Multislice computed tomography versus intracardiac echocardiography to evaluate the pulmonary veins before radiofrequency catheter ablation of atrial fibrillation: a head-to-head comparison

The use of Intracardiac Echocardiography in Catheter Ablation of Atrial Fibrillation

PURPOSE OF THE REVIEW

Intracardiac echocardiography (ICE) provides real-time, fluoroless imaging of cardiac structures, allowing optimal catheter positioning and energy delivery during ablation procedures. This review summarizes the use of ICE in catheter ablation of atrial fibrillation (AF).

RECENT FINDINGS

Growing evidence suggests that the use of ICE improves procedural safety and facilitates radiofrequency and cryoballoon AF ablation. ICE-guided catheter ablation is associated with reduced procedural duration and fluoroscopy use. Recent studies have examined the role of ICE in guiding novel ablation techniques, such as pulsed field ablation. Finally, the use of ICE allows for early detection and timely management of potentially serious procedural complications. Intracardiac echocardiography offers significant advantages during AF ablation procedures and its use should be encouraged to improve procedural safety and efficacy.

A Simplified Approach to Pulmonary Vein Visualization during Cryoballoon Ablation of Atrial Fibrillation

Background and Objectives: Selective pulmonary vein (PV) angiography has been established as the gold standard for PV visualization in cryoballoon (CB)-based pulmonary vein isolation (PVI). We sought to simplify this approach to reduce procedural complexity and radiation exposure. Materials and Methods: Patients with paroxysmal and recently diagnosed persistent AF undergoing CB-based PVI from January 2015 to December 2017 were retrospectively analyzed. Patients underwent either selective PV angiography or conventional left atrial (LA) angiography for PV visualization. Results: A total of 336 patients were analyzed. A total of 87 patients (26%) received PV angiography and 249 (74%) LA angiography. LA angiography required fewer cine-sequences for PV visualization, translating into a significant reduction in procedure duration, fluoroscopy time and dose area product. Additionally, less contrast medium was utilized. PV occlusion by the CB, CB temperature and time to isolation showed no significant differences. The number of CB applications and total application time (LA angiography: 1.4 ± 0.02 vs. PV Angiography: 1.6 ± 0.05; p < 0.0001; LA angiography: 297.9 ± 4.62 vs. PV-Angiography: 348.9 ± 11.03; p < 0.001, respectively) per vein were slightly but significantly higher in the PV angiography group. We observed no difference in late AF recurrence (24.7% LA angiography vs. 21.3% PV angiography; p = 0.2657). Conclusions: A simplified protocol, using LA angiography for PV visualization, entails a reduction in procedure time and radiation exposure while equally maintaining procedural efficiency and safety in both groups.

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.

Medical image analysis on left atrial LGE MRI for atrial fibrillation studies: A review

Late gadolinium enhancement magnetic resonance imaging (LGE MRI) is commonly used to visualize and quantify left atrial (LA) scars. The position and extent of LA scars provide important information on the pathophysiology and progression of atrial fibrillation (AF). Hence, LA LGE MRI computing and analysis are essential for computer-assisted diagnosis and treatment stratification of AF patients. Since manual delineations can be time-consuming and subject to intra- and inter-expert variability, automating this computing is highly desired, which nevertheless is still challenging and under-researched. This paper aims to provide a systematic review on computing methods for LA cavity, wall, scar, and ablation gap segmentation and quantification from LGE MRI, and the related literature for AF studies. Specifically, we first summarize AF-related imaging techniques, particularly LGE MRI. Then, we review the methodologies of the four computing tasks in detail and summarize the validation strategies applied in each task as well as state-of-the-art results on public datasets. Finally, the possible future developments are outlined, with a brief survey on the potential clinical applications of the aforementioned methods. The review indicates that the research into this topic is still in the early stages. Although several methods have been proposed, especially for the LA cavity segmentation, there is still a large scope for further algorithmic developments due to performance issues related to the high variability of enhancement appearance and differences in image acquisition.

