Recurrent Persistent Atrial Fibrillation Research Articles

Arrhythmia Type After Persistent Atrial Fibrillation Ablation Predicts Success of the Repeat Procedure

The aim of the study was to investigate whether the type of arrhythmia recurrence after ablation of persistent atrial fibrillation (AF) has an impact on the maintenance of sinus rhythm after the repeat ablation procedure. Included were 78 consecutive patients (82% men; mean age, 61±10 years; mean left atrial diameter, 47±4 mm) with persistent AF who underwent ≥1 repeat ablation. The initial ablation procedure had consisted of pulmonary vein isolation with additional substrate modification (ablation of complex fractionated atrial electrograms [n=63] or linear lesions [n=15]). Patients presented for reablation either with persistent atrial tachycardia (AT) (group 1, n=36), persistent AF (group 2, n=37), or paroxysmal AF (group 3, n=5). The primary end point was freedom from any arrhythmia off antiarrhythmic drugs 6 and 9 months after the reablation procedure. Estimated proportions of patients reaching the primary end point were 59% for group 1, 28% for group 2, and 100% for group 3 at 6 months and 51%, 23%, and 100%, for groups 1, 2, and 3, respectively, at 9 months (P=0.002). In patients presenting for a repeat procedure after ablation of persistent AF, the occurrence of AT is associated with a significantly better outcome compared with recurrent persistent AF. These results suggest that AT might be considered as a step toward sinus rhythm.

Usefulness of Left Ventricular Diastolic Dysfunction Assessed by Pulsed Tissue Doppler Imaging as a Predictor of Atrial Fibrillation Recurrence After Successful Electrical Cardioversion

The impact of left ventricular (LV) diastolic dysfunction on risk of atrial fibrillation (AF) recurrence is still unknown. The aim of this study was to assess the role of LV diastolic dysfunction in predicting AF recurrence after successful electrical cardioversion in patients with nonvalvular AF. In 51 patients with a first episode of nonvalvular AF undergoing successful electrical cardioversion, tissue Doppler echocardiography was performed to measure peak early diastolic mitral annulus velocity (E(m)) and the ratio of mitral inflow to mitral annulus velocity at end-diastole (E/E(m)). Clinical end points were recurrent persistent AF at 2-week follow-up (early AF recurrence [ERAF]) and at 1-year follow-up (including ERAF and late AF recurrence). Seventeen patients showed evidence of ERAF, whereas late AF recurrence occurred in another 5 patients. In time-independent analysis E/E(m) (odds ratio [OR] 1.746, p = 0.0084) and indexed LV end-systolic volume (OR 1.083, p = 0.040) were independent predictors of ERAF. Based on a logistic model risk of ERAF was 25% for an E/E(m) of 5.6 but increased to 50% for an E/E(m) of 8.1 and to 75% for an E/E(m) of 10.5. In time-dependent analysis E/E(m) emerged as the only predictor of ERAF (OR 1.757, p = 0.0078). E/E(m) also independently predicted risk of recurrence at 1 year in time-independent (OR 1.757, p = 0.0078) and time-dependent (OR 1.319, p = 0.0003) analyses. In conclusion LV diastolic dysfunction independently predicts AF recurrence in patients with nonvalvular AF undergoing successful electrical cardioversion.

Phrenic Nerve Identification With Cardiac Multidetector Computed Tomography

Cryoballoon ablation of the pulmonary veins is a new technique that has proven useful in preventing paroxysmal and persistent atrial fibrillation recurrence. One of the most serious complications of this method is right phrenic nerve palsy. The usefulness of multidetector computed tomography to locate the right phrenic nerve and artery and predict the risk of phrenic nerve palsy during cryoablation according to the distance between the right phrenic neurovascular bundle and the right superior pulmonary vein ostium has recently been described. Fifty-five consecutive patients with paroxysmal atrial fibrillation (52 ± 12 years) underwent balloon cryoablation, following multidetector computed tomography to measure the pulmonary veins. We were able to identify segments of the right pericardiacophrenic artery (mean length 25 mm [range 7-68 mm]) in only 10 patients (20%).

