Morphologic Analysis of Left Atrial Anatomy by Magnetic Resonance Angiography in Patients With Atrial Fibrillation: A Large Single Center Experience

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Electro-Mechanical Alterations in Atrial Fibrillation: Structural, Electrical, and Functional Correlates

Atrial fibrillation is the most common arrhythmia encountered in clinical practice affecting both patients’ survival and well-being. Apart from aging, many cardiovascular risk factors may cause structural remodeling of the atrial myocardium leading to atrial fibrillation development. Structural remodelling refers to the development of atrial fibrosis, as well as to alterations in atrial size and cellular ultrastructure. The latter includes myolysis, the development of glycogen accumulation, altered Connexin expression, subcellular changes, and sinus rhythm alterations. The structural remodeling of the atrial myocardium is commonly associated with the presence of interatrial block. On the other hand, prolongation of the interatrial conduction time is encountered when atrial pressure is acutely increased. Electrical correlates of conduction disturbances include alterations in P wave parameters, such as partial or advanced interatrial block, alterations in P wave axis, voltage, area, morphology, or abnormal electrophysiological characteristics, such as alterations in bipolar or unipolar voltage mapping, electrogram fractionation, endo-epicardial asynchrony of the atrial wall, or slower cardiac conduction velocity. Functional correlates of conduction disturbances may incorporate alterations in left atrial diameter, volume, or strain. Echocardiography or cardiac magnetic resonance imaging (MRI) is commonly used to assess these parameters. Finally, the echocardiography-derived total atrial conduction time (PA-TDI duration) may reflect both atrial electrical and structural alterations.

Role of Cardiovascular Magnetic Resonance in the Management of Atrial Fibrillation: A Review

Atrial fibrillation (AF) is the most common arrhythmia, and its prevalence is growing with time. Since the introduction of catheter ablation procedures for the treatment of AF, cardiovascular magnetic resonance (CMR) has had an increasingly important role for the treatment of this pathology both in clinical practice and as a research tool to provide insight into the arrhythmic substrate. The most common applications of CMR for AF catheter ablation are the angiographic study of the pulmonary veins, the sizing of the left atrium (LA), and the evaluation of the left atrial appendage (LAA) for stroke risk assessment. Moreover, CMR may provide useful information about esophageal anatomical relationship to LA to prevent thermal injuries during ablation procedures. The use of late gadolinium enhancement (LGE) imaging allows to evaluate the burden of atrial fibrosis before the ablation procedure and to assess procedural induced scarring. Recently, the possibility to assess atrial function, strain, and the burden of cardiac adipose tissue with CMR has provided more elements for risk stratification and clinical decision making in the setting of catheter ablation planning of AF. The purpose of this review is to provide a comprehensive overview of the potential applications of CMR in the workup of ablation procedures for atrial fibrillation.

Variations in human pulmonary vein ostia morphology: A systematic review with meta-analysis

This study aimed to establish the most accurate and up-to-date anatomical knowledge of pulmonary veins (PV), ostia variations, diameters and ostial area, to provide physicians, especially heart and thoracic surgeons with exact knowledge concerning this area. The main online medical databases, such as PubMed, Embase, Scopus, Web of Science, and Google Scholar, were searched to gather all studies in which the variations, maximal diameter, and ostial area of the PVs were investigated. During the study, the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Additionally, the critical appraisal tool for anatomical meta-analysis (CATAM) was used to provide the highest quality findings. The most common ostia variation is the classical one, which contains the left superior pulmonary vein (LSPV), left inferior pulmonary vein (LIPV), right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV). The mean diameter and ostial area of each pulmonary vein were established in the general population and in multiple variations considering the method of collecting the data and geographical location. Significant variability in PV ostia is observed. Left-sided PVs have smaller ostia than the corresponding right-sided PVs, and the inferior PVs ostia are smaller than the superior. The LCPV ostium size is the largest among all veins analyzed, while the RMPV ostium is the smallest. The results of this meta-analysis are hoped to help clinicians in planning and performing procedures that involve the pulmonary and cardiac areas, especially catheter ablation for atrial fibrillation.

Secondary Stroke Prevention Following Embolic Stroke of Unknown Source in the Absence of Documented Atrial Fibrillation: A Clinical Review

Approximately one-third of ischemic strokes are classified as cryptogenic strokes. The risk of stroke recurrence in these patients is significantly elevated with up to one-third of patients with cryptogenic stroke experiencing a further stroke within 10 years. While anticoagulation is the mainstay of treatment for secondary stroke prevention in the context of documented atrial fibrillation (AF), it is estimated that up to 25% of patients with cryptogenic stroke have undiagnosed AF. Furthermore, the historical acceptance of a causal relationship between AF and stroke has recently come under scrutiny, with evidence to suggest that embolic stroke risk may be elevated even in the absence of documented atrial fibrillation attributable to the presence of electrical and structural changes constituting an atrial cardiomyopathy. More recently, the term embolic stroke of unknown source has garnered increasing interest as a subset of patients with cryptogenic stroke in whom a minimum set of diagnostic investigations has been performed, and a nonlacunar infarct highly suspicious of embolic etiology is suspected but in the absence of an identifiable secondary cause of stroke. The ongoing ARCADIA (Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke) randomized trial and ATTICUS (Apixiban for Treatment of Embolic Stroke of Undetermined Source) study seek to further define this novel term. This review summarizes the relationship between AF, embolic stroke, and atrial cardiomyopathy and provides an overview of the clinical relevance of cardiac imaging, electrocardiographic, and serum biomarkers in the assessment of AF and secondary stroke risk. The implications of these findings on therapeutic considerations is considered and gaps in the literature identified as areas for future study in risk stratifying this cohort of patients.

