Echocardiographic changes and predictors of arrhythmia recurrence after long-term use of the atrial defibrillator

BACKGROUND: The patient-activated atrial defibrillator allows patients to cardiovert themselves from atrial fibrillation soon after the onset of symptoms. The long-term effects of early cardioversion from persistent atrial fibrillation on left ventricular performance and left atrial size are unknown. METHODS: Eighteen patients, mean age 63.4, 83% male, had the Jewel((R)) AF atrial defibrillator implanted for persistent atrial fibrillation only. Transthoracic echocardiography was performed 3-monthly following implant. Parasternal long axis measurements were taken using conventional M-mode techniques. RESULTS: Over follow-up of 28.0+/-9 months, 377 episodes of persistent atrial fibrillation were terminated by patient-activated cardioversion (median 15 per patient). Echocardiographic measurements at implant were; left atrium 44+/-6 mm, left ventricular end-diastolic diameter 49+/-7 mm, left ventricular end-systolic diameter 34+/-7 mm, fractional shortening 33+/-10% and ejection fraction 65+/-17%. After 1 year there had been a significant decrease in mean left atrial size to 41+/-6 mm (P=0.02) and an increase in mean ejection fraction to 73+/-8% (P=0.04). At long-term follow-up however, all parameters reverted to pre-implant levels. Baseline echocardiographic variables did not predict which patients would demonstrate serial increases in sinus rhythm duration between shocks during long-term follow-up. Patients on antiarrhythmic drug therapy however were more likely to demonstrate "sinus rhythm begetting sinus rhythm". CONCLUSIONS: Use of the atrial defibrillator for spontaneous persistent atrial fibrillation is associated with a medium-term (1 year) reduction in left atrial size and an increase in ejection fraction. These changes were not maintained in the long-term. Synergistic therapy with antiarrhythmic drugs may prolong periods of sinus rhythm between arrhythmia recurrences.     

Low-energy internal cardioversion in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion: results and long-term follow-up.

AIM: Low-energy internal cardioversion is a new electrical treatment for patients with persistent atrial fibrillation. This paper evaluates the efficacy and safety of low-energy internal cardioversion in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion, and the clinical outcome of such patients. METHOD AND RESULTS: The study population consisted of 55 patients [32 male, mean age 65 +/- 10 years, 48 (87%) with underlying heart disease] with long-lasting (mean 18 +/- 34 months) atrial fibrillation in whom external cardioversion had failed to restore sinus rhythm. Two custom-made catheters were used: one positioned in the right atrium and one in the coronary sinus or the left pulmonary artery. A standard catheter was inserted into the right ventricular apex to provide R wave synchronization. Sinus rhythm was restored in 52 patients (95%) with a mean defibrillating energy of 6.9 +/- 2.6 J (320 +/- 60 V). No complications were observed. During follow-up (mean 18 +/- 9 months), 16 patients (31%) suffered early recurrence (< or = 1 week) of atrial fibrillation and 20 patients (38%) had late recurrence (> 1 week, mean 3.5 +/- 3.6 months) of atrial fibrillation. Six patients with a late recurrence again underwent cardioversion and five of these maintained sinus rhythm. Therefore, a total of 21/52 patients (40%) were in sinus rhythm at the end of follow-up. No clinical difference was found between patients with and without recurrences. CONCLUSIONS: Low-energy internal cardioversion is a useful means of restoring sinus rhythm in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion. More than one-third of patients maintained sinus rhythm during long-term follow-up.     

Prediction of atrial fibrillation recurrence after cardioversion by P wave signal-averaged electrocardiography.

