Catheter Ablation for Atrial Fibrillation

Association of Paroxysmal Versus Persistent Atrial Fibrillation with In-hospital Outcomes and 30-day Readmission After Inpatient Atrial Fibrillation Ablation

Knowledge of the impact of paroxysmal and persistent atrial fibrillation (AF) after catheter ablation on in-hospital outcomes and 30-day readmission remains limited. This study aimed to evaluate the procedural outcomes and 30-day readmission rates among patients with paroxysmal or persistent AF who were hospitalized for AF ablation. Using the Nationwide Readmissions Database, our study included patients aged ≥18 years with AF who were hospitalized and underwent catheter ablation during 2017-2020. Then, we compared the in-hospital procedural outcomes and 30-day readmission rates between patients with paroxysmal and persistent AF, respectively. Our study included 7310 index admissions for paroxysmal AF ablation and 9179 index admissions for persistent AF ablation. According to our analysis, there was no significant difference in procedural complications-namely, cerebrovascular accident, vascular complications, major bleeding requiring blood transfusion, phrenic nerve palsy, pericardial complications, and systemic embolization-between the persistent and paroxysmal AF groups. There was also no significant difference in early mortality between these groups (0.5% vs. 0.7%; P = .22). Persistent AF patients had significantly higher rates of prolonged index hospitalization (9.9% vs. 7.2%; P < .01) and non-home discharge (4.8% vs. 3.1%; P < .01). The 30-day readmission rates were comparable in both groups (10.0% vs. 9.5%; P = .34), with recurrent AF and heart failure being two of the most common causes of cardiac-related readmissions. Catheter ablation among hospitalized patients with paroxysmal or persistent AF resulted in no significant difference in procedural complications, early mortality, or 30-day readmission. This suggests that catheter ablation of AF can be performed with a relatively similar safety profile for both paroxysmal and persistent AF.

Left Atrium Volume Measured with Multislice Computed Tomography as a Prognostic Predictor for Atrial Fibrillation Catheter Ablation Outcomes

Background: Current guidelines consider atrial fibrillation (AF) type as the prognostic factor for a recommendation of catheter ablation. We aimed to determine whether LA and LA appendage (LAA) volumes measured using multislice computed tomography (MSCT) were related to long-term outcomes in AF following radiofrequency catheter ablation (RFCA). Methods: We evaluated 152 consecutive patients with drug-refractory AF (median age, 55.8 ± 9.6 years), including 110 male patients, who underwent RFCA in a single center. All patients underwent MSCT imaging for anatomical assessment. The endpoint of this study was documented AF recurrence after RFCA. Results: The overall procedure success rate was 77.6% (n = 118) during a mean follow-up period of 12.6 months. The LA volume was significantly larger for those who experienced AF recurrence after RFCA than for the patients without recurrent AF after the procedure (153.8 ± 29.9 mL vs. 139.2 ± 34.1 mL, p = 0.025). However, LAA volumes were nearly equivalent between the patients with and without AF recurrence after RFCA (16.2 ± 6.3 mL and 14.7 ± 6.5 mL, respectively; p = 0.235). LA volume ≥ 153.2 mL was the optimal cutoff value for estimating AF recurrence after RFCA, with 94% sensitivity and 66% specificity. LA volume remained an independent predictor of both AF recurrence and permanent AF. Conclusions: LA volume as assessed by MSCT might be helpful for identifying patients likely to achieve successful AF ablation. LA volume ≥ 153.2 mL, but not LAA volume, showed good accuracy in predicting AF recurrence after RFCA.

Overview of Cardiac Arrhythmias and Treatment Strategies

Maintenance of normal cardiac rhythm requires coordinated activity of ion channels and transporters that allow well-ordered propagation of electrical impulses across the myocardium. Disruptions in this orderly process provoke cardiac arrhythmias that may be lethal in some patients. Risk of common acquired arrhythmias is increased markedly when structural heart disease caused by myocardial infarction (due to fibrotic scar formation) or left ventricular dysfunction is present. Genetic polymorphisms influence structure or excitability of the myocardial substrate, which increases vulnerability or risk of arrhythmias in patients. Similarly, genetic polymorphisms of drug-metabolizing enzymes give rise to distinct subgroups within the population that affect specific drug biotransformation reactions. Nonetheless, identification of triggers involved in initiation or maintenance of cardiac arrhythmias remains a major challenge. Herein, we provide an overview of knowledge regarding physiopathology of inherited and acquired cardiac arrhythmias along with a summary of treatments (pharmacologic or non-pharmacologic) used to limit their effect on morbidity and potential mortality. Improved understanding of molecular and cellular aspects of arrhythmogenesis and more epidemiologic studies (for a more accurate portrait of incidence and prevalence) are crucial for development of novel treatments and for management of cardiac arrhythmias and their consequences in patients, as their incidence is increasing worldwide.

Identification of Long Non-Coding RNA and Circular RNA Expression Profiles in Atrial Fibrillation

BACKGROUND

Long non-coding RNA (lncRNA) and circular RNA (circRNA) have both been found to play important roles in cardiovascular diseases, including myocardial infarction, heart failure, and atherosclerosis. However, the role of lncRNA and circRNA in atrial fibrillation (AF) has rarely been investigated. This study aimed to identify lncRNA and circRNA expression profiles in AF patients.