Clinical applications of cardiac computed tomography: a consensus paper of the European Association of Cardiovascular Imaging-part II

Cardiac computed tomography (CT) was initially developed as a non-invasive diagnostic tool to detect and quantify coronary stenosis. Thanks to the rapid technological development, cardiac CT has become a comprehensive imaging modality which offers anatomical and functional information to guide patient management. This is the second of two complementary documents endorsed by the European Association of Cardiovascular Imaging aiming to give updated indications on the appropriate use of cardiac CT in different clinical scenarios. In this article, emerging CT technologies and biomarkers, such as CT-derived fractional flow reserve, perfusion imaging, and pericoronary adipose tissue attenuation, are described. In addition, the role of cardiac CT in the evaluation of atherosclerotic plaque, cardiomyopathies, structural heart disease, and congenital heart disease is revised.

Extracardiac findings on cardiac computed tomography in patients undergoing atrial fibrillation catheter ablation

Abstract Background and Aim

To assess the prevalence of incidental extracardiac findings in patients who underwent cardiac CT for the evaluation of left atrial (LA) anatomy before atrial fibrillation (AF) catheter ablation. We also aimed to determine the independent predictors of relevant extracardiac alterations.

Patients and Methods

We studied consecutive patients who underwent cardiac CT with a 256-slice scanner for the visualization of LA anatomy before AF ablation. Prevalence of clinically significant and not significant extracardiac findings were recorded. Moreover, we determined the variables associated with relevant extracardiac alterations with uni- and multivariate logistic regression analyses.

Results

In total, 1,952 consecutive patients who underwent cardiac CT examination between 2010 and 2020 were included in our study (mean age 61.2±10.6 years; 66.2% male). Incidental extracardiac findings were detected in 820 (42.0%; 95%CI=0.40-0.44%) patients, while clinically significant alterations were reported in 416 (21.3%; 95%CI=20.0-23.2%) patients. When analyzing the predictors of clinically relevant alterations, age (OR=1.04; 95%CI=1.03- 1.05), male sex (OR=1.39; 95%CI=1.12-1.73), chest pain (OR=1.46; 95%CI=1.09-1.93), hypertension (OR=1.42; 95%CI=1.12-1.81), heart failure (OR=1.68; 95%CI=1.09-2.53), obstructive CAD (OR=1.56; 95%CI=1.16-2.09) and prior stroke/TIA (OR=1.56; 95%CI=1.04- 2.30) showed association with clinically significant incidental findings in the univariate analysis (all p<0.05). In the multivariate analysis, age (OR=1.04; 95%CI=1.02-1.06; p<0.001) proved to be the only significant predictor of clinically relevant extracardiac finding.

Conclusion

Cardiac CT performed before AF ablation is not only helpful in understanding LA anatomy, but might also identify clinically significant pathologies. These incidental findings might have further diagnostic or therapeutic consequences.

INtra-procedural ultraSound Imaging for DEtermination of atrial wall thickness and acute tissue changes after isolation of the pulmonary veins with radiofrequency, cryoballoon or laser balloon energy: the INSIDE PVs study

