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

Evaluating the Efficacy and Safety of Internal Cardioversion with Implantable Cardioverter Defibrillator Device for Atrial Fibrillation in Systolic Heart Failure Patients

BACKGROUND

Atrial fibrillation (AF) commonly observed in patients with heart failure and cardioversion was often needed to restore the sinus rhythm. Previously, there is no study evaluating usefulness of internal cardioversion with implantable cardioverter defibrillator (ICD) device. In this study, we aimed to compare the efficacy and long-term effects of internal cardioversion with ICD devices compared to conventional external cardioversion in patients with AF and heart failure.

METHODS

Seventy patients with AF and heart failure who underwent electrical cardioversion were enrolled in the study. Forty patients (mean age 65.36 ± 10.37, 35 male) were assigned to undergo internal cardioversion with approximately 35 J shocks delivered through the ICD electrode. Standard external cardioversion was performed for the remaining patients (30 patients; mean age 66.20 ± 11.89; 24 male) that were similar with regard to baseline, and electrocardiographic characteristics.

RESULTS

Sinus rhythm was restored in 32 of 40 patients (80.0%) assigned to internal cardioversion compared with 25 of 30 patients (83.3%) assigned to external cardioversion (P = 0.725). We did not witness any serious complication during the procedure and hospitalization. On the follow-up, there was no statistically significant difference in recurrence of AF and incidence of major cardiovascular events between the internal and external cardioversion groups.

CONCLUSIONS

Internal cardioversion with ICD device is an effective and safe method to restore sinus rhythm in heart failure patients with AF.

Predictors of atrial fibrillation recurrence in patients with long-lasting atrial fibrillation

BACKGROUND

Limited data are available on the predictors of atrial fibrillation (AF) recurrence in patients with chronic AF.

OBJECTIVES

To evaluate potential clinical, echocardiographic and electrophysiological predictors of AF recurrence, after internal cardioversion for long-lasting AF.

METHODS

A total of 99 consecutive patients (63 men and 36 women, mean age 63.33+/-9.27 years) with long-standing AF (52.42+/-72.02 months) underwent internal cardioversion with a catheter that consisted of two defibrillating coils. Shocks were delivered according to a step-up protocol. Clinical follow-up and electrocardiographic recordings were performed on a monthly basis for a 12-month period or whenever patients experienced symptoms suggestive of recurrent AF.

RESULTS

Ninety-three patients (93.94%) underwent a successful uncomplicated cardioversion, with a mean atrial defibrillation threshold of 10.69+/-6.76 J. Immediate reinitiation of AF was observed in 15 patients (15.78%) of whom a repeated cardioversion restored sinus rhythm in 13 cases. Early recurrence of AF (within one week) was observed in 12 of 93 patients (12.90%). At the end of the 12-month follow-up period, during which seven patients were lost, 42 of the 86 remaining patients (48.84%) were still in sinus rhythm. Multivariate regression analysis showed that left atrial diameter (OR 1.126, 95% CI 1.015 to 1.249; P=0.025) and mitral A wave velocity (OR 0.972, 95% CI 0.945 to 0.999; P=0.044) were significant and independent predictors of AF recurrence, whereas age, left ventricular ejection fraction and AF cycle length were not predictive of arrhythmia recurrence.

CONCLUSION

The present study showed that the left atrial diameter and mitral A wave velocity are the only variables associated with AF recurrence after successful cardioversion.

Rate of conversion and recurrence after sotalol treatment in patients with direct current-refractory atrial fibrillation

BACKGROUND

A number of patients with persistent atrial fibrillation (AF) will not have sinus rhythm (SR) restored by direct current (DC) cardioversion.

HYPOTHESIS

In patients with DC-refractory AF, oral pretreatment with sotalol increases the success rate at DC cardioversion.

METHODS

Consecutive patients with persistent AF, refractory at a first DC cardioversion, were prospectively included. A comparative group of patients with AF not refractory at DC cardioversion was studied. Oral sotalol treatment was started after unsuccessful DC cardioversion and given at least 7 days before renewed cardioversion. Four weeks after cardioversion, an electrocardiogram was performed.

RESULTS

In all, 53 patients were enrolled in the study. Forty-three (81%) in the sotalol group regained sinus rhythm (SR): 10 (19%) of these converted pharmacologically and 33 (62%) after a second DC cardioversion; SR was never restored in 10 patients (19%). After 4 weeks, SR was maintained in 29 patients (67%). The comparative group included 132 patients and differed significantly from the DC-refractory patients only with regard to weight. After 4 weeks, SR was maintained by 50 patients (37%) in this group.

CONCLUSIONS

In patients with persistent AF refractory to DC cardioversion, oral pretreatment with sotalol results in a high rate of SR restoration, either pharmacologically or by DC cardioversion. Maintenance of SR at 4 weeks is of sufficient clinical relevance to consider this treatment option in patients with AF refractory to DC cardioversion.

Internal atrial shock delivery by standard diagnostic electrophysiology catheters in goats: effects on atrial electrogram amplitude and tissue architecture

AIMS

In this study, we evaluated the effects of atrial shock delivered via diagnostic electrophysiology catheters.