METHODS

Atrial tissues from seven patients with AF and seven matched controls were collected. The lncRNA and circRNA expression profiles of atrial tissues were identified using Hiseq/Proton RNA sequencing. Validation was performed by reverse transcription quantitative real-time PCR (qRT-PCR) on 35 pairs of AF patients and controls. Gene Ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. A competing endogenous RNA (ceRNA) network was constructed.

RESULTS

A total of 557 lncRNAs and 280 circRNAs were significantly differentially expressed with fold change >1.5 (p<0.05). An lncRNA Voltage Dependent Anion Channel 2 Pseudogene 2 (VDAC2P2) and two circRNAs chr13_41887361_41865736_-21625 and chr13_100368574_100301460_-67114 were validated, using qRT-PCR, to have significantly different expression levels. GO and KEGG pathway analysis showed that some pathways such as ribosome and chromatin modification, Rap1 signalling and cardiac muscle contraction were involved in the pathogenesis of AF. Competing endogenous RNAs were predicted based on constructional network analysis. The LncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks were constructed by co-expressing lncRNA/circRNA and mRNAs, which were competitively combined with miRNAs.

CONCLUSION

This study characterised lncRNA and circRNA expression and their interaction with mRNA and miRNA in AF.

Modeling Left Atrial Flow, Energy, Blood Heating Distribution in Response to Catheter Ablation Therapy

Introduction: Atrial fibrillation (AF) is a widespread cardiac arrhythmia that commonly affects the left atrium (LA), causing it to quiver instead of contracting effectively. This behavior is triggered by abnormal electrical impulses at a specific site in the atrial wall. Catheter ablation (CA) treatment consists of isolating this driver site by burning the surrounding tissue to restore sinus rhythm (SR). However, evidence suggests that CA can concur to the formation of blood clots by promoting coagulation near the heat source and in regions with low flow velocity and blood stagnation.

Methods: A patient-specific modeling workflow was created and applied to simulate thermal-fluid dynamics in two patients pre- and post-CA. Each model was personalized based on pre- and post-CA imaging datasets. The wall motion and anatomy were derived from SSFP Cine MRI data, while the trans-valvular flow was based on Doppler ultrasound data. The temperature distribution in the blood was modeled using a modified Pennes bioheat equation implemented in a finite-element based Navier-Stokes solver. Blood particles were also classified based on their residence time in the LA using a particle-tracking algorithm.

Results: SR simulations showed multiple short-lived vortices with an average blood velocity of 0.2-0.22 m/s. In contrast, AF patients presented a slower vortex and stagnant flow in the LA appendage, with the average blood velocity reduced to 0.08–0.14 m/s. Restoration of SR also increased the blood kinetic energy and the viscous dissipation due to the presence of multiple vortices. Particle tracking showed a dramatic decrease in the percentage of blood remaining in the LA for longer than one cycle after CA (65.9 vs. 43.3% in patient A and 62.2 vs. 54.8% in patient B). Maximum temperatures of 76° and 58°C were observed when CA was performed near the appendage and in a pulmonary vein, respectively.

Conclusion: This computational study presents novel models to elucidate relations between catheter temperature, patient-specific atrial anatomy and blood velocity, and predict how they change from SR to AF. The models can quantify blood flow in critical regions, including residence times and temperature distribution for different catheter positions, providing a basis for quantifying stroke risks.

Age-Dependent Predictive Value of Endothelial Dysfunction for Arrhythmia Recurrence Following Pulmonary Vein Isolation

Background

The mechanisms of atrial fibrillation (AF) are highly divergent. The prevalence of AF increases significantly with age, and underling mechanisms might vary with age. Endothelial dysfunction may be associated with AF and atrial arrhythmia recurrence after catheter ablation. We tested the hypothesis that the impact of endothelial dysfunction on arrhythmia recurrence following catheter ablation is age dependent.

Methods and Results

This study enrolled 92 participants with AF undergoing catheter ablation. Endothelial function was assessed by peripheral arterial tonometry before ablation, and the natural logarithmic transformation of reactive hyperemia index was calculated. Endothelial dysfunction was defined as a natural logarithmic transformation of reactive hyperemia index <0.618 (median). Participants were followed for atrial tachycardia, flutter, and fibrillation recurrence for a median of 14 months. The mean age was 57±10 years. There was significant interaction between age and endothelial dysfunction in association with recurrence of AF (P=0.029) and any atrial arrhythmia (P=0.015), and the risk associated with endothelial dysfunction for arrhythmia recurrence was higher in younger versus older participants. Participants were divided into 2 age groups at a threshold of 60 years. Among participants aged ≤60 years, multivariate Cox proportional hazards analysis revealed the independent association between endothelial dysfunction and increased risk of arrhythmia recurrence (hazard ratio for AF 4.18 [95% CI 1.33–15.82], P=0.014, and for any atrial arrhythmia 3.62 [95% CI 1.29–11.81], P=0.014). Kaplan–Meier analysis showed that participants with endothelial dysfunction had significantly higher rates of recurrence of AF (P=0.01) and any atrial arrhythmia (P=0.002).