Preliminary data in human suggest that both Intracardiac echocardiography (ICE) and Intravascular ultrasound (IVUS) can be used for real-time information on the left atrial (LA) wall thickness and on the acute tissue changes produced by energy delivery. This pilot study was conducted to compare ICE and IVUS for real-time LA wall imaging and assessment of acute tissue changes produced by radiofrequency (RF), cryo and laser catheter ablation. Patients scheduled for RF, cryoballoon or laser balloon Pulmonary Vein Isolation (PVI) catheter ablation were enrolled. Each pulmonary vein (PV) was imaged before and immediately after ablation with either ICE or IVUS. The performance of ICE and IVUS for imaging were compared. Pre- and post-ablation measurements (lumen and vessel diameters, areas and sphericity indexes, wall thickness and muscular sleeve thickness) were taken at the level of each PV ostium. A total of 48 PVs in 12 patients were imaged before and after ablation. Both ICE and IVUS showed acute tissue changes. Compared to IVUS, ICE showed higher imaging quality and inter-observer reproducibility of the PV measurements obtained. Acute wall thickening suggestive of oedema was observed after RF treatment (p = 0.003) and laser treatment (p = 0.003) but not after cryoablation (p = 0.69). Our pilot study suggests that ICE might be preferable to IVUS for LA wall thickness imaging at the LA-PV junctions during ablation. Ablation causes acute wall thickening when using RF or laser energy, but not cryoenergy delivery. Larger studies are needed to confirm these preliminary findings.

Multidetector computed tomography in planning the treatment of atrial fibrillation

OBJECTIVE

To know the anatomy of the pulmonary veins (PVs) by multidetector computed tomography (MDCT) in patients with atrial fibrillation (AF) prior to ablation.

MATERIALS AND METHODS

MDCT was performed in 89 patients with AF, analyzing the number of PVs, accessory variants and veins, diameter and ostial shape, distance to the first bifurcation and thrombus in the left atrial appendage.

RESULTS

The most frequent venous pattern was 4 PVs (two right and two. left) in 49 patients (55.1%). The superior veins had a statistically significant greater mean ostial diameter than the inferior veins (Right Superior Pulmonary Vein (RSPV)> Right Inferior Pulmonary Vein (RIPV); p=0.001 and Left Superior Pulmonary Vein (LSPV)> Left Inferior Pulmonary Vein (LIPV); p<0.001). The right pulmonary veins ostial diameters were significantly larger than the left pulmonary veins ostial diameters (RSPV> LSPV; p<0.001 and RIPV> LIPV; p<0.001). The most circular ostium was presented by the VPID (ratio: 0.885) compared to the LIPV (p<00.1) and LSPV (p<0.001). The superior veins had a statistically significant greater mean distance to first bifurcation than the inferior veins (RSPV> RIPV; p=0.008 and LSPV> LIPV; p=0.038). Mean distance to first bifurcation has been greater in left PVs respect to the right PVs (LSPV> RSPV; p<0.001and LIPV> RIPV; p<0.001). Other findings found in AI: diverticula (30), accessory auricular appendages (5), septal aneurysms (8), septal bags (6) and 1 thrombus in the left atrial appendage.

CONCLUSION

MDCT prior to ablation demonstrates the anatomy of the left atrium (LA) and pulmonary veins with significant differences between the diameters and morphology of the venous ostia.

Pulmonary vein volume predicts the outcome of radiofrequency catheter ablation of paroxysmal atrial fibrillation

PURPOSE

Catheter ablation of atrial fibrillation (AF) is an effective therapy for selected groups of patients. We evaluated whether quantification of left atrium (LA) or pulmonary vein (PV) by using multi-detector computed tomography (MDCT) may predict the success rate of PV isolation procedure.

METHODS

We included 118 patients younger than 65 years with symptomatic AF (73 paroxysmal, PAF; 45 non-paroxysmal, non-PAF). All patients underwent 256-slice MDCT prior to circumferential PV isolation to evaluate anatomy, volume and dimensions of LA and PV.

RESULTS

After a mean follow-up of 14 months, complete success was achieved in 50 patients (68.5%) of PAF and in 26 patients (57.8%) of non-PAF. In the PAF group, total PV volume was found to be an independent predictor of AF recurrence, whereas LA volume was not. Logistic regression analysis showed that the probability of AF recurrence was higher in patients with total PV volume greater than 12.0 cm3/BSA (m2) (AUC 0.682, 95%CI 0.541-0.822). In the non-PAF group, no independent risk factor of LA or PV size was observed for the postoperative recurrence.

CONCLUSIONS

The PV volume quantification may predict the success of AF ablation in PAF patients.

