A comparison of treatment of atrial fibrillation with low-energy intracardiac cardioversion and conventional external cardioversion

Role of Intracardiac Defibrillation During the Ablation Procedure as a Predictor of Atrial Fibrillation Recurrence After Catheter Ablation

Intracardiac defibrillation (IDF) is performed to restore sinus rhythm (SR) during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). This study aimed to investigate the change in the IDF threshold before and after RFCA during the ablation procedure and determine whether the IDF threshold after RFCA was associated with the AF substrate and AF recurrence. A total of 141 consecutive patients with drug-refractory persistent AF (age 62.5 ± 10.3 years, 84.4% male) were enrolled in this study. Before RFCA, we initially performed IDF with an output of 1 J. When IDF failed to restore SR, the output was gradually increased to 30 J. After RFCA, we attempted pacing-induced AF to provoke other focuses of AF. When AF was induced, we performed IDF again to terminate AF with outputs of 1 to 30 J. The change in the IDF threshold to restore SR before and after RFCA was evaluated. After RFCA, the IDF threshold for restoring SR significantly decreased (from 11.5 ± 8.6 J to 4.0 ± 3.8 J, P < 0.001). During the follow-up (24.3 ± 12.2 months), SR was maintained in 107 patients (75.9%). The multivariate analysis using a Cox proportional-hazards model revealed that an IDF threshold of > 5 J after RFCA was significantly associated with the AF recurrence (HR, 3.99; 95% confidence interval 1.93-8.22; P = 0.0001). RFCA decreased the IDF threshold for restoring SR in patients with persistent AF. The IDF output of > 5 J after RFCA could be a predictor of AF recurrence independent of the AF substrate.

External versus internal cardioversion for atrial fibrillation: a meta-analysis of randomized controlled trials

BACKGROUND

Patients with atrial fibrillation (AF) often require rhythm control strategy for amelioration of symptoms. It is unclear if there is any difference between external cardioversion (ECV) and internal cardioversion (ICV) for successful conversion of AF to normal sinus rhythm.

METHODS

We performed a meta-analysis of published randomized controlled trials (RCTs) evaluating success of cardioversion using ECV versus ICV.

RESULTS

In the pooled analysis of 5 RCTS, there was no difference in success of cardioversion using ECV versus ICV (OR 1.69, 95% CI 0.24-11.83, p = 0.6). In the subgroup analysis, there was no difference between ECV and direct electrode ICV (OR 0.41, 95% CI 0.09-1.83, p = 0.24). However, ECV was significantly better compared with ICV using ICD (OR 11.97, 95% CI 1.87-76.73, p = 0.009).

CONCLUSIONS

There was no difference between ECV versus ICV in effectiveness for termination of AF. Larger well-designed randomized controlled trials are needed to confirm our findings.

Amiodarone Versus Propafenone to Treat Atrial Fibrillation after Coronary Artery Bypass Grafting: A Randomized Double Blind Controlled Trial

Background

Atrial fibrillation (AF) is one of the most common complications after cardiac surgery. Several therapeutic and preventive strategies have been introduced for postoperative AF, but the treatment and prophylaxis of AF remain controversial. We aimed to compare the efficacy of intravenous amiodarone and oral propafenone in the treatment of AF after coronary artery bypass grafting (CABG).

Methods

This was a randomized controlled trial performed in two hospitals in Shiraz, Iran from 2009 to 2012. We included all patients who underwent elective CABG and developed AF postoperatively. The patients were randomly assigned to receive propafenone or amiodarone. The duration of AF, the success rate of the treatment, the need for cardioversion, the frequency of repeated AF, and the need for repeating the treatment were compared.

Results

The duration of the first (p=0.361), second (p=0.832), and third (p=0.298) episodes of AF, the need for cardioversion (p=0.998), and the need to repeat the first and second doses of drugs (p=0.557, 0.699) were comparable between the study groups. Repeated AF was observed in 17 patients (30.9%) in the propafenone group and 23 patients (34.3%) in the amiodarone group (p=0.704).

Conclusion

Oral propafenone and intravenous amiodarone are equally effective in the treatment and conversion of recent-onset AF after CABG.

Novel Pharmacological Interventions to Maintain Sinus Rhythm after DC Cardioversion

Despite the availability of potentially curative interventions for atrial fibrillation, there remains an important role for conventional anti-arrhythmic therapy and anti-coagulation combined with direct current cardioversion. Unfortunately, the latter approach is disturbed by high recurrence rates of atrial fibrillation. In recent years, several adjunctive therapies have emerged which may facilitate the maintenance of sinus rhythm. These novel therapies and their potential mechanisms of action are reviewed in this article.

Noninvasive time and frequency predictors of long-standing atrial fibrillation early recurrence after electrical cardioversion

BACKGROUND

Several clinical factors have been studied to predict atrial fibrillation (AF) recurrence after electrical cardioversion (ECV) with limited predictive value.

METHODS

 A method able to predict robustly long-standing AF early recurrence by characterizing noninvasively the electrical atrial activity (AA) with parameters related to its time course and spectral features is presented. To this respect, 63 patients (20 men and 43 women; mean age 73.4 ± 9.0 years; under antiarrhythmic drug treatment with amiodarone) who were referred for ECV of persistent AF were studied. During a 4-week follow-up, AF recurrence was observed in 41 patients (65.1%).

RESULTS

 RR variability and the studied AA spectral features, including dominant atrial frequency (DAF), its first harmonic and their amplitude, provided poor statistical differences between groups. On the contrary, f waves power (fWP) and Sample Entropy (SampEn) of the AA behaved as very good predictors. Patients who relapsed to AF presented lower fWP (0.036 ± 0.019 vs 0.081 ± 0.029 n.u.(2) , P < 0.001) and higher SampEn (0.107 ± 0.022 vs 0.086 ± 0.033, P < 0.01). Furthermore, fWP presented the highest predictive accuracy of 82.5%, whereas SampEn provided a 79.4%. The remaining features revealed accuracies lower than 70%. A stepwise discriminant analysis (SDA) provided a model based on fWP and SampEn with 90.5% of accuracy.

CONCLUSIONS

 The fWP has proved to predict long-standing AF early recurrence after ECV and can be combined with SampEn to improve its diagnostic ability. Furthermore, a thorough analysis of the results allowed outlining possible associations between these two features and the concomitant status of atrial remodeling.

Termination of sustained atrial flutter and fibrillation using low-voltage multiple-shock therapy

BACKGROUND

Defibrillation therapy for atrial fibrillation (AF) and flutter (AFl) is limited by pain induced by high-energy shocks. Thus, lowering the defibrillation energy for AFl/AF is desirable.

OBJECTIVE

In this study we applied low-voltage multiple-shock defibrillation therapy in a rabbit model of atrial tachyarrhythmias comparing its efficacy to single shocks and antitachycardia pacing (ATP).