Conclusions

The risk associated with endothelial dysfunction for arrhythmia recurrence following catheter ablation was age dependent and was higher in younger participants.

Update on atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia with a substantial effect on individual morbidity and mortality as well as healthcare expenditure. The management of AF is complex and fraught with many uncertain and contentious issues. We have seen substantial progress in AF management in the last two decades including better understanding of the epidemiology, genomics, monitoring, drug and non-pharmacological treatment of the arrhythmia, its complications and stroke risk reduction. In this review, we present a comprehensive discussion on AF with emphasis on most recent updates.

Meta-Analysis of Continuous Positive Airway Pressure as a Therapy of Atrial Fibrillation in Obstructive Sleep Apnea

Atrial fibrillation (AF) is a significant health care problem for patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) as a therapy for OSA is underused, and it is unknown if CPAP might reduce rates of AF. We systematically reviewed the published reports on CPAP use and risk of AF. MEDLINE, EMBASE, CINAHL, Web of Science, meeting abstracts, and Cochrane databases were searched from inception to June 2015. Studies needed to report the rates of AF in participants who were and were not on CPAP. Data were extracted by 2 authors. A total of 8 studies on OSA were identified (1 randomized controlled trial) with 698 CPAP users and 549 non-CPAP users. In a random effects model, patients treated with CPAP had a 42% decreased risk of AF (pooled risk ratio, 0.58; 95% confidence interval, 0.47 to 0.70; p <0.001). There was low heterogeneity in the results (I(2) = 30%). In metaregression analysis, benefits of CPAP were stronger for younger, obese, and male patients (p <0.05). An inverse relationship between CPAP therapy and AF recurrence was observed. Results suggest that more patients with AF also should be tested for OSA.

The impact of catheter ablation in the interpulmonary isthmus on atrial fibrillation ablation outcomes: a randomized study

INTRODUCTION

Previous studies have underscored the importance of the interpulmonary isthmus in the initiation and maintenance of atrial fibrillation (AF). The efficacy of additional radiofrequency energy delivery in the interpulmonary isthmus following pulmonary vein antral isolation (PVAI) was investigated.

METHODS AND RESULTS

A total of 76 patients (49 males, mean age 56.8 ± 10.3) with drug-resistant paroxysmal (n = 64) and short-lasting persistent AF (n = 12) underwent PVAI. Patients were then randomly assigned to receive either "no further ablation" (group I, n = 38) or additional lesions in the interpulmonary isthmus of both ipsilateral pulmonary veins (group II, n = 38). There were no significant differences between study groups regarding the clinical and echocardiographic data. A trend towards a longer fluoroscopy time was observed in group II (P = 0.076). After a mean follow-up period of 11.1 ± 2.6 months, 22 patients in group I (57.9%) and 25 patients in group II (65.8%) were free from arrhythmia recurrence without any antiarrhythmic drug treatment after a single ablation procedure. The Kaplan-Meier arrhythmia-free survival curves showed no significant differences between study groups (P = 0.460).

CONCLUSIONS

Additional lesions in the interpulmonary isthmus following PVAI do not have incremental value in preventing AF recurrence.

Atrial Fibrillation Ablation: Do We Really Need Preprocedural Imaging?

Atrial fibrillation is the most common human arrhythmia, causing significant mortality and morbidity. Because of the potential for complications, it is important that procedures be made as safe and effective as possible by combining safe procedural planning with effective therapy delivery. To change the current approach, large randomized studies are needed to guide the selection of patients who may safely undergo ablation without transesophageal echocardiography to exclude thrombus. For institutions routinely using computed tomography and magnetic resonance imaging to assess pulmonary vein anatomy before procedures, the possibility of excluding intracardiac thrombi using these imaging modalities should be considered.

Intra-atrial endothelial lesion resulting from transseptal puncture for catheter ablation of atrial fibrillation

Thromboembolic events are known complications of left atrial ablation therapy. We describe a complication which may also lead to systemic thromboembolism that has not been reported so far: the formation of a moving structure attached to the fossa ovalis after an attempted transseptal puncture in a 66-year old patient with symptomatic paroxysmal atrial fibrillation.

Role of the coronary sinus ostium musculature in reentrant formation

BACKGROUND

Radiofrequency ablation of focal atrial tachycardias (AT) is a validated technique with high success rates. However, electrophysiological (EP) characteristics and ablation strategy of localized reentrant AT originating from the coronary sinus ostium (CSo) have not been reported in detail so far.

METHODS

From January 2009 to July 2010, 1,453 patients underwent clinically motivated EP studies. Four patients were diagnosed with localized reentrant AT originating from the CSo. P wave morphology and consistency of tachycardia cycle length were studied. Subsequently, if reentry was suggested as an underlying mechanism for AT, color-coded 3-dimensional (3D) entrainment mapping was performed to localize the reentrant circuit or differentiate a localized reentrant AT from macroreentant AT, and also confirm reentry as an underlying mechanism of AT by evaluating consistency of return cycles after entrainment at multiple sites in both atria. Finally, activation mapping was performed to localize the earliest activation site.

