Frequent Episodes Of Atrial Fibrillation Research Articles

Predictors of Recurrence after Catheter Ablation of Paroxysmal Atrial Fibrillation in Different Follow-Up Periods.

Background and objectives: Pulmonary vein (PV) reconnection is a major reason for recurrence after catheter ablation of paroxysmal atrial fibrillation (PAF). However, the timing of the recurrence varies between patients, and recurrence >1 year after ablation is not uncommon. We sought to elucidate the characteristics of atrial fibrillation (AF) that recurred in different follow-up periods. Materials and Methods: Study subjects comprised 151 consecutive patients undergoing initial catheter ablation of PAF. Left atrial volume index (LAVi) and atrial/brain natriuretic peptide (ANP/BNP) levels were systematically measured annually over 3 years until AF recurred. Results: Study subjects were classified into four groups: non-recurrence group (n = 84), and short-term- (within 1 year) (n = 30), mid-term- (1–3 years) (n = 26), and long-term-recurrence group (>3 years) (n = 11). The short-term-recurrence group was characterized by a higher prevalence of diabetes mellitus (hazard ratio 2.639 (95% confidence interval, 1.174–5.932), p = 0.019 by the Cox method), frequent AF episodes (≥1/week) before ablation (4.038 (1.545–10.557), p = 0.004), and higher BNP level at baseline (per 10 pg/mL) (1.054 (1.029–1.081), p < 0.0001). The mid-term-recurrence group was associated with higher BNP level (1.163 (1.070–1.265), p = 0.0004), larger LAVi (mL/m2) (1.033 (1.007–1.060), p = 0.013), and longer AF cycle length at baseline (per 10 ms) (1.194 (1.058–1.348), p = 0.004). In the long-term-recurrence group, the ANP and BNP levels were low throughout follow-up, as with those in the non-recurrence group, and AF cycle length was shorter (0.694 (0.522–0.924), p = 0.012) than those in the other recurrence groups. Conclusions: Distinct characteristics of AF were found according to the time to first recurrence after PAF ablation. The presence of secondary factors beyond PV reconnections could be considered as mechanisms for the recurrence of PAF in each follow-up period.

Diagnostic pitfalls: unexpectedly severe pulmonary hypertension with pulmonary hemorrhage after atrial septal defect closure - a case report

Introduction Certain elderly patients may suffer from an uncorrected congenital heart disease (CHD) and severe pulmonary hypertension (PHT). Methods A 69-year-old male patient presented for elective surgical closure of an atrial septal defect (ASD) and for a radiofrequency (RF) ablation of the pulmonary veins due to frequent episodes of atrial fibrillation. A transthoracic echocardiography revealed a small defect in the middle part of the atrial septum with a pulmonary to systemic blood flow ratio of 3:1 and a right ventricle (RV) systolic pressure of 45 mmHg. Results Following the cardiopulmonary bypass institution, surgical inspection detected a sinus venosus defect with anomalous drainage of the right upper pulmonary vein into the left atrium, apart from the ASD type secundum. A pericardial patch reconstruction and Cox-Maze IV procedure was performed. Several hours after the intervention, blood was noted, refluxing from the endotracheal tube. Simultaneously, a severe hemodynamic instability appeared with nodal cardiac rhythm, due to a malposition of the atrial pace-maker wire. Pulmonary artery pressure measured 45/35 mmHg, pulmonary capillary wedge pressure (PCWP): 16 mmHg, right heart chambers were enlarged and RV contractility was severely reduced. A chest X-ray and a CT scan revealed massive hemorrhage in the right upper pulmonary lobe. A bronchial blocker was placed immediately and a resection of the affected lobe was performed. Discussion This case illustrates underestimated severity of pulmonary hypertension under conditions of the reduced RV function. An assessment of PCWP indicates precapillary PHT. The permanent left to right shunt with increased pulmonary blood flow resulted in progressive endothelial and medial disturbances of the pulmonary vessels, and in creation of the complex vascular lesions with consequential intrapulmonary hemorrhage. Adult patients with CHD remain a high-risk perioperative population, requiring all available resources and a multidisciplinary approach.

