 23.5 +/- 13.6 cm x s(-1); P<0.0001). At multivariate logistic regression analysis, three parameters proved to be independent predictors of cardioversion success: the atrial fibrillation duration <2 weeks (P=0.011, OR=4.9, CI 95%=1.9-12.7), the mean left atrial appendage flow velocity >31 cm x s(-1) (P=0.0013, OR=2.8, CI 95%=1.5-5.4) and the left atrial diameter <47 mm (P=0.093, OR=2.0, CI 95%=1.2-3.4). These independent predictors of cardioversion success outperformed other univariate predictors such as left ventricular end-diastolic diameter <58 mm, ejection fraction >56% and the absence of left atrial spontaneous echo contrast. CONCLUSION: In patients with non-valvular atrial fibrillation, measurement of the left atrial appendage flow velocity profile by transoesophageal echocardiography before cardioversion provides valuable information for prediction of cardioversion outcome.     

The optimal technique for electrical cardioversion of atrial fibrillation

The optimal approach to electrical cardioversion of atrial fibrillation includes appropriate patient selection, anticoagulation, careful selection and monitoring of antiarrhythmic therapy, and proper electrical cardioversion technique. The optimal technique requires the use of metal electrodes, with one electrode of at least 8 cm in diameter placed in the anterior position, and the second of 12–13 cm diameter placed posteriorly just below the left scapulae, with generous amounts of the appropriate gel (such as Hewlett-Packard Redux Paste) as the electrode-skin interface and firm pressure to the paddle electrode with the patient in expiration. Thus the anterior-posterior chest diameter is decreased and less air between the electrodes is assured. The initial shock strength should be 200 J. The shock is synchronized with the electrocardiographic QRS complex. This report reviews the justification for these recommendations.     

Intravenous amiodarone for cardioversion of recent-onset atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is one of the most common causes of hospital admission, with a prevalence of up to 5% of the population, increasing with advancing age. Emergency direct current cardioversion is the therapy of choice when arrhythmia leads to hemodynamic compromise, but in patients who are hemodynamically stable, antiarrhythmic drugs are usually given to restore sinus rhythm. HYPOTHESIS: The study was undertaken to assess the efficacy of intravenous amiodarone in cardioversion of recent-onset paroxysmal atrial fibrillation (AF). No standard antiarrhythmic therapy has been accepted for pharmacologic cardioversion of AF. Amiodarone seems to be a promising candidate, but only few randomized trials are available and the results are inconsistent. METHODS: In all, 160 patients with AF lasting < 24 h were randomly assigned (2:1 fashion) to the amiodarone group (n = 106) receiving 5 mg/kg as a 30 min intravenous (i.v.) infusion, followed by i.v. infusion of 10 mg/kg during 20 h diluted in 1000 ml of 10% glucose with 20 IU of rapid-action insulin, 80 mEq of potassium chloride, and 8 g of magnesium sulphate (GIKM), or to the control group (n = 54) receiving 1000 ml of GIKM alone. Treatment was continued up to 20 h independent of sinus rhythm restoration. RESULTS: Sinus rhythm was restored 20 h after initiation of therapy in 88 (83%) patients in the amiodarone group and in 24 (44%) patients in the control group (p < 0.0001). The difference between efficacy of the two treatment modalities became significant already after 8 h of therapy (53 vs. 14 patients with sinus rhythm, respectively, p < 0.05). The mean dose of amiodarone administered until sinus rhythm restoration was 740 +/- 296 mg. The presence and the type of underlying heart disease did not influence the conversion rate in either group. In two patients (1.8%) treated with amiodarone, the return of sinus rhythm was preceded by asystole. CONCLUSION: Amiodarone is effective in the termination of AF lasting < 24 h. It may be particularly useful in patients with organic heart disease in whom class I antiarrhythmic agents may be contraindicated. During treatment, the heart rhythm should be monitored continuously.     

Randomised comparison of electrode positions for cardioversion of atrial fibrillation