The purpose of this report was to determine prospectively whether P wave signal-averaged electrocardiography (ECG) is useful for the prediction of recurrences of atrial fibrillation after cardioversion. The P wave signal-averaged ECG was recorded in 73 patients after successful cardioversion. Duration of the filtered P wave and the root mean square voltages for the last 20 ms of the P wave were calculated. In addition to signal-averaged ECG P wave analysis, all patients were evaluated by echocardiography. During 6 months follow-up period recurrence of atrial fibrillation was observed in 31 (42.5%) patients and in 42 (57.5%) patients sinus rhythm was maintained. There was no difference in gender, age, presence of organic heart disease, left atrial diameter, left ventricular ejection fraction, use of antiarrhythmic drug, and duration of atrial fibrillation (P>0.05). The filtered P-wave duration was longer and the root mean square voltages for the last 20 ms of the P wave was lower in patients with recurrence of atrial fibrillation than in patients who maintained sinus rhythm (138.3+/-12.5 ms vs. 112.4+/-11.8 ms, P = 0.001; 1.9+/-0.7 microV vs. 2.5+/-0.6 microV, P = 0.001). A filtered P-wave duration > or =128 ms associated with a root mean square voltage for the last 20 ms of the P wave < or =2.1 microV had a sensitivity of 70% and specificity of 76% for the detection of patients with recurrence of atrial fibrillation after successful cardioversion of atrial fibrillation. We found that the likelihood of recurrence of atrial fibrillation after cardioversion was increased 4.31-fold (95% confidence interval 2.08-9.83) if these parameters were used. These results suggest that P wave signal-averaged ECG could be useful to identify patients at risk for recurrence of atrial fibrillation after cardioversion.     

High maintenance rate of sinus rhythm after cardioversion in post-thyrotoxic chronic atrial fibrillation

We performed rhythm conversion on 33 euthyroid patients with post-thyrotoxic atrial fibrillation who do not revert spontaneously to sinus rhythm from atrial fibrillation. The duration of atrial fibrillation ranged from 9 to 59 months (mean 25 +/- 14). The protocol of rhythm conversion was to first attempt pharmacological conversion with disopyramide and then to perform electrical cardioversion on the non-converters. Of 33 patients, 25 were converted to sinus rhythm (6 by disopyramide and 19 by electrical cardioversion), resulting in 8 non-converters. However, it was later discovered that cardioversion had been applied to 4 of the 8 non-converters when these patients had had a recurrence of thyrotoxicosis. These 4 patients were subjected to a second electrical cardioversion after attaining the euthyroid state. Sinus rhythm was restored in all 4 patients, giving a cardioversion rate of 88%. The sinus rhythm was maintained in 25 of the total 29 converters (86%) at the time of follow-up (10-68 months, mean 35 +/- 19 months). Our studies suggest that cardioversion should be encouraged for thyrotoxic atrial fibrillation, even if the duration of atrial fibrillation is long-standing, since there is excellent maintenance of sinus rhythm and even delayed application of cardioversion may improve its success rate.     

Transvenous Cardioversion of Atrial Fibrillation using Low-Energy Shocks

Recent reports have suggested that transvenous cardioversion ofatrial fibrillation is feasible using low-energy shocks and a right atriumcoronary sinus electrode configuration. We evaluated in a prospective studythe efficacy and safety of low-energy internal cardioversion of atrialfibrillation in 104 consecutive patients. Sixty-two patients presented withchronic atrial fibrillation (group I), 16 had paroxysmal atrial fibrillation(group II), and 26 had an induced atrial fibrillation episode (group III).The mean duration of the presenting episode of atrial fibrillation was 9± 19 months for group I, 4 ± 2 days for group II, and 18± 7 minutes for group III. Atrial defibrillation was performed usingtwo intracardiac catheters: one was placed in the right atrium (cathode) andthe other in the coronary sinus or in the left branch of the pulmonaryartery (anode). The catheters were connected to a customized externaldefibrillator capable of delivering 3/3-ms biphasic waveform shocks with avoltage programmable between 10 and 400 volts. The shocks were synchronizedto the R wave. Sinus rhythm was restored in 44 of the 62 patients in group I(70%), in 12 of the 16 patients in group II (75%), and in 20of 26 patients in group III (77%). The mean voltage and energyrequired for cardioversion were respectively 300 ± 68 V and 3.5± 1.5 J, for group I, 245 ± 72 V and 2.0 ± 0.9 J forgroup II, and 270 ± 67 V and 2.6 ± 1.2 J for group III. Theleading-edge voltage required for sinus rhythm restoration was significantlyhigher (p < 0.05) in the chronic atrial fibrillation group than in theparoxysmal or induced groups. No proarrhythmic effects ocurred for thedelivered 686 R-wave synchronized shocks. This study of a large group ofpatients confirms and extends the results of previous reports. Such findingsmay have clinical implications for elective cardioversion of atrialfibrillation and the development of an implantable atrial defibrillator.     

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.     

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.     