METHODS

Optical mapping was performed in Langendorff-perfused rabbit hearts (n = 18). Acetylcholine (7 ± 5 to 17 ± 16 μM) was administered to promote sustained AFl and AF, respectively. Single and multiple monophasic shocks were applied within 1 or 2 cycle lengths (CLs) of the arrhythmia.

RESULTS

We observed AFl (CL = 83 ± 15 ms, n = 17) and AF (CL = 50 ± 8 ms, n = 11). ATP had a success rate of 66.7% in the case of AFl, but no success with AF (n = 9). Low-voltage multiple shocks had 100% success for both arrhythmias. Multiple low-voltage shocks terminated AFl at 0.86 ± 0.73 V/cm (within 1 CL) and 0.28 ± 0.13 V/cm (within 2 CLs), as compared with single shocks at 2.12 ± 1.31 V/cm (P < .001) and AF at 3.46 ± 3 V/cm (within 1 CL), as compared with single shocks at 6.83 ± 3.12 V/cm (P =.06). No ventricular arrhythmias were induced. Optical mapping revealed that termination of AFl was achieved by a properly timed, local shock-induced wave that collides with the arrhythmia wavefront, whereas AF required the majority of atrial tissue to be excited and reset for termination.

CONCLUSION

Low-voltage multiple-shock therapy terminates AFl and AF with different mechanisms and thresholds based on spatiotemporal characteristics of the arrhythmias.

Outcomes in patients requiring cardioversion following catheter ablation of atrial fibrillation

INTRODUCTION

Early recurrence of atrial tachyarrhythmias is commonly noted after catheter ablation of atrial fibrillation (AF). The long-term outcomes of patients who require cardioversion for persistent AF after AF ablation is not known. This study reports the outcomes of patients who underwent cardioversion for persistent AF or atrial flutter following an AF ablation procedure.

METHODS

The patient population comprised 55 patients (mean age 58 +/- 10 years, 35% paroxysmal) who underwent catheter ablation of AF and subsequently required electrical cardioversion for persistent AF (45 patients) or atrial flutter (10 patients). Cardioversion was defined as early (within 90 days of the ablation procedure) or late (between 90 and 180 days following ablation).

RESULTS

The mean follow-up duration was 15 +/- 8 months. Forty-six of the 55 patients (84%) patients experienced recurrence during follow-up. The average time to recurrence after cardioversion was 37 days. Of the 55 patients, 8 (15%) patients had a complete success, 11 (20%) patients had a partial success and 36 patients (65%) had a failed outcome. Seven of the 43 patients (16%) who underwent early cardioversion had a complete success as opposed to one of 12 patients (8%) who underwent late cardioversion (P = 0.49).

CONCLUSIONS

This study shows that >80% of patients who undergo cardioversion for persistent AF or atrial flutter after AF ablation have recurrence. The timing of cardioversion did not affect the outcome. These findings allow clinicians to provide realistic expectations to patients regarding the long-term outcome and/or requirement for a second ablation procedure.

Time and frequency recurrence analysis of persistent atrial fibrillation after electrical cardioversion

Electrical cardioversion (ECV) has become a mainstay of therapy for the treatment of persistent atrial fibrillation (AF), which is an arrhythmia that affects up to 1% of the general population. The procedure is initially effective, but it is also characterized by a high rate of AF recurrence. As a consequence, it would be clinically useful to predict normal sinus rhythm (NSR) maintenance after ECV before it is attempted. In this respect, several clinical, echocardiographic and demographic parameters have been analyzed by other authors. However, these indices are weak predictors of ECV outcome. In this work, surface electrocardiographic (ECG) recordings were used to extract the atrial activity (AA) signal and parametrize the fibrillatory (f) waves, both in time and frequency, to obtain AF recurrence predictors. Parameters as f waves amplitude (fWA), AA mean power, dominant atrial frequency (DAF), its first harmonic, etc were studied. Obtained results showed that fWA was the most significant predictor of AF recurrence 1 month later. Concretely, 72.73% of the patients resulting in NSR, 83.87% relapsing to AF and 80.0% with unsuccessful ECV, were correctly identified. Therefore, fWA classified satisfactorily 79.37% of the analyzed patients. In addition, a forward stepwise discriminant analysis, with a leave-one-out cross validation approach, proved that fWA and DAF combination provided an improved diagnostic ability of 85.71%. In this case 86.36%, 83.87% and 90% of the patients who resulted in NSR, relapsed to AF and with unsuccessful ECV, were correctly discerned, respectively. In conclusion, fWA could be considered as a promising predictor of ECV outcome during the first month following the procedure. Additionally, time and frequency indices could yield complementary information useful to predict the cardioversion outcome. Finally, further studies are needed to validate the robustness of these parameters and the repeatability of the obtained results on wider databases.

Transvenous electrical cardioversion of atrial fibrillation in six horses using custom made cardioversion catheters

Pharmacological conversion of atrial fibrillation (AF) to sinus rhythm in horses can be difficult. The objective of this study was to investigate the feasibility of transvenous electrical cardioversion with custom made catheters in eight horses, of which three had failed cardioversion using quinidine sulfate. Two cardioversion catheters and one pacing/sensing electrode were inserted via the right jugular vein and placed using ultrasound guidance into the left pulmonary artery, the right atrium and the right ventricle, respectively. Because immediate recurrence of AF was encountered in the second horse treated, pre-treatment with amiodarone was given to each of the remaining six horses. Induction of general anaesthesia was associated with dislocation of the cardioversion catheter in three horses, requiring a second catheterisation procedure. During general anaesthesia, biphasic R wave synchronised shocks of up to 360 J were delivered between both cardioversion electrodes. In six horses (75%), including two which had failed quinidine sulfate treatment, sinus rhythm was restored with a mean energy level of 295+/-62 J. No side effects were observed. Blood analysis 3 h after cardioversion revealed normal parameters, including cardiac troponin I values. Transvenous electrical cardioversion of atrial fibrillation with custom made cardioversion catheters can be considered as a treatment option for atrial fibrillation in horses, especially when conventional drugs fail.

Treatment satisfaction of internal versus external cardioversion in patients with chronic atrial fibrillation--a randomized, prospective, 28-day follow-up study

BACKGROUND AND HYPOTHESIS

The use of internal cardioversion (IC) in chronic atrial fibrillation (AF) may be limited by procedure-related distress. This procedure may be efficacious but is not necessarily perceived as satisfactory by the patient because of the frequent procedure-related distress.

METHODS

We compared treatment satisfaction in 55 patients with chronic AF referred for cardioversion (CV). Satisfaction with conventional external cardioversion (EC, n = 27) and low-energy IC (n = 28) was compared immediately after the approach and at 28-day follow-up.