The Impact of Pulmonary Vein Anatomy on the Outcomes of Catheter Ablation for Atrial Fibrillation

Background and Objectives: Prior studies have identified a number of predictors for Atrial fibrillation (AF) ablation success, including comorbidities, the type of AF, and left atrial (LA) size. Ectopic foci in the initiation of paroxysmal AF are frequently found in pulmonary veins. Our aim was to assess how pulmonary vein anatomy influences the recurrence of atrial fibrillation after radiofrequency catheter ablation. Materials and Methods: Eighty patients diagnosed with paroxysmal or persistent AF underwent radiofrequency catheter ablation (RFCA) between November 2016 and December 2017. All of these patients underwent computed tomography before AF ablation. PV anatomy was classified according to the presence of common PVs or accessory PVs. Several clinical and imagistic parameters were recorded. After hospital discharge, all patients were scheduled for check-up in an outpatient clinic at 3, 6, 9, and 12 months after RFCA to detect AF recurrence. Results: A total of 80 consecutive patients, aged 53.8 ± 9.6 years, 54 (67.5%) men and 26 (32.5%) women were enrolled. The majority of patients had paroxysmal AF 53 (66.3%). Regular PV anatomy (2 left PVs, 2 right PVs) was identified in 59 patients (73.7%), a left common trunk (LCT) was detected in 15 patients (18.7%), an accessory right middle pulmonary vein (RMPV) was found in 5 patients (6.25%) and one patient presented both an LCT and an RMPV. The median follow-up duration was 14 (12; 15) months. Sinus rhythm was maintained in 50 (62.5%) patients. Age, gender, antiarrhythmic drugs, and the presence of cardiac comorbidities were not predictive of AF recurrence. The diagnosis of persistent AF before RFCA was more closely associated with an increase in recurrent AF after RFCA than after paroxysmal AF (p = 0.01). Longer procedure times (>265 minutes) were associated with AF recurrence (p = 0.04). Patients with an LA volume index of over 48.5 (mL/m²) were more likely to present AF recurrence (p = 0.006). Multivariate analysis of recurrence risk showed that only the larger LA volume index and variant PV anatomy were independently associated with AF recurrence. Conclusion: The study demonstrated that an increased volume of the left atrium was the most important predictive factor for the risk of AF recurrence after catheter ablation. Variant anatomy of PV was the only other independent predictive factor associated with a higher rate of AF recurrence.

Use of Intracardiac Echocardiography in Interventional Cardiology: Working With the Anatomy Rather Than Fighting It

The indications for catheter-based structural and electrophysiological procedures have recently expanded to more complex scenarios, in which an accurate definition of the variable individual cardiac anatomy is key to obtain optimal results. Intracardiac echocardiography (ICE) is a unique imaging modality able to provide high-resolution real-time visualization of cardiac structures, continuous monitoring of catheter location within the heart, and early recognition of procedural complications, such as pericardial effusion or thrombus formation. Additional benefits are excellent patient tolerance, reduction of fluoroscopy time, and lack of need for general anesthesia or a second operator. For these reasons, ICE has largely replaced transesophageal echocardiography as ideal imaging modality for guiding certain procedures, such as atrial septal defect closure and catheter ablation of cardiac arrhythmias, and has an emerging role in others, including mitral valvuloplasty, transcatheter aortic valve replacement, and left atrial appendage closure. In electrophysiology procedures, ICE allows integration of real-time images with electroanatomic maps; it has a role in assessment of arrhythmogenic substrate, and it is particularly useful for mapping structures that are not visualized by fluoroscopy, such as the interatrial or interventricular septum, papillary muscles, and intracavitary muscular ridges. Most recently, a three-dimensional (3D) volumetric ICE system has also been developed, with potential for greater anatomic information and a promising role in structural interventions. In this state-of-the-art review, we provide guidance on how to conduct a comprehensive ICE survey and summarize the main applications of ICE in a variety of structural and electrophysiology procedures.

Radiofrequency catheter ablation for paroxysmal atrial fibrillation: outcomes during a 3-year follow-up period

Objective

This study was performed to observe the effect of radiofrequency catheter ablation (RFCA) in patients with paroxysmal atrial fibrillation (PAF) and to explore the risk factors for late recurrence of atrial fibrillation (LRAF) after a single RFCA session.

Methods

In this retrospective study, 243 patients with PAF underwent RFCA and were followed up regularly.

Results

At a median follow-up of 37 months after a single procedure, 60.5% of patients maintained sinus rhythm (SR), and at a median follow-up of 42 months after multiple procedures, 74.9% of patients maintained SR. The statistically significant risk factors for LRAF after a single RFCA session were the left atrial diameter (LAD), left inferior pulmonary vein superior–inferior diameter (LIPV SID), PV number variation, circumferential pulmonary vein isolation (CPVI) combined with additional ablation, and early recurrence of atrial fibrillation (ERAF). The best cut-off value for LAD was 35.5 mm.

Conclusions

During a 3-year follow-up, about 70% of the patients with PAF maintained SR. LRAF after a single procedure was associated with the LAD, LIPV SID, PV number variation, CPVI combined with additional ablation, and ERAF.

Impact of an additional right pulmonary vein on second-generation cryoballoon ablation for atrial fibrillation: a propensity matched score study

PURPOSE

Cryoballoon (CB) technology in the context of anatomical pulmonary vein (PV) variants might hypothetically hamper successful PV isolation (PVI). Our aim was to assess the impact of a right middle PV (RMPV) in the setting of second-generation cryoballoon (CB advance-CB-A), on procedural parameters and on mid-term follow-up.