Effect of verapamil on immediate recurrence of atrial fibrillation

INTRODUCTION: The purpose of this study was to assess the effect of verapamil on immediate recurrences of atrial fibrillation occurring after successful electrical cardioversion. METHODS AND RESULTS: The effect of verapamil on the recurrence of atrial fibrillation within 5 minutes after successful transthoracic cardioversion was assessed in 19 (5%) of 364 patients undergoing electrical cardioversion. The mean duration of atrial fibrillation was 4.44+/-3.0 months. In the 19 patients, cardioversion was successful after each of three consecutive cardioversion attempts per patient; however, atrial fibrillation recurred 0.4+/-0.3 minutes after cardioversion. Verapamil 10 mg was administered intravenously and a fourth cardioversion was performed. Cardioversion after verapamil was successful in each patient, and atrial fibrillation did not recur in 9 (47%) of 19 patients (P < 0.001 vs before verapamil). In the remaining 10 patients in whom atrial fibrillation recurred, the duration of sinus rhythm was significantly longer compared with before verapamil (3.6+/-2.4 min, P < 0.001). The density of atrial ectopy occurring after cardioversion was significantly less after verapamil (21+/-14 ectopic beats per min) compared with before verapamil (123+/-52 ectopic beats per min, P < 0.001). CONCLUSION: Among patients with immediate recurrence of atrial fibrillation after electrical cardioversion, acute calcium channel blockade by verapamil reduces recurrence of atrial fibrillation and extends the duration of sinus rhythm.     

Echocardiographic and clinical predictors for outcome of elective cardioversion of atrial fibrillation

Previous studies have suggested that success of elective direct-current cardioversion for atrial fibrillation (AF) can be predicted from clinical features and M-mode echocardiographic left atrial diameter. We evaluated clinical variables as well as M-mode and 2-dimensional echocardiographic measurements of atrial size in 85 patients undergoing electrical cardioversion for AF. Of 65 patients who were initially converted to sinus rhythm, 45 (69%) and 38 (58%) remained in sinus rhythm at 1 and 6 months, respectively. No historical feature predicted initial success, although patients with cardiomyopathy or pulmonary disease underlying their AF had significantly lower success rates compared with those having other etiologies. Furthermore, no M-mode or 2-dimensional echocardiographic measurements of atrial size predicted initial success of cardioversion. Maintenance of sinus rhythm at 1 month was related to short duration of AF before cardioversion (less than 3 months vs greater than 12 months, p less than 0.05). Left atrial area and long axis dimension by 2-dimensional echocardiography were significantly larger in patients remaining in sinus rhythm than in those who had reverted to AF at 1 month (28 +/- 7 vs 24 +/- 5 cm2 and 65 +/- 9 vs 59 +/- 8 mm, respectively, both p less than 0.05), but overlap was great. No significant difference in atrial dimensions was noted at 6-month follow-up. It appears that, although no clinical or echocardiographic variable predicts initial success for cardioversion of AF, duration of AF does predict maintenance of sinus rhythm 1 month after initial success.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Significant prolongation of atrial monophasic action potential duration: short-term reverse electrophysiological changes after internal cardioversion of atrial fibrillation

OBJECTIVE: Since short action potentials and short refractory periods facilitate the induction of atrial reentry, this maladaptation has been proposed as the pathophysiological basis of the frequent immediate recurrences of atrial fibrillation (IRAF) after internal cardioversion. However, short-term reverse electrophysiological changes of the atria after cardioversion have not been studied in humans. METHODS: Thirty-seven patients with chronic atrial fibrillation of 16+/-19 months and ten patients with an atrial fibrillation duration < or =48 h underwent internal cardioversion. Antiarrhythmic medication was only continued in 10 patients (21%), who were on amiodarone before cardioversion. Atrial monophasic action potential duration at 90% repolarization (APD(90)), sinus rate, P wave duration and interatrial conduction times between high right atrium and coronary sinus were recorded at min 0, 1, 3, 5, 10, 15 and 20 after cardioversion. RESULTS: Internal cardioversion was successful in all patients, but twelve of the patients with chronic AF (32%) and three of the patients with intermittent AF (30%) had one to four episodes of IRAF after 16+/-28 s. There was a significant 52+/-30 ms APD(90) prolongation, 83% of which occurred in min 0-3 (P<0.0001) and 17% in min 3-20 (P<0.05) after internal cardioversion. There was no significant temporal change in sinus rate, P-wave and interatrial conduction time during the time studied. APD(90) prolongation and its time dependence did not show a detectable difference in subgroups with chronic AF, IRAF, left atrial size >40 mm and treatment with amiodarone. CONCLUSIONS: There is a significant prolongation of action potential duration in min 0-3 after internal cardioversion of atrial fibrillation, whereas sinus rate and intra- and interatrial conduction time remain unchanged. APD(90) prolongation in min 0-3 shows a temporal relationship to the high rate of immediate recurrences of atrial fibrillation during this time interval. The data imply that there is a transient recovery of atrial refractoriness after cardioversion and suggest a mechanism of the high rate of early recurrences of atrial fibrillation.     