RESULTS

Four hours after CV, satisfaction scores (ranging from 0 to 7) were higher with EC (mean 6.1 standard deviation [SD] +/- 1.4) versus IC (m = 5.4 SD +/- 1.8) (p = 0.09). At 28 days, treatment satisfaction decreased in EC (m = 5.5 SD +/- 2.1) and increased in the IC group (5.7 SD +/- 1.8) because of a decrease in the trustful attitude subscale (p = 0.026) followed by tolerance for distressing factors (p = 0.059). The analysis of variance for repeated measures revealed a significant time by method interaction effect (p = 0.04). Patients prone to developing low treatment satisfaction (LTS) at follow-up were more anxious (p = 0.007) before treatment. They suffered more from sleeping disorders (p = 0.009) and considered their disease condition to be worse than that in their counterparts (p = 0.027). Low treatment satisfaction at 28 days was associated with anxiety (p = 0.017), depression (p = 0.01), and the perception of heart-related symptoms (p = 0.001). Multivariate analysis revealed the failure to maintain sinus rhythm (p = 0.001) as the most powerful contributor to LTS.

CONCLUSIONS

The novel IC approach causes acute procedure-related distress but has no enduring negative psychological side effects. Despite a greater patient perception of distressing procedure-related factors during IC compared with EC, the IC approach provides a greater 28-day benefit in terms of tolerability and acceptance on the part of the patients. Failure to maintain sinus rhythm rather than the method applied contributes most to LTS.

Prospective randomized trial of transthoracic versus low-energy internal cardioversion in persistent atrial fibrillation: long term follow-up

Low energy internal cardioversion (ICV) is a relatively new method. This report describes the long-term follow-up results of a prospective randomized comparison of low energy ICV and transthoracic cardioversion (TT CV) in patients with persistent atrial fibrillation (AF). Fifty-two patients (mean age, 60.6 +/- 10.1 years, 23 males) with persistent AF were randomly assigned to either TT (n = 26) or ICV (n = 26). The baseline characteristics of the 2 groups were similar. Transthoracic CV was performed under sedation with hand-held electrodes in the apex-anterior position and high energy (100-360 J) monophasic shocks. ICV was performed by a dedicated balloon-directed catheter utilizing truncated, biphasic shocks of low energy (1-15 J). Sinus rhythm (SR) was restored in 24/26 (92%) patients in the ICV group and in 22/26 (85%) patients in the TT CV group (P > 0.05). Immediate recurrence of AF (IRAF), defined as reappearance of AF within 2 minutes of successful CV, occurred in 5 patients (21%) in the ICV group and in 1 patient (4.5%) in the TT group (P > 0.05). Successfully cardioverted patients in whom no IRAF occurred were followed-up for 18 months under both warfarin and Class 1 or 3 antiarrhythmic drugs, as guided by the current ACC/AHA/ESC Guidelines. The rate of SR at 1, 3, 6, 12, and 18 months of follow-up was not significantly different between the 2 groups, and in an intention-to-treat analysis at 18 months, SR was present in 6 patients (23%) in the ICV group and in 10 patients (38%) in the TT group (P > 0.05). The majority of AF recurrences occurred within a month of successful CV in both groups (8/12 [67%] in the TT group and 15/18 [83%] in the ICV group, P > 0.05). The mortality, thromboembolic, and bleeding complication rates were similar in the 2 groups. In this prospective randomized comparison of TT and low energy ICV in patients with persistent AF, the 18-month rates of SR and major adverse clinical events were found to be similar.

How to perform transvenous electrical cardioversion in horses with atrial fibrillation

Electrical cardioversion of atrial fibrillation is a well-established technique for restoration of sinus rhythm in humans. While transthoracic cardioversion is more commonly used, transvenous electrical cardioversion (TVEC) has been reported as having higher efficacy at substantially lower energy levels. In horses, treatment of atrial fibrillation has essentially been limited to the administration of quinidine salts either orally or intravenously. TVEC provides an alternative to quinidine salts, especially for those animals in which quinidine is neither effective nor tolerated. The present report details this technique in horses, discusses possible complications of the procedure, and provides guidance for successful outcome. Still and video images are used to illustrate details with regard to TVEC techniques in horses. Please view supplemental material for the videos.

Outpatient electrical cardioversion of atrial fibrillation: Efficacy, safety and patients' quality of life

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia. To lower costs and to reduce hospitalization electrical cardioversion (CV) is frequently performed in an outpatient setting although data on safety and patient-acceptance are sparse. Aims of this study were to fill this gap by evaluating efficacy, complication rate, quality of life after CV and patient-acceptance of outpatient CV.

METHODS

One-hundred and eleven consecutive patients with persistent AF were included. Patients were under continuous monitoring throughout the procedure and 3 h after. CV was done in deep sedation using rising energies (200->360 J). Quality of life (QoL), late adverse events and patient-acceptance were assessed 4 weeks after CV.

RESULTS

AF could be terminated with a mean of 1.4 shocks in all patients. Acute adverse events could be observed in 3.6%. Late adverse events were noted in 8.2%. Seventy-four percent of the patients felt "good" or "very good" the day of CV. Eighty-nine percent of the patients would undergo a CV again and in case of a further CV 69% of the patients would prefer an outpatient setting. Patients with a lower QoL-classification had longer duration of atrial fibrillation (median 1 vs. 3 months, p<0.05). No other clinical predictor for adverse events or a low QoL-classification could be identified.

CONCLUSION

Electrical CV of persistent AF in an outpatient setting is feasible, safe and has a high patient-acceptance.

Ibutilide in persistent atrial fibrillation refractory to conventional cardioversion methods

BACKGROUND

Electrical cardioversion of atrial fibrillation seems to be enhanced by pretreatment with ibutilide, but only few is known about the effects of ibutilide in atrial fibrillation which failed to convert with class III antiarrhythmic agents and electrical cardioversion. The objectives of this study were to evaluate the efficacy and safety of ibutilide administration in patients with persistent atrial fibrillation refractory to long-term therapy with class III antiarrhythmic drugs and transthoracic cardioversion.

METHODS

Prospective study in 22 patients (16 men and 6 women, mean age 63+/-9 years) with structural heart disease and persistent atrial fibrillation for a mean duration of 39+/-50 (range 1-145) months. All patients had failed to convert to sinus rhythm after transthoracic cardioversion while on treatment with class III antiarrhythmic drugs (amiodarone in 82%, sotalol in 18%). One milligram of ibutilide was administered in all patients and electrical cardioversion was performed again, if necessary.

RESULTS

The total conversion rate to sinus rhythm was 95% (21 of 22 patients). Two patients (9%) were successfully converted after ibutilide alone and 19 patients (86%) when transthoracic cardioversion was repeated after ibutilide. The QTc intervals increased from 451+/-28 to 491+/-49 ms (p<0.001) after ibutilide. No adverse effects occurred. The rate of freedom from atrial fibrillation after 1 month of follow-up was 64%.