METHODS

Consecutive patients with AF presenting RMPV (RMPV+) at the pre-procedural computed tomography who underwent PVI by CB-A were enrolled. Comparison with propensity score-matched patients without RMPV (RMPV-) was performed. Acute procedural parameters and clinical follow-up were assessed.

RESULTS

A total of 240 patients (80 RMPV+) were included in the analysis. Twelve of 80 (15%) RMPV+ patients underwent a direct cryo-application in this variant and accomplished the isolation without phrenic nerve palsy, whereas in 25 of 80 (31%) RMPV+ patients, the RMPVs were not targeted directly nor indirectly (by co-occlusion during application at a major PV). At a median follow-up of 17.3 [interquartile range 11.3-26.5] months, there was no significant difference in AF-free survival between RMPV+ and RMPV- patients (78.8 vs 78.1%, P = 1.00), and the recurrence of atrial arrhythmias among patients with versus without an intentional or indirect cryo-application to the RMPV was not different (22 vs 20%, P = 1.00).

CONCLUSIONS

Mid-term outcome after CB-A ablation did not differ between RMPV+ and RMPV- patients. Within RMPV+ patients, outcome was similar between those with versus without a cryo-application (either direct or indirect) to the additional vein.

Cryoballoon ablation in atrial fibrillation: Advantages and drawbacks

Pulmonary vein isolation is the cornerstone of atrial fibrillation ablation and is effective for preventing arrhythmias recurrences, especially in patients with paroxysmal atrial fibrillation. During the last years, cryoballoon ablation has emerged as an unquestionable alternative approach to radiofrequency ablation. Many non-randomized and randomized trials have proven undoubtedly that cryoballoon ablation displays similar efficacy and overall safety profile, when compared to radiofrequency ablation for the treatment of patients with drug-refractory paroxysmal atrial fibrillation. These results have been obtained in all types of pulmonary veins anatomical subsets, which confirms that there is no need to select patients according to the latter. The value of cryoablation in the setting of short persistent atrial fibrillation still needs more evidence. Importantly, cryoballoon ablation seems to be less operator-dependent and more reproducible than radiofrequency for the isolation of pulmonary veins.

Multimodality Cardiac Imaging for the Assessment of Left Atrial Function and the Association With Atrial Arrhythmias

Several cardiac imaging modalities are able to visualize the left atrium (LA) and, therefore, allow for quantification of both structural and functional properties of this cardiac chamber. In echocardiography, only the maximal LA volume is included in the assessment of diastolic function at the current moment. Numerous studies, however, have shown that functional measures may be superior to the maximal LA volume in several aspects and to possess clinical value even in the absence of structural abnormalities. Such functional measures could prove particularly useful in the setting of predicting atrial fibrillation, which will be a point of focus in this review. Pivotal cardiac magnetic resonance imaging studies have revealed high correlation between LA fibrosis and risk of atrial fibrillation recurrence after catheter ablation, and subsequent multimodality imaging studies have uncovered an inverse relationship between LA reservoir function and degree of LA fibrosis. This has sparked an increased interest into the application of advanced imaging modalities, including both speckle tracking echocardiography and tissue tracking by cardiac magnetic resonance imaging. Even though increasing evidence has supported the use of functional measures and proven its superiority to the maximal LA volume, they have still not been adopted in clinical guidelines. The reason for this discrepancy may rely on the fact that there is little to no agreement on how to technically perform deformation analysis of the LA. Such technical considerations, limitations, and alternate imaging prospects will be addressed in this review.

Plasma oxidative stress and inflammatory biomarkers are associated with the sizes of the left atrium and pulmonary vein in atrial fibrillation patients

BACKGROUND

Oxidative stress and inflammatory processes are responsible for the pathogenesis of AF, but their relationship with the sizes of the LA and PVs in AF patients remains unclear.

HYPOTHESIS

Oxidative stress and inflammatory processes are associated with the sizes of the LA and PVs in AF patients.

METHODS

82 AF patients were compared to 30 control patients by using a case-control study design. Oxidative stress, inflammatory biomarkers and the sizes of the LA and PVs were detected.

RESULTS

(1) Hs-CRP, IL-6, IL-8, TNF-α, MDA and ox-LDL were higher, and SOD was lower in AF patients than in control patients. Hs-CRP, MDA and ox-LDL were higher in permanent AF patients than in paroxysmal and persistent AF patients. (2) CsA of LSPV, RSPV, RIPV, LAA and LAV were statistically higher in AF patients than in control patients. CsA of RSPV, LSPV, LIPV and LAV were higher in permanent AF patients than in paroxysmal and persistent AF patients. (3) In the AF group, hs-CRP and TNF-α were positively correlated with LAV; MDA was positively correlated with CsA of LAA, LSPV and LAV; SOD was passively correlated with CsA of LAA and LAV; ox-LDL was positively correlated with CsA of LAA and LAV. Multivariate logistic regression analysis showed hs-CRP, ox-LDL, RSPV CsA, LIPV CsA and LAV were associated with AF.

CONCLUSIONS

Oxidative stress, inflammatory biomarkers and the sizes of the LA and PVs were significantly increased in AF patients. Hs-CRP, ox-LDL, RSPV CsA, LIPV CsA and LAV were associated with AF persistence.