Pulmonary vein anatomy variants as a biomarker of atrial fibrillation - CT angiography evaluation

Background

It has been suggested that changes in pulmonary veins (PV) and left atrium (LA) anatomy may have an influence on initiating atrial fibrillation (AF) and the effectiveness of pulmonary vein isolation (PVI) in patients (pts) with atrial fibrillation.

The aim of the study was to assess anatomy abnormalities of the PV and LA in the patients with the history of AF and compare it with the control group(CG).

Methods

The multi-slice tomography (MSCT) scans were performed in 224 AF pts. before PVI (129 males, mean age 59 ± 9 yrs). The CG consisted of 40 pts. without AF (26 males, age 45 ± 9 yrs). LA and PV anatomy were evaluated. Diameters of PV ostia were measured in two directions: anterior-posterior (AP) and superior-inferior (SI) automatically using Vitrea 4.0.

Results

Pulmonary veins anatomy variants were observed more frequently in the atrial fibrillation group - 83 pts. (37%) vs 6 pts. (15%) in CG; 9% (21 pts) left common ostia (CO), 2% (5 pts) right CO, 19% (42 pts) additional right PV (APV), (1.8%) 4 pts. APV left, 8% right early branching (EB) and 3.5% left EB. The LA diameter differed significantly in AF vs CG group (41.2 ± 6 mm vs 35 ± 4.2 mm, p < 0.0001) respectively.

Conclusions

The anomalies of pulmonary vein anatomy occurred more often in pts. with AF. They can be defined as an image biomarkers of atrial fibrillation. Right additional (middle) pulmonary vein was the most important anomaly detected in AF patients as well as enlargered diameters of the LA and PV ostia.

Comprehensive Cross-sectional Imaging of the Pulmonary Veins

The pulmonary veins carry oxygenated blood from the lungs to the heart, but their importance to the radiologist extends far beyond this seemingly straightforward function. The anatomy of the pulmonary veins is variable among patients, with several noteworthy variant and anomalous patterns, including supernumerary pulmonary veins, a common ostium, anomalous pulmonary venous return, and levoatriocardinal veins. Differences in pulmonary vein anatomy and the presence of variant or anomalous anatomy can be of critical importance, especially for preoperative planning of pulmonary and cardiac surgery. The enhancement or lack of enhancement of the pulmonary veins can be a clue to clinically important disease, and the relationship of masses to the pulmonary veins can herald cardiac invasion. The pulmonary veins are also an integral part of thoracic interventions, including lung transplantation, pneumonectomy, and radiofrequency ablation for atrial fibrillation. This fact creates a requirement for radiologists to have knowledge of the pre- and postoperative imaging appearances of the pulmonary veins. Many of these procedures are associated with important potential complications involving the pulmonary veins, for which diagnostic imaging plays a critical role. A thorough knowledge of the pulmonary veins and a proper radiologic approach to their evaluation is critical for the busy radiologist who must incorporate the pulmonary veins into a routine "search pattern" at computed tomography (CT) and magnetic resonance imaging. This article is a comprehensive CT-based imaging review of the pulmonary veins, including their embryology, anatomy (typical and anomalous), surgical implications, pulmonary vein thrombosis, pulmonary vein stenosis, pulmonary vein pseudostenosis, and the relationship of tumors to the pulmonary veins. Online supplemental material is available for this article. ^©RSNA, 2017.

Usefulness of multidetector computed tomography before and after pulmonary vein isolation

OBJECTIVE

To analyze the usefulness of multidetector computed tomography (MDCT) in the preprocedural evaluation and follow-up of patients undergoing radiofrequency ablation of pulmonary veins and the impact of the MDCT findings on the approach to treatment.

METHOD

We retrospectively analyzed 92 consecutive MDCT studies done in 80 patients between January 2011 and June 2013; 70 (76%) studies were done before a first ablation procedure and 22 (24%) were done in patients who had undergone an ablation procedure.