OBJECTIVE: To compare the relative efficacy of anteroanterior v anteroposterior electrode pad positions for external cardioversion of atrial fibrillation. DESIGN: Prospective randomised trial. SETTING: Tertiary referral cardiology centre in the United Kingdom. PATIENTS: 90 patients undergoing elective cardioversion for atrial fibrillation. INTERVENTIONS: Cardioversion was attempted with self adhesive electrode pads with an area of 106 cm2 placed either in the anteroanterior (AA) or anteroposterior (AP) positions. Initial shock was 100 J which, if unsuccessful, was followed by 200 J, 300 J, and 360 J if required. Peak current and transthoracic impedance were measured. MAIN OUTCOME MEASURES: Cardioversion success rate and energy requirements. RESULTS: Cardioversion was successful in 81% of the patients (73/90). There was no statistically significant difference in the cardioversion success rate (AA 84%, 38/45 patients; AP 78%, 35/45 patients; p = 0.42) or mean (SD) energy requirement for all patients (AA 223 (96.1) J; AP 232 (110) J) or for patients who were successfully cardioverted (AA 197.9 (82.4) J; AP 195.4 (97.2) J; p = 0.9) between the two pad positions. The mean transthoracic impedance (TTI) for the first shock (AA 77.5 (18.4) ohms; AP 73.7 (18.7) ohms; p = 0.34) was not significantly different between the two groups. TTI correlated significantly with body mass index, percentage body fat, and chest AP diameter. There was a progressive decrease in TTI with serial shocks. While aetiology and TTI were the two independent significant predictive factors for energy requirement, duration of atrial fibrillation was the only independent predictor of cardioversion success in a multivariate analysis. CONCLUSIONS: Electrode pad position is not a determinant of cardioversion success rate or energy requirement.     

Recurrent cerebral embolism and impending detachment of a previous nonmobile left atrial thrombus following initiation of anticoagulant therapy in a patient with nonvalvular atrial fibrillation

A 65-year-old female with nonvalvular atrial fibrillation who presented with a transient ischemic attack was admitted to our hospital. Transesophageal echocardiography (TEE) revealed a nonmobile thrombus attached to the wall of the left atrial appendage. She suffered from a new episode of syncope on the 8th day following initiation of anticoagulant therapy. Follow-up TEE indicated not only that the left atrial (LA) thrombus decreased in size but also that the previous nonmobile thrombus became mobile and showed impending detachment. Urgent surgery was subsequently performed to remove the LA thrombus, and the patient recovered uneventfully. In conclusion, anticoagulant therapy may precipitate partial fragmentation or partial detachment of LA thrombus.     

Temporal changes in atrial refractoriness following DC cardioversion of persistent atrial fibrillation in man.

AIMS: Studies have demonstrated shortening of the atrial effective refractory period (ERP) after episodes of atrial fibrillation (AF). This is termed atrial remodelling. It is unclear whether restoration of SR after persistent AF in patients with a clinical substrate results in reversal of this shortening and whether this is maintained long term. METHODS AND RESULTS: The ERP was determined at mid-lateral right atrial wall (MLRA) and right atrial appendage (RAA) at 600 ms and 400 ms drive cycle lengths and at basic sinus cycle length in 81 patients with persistent AF immediately, 24 h and 2 weeks following external DC cardioversion. All atrially active drugs were stopped for at least 5 half lives. (1) Prolongation of the ERP was observed at both atrial sites and all cycle lengths up to 24 h post cardioversion (p < 0.0001). (2) However, between 24 h and 2 weeks a subsequent shortening occurred in the ERP returning it to near post cardioversion levels. (3) The ERP was significantly longer at 24 h post cardioversion in patients who remained in SR for 2 weeks or longer compared with those who reverted to AF. CONCLUSION: Prolongation of the atrial ERP occurred following restoration of SR in persistent AF patients but was not maintained and displayed a biphasic pattern such that by 2 weeks the ERP had returned to baseline values. Despite this finding, a longer ERP at 24 h post cardioversion was associated with maintenance of SR in the medium-term.     

Ibutilide-induced cardioversion of atrial fibrillation during pregnancy

We present two cases of successful cardioversion of atrial fibrillation using intravenous ibutilide during pregnancy. One patient had atrial fibrillation, complicating the Wolff-Parkinson-White syndrome and the other had a history of nonobstructive hypertrophic cardiomyopathy. No adverse maternal or fetal effects were observed during or after pregnancy in either case.     

Factors predicting success rate and recurrence of atrial fibrillation after first electrical cardioversion in patients with persistent atrial fibrillation