Effect of left atrial volume and pulmonary vein anatomy on outcome of nMARQ™ catheter ablation of paroxysmal atrial fibrillation

PURPOSE

Left atrial volume (LA) and pulmonary vein (PV) anatomy may potentially relate to technical challenges in achieving stable and effective catheter position in case of atrial fibrillation (AF) ablation by means of "one-shot" catheters. The aim of this study was to investigate whether LA volume and PV anatomy, evaluated by computed tomography (CT) or magnetic resonance (MR) prior to ablation, predict acute and midterm outcome of AF ablation by nMARQ™.

METHODS

We included 75 patients (mean age 58 ± 11 years, 67 % male) with symptomatic paroxysmal AF. All patients underwent CT/MR scanning prior to catheter ablation to evaluate LA volume and PV anatomy. All the patients underwent PV isolation by nMARQ™, an open-irrigated mapping and radiofrequency (RF) decapolar ablation catheter. Ablation was guided by electroanatomic mapping allowing RF energy delivery in the antral region of PVs from ten irrigated electrodes simultaneously.

RESULTS

Mean LA volume was 75 ± 40 ml. A normal anatomy (4 PVs) was documented in 40 (53 %) patients and abnormal anatomy (common truncus or accessory PVs) in 35 patients. Mean procedural and fluoroscopy times were 94 ± 55 and 8 ± 5 min, respectively, without significant differences among patients with normal or abnormal anatomy (92 ± 45 vs 95 ± 64 min, p = 0.85 and 6 ± 3 vs 8 ± 4 min, p = 0.65, respectively). Mean ablation time was 14 ± 3 min, and 99 % of the targeted veins were isolated with a mean of 23 ± 5 RF pulses per patient. After a mean follow-up of 17 ± 8 months, 23 (31 %) patients had an atrial arrhythmia recurrence. Neither LA volume nor PV anatomy was a predictor of outcome.

CONCLUSIONS

LA volume and PV anatomy did not affect procedural data and outcome in patients who underwent PV isolation by an open-irrigated mapping and RF decapolar ablation catheter.

Cryoablation in persistent atrial fibrillation - a critical appraisal

Ablation of atrial fibrillation is an established treatment for the management of patients with paroxysmal and persistent atrial fibrillation. The complex pathophysiology of persistent atrial fibrillation has fuelled the concept of adjunctive substrate modification on top of pulmonary vein isolation. However, recent studies have failed to demonstrate additive benefit from complex ablation approaches, thus supporting that standalone pulmonary vein isolation may prove sufficient, at least as the initial ablation strategy in persistent atrial fibrillation. In this premise, the new-generation cryoballoon is an attractive option in this demanding subgroup of patients due to its reliable efficacy in achieving pulmonary vein isolation combined with collateral debulking of the neighbouring atrial myocardium. In this review, we present a critical appraisal of the role of cryoablation in patients with persistent atrial fibrillation, discussing related technical considerations and existing scientific evidence.

A Computer Simulation Study of Anatomy Induced Drift of Spiral Waves in the Human Atrium

The interaction of spiral waves of excitation with atrial anatomy remains unclear. This simulation study isolates the role of atrial anatomical structures on spiral wave spontaneous drift in the human atrium. We implemented realistic and idealised 3D human atria models to investigate the functional impact of anatomical structures on the long-term (∼40 s) behaviour of spiral waves. The drift of a spiral wave was quantified by tracing its tip trajectory, which was correlated to atrial anatomical features. The interaction of spiral waves with the following idealised geometries was investigated: (a) a wedge-like structure with a continuously varying atrial wall thickness; (b) a ridge-like structure with a sudden change in atrial wall thickness; (c) multiple bridge-like structures consisting of a bridge connected to the atrial wall. Spiral waves drifted from thicker to thinner regions and along ridge-like structures. Breakthrough patterns caused by pectinate muscles (PM) bridges were also observed, albeit infrequently. Apparent anchoring close to PM-atrial wall junctions was observed. These observations were similar in both the realistic and the idealised models. We conclude that spatially altering atrial wall thickness is a significant cause of drift of spiral waves. PM bridges cause breakthrough patterns and induce transient anchoring of spiral waves.

Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures

Objective

To investigate quantitatively the morphology, anatomy and function of the left atrial appendage (LAA) and its relation with adjacent structures.

Materials and Methods

A total of 860 patients (533 men, 62.0%, age 55.9±10.4 year) who had cardiac multidetector computed tomography angiography from May to October 2012 were enrolled for analysis.

Results

Seven types and 6 subtypes of LAA morphology were found with Type 2 being the most prevalent. Type 5 was more significantly (P<0.05) present in women (8.0%) than in men (4.2%). LAA orifice was oval in 81.5%, triangular in 7.3%, semicircular in 4%, water drop-like in 3.2%, round in 2.4% and foot-like in 1.6%. The LAA orifice had a significantly greater (P<0.01) major axis in men (24.79±3.81) than in women (22.68±4.07). The LAA orifice long axis was significantly (P<0.05) positively correlated with the height, weight and surface area of the patient. The LAA morphology parameters displayed strong positive correlation with the left atrium volume, aortic cross area long axis or LSPV long axis but poor correlation with the height, weight, surface area and vertebral body height of the patients. Four types of LAA ridge were identified: AI, AII, B and C with the distribution of 17.6%, 69.9%, 5.9% and 6.6%, respectively. The LAA had a significantly (P<0.05) greater distance from its orifice to the mitral ring in women than in men. The LAA had two filling and two emptying processes with the greatest volume at 45% phase but the least volume at 5% phase. The LAA maximal, minimal and emptying volumes were all significantly (P<0.05) positively correlated with the body height, weight and surface area, whereas the LAA ejection fraction had an inverse correlation with the LAA minimal volume but no correlation with the maximal volume.