CONCLUSIONS

The efficacy of concomitant use of ibutilide infusion and, if necessary, repeated transthoracic cardioversion for restoration of sinus rhythm in long-term persistent atrial fibrillation and previously failed antiarrhythmic and electrical cardioversion was 95%. There were no adverse effects associated with ibutilde administration. Our results suggest that this combined strategy may be safe and successful in patients with atrial fibrillation resistant to conventional cardioversion methods and may be an alternative to internal cardioversion.

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.

A randomized trial comparing monophasic and biphasic waveform shocks for external cardioversion of atrial fibrillation

BACKGROUND

We compared efficacy of and pain felt after biphasic truncated exponential (BTE) and monophasic damped sine (MDS) shocks in patients undergoing external cardioversion of atrial fibrillation (AF).

METHODS

Patients with AF were randomized to BTE or MDS waveform cardioversion. Successive shocks were delivered at 70, 100, 200, and 360 J until successful cardioversion, with one 360 J attempt of the alternate waveform when all 4 shocks failed. Success was determined by blinded over-read of electrocardiograms. Peak current was calculated from energy and impedance. Patients rated their pain at 1 and 24 hours after cardioversion.

RESULTS

Fourteen of 37 (38%) patients treated with MDS and 34 of 35 (97%) treated with BTE shocks were cardioverted at < or =200 J (P <.0001). Success rates of MDS versus BTE shocks were 5.4% versus 60% for 70 J, 19% versus 80% for < or =100 J, and 86% versus 97% for < or =360 J. BTE shocks cardioverted with less peak current (14.0 +/- 4.3 vs 39.5 +/- 11.2 A, P <.0001), less energy (97 +/- 47 vs 278 +/- 120 J, P <.0001), and less cumulative energy (146 +/- 116 vs 546 +/- 265 J, P <.0001). Patients felt less pain after BTE than MDS shocks at 1 hour (P <.0001) and 24 hours (P <.0001) after cardioversion.

CONCLUSION

This BTE waveform is superior to the MDS waveform for cardioversion of AF, requiring much less energy and current, and causing less postprocedural pain.

Defibrillation efficacy and pain perception of two biphasic waveforms for internal cardioversion of atrial fibrillation

Efficacy and Pain Perception of Two Biphasic Waveforms.

INTRODUCTION

We evaluated the influence of the peak voltage of waveforms used for internal cardioversion of atrial fibrillation on defibrillation efficacy and pain perception. A low peak voltage biphasic waveform generated by a 500-microF capacitor with 40% tilt was compared to a standard biphasic waveform generated by a 60-microF capacitor with 80% tilt.

METHODS AND RESULTS

In 19 patients with paroxysmal atrial fibrillation (79% male, age 55 +/- 11 years, 21% with heart disease), the atrial defibrillation threshold (ADFT) was determined during deep sedation with midazolam for both waveforms in a randomized fashion using a step-up protocol. Internal cardioversion with a single lead (shock vector: coronary sinus to right atrium) was successful in 18 (95%) of 19 patients. ADFT energy and peak voltage were significantly lower for the low-voltage waveform (2.1 +/- 2.4 J vs 3.5 +/- 3.9 J, P < 0.01; 100 +/- 53 V vs 290 +/- 149 V, P < 0.01). Sedation then was reversed with flumazenil after ADFT testing. Two shocks at the ADFT (or a 3-J shock if ADFT >3 J) were administered to the patient using each waveform in random order. Pain perception was assessed using both a visual scale and a numerical score. ADFTs were above the pain threshold in 17 (94%) of 18 patients, even though the ADFT with the 500-microF waveform was <100 V in 63% of the patients. Pain perception was comparable for both waveforms (numerical score: 6.5 +/- 2.4 vs 6.3 +/- 2.6; visual scale: 5.4 +/- 2.6 vs 5.2 +/- 3.1; P = NS, 500-microF vs 60-microF). The second shock was perceived as more painful in 88% of the patients, independent of the waveform used.

CONCLUSION

Despite a 66% lower peak voltage and a 40% lower energy, the 40% tilt, 500-microF capacitor biphasic waveform did not change the pain perceived by the patient during delivery of internal cardioversion shocks. Pain perception for internal cardioversion probably is not influenced by peak voltage alone and increases with the number of applied shocks.

Biphasic versus monophasic cardioversion in shock-resistant atrial fibrillation:

Biphasic versus Monophasic Cardioversion.

INTRODUCTION

Cardioversion of atrial fibrillation using monophasic transthoracic shocks occasionally is ineffective. Biphasic cardioversion requires less energy than monophasic cardioversion, but its efficacy in shock-resistant atrial fibrillation is unknown. Thus, we compared the efficacy of cardioversion using biphasic versus monophasic waveform shocks in patients with atrial fibrillation previously refractory to monophasic cardioversion.

METHODS AND RESULTS

Fifty-six patients with prior failed monophasic cardioversion were randomized to either a 360-J monophasic damped sinusoidal shock or biphasic truncated exponential shocks at 150 J, followed by 200 J and then 360 J, if necessary. If either waveform failed, patients were crossed over to the other waveform. The primary endpoint was defined as the proportion of patients achieving sinus rhythm following initial randomized therapy. Stepwise multivariate logistic regression examined independent predictors of shock success, including patient age, sex, left atrial diameter, body mass index, drug therapy, and waveform. Twenty-eight patients were randomized to the biphasic shocks and 28 to the monophasic shocks. Sinus rhythm was restored in 61% of patients with biphasic versus 18% with monophasic shocks (P = 0.001). Seventy-eight percent success was achieved in patients who crossed over to the biphasic shock after failing monophasic cardioversion, whereas only 33% were successfully cardioverted with a monophasic shock after crossover from biphasic shock (P = 0.02). Overall, 69% of patients who received a biphasic shock at any point in the protocol were cardioverted successfully, compared to 21% with the monophasic shock (P < 0.0001). The type of shock was the strongest predictor of shock success (P = 0.0001) in multivariate logistic regression.

CONCLUSION

An ascending sequence of 150-, 200-, and 360-J transthoracic biphasic cardioversion shocks are successful more often than a single 360-J monophasic shock. Thus, biphasic shocks should be the recommended configuration of choice for all cardioversions.