RESULTS

The P wave morphologies and isoelectric line between the P waves suggested most likely an AT originating from the CSo with a centrifugal activation pattern, which was confirmed by activation mapping. Consistency of return cycles and continuously fragmented local electrograms at successful ablation sites suggested reentry as an underlying AT mechanism. Color-coded 3D entrainment mapping in all 4 patients located the reentrant circuit in the CSo. There were also two specific features observed. One was fragmented and/or double potentials recorded in the CSo with prominent prolonged electrogram duration compared to those during sinus rhythm. The other is a significant conduction delay within the CS. The myocardium of the CSo was suggested as a part of the critical isthmus within the reentrant circuit, while the rest of atria distal to the CSo and myocardial coat of the distal CS were not involved in the tachycardia circuit, which was confirmed by entrainment mapping.

CONCLUSION

Although CSo myocardium has been implicated to be a part of atrioventricular nodal reentrant tachycardia, to the best of our knowledge, this is the first report showing the localized reentrant AT confined to the CSo. Three of our patients (75%) had concomitant atrial fibrillation (AF). Further studies should be warranted to clarify the role of AT from the CS in triggering AF.

Incidence and long-term follow-up of silent cerebral lesions after pulmonary vein isolation using a remote robotic navigation system as compared with manual ablation

BACKGROUND

The incidence of silent cerebral lesions (SCL) after atrial fibrillation (AF) ablation is highly variable, depending on the technology used. Recently, an increased risk for SCL has been described for a novel, nonirrigated ablation tool using multielectrode phased radiofrequency (PVAC). The aim of this prospective study was to evaluate the incidence and long-term follow-up of SCL in patients undergoing robotically assisted pulmonary vein isolation (RA-PVI) as compared with manual PVI.

METHODS AND RESULTS

Circumferential PVI using irrigated radiofrequency current was performed on 70 patients (41 patients with paroxysmal AF, 59%). Fifty patients underwent RA-PVI and 20 patients underwent a manual approach. Cerebral MRI was performed the day before and the day after the ablation procedure; follow-up MRI was performed on 9 of 12 (75%) patients after a follow-up period of 21 months. SCLs were found in 12 of 70 (17%) patients in this study; the incidence of SCLs was similar in patients undergoing RA-PVI as compared with manually ablated patients (n=9, 18% versus n=3, 15%; probability value=1.0). In 1 patient undergoing manual PVI (1%), an SCL with asymptomatic subarachnoid hemorrhage was detected; the bleeding completely resolved within 1 month. Transient ischemic attack occurred in 1 (1%) patient 2 days after manual PVI. After a median follow-up period of 21 months, no residual SCLs were detected.

CONCLUSIONS

The incidence of SCL using the robotic navigation system was 18% in this study. Incidence and size of SCL appears to be similar after RA-PVI as compared with manual PVI. Repeat MRI showed no residual SCLs at long-term follow-up.

Importance of evaluating conduction block in radiofrequency ablation for atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) is the most frequently diagnosed cardiac arrhythmia. Anti-arrhythmic drugs may be used to suppress ectopic foci and interrupt reentry circuits, but are often insufficient to treat recurrent AF and have a number of adverse effects. Alternative therapies, such as catheter and surgical ablation, have been explored. This investigation examines the importance of assessing exit block when performing surgical ablation during beating-heart treatment of AF.

METHODS

This was an evaluation of pooled data from multicenter prospective results obtained in AF patients who received ablation with a new, irrigated, vacuum-integrated device that creates linear lesions during beating-heart/open-chest or minimally invasive, port-access procedures. Electrocardiogram or Holter data were collected intra-operatively and at 1, 3, 6, and 12 months. Outcomes were also evaluated for patients who were or 'were not' tested for exit block following the ablation procedure.

RESULTS

A total of 93 patients were treated (61 open-chest surgeries, 32 port-access procedures). There were no device-related complications and no operative mortality. At 341 days' average follow-up, 71/86 (83%) patients were free from AF, 66/86 (77%) were in sinus rhythm, and 60/86 (70%) were free from AF and off Class I and III anti-arrhythmic drugs (AADs). At 12 months, 23/23 (100%) patients with exit block confirmed were AF free compared with 13/21 (62%) patients with exit block not tested (p≤0.01, Fisher's exact test); 20/23 (87%) were in sinus rhythm compared with 12/21 (57%) patients with exit block not tested (p≤0.05, Fisher's exact test); and 20/23 (87%) were AF free without Class I and III AADs compared with 10/21 (48%) patients with exit block not tested (p≤0.01, Fisher's exact test). Both open-chest and port-access procedures yielded decreases in left-atrial size from baseline to 6 months' follow-up. Patients undergoing port-access procedures also observed an increase in left-ventricular ejection fraction, which was also significant at 6 months.

CONCLUSION

Patients in whom exit block was confirmed following an ablation procedure were more likely to have successful clinical outcomes. Since testing for exit block must be performed on a beating heart, total epicardial beating-heart ablation may provide an important treatment for AF, providing intra-operative feedback indicative of long-term outcomes.

Atorvastatin for prevention of atrial fibrillation recurrence following pulmonary vein isolation: a double-blind, placebo-controlled, randomized trial

BACKGROUND

It is known that statins are effective in preventing atrial fibrillation (AF) in patients undergoing cardiac surgery.