Identificación del nervio frénico con tomografía computarizada cardiaca multidetector

Cryoballoon ablation of the pulmonary veins is a new technique that has proven useful in preventing paroxysmal and persistent atrial fibrillation recurrence. One of the most serious complications of this method is right phrenic nerve palsy. The usefulness of multidetector computed tomography to locate the right phrenic nerve and artery and predict the risk of phrenic nerve palsy during cryoablation according to the distance between the right phrenic neurovascular bundle and the right superior pulmonary vein ostium has recently been described. Fifty-five consecutive patients with paroxysmal atrial fibrillation (52 ± 12 years) underwent balloon cryoablation, following multidetector computed tomography to measure the pulmonary veins. We were able to identify segments of the right pericardiacophrenic artery (mean length 25 mm [range 7-68 mm]) in only 10 patients (20%). Full English text available from: www.revespcardiol.org

Complex Fractionated Atrial Electrogram or Linear Ablation in Patients with Persistent Atrial Fibrillation—A Prospective Randomized Study

Catheter ablation of complex fractionated atrial electrograms (CFAE) for persistent atrial fibrillation (AF) is a promising treatment strategy. We tested the hypothesis that CFAE ablation is superior to linear ablation in patients with persistent or long-standing persistent AF. In this study, 116 patients with persistent AF were randomly assigned to undergo circumferential PVI plus additional lines (linear ablation group; 59 patients) or CFAE ablation plus ostial pulmonary vein isolation (PVI) (spot ablation group; 57 patients). Primary endpoint was freedom from atrial tachyarrhythmia after a single ablation procedure (clinical and repeat 7-day Holter), 12 months after ablation without antiarrhythmic medication. The primary endpoint was reached in 22 of 59 (37%) patients of the linear ablation group and in 22 of 57 (39%) patients of the spot ablation group (P = 0.9). Freedom from atrial tachyarrhythmias, including reablations, was achieved in 54% of patients (linear ablation group) versus 56% of patients (spot ablation group; P = 0.8). The incidence of recurrent persistent AF was higher after linear ablation than after spot ablation (21/37 vs 11/35 patients; P = 0.03); atrial tachycardia (AT) was seen more often after spot ablation (10/35 vs 4/37 patients; P = 0.03). In patients with persistent AF, CFAE ablation plus PVI reaches the same results as circumferential PVI plus lines, in terms of freedom from symptomatic atrial tachyarrhythmias within the first year after a single ablation procedure. Arrhythmia recurrences in patients after spot ablation were caused more often by AT, whereas recurrent persistent AF was more prevalent after the linear ablation approach.

Catheter ablation of persistent atrial fibrillation: anatomically based circumferential pulmonary vein ablation in combination with a potential-guided segmental approach to achieve complete pulmonary vein isolation