Late improvement in ventricular performance following internal cardioversion for persistent atrial fibrillation: an argument in support of concealed cardiomyopathy

The aim of the study was to evaluate the time course of atrial and ventricular function improvement following internal atrial cardioversion in patients with structural heart disease. Twenty-nine patients with chronic persistent atrial fibrillation (AF) and underlying structural heart disease were followed by serial echocardiograms performed at 1 and 6 hours, 1 day, 1, 2, and 3 weeks, and 1, 2, 3, and 6 months after successful cardioversion. Sinus rhythm was maintained at 6 months in 24 patients. Following cardioversion the time course of left atrial mechanical function (peak A wave, percent A wave filling) differed from that of left ventricular ejection fraction: peak A wave values (cm/s) increased significantly at 1 week (51 +/- 23 vs 35 +/- 15 at 1 hour, P < 0.05), percent A wave filling (%) increased significantly at 2 weeks (34 +/- 12 vs 22 +/- 9 at 1 hour, P < 0.05), whereas left ventricular ejection fraction (%) increased later (at 1 month 60 +/- 14 vs 55 +/- 14 at baseline, P < 0.05 and at 2 months 60 +/- 14 vs 56 +/- 14 at 1 hour, P < 0.05). In conclusion, restoration of sinus rhythm results in an improvement in left ventricular ejection fraction during follow-up, even in patients with structural heart disease without fast ventricular rates at baseline. The dissociation between the time course of atrial and ventricular function improvement suggests that the latter was partly due to regression of a concealed form of cardiomyopathy and/or of a ventricular dysfunction due to chronic AF.

Absence of an impact of emotional distress on the perception of intracardiac shock discharges

The pain of transvenous cardioversion shocks in awake patients is an important clinical problem. It is unknown whether psychological factors modulate any observed variation in pain perception. Thirty-seven patients with chronic atrial fibrillation (AF; mean age 61.9 years, 29 men, 8 women) were consecutively included in the study. Pain perception of a low energy test shock (60V, 0.1J) during internal cardioversion was assessed immediately following the stimulus. Before treatment anxiety, depression, somatization were evaluated. The intracardiac shock was perceived as hypalgesic in 15 (41%) patients, as normalgesic in 10 (27%), and as hyperalgesic in 10 (32%) patients. Pain threshold was significantly lower in patients in which AF was accidentally diagnosed (p < 0.029). Age, sex, and the level of education were equally distributed over the three pain groups. The hyperalgesic pain threshold was not associated with anxiety, depression, or the patients' tendency to amplify benign bodily sensations. This study discloses a wide range of perceived pain intensity caused by a homogenous intracardiac stimulation. Anxiety and depression do not amplify perception of intracardiac shocks. Sensory gating mechanisms may play a more important role in the level of intracardiac shock perception than distressing affective factors.

Plasma Levels of Nitrites/Nitrates in Patients with Chronic Atrial Fibrillation are Increased after Electrical Restoration of Sinus Rhythm

INTRODUCTION

Patients with persistent atrial fibrillation (AF) have hemodynamic changes, which impair endothelial cell function resulting in decreased nitric oxide (NO) production. The aim of this work was to assess endothelial function in AF patients before and at various time points after cardioversion.

METHODS

Forty-two patients with AF and 21 normal and age-adjusted healthy controls were studied. Nitrites and nitrates (NO(x)) and von Willebrand factor (vWf) concentrations were measured on blood samples taken just before cardioversion and over a 30 day period after the procedure.

RESULTS

Plasma levels of NO(x) in AF were significantly lower compared to healthy controls (p < 0.001), but after cardioversion gradually increased to approach to those of the healthy controls by the end of the first month of sustained sinus rhythm (p = 0.004). Interestingly plasma levels of NO(x) were negatively correlated to left atrial volume measured by ultrasonography (r = -0.34, p < 0.05). Plasma levels of vWf in AF patients were significantly higher compared to the healthy controls (p < 0.01) but with sustained sinus rhythm decreased (p = 0.02).

CONCLUSION

The parallel normalization of the NO(x) titers and vWf levels suggests that vascular endothelial function improves after 30 days of normal sinus rhythm.

Atrial mechanical performance after internal and external cardioversion of atrial fibrillation: an echocardiographic study

OBJECTIVES

To compare the time course of resumption of mechanical performance of the left and right atrium after the novel method of internal low-energy cardioversion (CV) and conventional external CV of atrial fibrillation (AF).

BACKGROUND

Right atrial performance has been shown to normalize before the left atrium after external CV. However, no data on atrial function after internal CV are available.

PATIENTS AND INTERVENTIONS

Sixty-three patients with chronic AF were randomized to participate in either external or internal CV.

MEASUREMENTS

Echocardiographic examinations were carried out before as well as immediately after CV (day 0), and at days 1, 7, and 28 thereafter for the determination of cardiac dimensions, volumes, and transvalvular flow patterns.

RESULTS

After randomized internal CV or external CV, stable sinus rhythm was restored in 59 patients. Irrespective of the mode of CV, the right atrium resumed its mechanical function immediately after CV, whereas the left atrium was stunned beyond day 7. The mode of CV, internal or external, had no influence on the recovery of atrial mechanical function.

CONCLUSIONS

The right atrium resumes its normal function immediately after internal as well as external CV, whereas left atrium function is delayed. In contrast to the assumption that low-energy internal CV would impact less on atrial mechanical recovery, the type of method of CV used has no effect on such recovery.

[Independent predictive factors of acute and first year success after electrical cardioversion in patients with chronic atrial fibrillation]

OBJECTIVES

We retrospectively analyzed the predictive factors of successfully electrical cardioversion in patients with chronic atrial fibrillation.

METHODS

We included 118 patients, 68 men and 50 women, with a mean age of 65.1 years and a length of arrhythmia evolution of 83.3 days. These patients consecutively underwent electrical cardioversion in our Cardiology Department with a follow-up of one year to determine relapses. Structural cardiopathy was observed in 63.6% of the patients and 43.7% presented a left atrium between 4 and 5 cms. We analyzed the clinical and echocardiographic factors which predict the acute and first year success of electrical cardioversion.

RESULTS

The cardioversion was effective in 73.7% (CI 95%, 64.6%-81.1%) of the patients and 35.6% (CI 95%, 25.8%-46.6%) had a relapse within the first year. The inexistence of cardiomyopathy and therapy with amiodarone were predictive of acute success (p < 0.04 and p < 0.03, respectively). The length of arrhythmia evolution did not predict acute success but did so when relapses were analyzed. The size of the left atrium is predictive of both acute and long term success (p < 0.02 and p < 0.001, respectively). Logistic regression showed that the size of the left atrium and the patient's age were the only predictive factors of acute and first year success.

CONCLUSIONS

Electrical cardioversion is very efficient in the short-term, despite numerous relapses. Patient age and the size of left atrium are associated with acute and long-term success of cardioversion.

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.

Internal low energy atrial cardioversion: efficacy and safety in older patients with chronic persistent atrial fibrillation

BACKGROUND

Low-energy internal atrial cardioversion is a relatively new technique based on delivery of intracardiac shocks through transvenous catheters placed into the atria or the vessels.