OBJECTIVE

The purpose of this study was to evaluate the efficacy of statins in preventing AF recurrence following left atrial ablation.

METHODS

One hundred twenty-five patients who had no statin indication undergoing catheter ablation due to drug-refractory paroxysmal (n = 90) or persistent (n = 35) AF were randomized in a prospective, double-blind, placebo-controlled trial to receive 80 mg atorvastatin (n = 62) or placebo (n = 63) for 3 months. The primary endpoint was freedom from symptomatic AF at 3 months. Secondary endpoints included freedom from any atrial arrhythmia recurrence irrespective of symptoms, quality of life (QoL), and reduction in C-reactive protein (CRP).

RESULTS

At 3 months, 95% of patients in the atorvastatin group were free of symptomatic AF compared with 93.5% in the placebo group (P = .75). Similarly, 85% of patients treated in the atorvastatin group remained free of any recurrent atrial arrhythmia vs 88% of patients in the placebo group (P = .37). Mean CRP levels decreased in the atorvastatin group (mean change -0.75 ± 3, P = .02) and increased in the placebo group (mean change 2.1 ± 19.9, P = .48). Mean QoL score improved significantly in both groups (mean change 13.14 ± 18.2 in the atorvastatin group and 11.10 ± 17.7 in the placebo group, P = .53).

CONCLUSION

In patients with no standard indication for statin therapy, treatment with atorvastatin 80 mg/day following AF ablation does not decrease the risk of AF recurrence in the first 3 months and should not be routinely administered to prevent periprocedural arrhythmias.

Pulmonary vein isolation of symptomatic refractory paroxysmal and persistent atrial fibrillation: A single centre and single operator experience in the Netherlands

Aim. To investigate long-term outcome and to determine predictors of successful pulmonary vein isolation (PVI) in patients with symptomatic paroxysmal or persistent atrial fibrillation (AF) who are refractory or intolerant to antiarrhythmic drugs.Background. The treatment of AF has traditionally been pharmacological aimed at rate or rhythm control. However, rhythm control remains difficult to establish. PVI is reported to be effective in selected patient groups.Methods. Ninety-nine consecutive patients with a mean age of 54+/-10 years who had paroxysmal or persistent AF were treated in the University Medical Center Groningen. All patients underwent PVI by the same electrophysiologist. Successful PVI was defined as absence of AF on Holter or electrocardiogram (ECG), and no symptoms of AF.Results. After six months of follow-up, 60 (61%) patients were free of AF episodes, both on 96-hour Holter monitoring and on ECGs, and had no symptoms related to AF. Thirty-nine of these 60 patients (65%) were no longer treated with any class I or III antiarrhythmic drugs. Independent determinants of successful PVI were paroxysmal AF (OR 18 [3.5-93], p=0.001), and left pulmonary vein ablation time >55 minutes (OR 15 [2.7-81], p=0.002). Left atrial (parasternal view 42+/-6 vs. 40+/-5 mm, p<0.05 and apical view 61+/-9 vs. 58+/-8 mm, p<0.05) and right atrial (59+/-7 vs. 56+/-5 mm, p<0.05) sizes decreased significantly in the successfully treated patients after six months of follow-up.Conclusion. Independent determinants of a successful outcome after PVI are paroxysmal AF and a longer left atrial ablation time. (Neth Heart J 2009;17:366-72.).

Inducibility of atrial fibrillation in the absence of atrial fibrillation: what does it mean to be normal?

BACKGROUND

While inducibility of atrial fibrillation (AF) is often used as an endpoint for radiofrequency ablation of AF, little is known regarding inducibility among normals. We therefore evaluated the inducibility of AF with rapid atrial pacing in patients without a clinical history of AF after catheter ablation of supraventricular tachycardia (SVT).

METHODS

We prospectively evaluated 86 patients with no history of AF who were referred for catheter ablation of SVT. After successful ablation, two different rapid atrial pacing protocols for induction of AF were tested. First, AF induction was attempted by 5-second bursts of atrial pacing from the coronary sinus ostium (CSO) at three different cycle lengths (CLs). Next, decremental pacing was performed from the CSO starting at a CL of 250 ms to the loss of 1:1 atrial capture. This protocol was repeated 3 times for each subject.

RESULTS

Three of the subjects (3.5%) enrolled had inducible AF with the first pacing protocol. However, with the second protocol, AF was inducible in 22 patients (25.6%), including sustained AF in 16 patients (18.6%). There were significant differences in the inducibility of AF between the two atrial pacing protocols. Additionally, with the second pacing protocol, patients with a loss of 1:1 atrial capture at CL <180 ms were more easily inducible for AF (21/63 vs. 1/23; P = .006).

CONCLUSION

Using a specific, decremental pacing protocol, 26% of patients without a history of AF had inducible AF. These findings suggest that significant further investigation is needed to optimize the specificity of using AF induction as an endpoint for AF ablation.

Normal pulmonary veins anatomy is associated with better AF-free survival after cryoablation as compared to atypical anatomy with common left pulmonary vein

BACKGROUND

Pulmonary vein cryoablation (PVC) is a new approach in the treatment of recurrent atrial fibrillation (AF). Computed tomography (CT) can be used to evaluate the left atrium anatomy and PVs dimensions to facilitate the procedure. In radiofrequency procedures, some anatomic variants such as common left (CLPV) or right (CRPV) PV were reported as factors associated with technical procedure difficulties and potential long-term complications. We hypothesized that the absence of CLPV as determined by CT would predict better AF-free survival after PVC.