RESULTS

Findings were useful in 34% of the patients who underwent MDCT before the first ablation procedure and in 68% of the studies done after a procedure. The incidence of stroke associated with the ablation procedure was 3%, similar to the incidence recorded in our center before we started to use MDCT to evaluate the anatomy of the left atrium. All symptomatic patients had some pulmonary vein stenosis, and 80% had significant stenosis. Furthermore, the stenoses progressed very rapidly; treatment with balloon angioplasty was associated with early restenosis. Stenting was an alternative in cases of failed angioplasty.

CONCLUSION

In the preprocedural evaluation and postprocedural follow-up of patients undergoing pulmonary vein isolation, MDCT is useful for guiding treatment and detecting complications.

Guidelines for the Use of Echocardiography in the Evaluation of a Cardiac Source of Embolism

Embolism from the heart or the thoracic aorta often leads to clinically significant morbidity and mortality due to transient ischemic attack, stroke or occlusion of peripheral arteries. Transthoracic and transesophageal echocardiography are the key diagnostic modalities for evaluation, diagnosis, and management of stroke, systemic and pulmonary embolism. This document provides comprehensive American Society of Echocardiography guidelines on the use of echocardiography for evaluation of cardiac sources of embolism. It describes general mechanisms of stroke and systemic embolism; the specific role of cardiac and aortic sources in stroke, and systemic and pulmonary embolism; the role of echocardiography in evaluation, diagnosis, and management of cardiac and aortic sources of emboli including the incremental value of contrast and 3D echocardiography; and a brief description of alternative imaging techniques and their role in the evaluation of cardiac sources of emboli. Specific guidelines are provided for each category of embolic sources including the left atrium and left atrial appendage, left ventricle, heart valves, cardiac tumors, and thoracic aorta. In addition, there are recommendation regarding pulmonary embolism, and embolism related to cardiovascular surgery and percutaneous procedures. The guidelines also include a dedicated section on cardiac sources of embolism in pediatric populations.

Assessments of pulmonary vein and left atrial anatomical variants in atrial fibrillation patients for catheter ablation with cardiac CT

OBJECTIVES

To provide a road map of pulmonary vein (PV) and left atrial (LA) variants in patients with atrial fibrillation (AF) before catheter ablation procedure using cardiac CT.

METHODS

Cardiac CT was performed in 1420 subjects for accurate anatomical information, including 710 patients with AF and 710 matched controls without AF. PV variants, PV ostia and spatial orientation, LA enlargement, and left atrial diverticulum (LAD) were measured, respectively. Differences between these two groups were also respectively compared. Some risk factors for the occurrence of LAD were analyzed.

RESULTS

In total, PV variants were observed in 202 (28.5 %) patients with AF patients and 206 (29.0 %) controls without AF (p = 0.8153). The ostial sizes of all accessory veins were generally smaller than those of the typical four PVs (p = 0.0153 to 0.3958). There was a significant difference of LA enlargement between the AF and control groups (36.3 % vs. 12.5 %, p < 0.0001), while the prevalence of LAD was similar in these two groups (43.2 % vs. 41.9 %, p = 0.6293).

CONCLUSION

PV variants are common. Detailed knowledge of PVs and LA variants are helpful for providing anatomical road map to determine ablation strategy.

KEY POINTS

• PVs variants are helpful for providing anatomical road map to ablation. • PV variants are common. • DSCT could recognize these anatomic features before ablation as a non-invasive imaging.

Reversal of pulmonary vein remodeling after catheter ablation of atrial fibrillation

Background

Pulmonary veins (PV) and the atria undergo electrical and structural remodeling in atrial fibrillation (AF). This study aimed to determine PV and left atrial (LA) reverse remodeling after catheter ablation for AF assessed by chest computed tomography (CT).