BACKGROUND: The recurrence rate of atrial fibrillation (AF) after elective cardioversion is high. HYPOTHESIS: The study aimed to identify clinical predictors for successful electrical cardioversion and maintenance of sinus rhythm after a first electrical cardioversion in patients with persistent AF without concomitant antiarrhythmic drugs of class I and III. METHODS: Consecutive outpatients (n = 166) with persistent AF for > 1 month, scheduled for elective cardioversion, were prospectively included in the study. A clinical investigation, echocardiographic assay, and Holter electrocardiogram (ECG) before and ECG 4 weeks after cardioversion, were performed in all patients. RESULTS: The mean age of the patients was 68 years (range 45-83) and duration of AF was 5 (1-48) months. Sinus rhythm was established in 124 (75%) patients. In multivariate analysis, only duration of AF < 6 months (p < 0.04, odds ratio [OR] 2.2, 95% confidence interval [CI] 1.1 to 4.7) and patients weight (p < 0.03, OR 2.3, 95% CI 1.1 to 4.8 for weight < 80 kg) were identified as independent predictors of successful cardioversion. At 4 weeks after cardioversion, only 46 (37%) of 124 patients maintained sinus rhythm. Independent factors for maintenance of sinus rhythm, in multivariate analysis, were AF <3 months (p < 0.04, OR 2.5, 95% CI 1.1 to 5.6), treatment with beta blockers (p < 0.00001, OR 7.0, 95% CI 3.0 to 16.3) or verapamil/diltiazem (p < 0.04, OR 3.6, 95% CI 1.1 to 12.1), and right atrial dimension < 37 mm (p < 0.02, OR 5.9, 95% CI 1.4 to 25.4). CONCLUSIONS: In patients with persistent AF, the patient's weight and the duration of AF are independent predictors for a successful cardioversion. Short duration of AF, treatment with beta blockers or verapamil/diltiazem, and right atrial area/dimension are independent predictors for maintenance of sinus rhythm.     

Effect of atrial fibrillation duration on probability of immediate recurrence after transthoracic cardioversion

INTRODUCTION: An immediate recurrence of atrial fibrillation (IRAF) appears to be more common after early restoration of sinus rhythm with an implantable atrial defibrillator than after elective transthoracic cardioversion, which suggests that the probability of IRAF may be related to the duration of AF. METHODS AND RESULTS: Transthoracic cardioversion was performed 85 +/- 187 days (range 7 minutes to 8 years) after the onset of atrial fibrillation in 315 patients (mean age 61 +/- 13 years). IRAF was defined as a recurrence of AF within 60 seconds after restoration of sinus rhythm. IRAF occurred in 56% of patients when cardioversion was performed within 1 hour of the onset of AF compared with 12% of patients when cardioversion was performed after 24 hours of AF (P < 0.001). The duration of AF was the only independent predictor of IRAF among the clinical variables of age, gender, structural heart disease, antiarrhythmic drug therapy, and cardioversion energy (P < 0.01). CONCLUSION: IRAF is more likely to occur when the duration of AF is <1 hour than when the duration is >24 hours. This observation has clinical implications for the most appropriate timing of cardioversion, particularly in patients who receive device therapy for AF.     

Prevalence and significance of focal sources of atrial arrhythmia in patients undergoing cardioversion of persistent atrial fibrillation

INTRODUCTION: Recent reports have high-lighted the importance of focal atrial arrhythmias as a curable cause for a group of patients with frequently recurrent paroxysmal atrial fibrillation (AF). The importance of this arrhythmia mechanism in the general population of patients with persistent AF is unknown. METHODS AND RESULTS: After successful internal cardioversion of 50 consecutive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate postcardioversion period was analyzed for the presence of focal atrial activity. Postcardioversion atrial arrhythmias were considered to be focal if there was evidence of a localized source of repetitive early atrial activation, either in the form of (1) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first five beats) that was both monomorphic and reproducible with repeated recurrences. Evidence for a focal atrial arrhythmia was present in 20 of the total group of 50 patients (40%). Multivariate analysis of clinical characteristics revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028). Thirty-nine patients were discharged from hospital in sinus rhythm. At 1-month follow-up, 25 (64%) of these 39 patients had suffered AF recurrence. The only significant predictor of AF recurrence was evidence of a focal source of atrial arrhythmia immediately after cardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015). CONCLUSION: Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the generation of this common arrhythmia.     

Predictors for maintenance of sinus rhythm after cardioversion in patients with nonvalvular atrial fibrillation

Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. Transesophageal echocardiographic (TEE) parameters have been the focus of clinicians' interests for restoring and maintaining SR. This study determined the clinical, transthoracic, and TEE parameters that predict maintenance of SR in patients with nonvalvular AF after CV. We enrolled 173 patients with nonvalvular AF in the study. TEE could not be performed in 26 patients prior to CV. Twenty-five patients had spontaneously CV prior to TEE. Six patients were excluded because of left atrial (LA) thrombus assessed by TEE. CV was unsuccessful in 6 patients. The remaining 110 consecutive patients (56 men, 54 women, mean age 69 +/- 9 years), who had been successfully cardioverted to SR, were prospectively included in the study. Fifty-seven (52%) patients were still in SR 6 months after CV. Age, gender, the configuration of the fibrillation wave on the electrocardiogram, pulmonary venous diastolic flow, and the presence of diabetes, hypertension, coronary artery disease, mitral annulus calcification, and mitral valve prolapse (MVP) did not predict recurrence. Duration of AF, presence of chronic obstructive pulmonary disease (COPD), LA diameter, left ventricular ejection fraction (EF), left atrial appendage peak flow (LAAPF), LAA ejection fraction (LAAEF), pulmonary venous systolic flow (PVSF), and the presence of LA spontaneous echo contrast (LASEC) predicted recurrence of AF 6 months after CV. In multivariate analysis, LAAEF < 30% was found to be the only independent variable (P < 0.0012) predicting recurrence at 6 months after CV in patients with nonvalvular AF. LAAEF more than 30% had a sensitivity of 75% and a specificity of 88% in predicting maintenance of SR 6 months after CV in patients with nonvalvular AF. In conclusion, TEE variables often used to determine thromboembolic risk also might be used to predict the outcome of CV.     