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. However, catheter ablation of persistent atrial fibrillation is still a challenge. Various rather complex ablation strategies exist and their results are not very favorable. Therefore, the aim of our study was to evaluate a well-defined reasonable approach to catheter ablation of persistent atrial fibrillation. The strategy consisted of a circumferential pulmonary vein ablation in combination with a potential-guided segmental approach to achieve complete pulmonary vein isolation and a linear lesion at the roof of the left atrium. A total of 43 patients (30 men, 13 women; mean age 55 years (SD ± 9 years)) with symptomatic persistent atrial fibrillation were enrolled in this study. All patients underwent catheter ablation of persistent atrial fibrillation using the above-mentioned approach (with the CARTO or the NAVX system). Additionally, catheter ablation of the mitral isthmus and the right atrial isthmus was performed in selected cases. In all patients, cardiac MRI or multi-detector spiral computed tomography was performed prior to the ablation procedure and a surface rendered model of the left atrium was created. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, 6, 9, and 12 months after the ablation procedure. The ablation procedure could be performed as planned in all 43 patients. Nine patients had to undergo a repeat ablation procedure, so that a total of 52 procedures were evaluated. An additional linear lesion was created at the mitral isthmus in three patients (7%) during the initial procedure and in one patient (2.3%) during the second procedure. Catheter ablation of the right atrial isthmus was performed in 11 patients (25.6%) during the first procedure and in four additional patients during the redo procedure (9.3%). Twenty-four out of 43 patients (55.8%) experienced an arrhythmia recurrence within the first 3 months after ablation requiring an electrical cardioversion. At 1-year follow-up, analysis of a 7-day Holter monitoring revealed no evidence for an arrhythmia recurrence in 26 of 43 patients (60.5%). In nine of 43 patients (20.9%), only short episodes of paroxysmal atrial fibrillation were documented. In eight patients (18.6%), a recurrence of persistent atrial fibrillation (>48 h) was revealed by the long-term recordings. A duration of persistent atrial fibrillation >3 months was the most powerful predictor for arrhythmia recurrences at 1-year follow-up. A subgroup analysis revealed a markedly higher rate of stable sinus rhythm at 1-year follow-up in patients with a short duration of atrial fibrillation (≤ 3 months) compared to patients with a longer duration of AF (>3 months) prior to the procedure (72.0% versus 44.4%). There were no major complications. Catheter ablation of persistent atrial fibrillation can be performed safely and effectively using this ablation strategy (especially in patients with short-lasting persistent atrial fibrillation (≤ 3 months)).

Marshall Vein as a Tract Connecting Both Sides of Mitral Isthmus Line in a Patient Post Radiofrequency Catheter Ablation of Atrial Fibrillation

A 69-year-old man underwent the second radiofrequency (RF) ablation for the recurrence of persistent atrial fibrillation (AF). After re-isolation of the PV and making linear lesions to LA roof, bottom, and mitral annulus, AT with the cycle length of 370 msec was induced by programmed stimulation. Left atrial activation map exhibited counter-clockwise activation along the mitral annulus, with the total activation time for 290 msec and missing period for 80 msec at the mitral isthmus line. The post-pacing interval (PPI) at the mitral annulus anterior and inferior to the mitral isthmus line exceeded the tachycardia cycle length (TCL) by 30 ms. Extensive RF applications to the mitral isthmus and to the CS failed to terminate the AT. Then, a sharp small potential was recorded when the tip of ablation catheter was wedged in the proximal Marshall vein, which was confirmed by injection of contrast media from the irrigation catheter. The PPI was identical to the TCL. RF application using irrigation catheter successfully terminated the AT. Marshall vein may work as a bridge connecting both sides of mitral isthmus line. This is the first report of the perimitral AT that was successfully eliminated by the RF application in the Marshall vein.

Chronic Fish Oil Supplementation Reduces the Recurrence of Persistent Atrial Fibrillation after Cardioversion

Chronic Fish Oil Supplementation Reduces the Recurrence of Persistent Atrial Fibrillation after Cardioversion