OBJECTIVE

The aim of this study was to assess in older and younger patients with chronic persistent atrial fibrillation (AF) the efficacy and safety of transvenous low-energy internal atrial cardioversion performed without routine administration of sedatives or anesthetics.

DESIGN

A prospective longitudinal study.

SETTING

A cardiological university hospital.

PARTICIPANTS

82 patients, divided into older (> or = 60 years) (n = 49) and younger (n = 33) subjects.

MEASUREMENTS

Atrial defibrillation threshold for internal cardioversion, measured as leading edge voltage (V) and delivered energy (J) of effective shocks, percentage of patients maintaining sinus rhythm at short-term (within 3 days) and at long-term follow-up.

METHODS

Patients with chronic persistent AF, treated with oral anticoagulants for at least 3 to 4 weeks, were admitted to hospital. Following a clinical work-up, patients were subjected to low-energy internal atrial cardioversion with shock delivery according to a step-up protocol.

RESULTS

Internal cardioversion was effective in restoring sinus rhythm in 90% (44/49) of the older patients and in 94% (31/33) of the younger patients. Shocks were effective at a mean energy between 6 and 8 joules (range 0.9-23) and administration of sedatives or anesthetics was required during the procedure in 22% (11/49) of older and in 48% (16/33) of younger patients (P = .026 at chi-square). No major complications occurred during the procedure. Pharmacological prophylaxis of AF recurrences was instituted immediately following the procedure. During inhospital stay and during the follow-up (mean 12 +/- 9 months for older patients and 15 +/- 10 months for younger patients), AF recurred in 39% (17/44) of older patients and in 16% (5/31) of younger subjects (P = .064 at chi-square).

CONCLUSIONS

Internal low energy cardioversion is a very effective procedure for restoring sinus rhythm in patients with AF; it can be performed in older patients, and administration of sedatives or anesthetics can be avoided or minimized in a substantial proportion of subjects. Recurrences of AF in the long term tend to be higher in older subjects and intensive prophylaxis with antiarrhythmic drugs is required.

Reduction of atrial defibrillation threshold with an interatrial septal electrode

BACKGROUND

The standard lead configuration for internal atrial defibrillation consists of a shock between electrodes in the right atrial appendage (RAA) and coronary sinus (CS). We tested the hypothesis that the atrial defibrillation threshold (ADFT) of this RAA-->CS configuration would be lowered with use of an additional electrode at the atrial septum (SP).

METHODS AND RESULTS

Sustained atrial fibrillation was induced in 8 closed-chest sheep with burst pacing and continuous pericardial infusion of acetyl-ss-methylcholine. Defibrillation electrodes were situated in the RAA, CS, pulmonary artery (PA), low right atrium (LRA), and across the SP. ADFTs of RAA-->CS and 4 other lead configurations were determined in random order by use of a multiple-reversal protocol. Biphasic waveforms of 3/1-ms duration were used for all single and sequential shocks. The ADFT delivered energies for the single-shock configurations were 1.27+/-0.67 J for RAA-->CS and 0. 86+/-0.59 J for RAA+CS-->SP; the ADFTs for the sequential-shock configurations were 0.39+/-0.18 J for RAA-->SP/CS-->SP, 1.16+/-0.72 J for CS-->SP/RAA-->SP, and 0.68+/-0.46 J for RAA-->CS/LRA-->PA. Except for CS-->SP/RAA-->SP versus RAA-->CS and RAA-->CS/LRA-->PA versus RAA+CS-->SP, the ADFT delivered energies of all of the configurations were significantly different from each other (P:<0. 05).

CONCLUSIONS

The ADFT of the standard RAA-->CS configuration is markedly reduced with an additional electrode at the atrial SP.

Predictors of atrial defibrillation threshold in internal cardioversion

This study examined the clinical, echocardiographic, and electrophysiological factors influencing the atrial defibrillation threshold (ADFT) in patients with chronic, persistent AF undergoing transvenous, low energy, atrial cardioversion. Twenty-two patients (age 57 +/- 15 years) with a mean AF duration of 7.8 +/- 7.1 months (range 2-32 months) underwent internal cardioversion with catheters placed in the right atrium and coronary sinus. Biphasic shocks (3/3 ms) were delivered in a step-up protocol. ADFT was defined as the lowest energy shock that converted AF to sinus rhythm. All patients were successfully cardioverted at a mean ADFT of 5.62 +/- 2.82 J (range 2.6-12.9 J). Fifteen variables, including clinical characteristics (age, body mass index, AF duration, etiology), echocardiographic measurements (atrial diameter and volumes, indexes of ventricular performance), hemodynamic measurements, and mean atrial cycle during AF were analyzed as possible predictors of ADFT. In univariate regression analysis, AF duration, mean RR interval, and cardiac index correlated with ADFT. In multivariate regression analysis, AF duration remained as the only significant predictor of ADFT (B coefficient 0.311, P < 0.001; 95% confidence interval [CI] 0.194-0.427). AF duration was the most powerful predictor of ADFT. It should be considered when planning internal CV of AF to limit the number of shocks delivered. Furthermore, long intervals between AF onset and CV should be avoided.

Marked reduction in atrial defibrillation thresholds with repeated internal cardioversion

OBJECTIVES

This study was performed to assess the atrial defibrillation threshold in patients with recurrent atrial fibrillation (AF) using repeated internal cardioversion.

BACKGROUND

Previous studies in patients with chronic AF undergoing internal cardioversion have shown this method to be effective and safe. However, current energy requirements might preclude patients with longer-lasting AF from being eligible for an implantable atrial defibrillator.

METHODS

Internal shocks were delivered via defibrillation electrodes placed in the right atrium (cathode) and the coronary sinus (anode) or the right atrium (cathode) and the left pulmonary artery. After cardioversion, patients were orally treated with sotalol (mean 189 +/- 63 mg/day). Eighty consecutive patients with chronic AF (mean duration 291 +/- 237 days) underwent internal cardioversion, and sinus rhythm was restored in 74 patients. Eighteen patients underwent repeated internal cardioversion using the same electrode position and shock configuration after recurrence of AF (mean duration 34 +/- 25 days).

RESULTS

In these 18 patients, the overall mean defibrillation threshold was 6.67 +/- 3.09 J for the first cardioversion and 3.83 +/- 2.62 J for the second (p = 0.003). Mean lead impedance was 55.6 +/- 5.1 ohms and 57.1 +/- 3.7 ohms, respectively (not significant). For sedation, 6.7 +/- 2.9 mg and 3.9 +/- 2.2 mg midazolam were administered intravenously (p = 0.003), and the pain score (0 = not felt, 10 = intolerable) was 5.1 +/- 1.9 and 2.7 +/- 1.8 (p = 0.001). Uni- and multivariate analyses revealed only the duration of AF before cardioversion to be of relevance, lasting 175 +/- 113 days before the first and 34 +/- 25 days before the second cardioversion in these 18 patients (p = 0.002).