Conclusion

The LAA has substantially variable morphologies and relation with the adjacent structures, which may be helpful in guiding the LAA trans-catheter occlusion or catheter ablation procedures.

Predictors of Luminal Loss in Pulmonary Veins After Radiofrequency Ablation

INTRODUCTION AND OBJECTIVES

The reported incidences of stenosis after radiofrequency ablation of pulmonary veins are highly variable. Moreover, most studies have focused on severe stenosis and have overlooked mild stenosis. Our aims were to study postablation morphological changes in the pulmonary veins and to evaluate preablation magnetic resonance imaging predictors for stenosis.

METHODS

Eighty consecutive patients with atrial fibrillation underwent cardiac magnetic resonance imaging before undergoing radiofrequency ablation. Magnetic resonance imaging was repeated a median of 95 days after ablation. Ostium area/ellipticity and atrial volume were blindly assessed. We evaluated the presence of stenosis and classified it as mild (< 50% area reduction), moderate (50%-70%), and severe (> 70%).

RESULTS

Postablation stenosis was identified in 78 of 322 veins (24.2%). The stenosis was mild in 66 (84.6%), moderate in 11 (14.1%), and severe in 1 (1.3%). All of them were asymptomatic. The left inferior pulmonary vein showed the highest frequency of stenosis, which was detected in 26% of them (P < .001). A multiple regression analysis revealed that left inferior pulmonary vein (odds ratio = 3.089; P = .02) and a greater preablation ostium area (odds ratio = 1.009; P < .001) were independent predictors for postablation stenosis. Age (odds ratio = 1.033) showed a strong trend to statistical significance (P = .06).

CONCLUSIONS

After ablation, vein ostia size is reduced and stenosis is detected in less than one third of patients. Most cases are mild, and severe stenosis is rare. Postablation stenosis is more likely to develop in older patients, those with larger vein ostia, and in the left inferior pulmonary veins.

Topographic variability of the left atrium and pulmonary veins assessed by 3D-CT predicts the recurrence of atrial fibrillation after catheter ablation

BACKGROUND

Catheter ablation (CA) is an established therapy for atrial fibrillation (AF). However, the assessment of anatomical information and predictors of AF recurrence remain unclear. We investigated the relationship between anatomical information on the left atrium (LA) and pulmonary veins (PVs) from three-dimensional computed tomography images and the recurrence of AF after CA.

METHODS

Sixty-seven consecutive AF patients (mean age: 62±10 years, median AF history: 42 (12; 60) months, mean LA size: 41±7 mm, paroxysmal: 56%) underwent CA and were followed for 19±10 months. The segmented surface areas (antral, posterior, septal, and lateral) and dimensions (between the anterior and posterior walls, the right inferior PV and mitral annulus [MA], the right superior PV and MA, the left superior PV and MA, and the mitral isthmus) of the LA were evaluated three dimensionally using the NavX system. The cross-sectional areas of the PVs were also evaluated.

RESULTS

After the follow-up period, 49 patients (73%) remained free from AF. A multivariate analysis showed that the diameter of the mitral isthmus and cross-sectional area of the right upper PV were associated with AF recurrence (odds ratio: 1.070, CI: 1.02-1.12, p=0.001; odds ratio: 0.41, CI: 0.21-0.77, p=0.006).

CONCLUSION

Enlargement of the mitral isthmus and a smaller right superior PV cross-sectional area were associated with AF recurrence.

Catheter Ablation of Atrial Fibrillation Without Radiation Exposure Using A 3D Mapping System

Transcatheter ablation procedures have been traditionally performed under fluoroscopic guidance. However, x-ray exposure is afflicted by the risk of developing malignancies as well as other deterministic effects of radiation. For this reason, radiation doses in the interventional laboratory should be reduced "As Low As Reasonably Achievable", with respect to the safety of the patients and the medical staff. This is of utmost importance in atrial fibrillation (AF) ablations, which are usually lengthy procedures. With the improvement of technology, the development of additional imaging tools and the widespread of 3D electroanatomic mapping systems (EAM), near-zero fluoroscopy AF ablation procedure is becoming a reality, limiting fluoroscopy use mainly to guide transseptal puncture. In the present paper we reviewed the risks to health related to x-ray exposure and we discussed the current state of knowledge of catheter ablation of AF without fluoroscopy in the 3D EAM system era.

Pulmonary vein isolation with a new multipolar irrigated radiofrequency ablation catheter (nMARQ™): feasibility, acute and short-term efficacy, safety, and impact on postablation silent cerebral ischemia

BACKGROUND

Simultaneous multipolar ablation catheters have been proposed to simplify pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (AF). Recently, a new multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™, Biosense Webster Inc., Diamond Bar, CA, USA) combining both 3-dimensional electroanatomic mapping and multipolar open-irrigated ablation capability has been developed. Aim of our study was to assess feasibility, acute and short-term success and safety of PVI by the use of this new technology with particular regard to the incidence of postablation silent cerebral ischemia (SCI).

METHODS AND RESULTS

Twenty-five patients (76% males; age 57 ± 13 years) with paroxysmal AF underwent PVI using the nMARQ™ catheter. PVI, confirmed by Lasso catheter mapping, was achieved in 100 out of 102 pulmonary veins (98%) identified, and final PVI was obtained in 24 out of 25 (96%) patients. The overall concordance between Lasso and nMARQ™ signals in demonstrating PVI was 78%. No major procedural complications occurred and no patient suffered SCI, on the basis of cerebral magnetic resonance imaging performed before and after the procedure. Following a 6-month follow-up, 17/25 (68%) patients remained free from AF without antiarrhythmic drugs.