Atrial fibrillation: how effectively can sinus rhythm be restored and maintained after balloon mitral valvotomy?

Atrial fibrillation, commonly associated with rheumatic mitral stenosis, worsens the prognosis. We studied the efficacy of achieving and maintaining sinus rhythm in patients with chronic atrial fibrillation who underwent a successful balloon mitral valvotomy. Fifty-four patients (26 men, 28 women; age 36+/-8 years) received amiodarone 200 mg thrice daily in the first week, and thereafter a maintenance dose of 200 mg once daily. Electrical cardioversion was attempted at 1 and 3 months and patients were followed up at 6, 12 and 18 months. At the end of 1, 3, 6, 12 and 18 months 81 percent, 72 percent, 60 percent, 54 percent and 49 percent of patients, respectively, were in sinus rhythm. Only one patient had a severe adverse effect (hypothyroidism). Univariate analysis revealed that lower age, shorter duration of atrial fibrillation and smaller left atrial size was associated with successful restoration to sinus rhythm. On multivariate analysis, the duration of atrial fibrillation was the only significant predictor of long-term maintenance of sinus rhythm. Amiodarone seems safe and reasonably effective in restoration and maintenance of sinus rhythm in patients of atrial fibrillation with rheumatic heart disease.     

Pulmonary vein flow analysis by transoesophageal echocardiogr phy in patients with chronic atrial fibrillation; 1 year follow-up after cardioversion.

AIMS: Left and right upper pulmonary vein flow can be adequately recorded by transoesophageal Doppler echocardiography. The aim of this study was to investigate whether analysis of the pulmonary venous flow velocity pattern can predict the long-term maintenance of sinus rhythm after successful cardioversion of chronic atrial fibrillation. METHODS AND RESULTS: Thirty-six consecutive patients, aged 53+/-9 years, with chronic atrial fibrillation of 5.33+/-2 months duration, were subjected to transoesophageal Doppler echocardiography to record left and right upper pulmonary venous flow, 24 h and 3 months following successful cardioversion. One year following cardioversion, 12 patients (33.3%) were in sinus rhythm (sinus rhythm group) while the remaining 24 patients were in atrial fibrillation (atrial fibrillation group). At 24 h following cardioversion, biphasic systolic forward flow in the left and/or right upper pulmonary venous flow velocity was detected in 10 patients of the sinus rhythm group and in four patients of the atrial fibrillation group (P<0001). The systolic fraction was significantly higher in the sinus rhythm group, 0.48+/-0.04 and 0.39+/-0.06, P<0.001 for the left upper pulmonary venous flow, and 0.52+/-0.05 and 0.41+/-0.04, P<0.001 for the right upper pulmonary venous flow, respectively. In patients who displayed a biphasic systolic forward flow and in whom the right upper pulmonary venous flow systolic fraction was higher than 0.50 at 24 h post-cardioversion, the probability of maintenance of sinus rhythm at 1 year exceeded 95%. CONCLUSION: The detection of a biphasic systolic forward flow in the pulmonary venous flow velocity, and of a right upper pulmonary vein systolic fraction higher than 0.50 as early as 24 h following cardioversion of chronic atrial fibrillation, identifies patients who will remain in sinus rhythm 1 year after cardioversion.     

Is there a place for the late cardioversion of atrial fibrillation? A long-term follow-up study of patients with post-thyrotoxic atrial fibrillation.

AIMS: As atrial fibrillation is associated with significant mortality and morbidity, restoration of sinus rhythm is desirable. However, previous data suggest that cardioversion should be restricted to patients in whom the fibrillation is of limited duration (<1-2 years) because of high relapse rates. It may be the frequent association with cardiac disease, rather than the duration of fibrillation itself, which determined the high relapse of earlier studies. The aim of this study was to investigate rates of cardioversion, maintenance of sinus rhythm and predictors of subsequent relapse in a homogeneous group of patients without evidence of any co-existent cardiac disease. METHODS AND RESULTS: We report on a retrospective series of 106 patients with thyrotoxicosis-induced fibrillation but no other heart disease: 87% had been in atrial fibrillation for >12 months (median duration 28.5, interquartile range 15-47 months). Cardioversion was attempted using disopyramide and then electric shock. Ninety-eight patients were successfully cardioverted: at late follow-up, 80.6+/-37 months (mean+/-SD), 67% were in sinus rhythm. CONCLUSION: Although a relationship between the duration of fibrillation and maintenance of sinus rhythm was found, the high proportion remaining in sinus rhythm, compared with other series, suggests this influence may be less important than the presence or absence of structural heart disease.     