Abstract 21054: Hematopoietic Factors Are Sufficient to Increase AF in Aged, Atherosclerotic Mice

Rationale: Aging is a strong risk factor for atrial fibrillation (AF), the most common sustained arrhythmia in the clinical practice. Atrial inflammation correlates with increased AF susceptibility but whether chronic age-related inflammation that occurs with atherosclerosis contributes to AF is unknown. Hypothesis: Hematopoietic factors contribute to AF inducibility in aged atherosclerotic mice. Methods: We used burst electrical stimulation (tachypacing) of the right atrium to test susceptibility to AF in-vivo in young and aged atherosclerotic, low density lipoprotein receptor knockout (C57BL/6 Ldlr -/- ) mice, and young and old wildtype (C57BL/6 WT) mice. We also determined the role of the stroma vs. the hematopoietic system, by creating bone marrow chimeras in which aged or young Ldlr -/- mice were transplanted with age-matched or mismatched bone Ldlr -/- bone marrow. We used whole-cell patch-clamping investigate atrial sodium currents. Confocal microscopy and patch-clamping in current clamp mode was used to simultaneously record action potentials and Ca 2+ transients. Results: Upon atrial tachypacing, aged atherosclerotic mice underwent longer and more frequent AF episodes than young (incidence, 0.47±0.09 vs 0.12±0.02 episodes/attempts; p&lt;0.05 ) and aged WT mice (0.47±0.09 vs 0.16±0.07 episodes/attempts; p&lt;0.05 ). Importantly, young-to-old bone marrow chimeric mice exhibited reduced AF incidence (0.23 ± 0.05 episodes/attempts), whereas old-to-young chimeric mice exhibited increased AF incidence (0.45 ± 0.08 episodes/attempts). Atrial myocytes from aged atherosclerotic mice presented a 50% reduction in the cardiac inward sodium current (I Na ). Moreover, compared to young, aged atherosclerotic mice showed prolonged action potential duration (APD90: 34.0±5.0 ms vs 48.1±7.0ms; p&lt;0.05), post-pacing spontaneous calcium releases (25% vs 81.8%; p&lt;0.05) and triggered activity (0% vs 27.2 %; p&lt;0.05). Conclusions: Aged atherosclerotic prone mice are susceptible to AF induction. Hematopoietic factors are sufficient to increase AF propensity with aging in the atherosclerotic host possibly by causing electrophysiological remodeling and intracellular Ca 2+ handling abnormalities.

Catheter Ablation of Atrial Fibrillation: An Overview for Clinicians.

Catheter ablation (CA) of atrial fibrillation (AF) is currently one of the most commonly performed electrophysiology procedures. Ablation of paroxysmal AF is based on the elimination of triggers by pulmonary vein isolation (PVI), while different strategies for additional AF substrate modification on top of PVI have been proposed for ablation of persistent AF. Nowadays, various technologies for AF ablation are available. The radiofrequency point-by-point ablation navigated by electro-anatomical mapping system and cryo-balloon technology are comparable in terms of the efficacy and safety of the PVI procedure. Long-term success of AF ablation including multiple procedures varies from 50 to 80%. Arrhythmia recurrences commonly occur, mostly due to PV reconnection. The recurrences are particularly common in patients with non-paroxysmal AF, dilated left atrium and the "early recurrence" of AF within the first 2–3 post-procedural months. In addition, this complex procedure can be accompanied by serious complications, such as cardiac tamponade, stroke, atrio-esophageal fistula and PV stenosis. Therefore, CA represents a second-line treatment option after a trial of antiarrhythmic drug(s). Good candidates for the procedure are relatively younger patients with symptomatic and frequent episodes of AF, with no significant structural heart disease and no significant left atrial enlargement. Randomized trials demonstrated the superiority of ablation compared to antiarrhythmic drugs in terms of improving the quality of life and symptoms in AF patients. However, nonrandomized studies reported additional clinical benefits from ablation over drug therapy in selected AF patients, such as the reduction of the mortality and stroke rates and the recovery of tachyarrhythmia-induced cardiomyopathy. Future research should enable the creation of more durable ablative lesions and the selection of the optimal lesion set in each patient according to the degree of atrial remodeling. This could provide better long-term CA success and expand indications for the procedure, especially among the patients with non-paroxysmal AF.