CONCLUSIONS

In our preliminary experience, PVI with nMARQ™ catheter appears to be feasible and safe, without incidence of SCI. Long-term clinical efficacy has to be evaluated in further studies.

Left atrial anatomy relevant to catheter ablation

The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences.

Use of oral gadobenate dimeglumine to visualise the oesophagus during magnetic resonance angiography in patients with atrial fibrillation prior to catheter ablation

BACKGROUND

Atrio-oesophageal fistula was first reported as a fatal complication of surgical endocardial and percutaneous endocardial radiofrequency ablation for atrial fibrillation, with an incidence after catheter ablation between 0.03% and 0.5%. Magnetic resonance angiography (MRA) was usually performed to obtain pre-procedural 3D images, used to merging into an electro-anatomical map, guiding step-by-step ablation strategy of AF. Our aim was to find an easy, safe and cost-effective way to enhance the oesophagus during MRA.

METHODS

In 105 consecutive patients, a right-left phase encoding, free breathing, 3D T1 MRA sequence was performed in the axial plane, >24 hours before catheter ablation, using an intravenous injection of gadobenate dimeglumine contrast medium. The oesophagus was enhanced using an oral gel solution of 0.7 mL gadobenate dimeglumine contrast medium mixed with approximately 40 mg thickened water gel, which was swallowed by the patients on the scanning table, immediately before the MRA sequence acquisition.

RESULTS

The visualisation of the oesophagus was obtained in 104/105 patients and images were successfully merged, as left atrium and pulmonary veins, into an electro-anatomical map, during percutaneous endocardial radiofrequency ablation. All patients tolerated the study protocol and no immediate or late complication was observed with the oral contrast agent administration. The free-breathing MRA sequence used in our protocol took 7 seconds longer than MRA breath-hold conventional sequence.

CONCLUSION

Oesophagus visualization with oral gadobenate dimeglumine is feasible for integration of oesophagus anatomy images into the electro-anatomical map during AF ablation, without undesirable side effects and without significantly increasing cost or examination time.

Role of magnetic resonance imaging in atrial fibrillation ablation

OPINION STATEMENT

Ablation therapy is widely used for treatment of drug-resistant atrial fibrillation (AF). Ablation success for AF, however, is relatively low, often requiring repeated procedures for long-term suppression of the arrhythmia. Utilization of imaging techniques that visualize cardiac anatomy, function, and tissue characteristics may improve ablation results. Compared to other imaging modalities, cardiac magnetic resonance (CMR) has several advantages, including the lack of ionizing radiation and unsurpassed soft tissue resolution. Chamber morphology images can be registered onto electroanatomic maps acquired during the procedure, thus improving procedural safety and efficacy. In addition, the ability of CMR to characterize myocardial tissues may optimize patient selection for ablation and thromboembolic risk stratification. Post-procedure CMR can be used to detect potential complications, and with improved resolution, it has the potential to assess the integrity of ablation lesions. In this paper we will review the role of CMR in the pre-ablation diagnostic workup of AF patients as well as during and after catheter ablation.

Anatomical characteristics of pulmonary veins for the prediction of postoperative recurrence after radiofrequency catheter ablation of atrial fibrillation

Background

The relationship between focal pulmonary vein potential and atrial fibrillation (AF) has been confirmed. Pulmonary vein (PV) isolation and circumferential pulmonary vein ablation have been the most commonly used procedures of radiofrequency ablation. However, few studies have investigated the relationship between anatomical characteristics of PV and AF recurrences after radiofrequency ablation.

Methodology

For 267 AF patients treated by radiofrequency catheter ablation, the anatomic structure characteristics of pulmonary veins were assessed by multi-slice spiral computed tomography while the values of left atrial diameter (LAD) were measured with transesophageal ultrasonic cardiogram. After radiofrequency catheter ablation, postoperative recurrence was evaluated during a 10-month term follow-up.

Principal Findings

During follow-up, postoperative recurrence occurred in 44 patients. The mean diameters of LAD, left superior PV, right superior PV, all left PV, and all superior PV were significantly larger in patients with postoperative recurrence (Recurrence vs. Non-recurrence group; 43.9 ± 6.4 mm vs. 40.7 ± 5.6 mm; 18.4 ± 2.1 mm vs. 17.1 ± 3.1 mm; 18.2 ± 2.8 mm vs. 17.2 mm ± 3.9 mm; 16.4 ± 1.5 mm vs. 15.6 ± 2.5 mm; 18.3 ± 2.1 mm vs. 17.1 ± 3.0 mm; respectively; all P < 0.05). Multivariable survival analysis showed that the type and the course of AF, LAD, and the diameters of all superior PV were the independent risk factors for the postoperative recurrence after radiofrequency catheter ablation.

Conclusions

The enlargements of all superior PV and LAD, long course of diseases, and persistent AF were the independent risk factors for the postoperative recurrence after radiofrequency catheter ablation.

Determinants of left atrial appendage volume in stroke patients without chronic atrial fibrillation

BACKGROUND

Left atrial appendage (LAA) volume has been shown to be increased in patients with acute cryptogenic stroke. Atrial fibrillation (AF) is a well-recognized risk factor but it is not the only one associated with LAA enlargement. The aim of the study was to clarify the multifactorial etiology of LAA enlargement in cardiogenic stroke/TIA patients without AF.