Effect of Direct Current Shocks on Left Atrial Mechanical Function in Patients With Structural Heart Disease

Objectives. This study examined the effect of endocardial and transthoracic direct current (DC) shocks on left atrial and left atrial appendage function in humans with structural heart disease.Background. DC cardioversion of atrial fibrillation (AF) to sinus rhythm is associated with transient left atrial and left atrial appendage dysfunction and the development of spontaneous echo contrast (SEC). This phenomenon has been termed atrial “stunning” and may be associated with thrombus formation and embolic stroke. To what extent the shock itself contributes to atrial stunning is unclear.Methods. Thirteen patients in sinus rhythm undergoing implantation of a ventricular implantable cardioverter defibrillator (ICD) were prospectively evaluated. All patients had significant structural heart disease. To evaluate the effects of DC shocks on left atrial and left atrial appendage function, biphasic R wave synchronized endocardial shocks of 1, 10 and 20 J were delivered between the right ventricular electrode and the left pectoral generator of the ICD in sinus rhythm. R wave synchronized transthoracic shocks of 360 J were also delivered between anteriorly and posteriorly positioned chest electrodes. Transesophageal echocardiography was performed to evaluate left atrial appendage velocities, mitral inflow velocities and the presence of SEC before and immediately after each DC shock.Results. There were no significant changes in left atrial or left atrial appendage function after endocardial or transthoracic DC shocks. Left atrial SEC did not develop after endocardial or transthoracic DC shocks.Conclusions. Endocardial and transthoracic DC shocks are not directly responsible for left atrial and left atrial appendage stunning and do not contribute to the stunning that is observed after the cardioversion of AF to sinus rhythm.     

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.     

Low Energy Intracardiac Cardioversion After Failed Conventional External Cardioversion of Atrial Fibrillation

Objectives. This study was designed to evaluate the efficacy of intracardiac cardioversion in patients with chronic atrial fibrillation after unsuccessful external cardioversion.Background. Previous studies in patients with atrial fibrillation undergoing intracardiac cardioversion have suggested that intracardiac cardioversion is highly effective and safe. However, the characteristics of patients who benefit most from this invasive technique are unknown.Methods. We prospectively studied 25 consecutive patients with chronic atrial fibrillation (11 ± 9 months). All patients had undergone at least three attempts at conventional external transthoracic cardioversion by means of paddles in an anteroposterolateral position applying energies up to 360 J without success. Intracardiac shocks were delivered by an external defibrillator through defibrillation electrodes placed in the right atrium and coronary sinus or in the right atrium and left pulmonary artery. After conversion, all patients were treated orally with sotalol (mean 194 ± 63 mg/day).Results. Internal cardioversion was successful in 22 of 25 patients at a mean defibrillation threshold of 6.5 ± 3.0 J. Mean lead impedance was 56.4 ± 7.4 Ω. No severe complications were observed. At a mean follow-up of 15 ± 12 months, 12 (55%) of the patients treated successfully remained in sinus rhythm.Conclusions. In patients with failed external cardioversion, internal cardioversion offers a new option for restoring sinus rhythm. Intracardiac cardioversion is an effective and safe method and can be easily performed in patients with minimal sedation.     

Atrial natriuretic peptide response to cardioversion of atrial flutter and fibrillation and role of associated heart failure.