High-frequency vagal stimulation: Pacing fast to slow down

Atrial fibrillation is the most common arrhythmia requiring treatment. Although in the past few years there has been great interest in ablation for this arrhythmia, many patients are relatively asymptomatic and can be managed effectively with a rate-control strategy. 1 Wyse D.G. Waldo A.L. DiMarco J.P. et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med. 2002; 347: 1825-1833 Crossref PubMed Scopus (3626) Google Scholar , 2 Van Gelder I.C. Hagens V.E. Bosker H.A. et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med. 2002; 347: 1834-1840 Crossref PubMed Scopus (1970) Google Scholar , 3 Fuster V. Rydén L.E. Crijins H.J. et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation. J Am Coll Cardiol. 2006; 48: e149-e246 Abstract Full Text Full Text PDF Scopus (315) Google Scholar This strategy often uses beta-adrenergic blocking agents or calcium-channel blocking agents to control the ventricular rate while leaving the atrium in atrial fibrillation. Use of these drugs may be ineffective at controlling the ventricular rate, may cause significant side effects, or may be of limited use when a patient has severe left ventricular dysfunction or symptomatic hypotension. When these drugs fail, patients are often advised to have an atrioventricular (AV) nodal ablation and placement of a permanent pacemaker. This form of therapy improves symptoms but makes the patient pacemaker-dependent and may increase the incidence of congestive heart failure when a right-ventricular-only pacemaker is used. Vagal tone augmentation to the atrioventricular node in humans: Efficacy and safety of burst endocardial stimulationHeart RhythmVol. 7Issue 5PreviewControl of atrioventricular (AV) nodal conduction by endocardial stimulation of efferent AV nodal vagal fibers [atrioventricular nodal vagal stimulation (AVNS)] is a promising approach for long-term device-based modulation of ventricular rate during atrial fibrillation (AF). However, few data on the efficacy of AVNS delivered as high-frequency stimulus packages (burst AVNS) in humans are available. Full-Text PDF

Esophageal Fistula Formation Despite Esophageal Monitoring and Low-Power Radiofrequency Catheter Ablation for Atrial Fibrillation

Esophageal fistula is a rare but devastating complication that may occur after catheter ablation of atrial fibrillation.1 The mechanism of esophageal injury is not known. Potential mechanisms for injury include direct thermal injury and ischemic injury from damage to the esophageal blood supply. Current ablation strategies use various methods to avoid esophageal injury. We describe an unusual manifestation of esophageal injury despite multiple preventive measures. A 45-year-old man with a medical history of hypertension, mild aortic stenosis, body mass index of 26.78 kg/m2 (weight, 192 pounds; height, 5 feet, 11 inches), and symptomatic recurrent persistent atrial fibrillation refractory to amiodarone for 4 years underwent a radiofrequency catheter ablation procedure under general anesthesia using sevoflurane, fentanyl, midazolam and rocuronium. A preprocedure computed tomography (CT) scan was used to create 3D reconstruction of the left atrium and pulmonary veins. Intracardiac echo (Carto Sound, Biosense Webster, Diamond Bar, Calif) was used to create left atrial and pulmonary vein geometry, and this was merged with the CT image (Figure 1). An orogastric tube was placed in the esophagus at the level of left atrium, and barium was injected to obtain fluoroscopic images of …

The predictive value of inflammatory and oxidative markers following the successful cardioversion of persistent lone atrial fibrillation

Background Although there is evidence that inflammation and oxidative stress might contribute to the pathogenesis of atrial fibrillation (AF), the predictive value of inflammatory and oxidative stress markers in patients with AF has not been fully assessed. The aim of this study is to evaluate these markers as predictors of sinus rhythm (SR) maintenance, in patients with persistent lone AF. Methods Among 268 patients with symptomatic AF, we studied 46 patients with a first episode of recently established persistent lone AF. We measured the circulating levels of hs-CRP, TNF-α, IL-6, IL-10, sICAM-1, sVCAM-1, malondialdehyde (MDA) and nitrotyrosine (NT) before, 1 h, 24 h, 1, 2, 4 and 6 weeks after cardioversion. During a 12-month follow-up period, AF recurrence was evaluated by Holter ECG recordings every month and when symptoms were reported. Results Baseline levels of CRP, TNF-α, sICAM-1, MDA, and NT were elevated in patients with AF compared to controls, and higher in patients with than in those without persistent AF recurrence, while IL-6 levels were equally elevated in the two subgroups. SR maintenance was associated with lower baseline MDA values and faster decrease in IL-6, sICAM-1 and NT levels within the first 2 weeks following SR restoration. Conclusions Increased markers of inflammation and oxidative stress are found in patients with lone AF, implying that inflammation and oxidative stress may be associated with the presence of the arrhythmia. IL-6, sICAM-1, MDA and NT, assessed prior to and after the first cardioverted episode of persistent arrhythmia, appear to be reliable, early predictors of SR maintenance during the following year.