The development of AF over time in patients with permanent pacemakers: objective assessment with pacemaker diagnostics demonstrates distinct patterns of AF

To describe the long-term patterns of atrial fibrillation (AF) in patients with permanent pacemakers. A total of 2092 pacemaker Holter downloads were analysed in 323 patients with dual chamber permanent pacemakers, describing a cumulative 1031 patient-years of beat-to-beat monitoring. Four subtypes of AF were applied: (i) non-progressive low-burden PAF (NPLB-PAF, n = 120): such patients never have >1% AF burden throughout follow-up; (ii) chronic progressive PAF (CP-PAF, n = 55): AF burden increases but is never 100%; (iii) relapsing-remitting PAF (RR-PAF, n = 78): AF burden has reduced at least once by more than 2% and is never 100%; (iv) persistent AF (PersAF, n = 70): 100% AF burden for at least 28 days. Overall, mean AF burden rose 0.34% per year (P < 0.0001). After accounting for age, heart failure (HF) had a significant interaction with AF burden (P = 0.0022), but HATCH score and CVA/TIA did not. There were no differences in the frequency or duration of monitoring between the four AF subtypes. Atrial fibrillation episode frequency discriminated between subtypes (P = 0.0004). Eighteen of 70 (26%) patients with PersAF had pacemaker documented episodes of sinus rhythm (i.e. reversion to 'paroxysmal AF') after the onset of PersAF. In this cohort, the development of AF over time appears more complex than current definitions suggest. Atrial fibrillation can remain low burden without progression, remit-relapse, or progress as is described in currently accepted definitions. More frequent episodes of AF indicated a favourable subtype. Persistent AF is not inevitable, and can revert to paroxysmal AF. NCT02016950, http://clinicaltrials.gov/show/NCT02016950.

Impaired Transport Function of the Left Atrium in Patients with Lone Paroxysmal Atrial Fibrillation

Although lone paroxysmal atrial fibrillation (LPAF) is clinically defined as an arrhythmia that occurs in the absence of structural heart disease, it has been suggested that the presence of anatomical substrate is related to LPAF. The aim of the present study is to determine whether structural and functional remodeling of the left atrium (LA) occurs in patients with LPAF, and to identify whether frequent episodes of atrial fibrillation (AF) contribute to LA remodeling. Forty-five patients who diagnosed as LPAF and age-, gender-, and body mass index-matched healthy control subjects (n = 45) were enrolled. Patients were grouped based on the frequency of AF episodes. An echocardiography was performed >2 weeks after last episode of AF without antiarrhythmic drugs. There were no statistical differences in left ventricular (LV) diastolic and systolic functions as well as baseline characteristics between patients and controls, whereas, patients had significantly larger LA volume (LAV), lower active LA emptying fraction (LAEF(active) , P = 0.009) and total LAEF (LAEF(total) , P = 0.005) compared with controls. Passive LAEF (LAEF(passive) ) was not different between patients and controls (P = 0.664). LAEF(active) was significantly depressed in patients with frequent episodes of AF than the others (P = 0.034). Compared with healthy controls, patients with LPAF had increased LAV and depressed LAEF(active) and LAEF(total) without accompanying compensatory increase in LAEF(passive) . LAEF(active) was influenced by frequent episodes of AF. These findings may support the hypothesis that LPAF is "not-so-lone AF" and related to the concealed cardiac dysfunctions.

Linear Ablation with Duty-Cycled Radiofrequency Energy at the Cavotricuspid Isthmus