CONCLUSIONS

If the duration of AF is reduced, a significant reduction in defibrillation energy requirements for internal cardioversion ensues. This might extend the group of patients eligible for an implantable atrial defibrillator despite relatively high initial defibrillation thresholds.

Comparison of oral loading dose of propafenone and amiodarone for converting recent-onset atrial fibrillation. PARSIFAL Study Group

In patients with recent-onset atrial fibrillation (AF), restoration of sinus rhythm is considered to be the first-line therapeutic option. Although this conversion might be obtained by direct-current shock or intravenous antiarrhythmic drugs, administration of an oral loading dose of class I or III antiarrhythmic drugs is more simple and convenient. This prospective, randomized, multicenter study compares the time to conversion to sinus rhythm obtained with an oral loading dose of propafenone or amiodarone. Patients with recent-onset AF (<2 weeks), without contraindications for the 2 drugs, were randomly assigned to be treated with propafenone (600 mg for the first 24 hours and if necessary a repeated dose of 300 mg for 24 hours) or amiodarone (30 mg/kg for the first 24 hours and if necessary a repeated dose of 15 mg/kg for 24 hours). Exact conversion time during the first 24 hours was determined by Holter monitoring. In each treatment group 43 patients with the same baseline characteristics were included. The median time for restoration of sinus rhythm was shorter (p = 0.05) in the propafenone (2.4 hours) than in the amiodarone (6.9 hours) group. After 24 hours (56% in the propofenone and 47% in the amiodarone group) and 48 hours, the same proportion of patients in the 2 groups recovered sinus rhythm (no serious adverse events were noticed). Thus, oral loading dose of propafenone or amiodarone was safe with a similar conversion rate of recent-onset AF. Propafenone had a faster action.

Facilitating transthoracic cardioversion of atrial fibrillation with ibutilide pretreatment

BACKGROUND

Atrial fibrillation cannot always be converted to sinus rhythm by transthoracic electrical cardioversion. We examined the effect of ibutilide, a class III antiarrhythmic agent, on the energy requirement for atrial defibrillation and assessed the value of this agent in facilitating cardioversion in patients with atrial fibrillation that is resistant to conventional transthoracic cardioversion.

METHODS

One hundred patients who had had atrial fibrillation for a mean (+/-SD) of 117+/-201 days were randomly assigned to undergo transthoracic cardioversion with or without pretreatment with 1 mg of ibutilide. We designed a step-up protocol in which shocks at 50, 100, 200, 300, and 360 J were used for transthoracic cardioversion. If transthoracic cardioversion was unsuccessful in a patient who had not received ibutilide pretreatment, ibutilide was administered and transthoracic cardioversion attempted again.

RESULTS

Conversion to sinus rhythm occurred in 36 of 50 patients who had not received ibutilide (72 percent) and in all 50 patients who had received ibutilide (100 percent, P<0.001). In all 14 patients in whom transthoracic cardioversion alone failed, sinus rhythm was restored when cardioversion was attempted again after the administration of ibutilide. Pretreatment with ibutilide was associated with a reduction in the mean energy required for defibrillation (166+/-80 J, as compared with 228+/-93 J without pretreatment; P<0.001). Sustained polymorphic ventricular tachycardia occurred in 2 of the 64 patients who received ibutilide (3 percent), both of whom had an ejection fraction of 0.20 or less. The rates of freedom from atrial fibrillation after six months of follow-up were similar in the two randomized groups.

CONCLUSIONS

The efficacy of transthoracic cardioversion for converting atrial fibrillation to sinus rhythm was enhanced by pretreatment with ibutilide. However, use of this drug should be avoided in patients with very low ejection fractions.

The atrial defibrillator: a stand-alone device or part of a combined dual-chamber system?

Atrial fibrillation (AF) is an extremely common arrhythmia seen in clinical practice. Because of the limited efficacy of traditional therapeutic strategies to restore and maintain normal sinus rhythm, several nonpharmacologic options have evolved. The promising results achieved with internal atrial defibrillation have facilitated the development of an implantable atrial defibrilator. Preliminary results obtained from an initial study on a small number of highly selected patients with refractory AF suggest that atrial defibrillation can be performed effectively and safely with adequate patient tolerance by using a stand-alone device. The extension of this therapy will depend on the results of well-designed prospective studies comparing this new therapeutic option with traditional methods. Several acute studies have shown that internal conversion of AF is feasible at low energies with current endocardial transvenous lead configurations primarily designed for ventricular defibrillation, but long-term efficacy has, to date, only been demonstrated with atrial implantable defibrillator lead systems. As AF is a frequent arrhythmia in implantable cardioverter defibrillator (ICD) recipients, it would seem desirable to incorporate the capability for atrial defibrillation into an ICD. Clinical studies have shown that an atrial defibrillator, as part of a combined dual-chamber ICD system, may not require a potentially complicated switching network for establishing different electrode configurations for atrial and ventricular tachyarrhythmia. The efficacy in atrial cardioversion of such a combined, less complex device seems to be as high as reported for a pure atrial defibrillator, but generally at somewhat higher energy requirements. The results of further investigations will show whether a dual-chamber cardioverter defibrillator would be of clinical relevance in patients with ventricular and supraventricular tachyarrhythmia.

Atrial fibrillation in the elderly

Atrial fibrillation is the most common sustained arrhythmia seen in clinical practice. Although it occurs in any age patients, its frequency increases with age and is very common in the elderly. Atrial fibrillation causes substantial symptoms and morbidity and is an important cause of thromboembolism and stroke. The two approaches for therapy in those patients with intermittent or persistent atrial fibrillation are (1) maintenance of sinus rhythm with an antiarrhythmic drug or nonpharmacologic therapy, and (2) maintenance of atrial fibrillation with rate control. At the present time there are no data about the best approach and therapy must therefore be individualized.

[Internal cardioversion with low-energy shocks in atrial fibrillation resistant to external electric cardioversion]

BACKGROUND AND OBJECTIVE

Although external electrical cardioversion is effective in most patients with atrial fibrillation, there are cases refractory to external cardioversion. This study is aimed at showing our initial experience with an internal cardioversion system in patients with previous unsuccessful external cardioversion.

PATIENTS AND METHODS

Between February, 1997 and September, 1998 nine consecutive patients with spontaneous chronic or persistent atrial fibrillation that failed external cardioversion, were included. Internal cardioversion was performed under sedation with two electrodes that had a 5.5 cm coil placed in the lateral right atrium and coronary sinus. Both electrodes were connected to an external defibrillator capable of delivering R-wave synchronized low-energy biphasic shocks following a minimum RR interval of 500 ms. Energy between 2 J and 10 J was applied until the restoration of sinus rhythm or a maximum of 2 shocks of 10 J.