Clinical Effectiveness of Antiarrhythmic Treatment After Electrical Cardioversion in Patients Without Structural Heart Disease

The aim was to investigate the clinical effectiveness of using antiarrhythmic drugs after electrical cardioversion in patients without structural heart disease, including their effect on the maintenance of sinus rhythm. In total, 528 patients with persistent atrial fibrillation but without significant structural heart disease who underwent successful electrical cardioversion at 96 Spanish hospitals were followed up for 1 year. Patients were assessed at 1, 3, 6 and 12 months. The use and effectiveness of antiarrhythmic drugs for preventing the recurrence of persistent atrial fibrillation was evaluated. Some 80% of patients were receiving antiarrhythmic drugs at discharge, most frequently amiodarone. No specific clinical factor was associated with greater use of antiarrhythmics. Overall, 37% of patients were in sinus rhythm at all follow-up assessments. At the 1-year assessment, 59% of patients who remained in sinus rhythm were still taking antiarrhythmic drugs. Multivariate Cox regression analysis identified weight (hazard ratio [HR]=1.01 per kg; P=.04) and no antiarrhythmic treatment (HR=1.59; P=.001) as being independently associated with the recurrence of persistent atrial fibrillation. Amiodarone tended to be better than other antiarrhythmic drugs. In routine clinical practice, the large majority of patients without structural heart disease received antiarrhythmic drugs, most frequently amiodarone, after successful electrical cardioversion. Drug use was the principal factor associated with the maintenance of sinus rhythm at 1 year.

696 Persistent atrial fibrillation recurrence in the first year after cardioversion of recent onset atrial fibrillation is related with increased late high sensitivity C-reactive protein levels

696 Persistent atrial fibrillation recurrence in the first year after cardioversion of recent onset atrial fibrillation is related with increased late high sensitivity C-reactive protein levels

Estado inflamatorio de los pacientes con fibrilación auricular antes y después de la cardioversión eléctrica

To assess the inflammatory state in patients with persistent atrial fibrillation and to determine the predictive value in the success of cardioversion and recurrence at 30 days. Prospective observational case-control study. We included consecutively 49 patients with atrial fibrillation previously to scheduled electrical cardioversion in Coronary Care Unit. Clinical and echocardiographic variables were registered and High-sensivity C-reactive protein, interleukin-1beta, interleukin-6 and Tumour Necrosis Factor-alpha were measured. At 30-days follow-up, rhythm and biomarkers were reassessed. As control groups, we recruited 27 healthy volunteers and 16 patients matched for age, gender and cardiovascular risk factors. Median age was 66 +/- 10 years and 38% were women. All the markers were higher in patients than in both control groups (p < 0.05). FNT-alpha and Interleukin-6 levels were higher in non-cardiovertors but only an enlarged atria was related to unsuccessful cardioversion (p = 0.036). High-sensivity C-reactive protein values in the higher cuartile tended to be related to recurrence of persistent atrial fibrillation (p = 0.06). There is an increased inflammatory state in patients with atrial fibrillation. FNT-alpha and Interleukin-6 levels were increased in non-cardiovertors, but no biomarker was associated with success of cardioversion or rhythm state at 30-days. However, higher levels of hs-CRP showed a trend to be related to recurrence of atrial fibrillation.