How to enhance acute outcome of electrical cardioversion by drug therapy: importance of immediate reinitiation of atrial fibrillation

INTRODUCTION: In almost 20% of patients with persistent atrial fibrillation (AF), electrical cardioversion is unsuccessful because of shock failure (i.e., no single sinus beat) or immediate reinitiation of AF (IRAF; recurrence within 2 min). Relative prevalence of shock failure and IRAF are not well known because data on outcome of electrical cardioversion therapy mostly do not distinguish shock failure from IRAF. METHODS AND RESULTS: In this review, the role of pretreatment with antiarrhythmic drugs on prevention of shock failure and total outcome of the cardioversion procedure are investigated. Quinidine and propafenone seem to be effective in preventing IRAF. Verapamil given in addition to Class I or III drugs may strengthen the preventive effects of these drugs than if they were given alone. Ibutilide prevents shock failure, although neither ibutilide nor dofetilide seems to be effective in preventing IRAF. CONCLUSION: Pretreatment with antiarrhythmic drugs may enhance cardioversion outcome predominantly by preventing IRAF. Different antiarrhythmic drugs within the same Vaughan-Williams class have different effects on shock failure and IRAF.     

Effects of successful cardioversion of persistent atrial fibrillation on right ventricular refractoriness and repolarization.

AIM: Changes in ventricular refractoriness and repolarization after successful electrical cardioversion to sinus rhythm in persistent atrial fibrillation (AF) patients were studied. METHODS AND RESULTS: In 33 AF patients with controlled ventricular response, right ventricular ERP (VERP) at three basic cycle lengths (600, 500, 400 ms), as well as monophasic action potential duration (MAPd(90)) at a drive cycle length of 500 ms, were measured just before, 20 min and 24 h after cardioversion. VERP at 600 ms changed from 241+/-19 ms to 249+/-21 ms to 253+/-24 ms (P<0.001), VERP at 500 ms changed from 234+/-19 ms to 242+/-22 ms to 246+/-23 ms (P<0.001) and VERP at 400 ms changed from 224+/-20 ms to 232+/-23 ms to 236+/-24 ms (P<0.001). MAPd(90) changed from 247+/-16 ms preconversion to 252+/-17 ms 20 min postconversion to 253+/-19 ms after 24 h (P<0.05). Change in refractoriness at 500 ms was well correlated with change of mean RR interval before and 20 min after conversion (R=0.616, P<0.001). There was no correlation between RR variability and VERP before cardioversion. CONCLUSION: Restoration of sinus rhythm in persistent AF patients is followed by significant effects on ventricular refractoriness and repolarization related to cycle length change. No AF related ventricular electrophysiological alterations were found.     

Internal low-energy cardioversion: a therapeutic option for restoring sinus rhythm in chronic atrial fibrillation after failure of external cardioversion.

AIMS: Conventional external cardioversion remains the technique of choice for restoration of sinus rhythm in patients with chronic atrial fibrillation (AF). Recent reports have suggested that internal low-energy cardioversion is efficient and safe in terminating AF in patients with failed external cardioversion. METHODS AND RESULTS: In 20 of 118 consecutive patients with spontaneous chronic AF (>7/days), who underwent low-energy cardioversion, one or more attempts at restoring sinus rhythm with external cardioversion had failed. Low-energy internal cardioversion was performed under light sedation. Shocks were delivered (using an external custom defibrillator) between two nonapolar catheters positioned in the right atrium (cathode) and in the coronary sinus (anode). Heart disease was present in 12 and absent in eight patients ('lone' atrial fibrillation). Atrial fibrillation was established for a period ranging from 12 days to 53 months. Low-energy internal cardioversion restored sinus rhythm in 15 of the 20 patients (75%) with a mean energy of 4.5+/-1.2 J, a mean conversion voltage of 355+/-53 V and a mean impedance of 63+/-8 ohms. No complications were observed. With a mean follow-up of 6+/-7 months, 11 patients (73%) were in stable sinus rhythm. CONCLUSIONS: This study provides evidence in support of low-energy internal cardioversion as a valuable therapeutic option in patients in whom conventional external cardioversion failed. This technique is safe and does not require general anaesthesia.