Multielectrode catheters using duty-cycled radiofrequency (RF) have been developed to treat atrial fibrillation (AF). Many of these patients also have atrial flutter. Therefore, a linear multielectrode has been developed using the same RF energy. The concept and acute results of linear ablation using duty-cycled RF were tested in the cavotricuspid isthmus (CTI). The CTI was targeted in 75 patients, in 68 (90%) among them as an adjunct to AF ablation with the same technology. A linear electrode catheter with a 4-mm tip and five 2-mm ring electrodes was connected to a generator titrating duty-cycled RF at 20-45 W up to a target temperature of 70 degrees C in 1:1 unipolar/bipolar mode. During a mean procedure time of 20 +/- 12 minutes, complete CTI block was achieved by 4 +/- 3 applications of duty-cycled RF in 69 (92%) patients. No more than three RF applications were necessary in 60% of patients. During the initial learning curve, standard RF had to be used in five (7%) patients. Complete block was not achieved in one patient with frequent episodes of AF. Char was observed in five (7%) patients with poor electrode cooling; consequently, the temperature ramp-up was slowed and manually turned off in the event of low-power delivery. Two groin hematomas occurred; otherwise, no clinical complications were observed. Multielectrode catheters delivering duty-cycled RF can effectively ablate the CTI with few RF applications with promising acute results. Further modifications are necessary to improve catheter steering and prevent char formation. (PACE 2010; 444-450).

Efficacy of pulmonary vein isolation by cryoballoon ablation in patients with paroxysmal atrial fibrillation

Radiofrequency ablation of pulmonary veins (PVs) has emerged as an effective treatment for patients with paroxysmal atrial fibrillation (AF). However, serious complications raise concern about an even wider application. In terms of safety, cryoenergy has advantages compared with radiofrequency. A new cryoenergy balloon catheter has been recently developed to make AF ablation shorter and safer. The purpose of this study was to test the 6-month efficacy of this new device for ablation of paroxysmal AF. Twenty-one patients with highly symptomatic paroxysmal AF, normal left atrial size, and frequent episodes of AF were included. All PVs were targeted during cryoballoon ablation. Patients received 24-hour Holter electrocardiograms (ECGs) and event recorder during follow-up after 1, 3, and 6 months. A total of 81 (95%) of 85 PVs could be completely isolated with a single-balloon technique. Procedure time was 165 +/- 35 minutes, and fluoroscopy time was 39 +/- 9 minutes. After 6 months, 86% of the patients were free of symptomatic AF. In two of three patients with recurrence of AF, complete PV isolation has not been achieved initially. After a second procedure (1.04 procedures per patient), 90% of the patients were free of symptomatic AF. Three phrenic nerve palsies occurred during ablation of the right superior PV; two completely resolved after 6 and 9 months, and one is still persisting after 2 months. This is the first study that reports the results of the new cryoballoon AF ablation approach showing 86% freedom from AF recurrence after 6 months. Cryoballoon PV ablation promises to be effective for patients with paroxysmal AF and normally sized left atria.

A controlled study on the effect of verapamil on atrial tachycaarrhythmias in patients with brady-tachy syndrome implanted with a DDDR pacemaker

While verapamil has been proposed as a treatment for reducing electrophysiological remodeling due to atrial fibrillation and atrial tachyarrhythmias, no previous study has tested its effects in brady-tachy patients implanted with a dual-chamber pacemaker. Fourteen patients with frequent episodes of atrial fibrillation (≥2 episodes/month) in the setting of brady-tachy syndrome, implanted with a DDDR pacing system with extensive monitor function (Selection 900, Vitatron) were enrolled. Four months after implantation, they were randomly allocated to a 2-month period of treatment with verapamil (240 mg/day) or to no treatment, followed by a crossover. The burden of atrial tachyarrhythmias, the total number of hours spent in atrial tachyarrhythmia and the mean number of hours per day spent in atrial tachyarrhythmia were retrieved from diagnostic devices. The accuracy of atrial tachyarrhythmias detection was confirmed independently by two observers. The main results showed that treatment with verapamil was associated with a trend towards an higher percentage of atrial pacing in comparison with control (mean value±S.D.=63.2±29.9% vs. 57.3±30.6%, median value 53% vs. 49%, P value at Wilcoxon signed rank test=0.069), but without any significant reduction in atrial tachyarrhythmia burden (4.5±11.8 vs. 3.3±9.1%) or total hours spent in atrial tachyarrhythmia (65±161 vs. 48±131 h). Palpitation episodes were not significantly reduced by verapamil treatment in comparison with control (10.3±7.8 vs. 6.1±6.5). In conclusion, verapamil does not exert any beneficial effect on documented episodes of atrial tachyarrhythmia in patients with brady-tachy syndrome implanted with a DDDR device. Moreover, this drug was ineffective in reducing the number of palpitation episodes reported by the patient.

Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins.

Atrial fibrillation, the most common sustained cardiac arrhythmia and a major cause of stroke, results from simultaneous reentrant wavelets. Its spontaneous initiation has not been studied. We studied 45 patients with frequent episodes of atrial fibrillation (mean [+/-SD] duration, 344+/-326 minutes per 24 hours) refractory to drug therapy. The spontaneous initiation of atrial fibrillation was mapped with the use of multielectrode catheters designed to record the earliest electrical activity preceding the onset of atrial fibrillation and associated atrial ectopic beats. The accuracy of the mapping was confirmed by the abrupt disappearance of triggering atrial ectopic beats after ablation with local radio-frequency energy. A single point of origin of atrial ectopic beats was identified in 29 patients, two points of origin were identified in 9 patients, and three or four points of origin were identified in 7 patients, for a total of 69 ectopic foci. Three foci were in the right atrium, 1 in the posterior left atrium, and 65 (94 percent) in the pulmonary veins (31 in the left superior, 17 in the right superior, 11 in the left inferior, and 6 in the right inferior pulmonary vein). The earliest activation was found to have occurred 2 to 4 cm inside the veins, marked by a local depolarization preceding the atrial ectopic beats on the surface electrocardiogram by 106+/-24 msec. Atrial fibrillation was initiated by a sudden burst of rapid depolarizations (340 per minute). A local depolarization could also be recognized during sinus rhythm and abolished by radiofrequency ablation. During a follow-up period of 8+/-6 months after ablation, 28 patients (62 percent) had no recurrence of atrial fibrillation. The pulmonary veins are an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. These foci respond to treatment with radio-frequency ablation.

A focal source of atrial fibrillation treated by discrete radiofrequency ablation.

Atrial fibrillation is usually thought to be due to multiple circulating reentrant wavelets. From previous studies, a focal mechanism is considered to be very unlikely. In this report, focal atrial fibrillation is defined on an ECG pattern of atrial fibrillation and later demonstrated to be due to a focal source. Nine patients (five men and four women, age, 38 +/- 7 years) with paroxysmal focal atrial fibrillation are reported here. All were free of structural heart disease and had frequent episodes of atrial fibrillation despite the use of a mean of 4 +/- 2 antiarrhythmic drugs. Atrial fibrillation was associated with runs of irregular atrial tachycardia or monomorphic extrasystoles. The electrophysiological study demonstrated that all the atrial arrhythmias were due to the same focus firing irregularly and exhibiting a consistent and centrifugal pattern of activation. Three foci were found to be located in the right atrium, two near the sinus node and one in the ostium of the coronary sinus. Six others were located in the left atrium at the ostium of the right pulmonary veins (n = 5) and at the ostium of the left superior pulmonary vein (n = 1). All atrial arrhythmias were successfully treated by use of a mean of 4 +/- 4 radiofrequency pulses. In some patients, the surface ECG pattern of atrial fibrillation is due to a focal rapidly firing source of activity that can be eliminated by discrete radiofrequency energy applications.

Atrial and ventricular vulnerability in a patient with the Wolff-Parkinson-White syndrome.

An electrophysiologic study was carried out in a patient with the Wolff-Parkinson-White syndrome and a history of spontaneous atrial fibrillation but with no evidence of organic cardiac disease. A single induced premature ventricular depolarization resulted in ventricular tachycardia followed by ventricular fibrillation. Similarly, atrial pacing or premature atrial stimulation resulted in frequent episodes of atrial fibrillation or flutter. The atrial and ventricular effective refractory periods were 180 ms and less than 160 ms, respectively, at a driven cycle length of 480 ms. Intravenous administration of procainamide resulted in lengthening of the refractory periods and failure to induce either atrial or ventricular arrhythmias with pacing. In most patients with enhanced atrioventricular nodal or accessory atrioventricular nodal by-pass, the mechanism of ventricular tachycardia is related to an inordinately rapid ventricular response during supraventricular arrhythmias. In our patient, a unique mechanism was apparent: atrial and ventricular vulnerability to fibrillation was associated with extremely short myocardial effective refractory periods. The relationship of this finding to sudden cardiac death bears further study.