METHODS AND RESULTS

We included 118 consecutive patients (mean age 56 ± 10 years; 77% males) with drug refractory paroxysmal (72%)/persistent (28%) AF, with more than 6 months follow-up, who underwent PVC. On CT scanning images performed within 1 month prior to ablation, we evaluated PV anatomic patterns: presence of CLPV or CRPV. Each patient was evaluated by 24-hour Holter monitoring within 1 and 3 months and all patients were periodically evaluated at 1, 3, and 6 months, and every 6 months thereafter. Patients were asked to record their 12-lead electrocardiogram whenever they experienced symptoms suggestive of AF. Recurrence was defined as AF that lasted at least 30 seconds. CLPV was present in 30 (25%) patients and no patients with CRPV were identified. At the end of the 13 months follow-up, patients with normal PVs had significantly better AF-free survival compared to patients with CLPV (67% vs 50%, P = 0.02). The difference was present in patients with paroxysmal AF (P = 0.008) but not in patients with persistent AF (P = 0.92).

CONCLUSION

In patients undergoing cryoballoon PV isolation for AF, the presence of normal PVs pattern is associated with better AF-free survival as compared to atypical PV anatomy with CLPV, particularly in patients with paroxysmal AF.

Outcomes for surgical treatment of atrial fibrillation using cryoablation during concomitant cardiac procedures

BACKGROUND

Surgical treatment of atrial fibrillation (AF) with heat-based therapies has been associated with a high rate of arrhythmia recurrence. We studied the short-term to medium-term outcomes with a unique biatrial linear ablation procedure for AF treatment using an argon-based cryoablation device during concomitant cardiac operations.

METHODS

Between March 2005 and July 2008, 57 patients (47% men) with problematic AF underwent a linear endocardial ablation procedure (Star pattern) using the flexible argon-based cryoablation probe during concomitant cardiac operations. Procedures were performed with valve or coronary operations, including mitral valve replacement (25%), mitral valve repair (16%), coronary artery bypass grafts (21%), and congenital heart surgery (8%). Atrial fibrillation was persistent or long-standing persistent in 50.9% of patients.

RESULTS

Kaplan-Meier survival curves (with the standard error) demonstrated 91% (3.9%) of patients were still free of their first recurrence at 6 months, 81% (5.6%) at 12 months, and 70% (6.8%) at 24 months. Time to first recurrence was not significantly associated with age (p = 0.47), gender (p = 0.52), or type of AF (p = 0.69). There were no complications attributed to the cryoablation procedure. There was one in-hospital death and one death after discharge. Twelve patients (21%) required permanent pacemaker implantation postoperatively. There were no early or late thromboembolic events.

CONCLUSIONS

This study demonstrated the medium-term efficacy of cryoablation with a unique biatrial pattern of linear lesions for the treatment of AF during a concomitant cardiac operation. Short-term to medium-term outcomes were at least equivalent to those reported for other energy modalities.

Visual Balloon-Guided Point-by-Point Ablation

Background—

While conceptually straightforward, placing point-to-point contiguous radiofrequency lesions to achieve pulmonary vein isolation (PVI) is technically challenging in patients with paroxysmal atrial fibrillation. Furthermore, chronic efficacy is limited by late PV reconnections. A novel compliant balloon ablation catheter able to deliver visually guided short arcs/spots of laser energy was tested in initial preclinical and clinical cases to determine if visual guidance could predict reliable and persistent PVI.

Methods and Results—

This study consisted of (1) an experimental porcine phase with both acute (n=15 pigs) and 4-week chronic (n=10) data and (2) a single-center clinical feasibility phase (n=27 patients with paroxysmal atrial fibrillation), again with acute and 3-month chronic data. Under endoscopic guidance, point-by-point perivenous ablation was performed in a contiguous and overlapping manner. Each porcine PV was longitudinally sectioned for detailed histological analysis. At 3 months after ablation, patients underwent a prespecified remapping procedure regardless of symptomotology. In the acute and chronic animals, 29 of 30 (97%) PVs were electrically isolated after placing the initial circumferential lesion set. For the 4-week chronic animals, 80% of PVs remained isolated; lesions were histologically circumferential in 120 of 120 (100%) PV sections and transmural in 116 of 120 (96.7%) PV sections (average transmurality=99.0±5.5%). In patients, 100% of the PVs were isolated after 1.3 attempts per PV—84% of them (85 of 101) isolated after the initial visually guided lesion set. At 3 months, 61 of 68 (90%) PVs continued to be electrically isolated.

Conclusions—

Using a visually guided, compliant balloon ablation catheter with point-by-point ablative capability, PV isolation can be achieved in a reliable, reproducible, and persistent manner.