Methods

PV electrophysiologic studies and catheter ablation were performed in 63 patients (68% male; mean ± SD age: 56 ± 10 years) with symptomatic AF (49% paroxysmal, 51% persistent). Chest CT was performed before and 3 months after catheter ablation.

Results

At baseline, patients with persistent AF had a greater LA volume (91 ± 29 cm³vs. 66 ± 27 cm³; P = 0.003) and mean PV ostial area (241 ± 43 mm²vs. 212 ± 47 mm²; P = 0.03) than patients with paroxysmal AF. There was no significant correlation between the effective refractory period and the area of the left superior PV ostium. At 3 months of follow-up after ablation, 48 patients (76%) were AF free on or off antiarrhythmic drugs. There was a significant reduction in LA volume (77 ± 31 cm³ to 70 ± 28 cm³; P < 0.001) and mean PV ostial area (224 ± 48 mm² to 182 ± 43 mm²; P < 0.001). Patients with persistent AF had more reduction in LA volume (11.8 ± 12.8 cm³vs. 4.0 ± 11.2 cm³; P = 0.04) and PV ostial area (62 mm²vs. 34 mm²; P = 0.04) than those who have paroxysmal AF. The reduction of the averaged PV ostial area was significantly correlated with the reduction of LA volume (r = 0.38, P = 0.03).

Conclusions

Catheter ablation of AF improves structural remodeling of PV ostia and left atrium. This finding is more apparent in patients with persistent AF treated by catheter ablation.

Collateral findings during computed tomography scan for atrial fibrillation ablation: Let’s take a look around

The growing number of atrial fibrillation catheter ablation procedures warranted the development of advanced cardiac mapping techniques, such as image integration between electroanatomical map and cardiac computed tomography. While scanning the chest before catheter ablation, it is frequent to detect cardiac and extracardiac collateral findings. Most collateral findings are promptly recognized as benign and do not require further attention. However, sometimes clinically relevant collateral findings are detected, which often warrant extra diagnostic examinations or even invasive procedure, and sometimes need to be followed-up over time. Even though reporting and further investigating collateral findings has not shown a clear survival benefit, almost all the working groups providing data on collateral findings reported some collateral findings eventually coming out to be malignancies, sometimes at an early stage. Therefore, there is currently no clear agreement about the right strategy to be followed.

Clinical utility of multi-detector cardiac computed tomography in structural heart interventions

In recent years, there have been major advances in structural interventional cardiology, which have revolutionized the practice of cardiology. Appropriate selection and follow-up of patients undergoing these structural heart interventions is vital. Multi-detector computed tomography (MDCT) has emerged as a key imaging modality in the peri-procedural assessment of patients undergoing multiple structural cardiac interventions. The purpose of this review is to provide an evidence-based clinical update on the roles of MDCT in both established and evolving structural heart interventions, including transcatheter aortic valve replacement (TAVR) and transcatheter mitral valve implantation (TMVI). The utility of MDCT in the peri-procedural assessment of patients undergoing pulmonary vein isolation (PVI) for atrial fibrillation, cardiac resynchronization therapy (CRT) and left atrial appendage (LAA) closure will also be reviewed.

Anatomical mapping for atrial fibrillation ablation: a head-to-head comparison of ultrasound-assisted reconstruction versus fast anatomical mapping

BACKGROUND

Accuracy in left atrial (LA) anatomical reconstruction is crucial to the safe and effective performance of catheter ablation of atrial fibrillation (AF). The aim of this study was to evaluate the accuracy of LA reconstruction performed with intracardiac echocardiography (ICE) as compared to fast anatomical mapping (FAM) both integrated in the CARTO mapping system (Biosense Webster, Diamond Bar, CA, USA).

METHODS

A multislice computed tomography (MSCT) was preacquired from 29 patients with AF who underwent catheter ablation and 3D-LA geometry was reconstructed using both ICE and FAM separately. The accuracy of the LA anatomical definition was evaluated by comparing LA volumes, LA and pulmonary vein (PV) diameters obtained using ICE and FAM versus MSCT (gold standard).