METHODS AND RESULTS

In 11 anaesthetized goats, decapolar catheters were positioned in the right atrial appendage (RAA) and coronary sinus (CS). Three different catheters and two cardioversion protocols were evaluated. In four goats, 50 J shocks were delivered using catheters with 1 mm electrodes (surface area 70 mm(2)). In 6 goats, catheters with 2 mm electrodes (area 140 mm(2)) were used. In three of the six goats, 50 J shocks were given while in the other 3, 10 J shocks were delivered. In 1 goat 50 J shocks were delivered via 5 mm electrode catheters (area 310 mm(2)). No persisting adverse effects occurred. However, the electrogram amplitude at the RAA and CS decreased by >50-98% (P > 0.01). The amount of amplitude decrease was most pronounced at the CS site and for 50 J shocks. Goats were sacrificed after 9 +/- 1 days. Macroscopy revealed endocardial lesions at the electrode locations. Microscopy showed endocardial thrombosis, and necrosis with formation of granulation tissue. Changes were most marked with diagnostic catheters and 50 J shocks.

CONCLUSIONS

Atrial shock delivery via diagnostic catheters causes local ablation lesions. The amount of amplitude decrease, macroscopic and microscopic damages were related to the energy applied and electrode surface area.

Internal Atrial and Ventricular Defibrillation During Electrophysiology Procedures

Over the last twenty years internal defibrillation has evolved from an experimental technique into an important adjunctive procedure in the electrophysiology laboratory. Internal deflbrillation is used for treating persistent atrial fibrillation and refractory ventricular arrhythmias. Atrial defibrillation can be performed with several electrode configurations but generally shocks from 1 to 50 joules are delivered between electrodes placed in the coronary sinus and lateral wall of the right atrium. Ventricular defibrillation is usually performed with electrodes in the right ventricle and superior vena cava, although "unipolar" configurations with an internal ventricular electrode and a skin electrode can be used. Currently, internal deflbrillation can be required in 5-10% of cases within the electrophysiology laboratory and will become more commonly used as electrophysiologists perform more complex catheter ablation procedures.

Intracardiac low-energy versus transthoracic high-energy direct-current cardioversion of atrial fibrillation: a randomised comparison

Of 54 patients with long-standing atrial fibrillation (mean duration 8.3 months), 27 patients were randomised to transvenous low-energy intracardiac biphasic direct-current (DC) cardioversion (ICV) using a single-lead balloon-tipped catheter, and 27 patents were randomised to conventional high-energy transthoracic monophasic DC cardioversion (TCV). ICV was performed with increasing energy levels (7.5-10-12.5-15 J) during mild sedation. TCV was performed with 200-360-360 J during general anaesthesia. Cardioversion to sinus rhythm occurred in 93% (25/27) following ICV and in 67% (18/27) following TCV (p = 0.04). Due to the higher cardioversion rate following ICV, more patients were in sinus rhythm during 180 days of follow-up (log rank test, p = 0.04). Low-energy intracardiac cardioversion represents a highly efficacious alternative to high-energy transthoracic cardioversion.

Present treatment options for atrial fibrillation

Atrial fibrillation is the commonest sustained cardiac arrhythmia. It accounts for >35% of all hospital admissions for cardiac arrhythmias in the United States. The presence of atrial fibrillation increases the mortality of a population by up to twofold. The risk of stroke increases from 1.5% in patients with atrial fibrillation from 50-59 years of age to up to 23.5% for such patients aged 80-89 years. Although the diagnosis of atrial fibrillation is usually straightforward, effective treatment is not. This article will discuss how rhythm control of atrial fibrillation can best be achieved, the controversy over the rhythm versus rate control, the maintenance of sinus rhythm with antiarrhythmic drugs after cardioversion, and prevention of thromboembolism. Finally, the recent advances in various non-pharmacological approaches for the treatment of atrial fibrillation will be highlighted.

Safety and efficacy of low-energy cardioversion of 500 patients using two different techniques

AIM

To present some safety and efficacy issues of low-energy internal cardioversion of chronic atrial fibrillation from 500 consecutive procedures performed with two different techniques, using either two single-coil catheters, or a single twin-coil catheter.

METHODS AND RESULTS

Low-energy internal cardioversion was carried out in 368 patients by means of two defibrillation catheters: the former was positioned in the right atrium and the latter either in the left pulmonary artery (212 patients), or in the distal coronary sinus (156 patients). In the remaining 132 patients, a single twin-coil catheter was positioned with the distal coil either in the pulmonary artery (75 patients) or in the coronary sinus (57 patients), while the proximal coil was in the right atrium. The external defibrillator delivered truncated biphasic shocks (6/6 ms, tilt 50%), with a voltage of 10-400 V. In 283 patients (57%) external cardioversion had been unsuccessfully tried before low-energy internal cardioversion. After a total of 1118 shocks, the overall success rate was 92.2% (91.3% with two catheters and 94.7% with the single catheter); the success rate was 93.4 and 91.3% with the coronary sinus and the pulmonary artery approach, respectively. The mean energy used was 6.5 +/- 3.4 J (voltage: 320 +/- 45 V); no difference was found between the twin catheter (6.3 +/- 3.1 J) and the single catheter approach (6.9 +/- 3.7 J), while the coronary sinus configuration required a significantly lower energy than the pulmonary artery configuration (5.6 +/- 2.9 vs 7.2 +/- 3.8 J, P < 0.05). The duration of the current atrial fibrillation episode was the only clinical characteristic statistically different between the 461 successfully cardioverted patients and the 39 failures (295 vs 727 days, P < 0.01). No complication was recorded during or after the delivery of the therapy; no procedure had to be terminated because of patient's intolerance.

CONCLUSIONS

Low-energy internal cardioversion is a safe and effective procedure for converting chronic atrial fibrillation, confirmed by this large multicentre experience. The newly available twin-coil catheter seems to achieve a slightly better success rate compared with the traditional two-catheter technique, and is associated with the same safety profile.