Atrial fibrillation is a possible marker of frailty in hospitalized patients: results of the GIFA Study

BACKGROUND AND AIMS

Atrial fibrillation (AF) is the most common arrhythmia in elderly people, who are particularly exposed to its most severe complications, such as stroke, worsening heart failure and dementia. Some studies demonstrate that AF is associated with increased mortality in home-dwelling subjects, but little is known about the clinical impact of the arrhythmia in hospitalized patients. We studied the clinical associations and effects of AF on the 23,174 hospitalized patients enrolled in the GIFA (Gruppo Italiano di Farmacoepidemiologia nell'Anziano) Study.

METHODS

Patients were divided into three groups according to the absence or presence of AF (sinus rhythm, non_AF; AF as main diagnosis, AF_main; AF as comorbid condition, AF_associated) and stratified into four age-groups (< or =60, 61-70, 71-80 and >80 yrs).

RESULTS

AF_associated patients were older, more frequently disabled, and characterized by greater comorbidity and longer in-hospital length of stay. Urea nitrogen concentration was higher, and total cholesterol was lower in AF_associated patients, compared with the other two groups. Overall mortality was 6.0%. Mortality was higher in AF_associated patients (non_AF: 6.0% vs AF_associated: 7.1% vs AF_main: 0%, p<0.001).

CONCLUSIONS

Our results suggest that, in hospitalized patients, AF as a comorbid condition is associated with worse metabolic profile and clinical outcomes, and thus, may represent a marker of frailty.

Characterization, mapping, and catheter ablation of recurrent atrial tachycardias after stepwise ablation of long-lasting persistent atrial fibrillation

BACKGROUND

Atrial tachycardias (AT) often occur after ablation of long-lasting persistent AF (CAF) and are difficult to treat conservatively. This study evaluated mechanisms and success rates of conventional mapping and catheter ablation of recurrent ATs occurring late after stepwise ablation of CAF.

METHODS AND RESULTS

A total of 320 patients underwent de novo ablation of CAF using a stepwise ablation approach in 2006 to 2007 at our institution. This study comprised patients who presented with recurrent ATs at their first redo procedure after initial de novo CAF ablation. All procedures were guided by conventional mapping techniques exclusively. Sixty-one patients (63+/-10 years, 14 women) presented with their clinical AT at their redo procedure 7.7+/-4.4 months after initial de novo CAF ablation. A total of 133 ATs (2.2+/-0.9 per patient) were mapped. Forty-four (72%) were due to reentry; 17 (28%) were focal ATs. Reentry ATs were mainly characterized as roof and perimitral flutter (43% and 34%, respectively). Focal ATs mainly originated from the great thoracic veins (pulmonary veins: 41%, coronary sinus: 23%). Forty-five (74%) patients had conduction recovery of at least 1 pulmonary vein (mean, 1.2+/-0.8). Overall, 124 (93%) ATs could be ablated successfully. The mean procedure duration was 181+/-59 minutes, with a mean fluoroscopy time of 45+/-21 minutes. After a mean follow-up of 21+/-4 months, 50 (82%) patients were free of any arrhythmia recurrences after a single redo procedure.

CONCLUSIONS

Although late recurrent ATs may have complex mechanisms, catheter ablation guided exclusively by conventional techniques is highly effective with excellent acute and long-term success rates.

Ablation strategies for atrial fibrillation

Atrial fibrillation remains the most common arrhythmia in the USA and is associated with an increased risk for stroke, congestive heart failure and overall mortality. There has been a tremendous advance in the field of catheter ablation of atrial fibrillation that has resulted in better outcomes for patients. The approach for ablation of atrial fibrillation can be different depending on patients' presentation of paroxysmal or persistent atrial fibrillation. Pulmonary vein isolation remains the cornerstone of any ablation strategy for atrial fibrillation; however, further ablation, end points of the procedure, clinical end points for successful ablation and appropriate follow-up remain controversial. We aim to discuss these different approaches and the major controversies in catheter ablation of atrial fibrillation.

Left atrial radiofrequency ablation during mitral valve surgery: a prospective randomized multicentre study (SAFIR)

BACKGROUND

Randomized studies evaluating left atrial radiofrequency ablation (RFA) in patients with persistent atrial fibrillation undergoing mitral valve surgery are scarce and monocentric.

AIM

To evaluate the efficacy of left atrial RFA concomitant with mitral valve surgery to restore and maintain sinus rhythm.

METHODS

The SAFIR is a multicentre, double-blinded, centrally randomized study involving four university hospitals. Between December 2002 and September 2005, 43 patients with mitral valve disease and long-standing, persistent atrial fibrillation (duration>6 months) were included. We compared valvular surgery alone (n=22) or with left atrial RFA (n=21). The main endpoint was sinus rhythm at 12 months without recurrence of arrhythmia during follow-up. Secondary endpoints were surgical adverse events, atrial fibrillation relapses, stroke and echocardiographic measurements after three and 12 months' follow-up. Analyses of the efficacy criteria were performed on an intention-to-treat basis.

RESULTS

The primary endpoint occurred significantly more often in the RFA group than in the control group (respectively, 12/21 patients [57%] vs 1/22 patients [4%]; p=0.004). There were more patients with sinus rhythm in the RFA group than in the control group at discharge (72.7% vs 4.8%; p<0.005), 3-month follow-up (85.7% vs 23.8%; p<0.01) and 12-month follow-up (95.2% vs 33.3%; p<0.005). The patients in the RFA group had similar rates of postoperative complications and stroke during follow-up as those in the control group.