Plasma atrial natriuretic peptide (ANP) concentrations were measured before and 1 hour after cardioversion in 40 patients (27 with atrial flutter and 13 with atrial fibrillation) admitted for elective cardioversion. Fourteen (11 with atrial flutter and 3 with atrial fibrillation) had clinical evidence of congestive heart failure (CHF). Conversion to sinus rhythm was successful in 39 patients. The mean ANP concentration in the entire group decreased after cardioversion from 38 +/- 4 to 17 +/- 2 pmol/liter (p less than 0.001). In the subgroup with CHF, the ANP level, which was not significantly higher than that in the group without CHF, decreased from 47 +/- 8 to 19 +/- 3 pmol/liter (p less than 0.01). Neither mode of cardioversion (spontaneous 1, pharmacologic 2 and direct-current countershock 36) nor associated CHF influenced ANP response to cardioversion. One patient with atrial flutter and "failed cardioversion" had unchanged ANP level. The decrease after cardioversion in ANP concentration correlated with its control level (r = 0.88, p less than 0.001) but not with the decrease in heart rate. The ANP level in patients with atrial fibrillation was 45 +/- 9 vs 38 +/- 5 pmol/liter in those with atrial flutter (difference not significant). Arrhythmia duration, left atrial size, and ventricular rate or arterial blood pressure did not correlate with ANP concentration in any subgroup. It is concluded that (1) the ANP level is elevated comparably in patients with both atrial flutter and fibrillation regardless of the presence or absence of CHF; and (2) the level decreases, independent of the mode of cardioversion or presence of CHF, promptly after successful cardioversion.     

Atrial natriuretic peptide before and after cardioversion of persistent atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, affecting many millions of people world-wide. The treatment of AF has improved significantly during the past decade, but most patients suffer from symptoms and recurrences of arrhythmia. Studies on the neurohormonal remodelling in patients with AF are becoming increasingly important because they may improve the treatment of AF. AIM: To determine plasma atrial natriuretic peptide (ANP) concentrations in patients with persistent AF, before and one day after electrical cardioversion of AF. METHODS: We attempted cardioversion in 42 consecutive patients (30 men and 12 women), aged 57+/-8 years, with persistent nonvalvular AF of 7+/-6 month duration. The underlying heart disease was systemic hypertension in 20, ischaemic heart disease in 17, dilated cardiomyopathy in 3, and lone AF in 2 patients. All patients had left ventricular ejection fraction >45%. The control group comprised 11 subjects with sinus rhythm and no history of AF who were age-, gender- and concomitant disease-matched with the AF patients. Plasma samples of ANP were obtained at rest the day before and 24 hours after cardioversion. RESULTS: Cardioversion was successful in 35 patients. Patients with successful or non-successful cardioversion had similar clinical characteristics. The mean baseline ANP level before cardioversion was 59.5+/-15.6 pg/ml and was significantly higher than in the control group - 34.3+/-10.2 pg/ml (p<0.001). In patients in whom sinus rhythm was restored, a significant decrease in the ANP level was observed (59.4+/-16.6 versus 31.4+/-15.0 pg/ml; p<0.01) whereas it did not change in patients with ineffective cardioversion (59.4+/-10.7 versus 60.2+/-10.7 pg/ml, NS). CONCLUSIONS: Plasma ANP concentration in patients with AF was significantly reduced after successful cardioversion and remained stable in those with unsuccessful cardioversion.     

Brain natriuretic peptide predicts successful cardioversion in patients with atrial fibrillation and maintenance of sinus rhythm

BACKGROUND: Brain natriuretic peptide (BNP) is released from the heart by hemodynamically induced muscle stretch. Patients with atrial fibrillation have higher levels of BNP than those in sinus rhythm. OBJECTIVE: To assess the usefulness of BNP as a predictor of successful cardioversion in patients with persistent atrial fibrillation and subsequent maintenance of sinus rhythm. SUBJECTS AND METHODS: Twenty patients undergoing cardioversion for persistent atrial fibrillation were enrolled. BNP levels were measured before electric cardioversion, and 30 min and two weeks after cardioversion. Baseline echocardiograms and 12-lead electrocardiograms were obtained from all patients. Patients with valvular disease, previous mitral valve surgery or significant left ventricular dysfunction were excluded. RESULTS: The mean BNP level and the mean heart rate were significantly higher before cardioversion than 30 min after (197+/-132 pg/mL versus 164+/-143 pg/mL, P=0.02, and 77+/-17 beats/min versus 57+/-12 beats/min, P=0.0007, respectively). Patients who reverted back to atrial fibrillation after two weeks had a baseline BNP of 293+/-106 pg/mL, while those who remained in sinus rhythm for two weeks had a lower baseline BNP of 163+/-122 pg/mL (P=0.02). CONCLUSION: In patients with persistent atrial fibrillation, BNP levels are associated with successful cardioversion and maintenance of sinus rhythm two weeks after cardioversion.