A clinical and health-economic evaluation of pulmonary vein encircling ablation compared with antiarrhythmic drug treatment in patients with persistent atrial fibrillation (Catheter Ablation for the Cure of Atrial Fibrillation-2 study)

Catheter Ablation for the Cure of Atrial Fibrillation 2 study is a prospective, randomized trial aimed to demonstrate the efficacy of catheter ablation with combined lesions in the right and left atria, in preventing atrial fibrillation (AF) recurrences among patients with recurrent persistent AF refractory to one antiarrhythmic drug, in comparison with the best pharmacological therapy. Enrolment is limited to patients aged between 18 and 70 years who have experienced at least one documented relapse of persistent AF during antiarrhythmic drug therapy. One hundred and twenty-six patients will be randomized to ablation or antiarrhythmic drug therapy in a 2 : 1 manner. In the ablation group, the patients will undergo right and left atrial linear ablation. Control group patients will be treated with the best antiarrhythmic drug. After an initial blanking period of 2 months patients will be followed for 24 months. Primary endpoint of the study is the absence of documented persistent atrial tachyarrhythmias relapse during the first 24 months after the blanking period. Enrolment is scheduled in 14 centres in Italy, UK, Austria, and Finland. Seventy-two patients have currently been enrolled. This study will provide important data about the efficacy of catheter ablation in comparison with antiarrhythmic drugs for the treatment of persistent AF.

Characterization of the Electroanatomical Substrate in Human Atrial Fibrillation: The Relationship between Changes in Atrial Volume, Refractoriness, Wavefront Propagation Velocities, and AF Burden

Progressive remodeling occurs in experimental models of AF whereby slowing of conduction, shortening of refractoriness, and atrial dilatation are associated with an increased vulnerability to atrial fibrillation (AF). This study investigates the relative changes in atrial geometry and electrophysiology with increasing AF burden in humans. Patients undergoing ablation of AF or left-sided accessory pathways were recruited. Atrial volumes were determined by echocardiography. Wavefront propagation velocities (WPV), specifically in the direction of activation, were calculated from pre-ablation activation (Carto) maps of both atria. Dispersion, adaptation of, and effective refractoriness (ERP) were measured at 3 sites. A composite arrhythmogenic index (Atrial Volume/WPV x ERP) was derived to compare the degree of electroanatomical remodeling with AF burden. Fifty-nine patients (22 paroxysmal AF, 19 recurrent persistent AF, and 18 controls) were recruited. AF subjects had slower right atrial WPV (P = 0.01), but no difference in left atrial WPV compared with controls. ERP was reduced globally (P < 0.05), with increased dispersion (P < 0.05). WPV and ERP did not distinguish between patients with paroxysmal or persistent AF. Biatrial volumes were greater only in patients with persistent AF (P < 0.01). There was a stepwise increase in the AI with increasing AF burden (P < 0.0001). An arrhythmogenic substrate exists in human AF, characterized by globally decreased refractoriness with greater dispersion, slower right atrial conduction, and atrial dilatation. Persistence of AF is not accompanied by any further electrical remodeling, but only atrial dilatation. The degree of electroanatomical remodeling is associated with the clinical pattern of AF.

Self-limited bursts of atrial fibrillation following successful cardioversion

Background To evaluate if self-limited episodes of atrial fibrillation after DC cardioversion predict recurrence of persistent atrial fibrillation. To evaluate the incidence and duration of such episodes as well as their change over time. Methods Consecutive patients with persistent atrial fibrillation, scheduled for direct current cardioversion were prospectively included in the study. Ambulatory ECG Holter monitoring (24 h) was performed one, three and 6 weeks after successful cardioversion. Results A total of 84 patients were prospectively included in the study. Sinus rhythm was restored in 74 patients (88%). At 6 weeks of follow-up 40 patients out of 74 (54%) had sinus rhythm, and 34 patients (46%) had relapsed into persistent atrial fibrillation. Eight out of these 34 patients (24%) had bursts of atrial fibrillation at their first Holter recording, compared to 12 patients out of 40 (30%) in sinus rhythm at 6 weeks ( p > 0.05). On the first, second and third Holter recording 21 patients out of 51 (41%), 21 patients out of 43 (49%) and 15 out of 40 patients (38%) had self-limited bursts of atrial fibrillation, respectively. The incidence or duration of episodes did not vary over time during the 6 weeks of follow-up. Conclusion In patients successfully converted to sinus rhythm self-limited bursts of atrial fibrillation do not predict recurrence of persistent atrial fibrillation during 6 weeks of follow up. Brief self-limited episodes of atrial fibrillation are common, and the incidence and duration of such episodes are constant during a 6 weeks period after DC cardioversion.

Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation – the role of atrial cycle length

BackgroundAtrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies.The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF.MethodsDominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion.Results32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04).ConclusionIn this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.

Effects of amiodarone on electrical and structural remodeling induced in a canine rapid pacing-induced persistent atrial fibrillation model

Structural in addition to electrical remodeling may be induced by persistent atrial fibrillation per se and make atrial fibrillation refractory to antiarrhythmic drug therapy. Matrix metalloproteinases (MMPs) contribute to structural remodeling in the interstitial space. Amiodarone is effective in treating persistent atrial fibrillation compared with other antiarrhythmic drugs. In mongrel dogs, right atrial pacing at 540 beats/min (bpm) was performed along with ventricular pacing at 100 bpm for 6 weeks after atrioventricular node ablation. Right atrial pacing at 400 bpm was continued for 4 weeks with ( n = 5) or without ( n = 5) oral amiodarone (30 mg/kg/day). In sham dogs, only ventricular pacing was done with ( n = 4) or without ( n = 6) amiodarone. In atrial pacing without amiodarone group, electrical remodeling characterized by monophasic action potential duration shortening, loss of action potential duration-rate adaptation and depressed conduction velocity and structural remodeling characterized by slightly but significantly increased interstitial fibrosis and enhanced MMP-2 activity compared with sham group were observed, and sustained atrial fibrillation was easily induced. In atrial pacing with amiodarone group, both electrical and structural remodeling were reversed and sustained atrial fibrillation was not induced. In sham group with amiodarone, action potential duration prolongation and depressed conduction velocity compared with sham without amiodarone were observed, but either increased fibrosis or enhanced MMP-2 activity was not observed. Not only electrical but structural remodeling were induced in a canine persistent atrial fibrillation model. Amiodarone reversed both of them, which may be related to its high efficacy in preventing recurrence of persistent atrial fibrillation.

Pharmacological Cardioversion of Persistent Atrial Fibrillation With and Without a History of Drug-Resistant Paroxysmal Atrial Fibrillation

Suppression by antiarrhythmic drugs of the maintenance mechanisms could convert persistent atrial fibrillation (AF) to sinus rhythm (SR). Whether a history of drug-resistant paroxysmal AF (PAF) would affect the outcome of pharmacological conversion of persistent AF by bepridil or in combination with aprindine was evaluated in the present study. The study group comprised 51 consecutive patients (24 men, 61+/-8 years) undergoing pharmacological conversion of persistent AF lasting >1 month. Drug-resistant PAF was defined as AF and at least 2 ineffective antiarrhythmic drugs for suppression of AF recurrence. Fast Fourier transform analysis of fibrillation waves was used to measure fibrillation cycle length (FCL) from the peak frequency. Fifteen patients had a history of drug-resistant PAF (Group I), and the remaining 36 did not (Group II) before diagnosis of persistent AF. Ten patients (67%) in Group I and 26 patients (72%) in Group II were restored to SR by bepridil alone or in combination with aprindine after 29+/-15 days of drug administration. Before conversion to SR, bepridil increased the FCL more in Group II than in Group I. During a 12-month follow-up period, 4 of 10 patients in Group I and 2 of 26 patients in Group II (p<0.01) had recurrence of persistent AF with bepridil alone or in combination with aprindine. A history of drug-resistant PAF does not affect the efficacy of pharmacological conversion by bepridil or in combination with aprindine. However, recurrence of AF was significantly higher in patients with such a history.