CONCLUSIONS

This multicentre study suggests that left atrial RFA is effective and safe in patients with chronic atrial fibrillation and mitral valve disease.

Loss of pace capture on the ablation line: a new marker for complete radiofrequency lesions to achieve pulmonary vein isolation

BACKGROUND

Catheter ablation procedures for atrial fibrillation (AF) often involve circumferential antral isolation of pulmonary veins (PV). Inability to reliably identify conduction gaps on the ablation line necessitates placing additional lesions within the intended lesion set.

OBJECTIVE

This pilot study investigated the relationship between loss of pace capture directly along the ablation line and electrogram criteria for PV isolation (PVI).

METHODS

Using a 3-dimensional anatomic mapping system and irrigated-tip radiofrequency (RF) ablation catheter, lesions were placed in the PV antra to encircle ipsilateral vein pairs until pace capture at 10 mA/2 ms no longer occurred along the line. During ablation, a circular mapping catheter was placed in an ipsilateral PV, but the electrograms were not revealed until loss-of-pace capture. The procedural end point was PVI (entrance and exit block).

RESULTS

Thirty patients (57 +/- 12 years; 15 male [50%]) undergoing PVI in 2 centers (3 primary operators) were included (left atrial diameter 40 +/- 4 mm, left ventricular ejection fraction 60 +/- 7%). All patients reached the end points of complete PVI and loss of pace capture. When PV electrograms were revealed after loss of pace capture along the line, PVI was present in 57 of 60 (95%) vein pairs. In the remaining 3 of 60 (5%) PV pairs, further RF applications achieved PVI. The procedure duration was 237 +/- 46 minutes, with a fluoroscopy time of 23 +/- 9 minutes. Analysis of the blinded PV electrograms revealed that even after PVI was achieved, additional sites of pace capture were present on the ablation line in 30 of 60 (50%) of the PV pairs; 10 +/- 4 additional RF lesions were necessary to fully achieve loss of pace capture. After ablation, the electrogram amplitude was lower at unexcitable sites (0.25 +/- 0.15 mV vs. 0.42 +/- 0.32 mV, P < .001), but there was substantial overlap with pace capture sites, suggesting that electrogram amplitude lacks specificity for identifying pace capture sites.

CONCLUSION

Complete loss of pace capture directly along the circumferential ablation line correlates with entrance block in 95% of vein pairs and can be achieved without circular mapping catheter guidance. Thus, pace capture along the ablation line can be used to identify conduction gaps. Interestingly, more RF ablation energy was required to achieve loss of pace capture along the ablation line than for entrance block into PVs. Further study is warranted to determine whether this method results in more durable ablation lesions that reduce recurrence of AF.

Long-term results and the predictors of outcome of catheter ablation of atrial fibrillation using steerable sheath catheter navigation after single procedure in 674 patients

AIMS

Identifying suitable candidates for circumferential left atrial pulmonary vein ablation (CPVA). CPVA is widely used as an ablation strategy in patients with atrial fibrillation (AF). Understanding the predictors of long-term success of single catheter ablation procedure of AF based on CPVA can help to identify those patients who have a high risk of recurrence based on this approach.

METHODS AND RESULTS

In this retrospective analysis 674 consecutive patients (464 male, mean age 57.3 +/- 10.8 years) with AF (84.8%, paroxysmal) treated with CPVA ablation between May 2005 and August 2007 using a manually controlled steerable sheath (Agilis((R)) St. Jude Medical Inc., St. Paul, MN, USA), were included. The endpoint of the ablation was the completion of predefined lesions (CPVA for paroxysmal, and CPVA+mitral isthmus and roof line ablation for persistent AF). Seven day Holter recordings were done immediately, 3, 6, and 12 month after ablation. AF longer than 30 s was considered as recurrence. The success was defined as lack of recurrence during 7-day Holter recordings done 3, 6, and 12 months after ablation. Early recurrence was defined as recurrence during the first 7-day Holter recording immediately after ablation. Forty-five and 20.8% of the patients received antiarrhythmic medications for the first 3 and 6 months after ablation procedure, respectively. After 6 months all antiarrhythmics were discontinued. About 51.5% experienced early recurrence. Twelve months success rate was 75.7% (paroxysmal: 75.7%, persistent: 75.0%, P = 1.0). Using multivariate analysis left atrial (LA) diameter > or =50 mm was the predictor of early recurrence {Hazard Ratio (HR) [95% confidence interval (CI)] = 5.1 (2.0-12.9)}. LA Diameter > or =50 mm [HR (95% CI) = 4.6 (2.6-9.1)]; early recurrence [HR (95% CI) = 4.3 (2.0-9.1)]; and arterial hypertension [HR (95% CI) = 4.6 (2.6-9.1)] were predictors of late recurrence.

CONCLUSION

In our patients' cohort, a single catheter ablation procedure based on CPVA using steerable sheath for catheter navigation resulted in a 1 year success rate of 75.7% [without (91.0%) and with (58.6%) early recurrence, respectively, P = 0.0001]. Among those patients who are at high risk for recurrence after CPVA other ablation endpoints rather than completion of predefined lesions might be necessary to increase the success rate.