METHODS

Altogether 149 patients with suspected cardioembolic stroke/TIA (47 females; mean age 61 years) underwent cardiac CT. Diagnosed AF on admittance was an exclusion criteria but 24-hour Holter ambulatory ECG revealed paroxysmal AF (PAF) in 20 patients. Body surface area adjusted LAA volume was evaluated. Eighteen different variables were registered including general characteristics, definite and potential causal risk factors for ischemic stroke/TIA, clinical echoparameters and CT based cardiac volumetric and adipose tissue measurements. A stepwise linear regression analysis was performed to achieve a model adjusted for the number of predictors of LAA volume increase.

RESULTS

In linear regression analysis, the best model accounted for 30% of the variability in LAA volume, including PAF (19%) and enlarged left atrial volume (6%), enlarged left ventricle end-systolic diameter (3%) and decreased pericardial adipose tissue (2%). No multi-colinearity between variables was observed. In addition to PAF, no other definitive or potential causal risk factors could account for the LAA volume in these patients.

CONCLUSIONS

LAA volume increase seems to be poorly associated with currently known stroke/TIA risk factors, except for AF. Targeting more comprehensive ECG monitoring for stroke patients with increased LAA volume should be considered.

Impaired left ventricular filling in COPD and emphysema: is it the heart or the lungs? The Multi-Ethnic Study of Atherosclerosis COPD Study

BACKGROUND

COPD and heart failure with preserved ejection fraction overlap clinically, and impaired left ventricular (LV) filling is commonly reported in COPD. The mechanism underlying these observations is uncertain, but may include upstream pulmonary dysfunction causing low LV preload or intrinsic LV dysfunction causing high LV preload. The objective of this study is to determine if COPD and emphysema are associated with reduced pulmonary vein dimensions suggestive of low LV preload.

METHODS

The population-based Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited smokers aged 50 to 79 years who were free of clinical cardiovascular disease. COPD was defined by spirometry. Percent emphysema was defined as regions &lt; -910 Hounsfield units on full-lung CT scan. Ostial pulmonary vein cross-sectional area was measured by contrast-enhanced cardiac magnetic resonance and expressed as the sum of all pulmonary vein areas. Linear regression was used to adjust for age, sex, race/ethnicity, body size, and smoking.

RESULTS

Among 165 participants, the mean (± SD) total pulmonary vein area was 558 ± 159 mm2 in patients with COPD and 623 ± 145 mm2 in control subjects. Total pulmonary vein area was smaller in patients with COPD (-57 mm2; 95% CI, -106 to -7 mm2; P = .03) and inversely associated with percent emphysema (P &lt; .001) in fully adjusted models. Significant decrements in total pulmonary vein area were observed among participants with COPD alone, COPD with emphysema on CT scan, and emphysema without spirometrically defined COPD.

CONCLUSIONS

Pulmonary vein dimensions were reduced in COPD and emphysema. These findings support a mechanism of upstream pulmonary causes of underfilling of the LV in COPD and in patients with emphysema on CT scan.

Left atrial appendage volume increased in more than half of patients with cryptogenic stroke

BACKGROUND

Ischemic strokes without a well-defined etiology are labeled as cryptogenic, and account for 30-40% of strokes in stroke registries. The left atrial appendage (LAA) is the most typical origin for intracardiac thrombus formation when associated with atrial fibrillation. Here, we examined whether increased LAA volume detected with cardiac computed tomography (cCT) constitutes a risk factor in cryptogenic stroke patients.

METHODS

This study included 82 stroke/TIA patients (57 males; mean age, 58 years) with a diagnosis of cryptogenic stroke after extensive radiological and cardiological investigations. Cases were classified using the TOAST criteria modified by European Association of Echocardiography recommendations for defining cardiac sources of embolism. Forty age- and gender-matched control subjects without cardiovascular diseases were selected for pair-wise comparisons (21 males; mean age, 54 years). LAA volume adjusted for body surface area was measured three dimensionally by tracing the LAA borders on electrocardiogram-gated CT slices.

RESULTS

In control subjects, mean LAA volume was 3.4±1.1 mL/m(2). Mean+2SD, which was considered the upper limit for normal LAA volume was 5.6 mL/m(2). In paired Student t-test between the patient group and matched controls, LAA volume was 67% larger in cryptogenic stroke/TIA patients (5.7±2.0 mL/m(2) vs. 3.4±1.1 mL/m(2); P<0.001). Forty-five (55%) patients with cryptogenic stroke/TIA had enlarged LAA.

CONCLUSION

LAA is significantly enlarged in more than half of patients with cryptogenic stroke/TIA. LAA thrombosis may contribute to the pathogenesis of stroke in patients considered to have cryptogenic stroke after conventional evaluation.

Role of cardiac computed tomography and cardiovascular magnetic resonance imaging in guiding management and treatment of patients with atrial fibrillation: state of the art review

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with high morbidity and mortality. In view of an aging population, the prevalence and incidence of AF are on the rise and are expected to double in the coming decades, posing a huge economic burden on already strained resources. New innovative therapies such as pulmonary vein isolation and percutaneous closure of the left atrial appendage have emerged. The current applications of such therapies would not have been possible without the pivotal role of multimodality cardiovascular imaging. The role of echocardiography in guiding therapy has been extensively reviewed. However, there are new data in support of other complementary imaging modalities, mainly cardiac computed tomography and cardiovascular magnetic resonance imaging, which will be the focus of this review.

Spatial torsion of the ipsilateral superior and inferior pulmonary veins

PURPOSE

We sought to evaluate the disregarded spatial torsion of the ipsilateral superior and inferior pulmonary veins (PVs).