RESULTS

Sinus rhythm was achieved in the nine patients, but in two of them atrial fibrillation recurred after a few beats. Both had underlying structural heart disease. The other 7 patients, 5 of them without structural heart disease, were in sinus rhythm at discharge. No mechanic complications or ventricular arrhythmias were observed. Six patients are in sinus rhythm after 4 +/- 3 months of follow-up.

CONCLUSIONS

Low-energy intracardiac cardioversion is useful in some patients with atrial fibrillation that had failed external cardioversion and can be performed without general anesthesia.

Initial experience with a new balloon-guided single lead catheter for internal cardioversion of atrial fibrillation and dual chamber pacing

BACKGROUND

Based on the observation that internal cardioversion (IntCV) of atrial fibrillation is effective with electrodes in the right atrium and pulmonary artery, a new balloon-guided catheter and external defibrillation device with optional dual chamber pacing was evaluated.

METHODS

IntCV was attempted in 27 patients (age: 57 +/- 10 years, duration: 14 +/- 18 months, left atrial diameter 56 +/- 8 mm) using a new defibrillation device (Alert, EP MedSystems, Inc., NJ, USA) that allows the delivery of biphasic shocks (0.5-15 J, variable tilt), atrial and ventricular pacing, and online signal recording. Pacing and defibrillation shocks were applied via a 7.5 Fr balloon-guided catheter (EP MedSystems, Inc.). Pacing, sensing, and triggering were established through the proximal atrial array and an electrode ring between both defibrillation arrays and a single ventricular electrode ring. Catheters were inserted from the antecubital vein.

RESULTS

In 25 of 27 patients sinus rhythm was restored with a mean energy of 6.7 +/- 4.5 J. In five patients, atrial postshock pacing was required for bradycardia and atrial premature beats. The mean fluoroscopy time was 2.0 +/- 1.3 minutes.

CONCLUSION

The high success rate, ease of application, and backup dual chamber pacing suggest that this system is an alternative to established methods of cardioversion. In certain indications, such as failure of prior external cardioversion and situations in which a standard pulmonary balloon catheter is needed, this system would be advantageous.

Internal right atrial cardioversion of chronic atrial fibrillation: effects of low-energy biphasic shocks

This study evaluates the efficacy and safety of internal right atrial cardioversion of atrial fibrillation using a defibrillation right atrial catheter and 2 thoracic patches with low-energy biphasic shocks.

[Atrial defibrillator]

Atrial fibrillation (AF) is a frequent and costly health care problem representing the most common arrhythmia resulting in hospital admission. Total mortality and cardiovascular mortality are significantly increased in patients with AF compared to controls. In addition to symptoms of palpitations patients with AF have an increased risk of stroke and may also develop decreased exercise tolerance and left ventricular dysfunction. All of these problems may be reversed with restoration and maintenance of sinus rhythm. External electrical cardioversion has been a remarkably effective and safe method for termination of this arrhythmia. Originally described by Lown et al. in 1963, it has been a well accepted mode of acute therapy. However, this technique requires general anesthesia or heavy sedation. Internal atrial defibrillation has been evaluated as an alternative approach to the external technique for over 2 decades. Recent studies have shown that low-energy internal atrial defibrillation using biphasic shocks is an effective and safe means in restoring sinus rhythm in patients with AF and should be considered especially in patients in whom external cardioversion attempts have failed. IMPLANTABLE ATRIAL DEFIBRILLATOR: Recently, a stand alone IAD, the Metrix System (model 3000 and 3020), has entered clinical investigation. Atrial defibrillation is accomplished by a shock delivered between electrodes in the right atrium and the coronary sinus. The right atrium lead has an active fixation in the right atrium. The coronary sinus lead has a natural spiral configuration for retention in the coronary sinus, and can be straightened with a stylet. Both leads are 7 French in diameter and the defibrillation coils are each 6 cm in length. The electrodes may be placed using separate leads, or very soon by using a single bipolar lead. A separate bipolar right ventricular lead is used for R wave synchronization and post shock pacing. The Metrix defibrillator can be used to induce AF by using R wave synchronous shocks and can store intracardiac electrograms (EGMs) for up to 2 minutes from the most recent 6 AF episodes. The device can be programmed into one of the following operating modes: fully automatic, patient activated, monitor mode, bradycardia pacing only, and off. As AF is not life-threatening, in the automatic mode the device is only intermittently active in detecting and treating AF, and this "sleep wake-up" cycle interval is programmable. The device employs extensive processing both for detection and R wave synchronization. In April 1996, the phase I Metrix multicenter clinical trial was started. As of May 1997, a total of 51 Metrix systems had been implanted as part of the phase I multicenter clinical trial. Preliminary data suggest that both defibrillation thresholds and electrograms are stable over time (implant to 3 months). Detection accuracy has been excellent (100% specificity, 92.3% sensitivity) and there have been no errors of R wave selection for synchronization. No proarrhythmias have resulted from over 3700 shocks delivered. The device is effective in electrically converting 96% of the spontaneous episodes of AF. In 27% of episodes several shocks were required because of early recurrence of AF. In 5 patients, the atrial defibrillator was removed: 2 infections, 1 cardiac tamponade, 1 permanent loss of telemetry, 1 patient required His-Bundle ablation because of frequent episodes of drug refractory AF with rapid ventricular response. Initial clinical experience under controlled conditions with the Metrix system suggests that the implantable atrial defibrillator may offer a therapeutic alternative for a subgroup of patients with drug refractory, symptomatic, long lasting, and infrequent episodes of AF. Further efforts must be undertaken to reduce the patient discomfort associated with internal atrial defibrillation in an attempt to make this new therapy acceptable to a larger patient population with AF. (ABSTRACT TRUNCATED)

Patient characteristics and underlying heart disease as predictors of recurrent atrial fibrillation after internal and external cardioversion in patients treated with oral sotalol

The aim of this study was to identify predictors for recurrent atrial fibrillation after internal and external cardioversion in 157 patients. After cardioversion, patients were treated orally with sotalol (174 +/- 54 mg/day). Univariate predictors for recurrence included coronary artery disease (p < 0.05) and advanced age (p < 0.05). Multivariate adjusted risk for relapse increased with the presence of coronary artery disease (odds ratio [OR] 3.4, 95% confidence interval [CI] 1.6 to 8.0), presence of atrial fibrillation > 2 months before cardioversion (OR 2.3; 95% CI 1.4 to 4.5), left atrial diameter > 60 mm (OR 2.1; 95% CI 1.2 to 3.1), and age > 65 years (OR 1.6; 95% CI 1.3 to 3.3). In 26% of patients with lone atrial fibrillation, recurrence was observed compared with 51% of patients with underlying structural heart disease (p < 0.05). The mode of conversion, internal or external, had no impact on the recurrence rate. These findings might be useful for selection of the most appropriate therapy for the individual patient.