METHODS

Forty-eight consecutive atrial fibrillation patients, with four discrete PVs, were enrolled. The ostium plane of each PV, labeled by three landmarks on the CT image, was identified by three experienced observers respectively. Angle and distance between ostium planes were used to reach a consensus and to select the best ostium plane of each PV. A common ostium plane of the ipsilateral PV was computed using the two geometric centers of each side PVs and the axial center of the two geometric centers. The torsion angle was defined as the absolute difference of the two dihedral angles between the common ostium plane and the best ostium plane of the superior and inferior PVs.

RESULTS

The torsion angle >15° was found in 16 left PVs (16/48) and in nine right PVs (9/48, P = 0.104). Moreover, in two cases (2.1 %), the torsion angle exceeded 30° (one left PV and one right PV). The torsion angle of the left PVs was significantly greater than that of the right PVs (13.65 ± 5.90° vs. 10.61 ± 5.96°, P = 0.014). Furthermore, in 29 paroxysmal AF patients, the spatial torsion of the left side PVs was 13.70 ± 5.18°, which was significant greater than that of the right side PVs (10.69 ± 5.52°, P = 0.037).

CONCLUSIONS

There was a significant torsion between the ipsilateral PVs, which should be taken into account when physicians plan their ablation to avoid a single-plane circumferential ablation.

Comparison of ThermoCool® Surround Flow catheter versus ThermoCool® catheter in achieving persistent electrical isolation of pulmonary veins: a pilot study

INTRODUCTION

Aim of this study was to compare efficacy and safety of the new ThermoCool Surround Flow® catheter (SFc) versus the ThermoCool® (TCc) in achieving persistent circumferential electrical isolation of the pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

This multicenter, randomized, controlled study enrolled patients suffering from paroxysmal AF. Randomization was run in a one-to-one fashion between radiofrequency ablation by TCc or SFc. Aim of PVs ablation was documentation of electrical isolation with exit/entrance block recorded on a circular catheter. Among the 106 enrolled patients, 52 (49.0%) were randomized to TCc and 54 (51.0%) to SFc. Total volume of infused saline solution during the procedure was lower in the SFc than in TCc group (752.7 ± 268.6 mL vs 1,165.9 ± 436.2 mL, P < 0.0001). Number of identified and isolated PVs was similar in the 2 groups. Number of PVs remaining isolated 30 minutes after ablation was higher in the SFc than in TCc group (95.2% vs 90.5%, P < 0.03), mainly driven by acute ablation result in the left PVs (96.1% vs 89.7%, P < 0.04). Complications were seldom and observed only in the TCc group (0% vs 3.84%, P < 0.03). At 6-month follow-up SFc patients reported a trend toward less AF recurrences compared to those in the TCc group (22.9% vs 27.0%, P = 0.69).

CONCLUSION

PV isolation by SFc lowered the rate of left PV early reconnections and reduced the volume of infused saline solution while maintaining the safety profile of AF ablation.

The use of cardiac magnetic resonance imaging in the diagnostic workup and treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia and imposes a huge clinical and economic burden. AF is correlated with an increased morbidity and mortality, mainly due to stroke and heart failure. Cardiovascular imaging modalities, including echocardiography, computed tomography (CT), and cardiovascular magnetic resonance (CMR), play a central role in the workup and treatment of AF. One of the major advantages of CMR is the high contrast to noise ratio combined with good spatial and temporal resolution, without any radiation burden. This allows a detailed assessment of the structure and function of the left atrium (LA). Of particular interest is the ability to visualize the extent of LA wall injury. We provide a focused review of the value of CMR in identifying the underlying pathophysiological mechanisms of AF, its role in stroke prevention and in the guidance of radiofrequency catheter ablation. CMR is a promising technique that could add valuable information for therapeutic decision making in specific subpopulations with AF.

Pulmonary vein isolation using a single size cryoballoon chosen according to transesophageal echocardiography information

BACKGROUND

Pulmonary vein isolation (PVI) using cryoballoon (CB) catheter is a new technique for atrial fibrillation (AF) ablation. Previous studies used computer tomography (CT) or magnetic resonance imaging (MRI) scan to determine the pulmonary vein (PV) diameter and anatomy for choosing the CB size. We evaluated pre-ablation transoesophageal-echocardiography (TEE) as an alternative to CT/MRI scan in patients undergoing AF ablation for determining the appropriate size of the CB.

METHODS

Fifty-five consecutive patients (men=43, women=12) with a mean age of 63 ± 12.5 years, and with drug-refractory paroxysmal AF (34 patients) or persistent AF (21 patients) were included in this prospective study. All patients underwent pre-ablation TEE.

RESULTS

Hypertension was present in 19 patients (34%). Mean anterior-posterior left atrium diameter was 45.1 ± 8.9 mm. In total, 217 PV were targeted using a single 23-mm (n=14) or 28-mm (n=40) CB catheter chosen according to TEE-obtained measurements. PVI was achieved in 195 PV (90%). Mean number of CB applications per patient was 9.8 ± 2.1 (range 8-14). Mean procedure duration and fluoroscopy times were 131 ± 27 min (90-190 min) and 36 ± 12 min (22-66 min) respectively. Phrenic nerve palsy occurred in 3 patients (5.4%) and was transient (<1 month) in all of them.

CONCLUSION

This study suggests that TEE is an easily available and effective tool to select the size of the CB for PVI according to evaluated PV diameters and anatomy.

Treating Atrial Fibrillation With Cryoballoon Technology

Cryoballoon ablation has emerged as a novel tool to perform pulmonary vein isolation. The aim of this paper is to review the advantages, drawbacks as well as possible complications and clinical outcomes of this technology and to discuss some important technical issues.