RESULTS

Anterior-posterior and superior-inferior LA diameters were shorter in ICE versus MSCT (32 ± 10 vs 46 ± 9 mm and 48 ± 7 vs 53 ± 7 mm, P < 0.01) but similar in FAM versus MSCT (45 ± 9 vs 46 ± 9 mm and 52 ± 10 vs 53 ± 7 mm). Latero-septal LA diameter was similar in ICE versus MSCT (63 ± 11 vs 63 ± 9 mm) but larger in FAM versus MSCT (69 ± 9 vs 63 ± 9 mm, P < 0.001). LA volume was lower in ICE versus MSCT (73 ± 30 mL vs 116 ± 45 mL, P < 0.0001) and slightly larger in FAM versus MSCT (132 ± 45 vs 116 ± 45 mL, P = 0.06). PV diameters were similar in FAM versus MSCT but significantly underestimated with ICE.

CONCLUSIONS

Overall accuracy in the LA and PV anatomical reconstruction was found to be superior with FAM compared to ICE-guided approach. ICE resulted in a significant underestimate of both LA and PV dimensions, while FAM slightly overestimated LA geometry.

Characterization of Pulmonary Vein Dimensions Using High-Definition 64-Slice Computed Tomography prior to Radiofrequency Catheter Ablation for Atrial Fibrillation

Background. Contrast-enhanced computed tomography is commonly acquired before radiofrequency catheter ablation (RFCA) for atrial fibrillation (AFib) to guide the procedure. We analyzed pulmonary vein (PV) ostial diameter and volumes on a high-definition 64-slice CT (HDCT) scanner in patients with AFib prior to RFCA. Methods and Results. This retrospective study included 50 patients (mean age 60.2 ± 11.4 years, 30 males) undergoing cardiac HDCT scanning before RFCA for drug refractory AFib and 50 age-, BMI-, and sex-matched controls with normal sinus rhythm undergoing HDCT. PV ostial diameter and volume were measured and calculated using a semiautomatic calliper tool. Total ostial PV volume was significantly increased in patients with AFib as compared to controls (P < 0.005). Similarly, total ostial PV diameter was significantly increased in AFib compared to controls (P < 0.001). In AFib, the largest PV volume and diameters were measured in right superior PV (P < 0.05 versus controls). The difference in PV volume between patients and controls was most pronounced in right superior PVs (P = 0.015). Right middle PVs were found more often in patients with AFib (16/50; 32%) than in normal subjects (7/50; 14%). Conclusion. Enlargement of PV ostial area and enlargement of volume are frequent findings in patients with drug refractory AFib. These parameters may add to the risk stratification for AFib recurrence following RFCA.

The incidence, pattern, and prognostic value of left ventricular myocardial scar by late gadolinium enhancement in patients with atrial fibrillation

OBJECTIVES

This study sought to identify the frequency, pattern, and prognostic significance of left ventricular (LV) late gadolinium enhancement (LGE) in patients with atrial fibrillation (AF).

BACKGROUND

There are limited data on the presence, pattern, and prognostic significance of LV myocardial fibrosis in patients with AF. LGE during cardiac magnetic resonance imaging is a marker for myocardial fibrosis.

METHODS

A group of 664 consecutive patients without known prior myocardial infarction who were referred for radiofrequency ablation of AF were studied. Cardiac magnetic resonance imaging was requested to assess pulmonary venous anatomy.

RESULTS

Overall, 73% were men, with a mean age of 56 years and a mean LV ejection fraction of 56 ± 10%. LV LGE was found in 88 patients (13%). The endpoint was all-cause mortality, and in this cohort, 68 deaths were observed over a median follow-up period of 42 months. On univariate analysis, age (hazard ratio [HR]: 1.05; 95% confidence interval [CI]: 1.03 to 1.08; chi-square likelihood ratio [LRχ(2)]: 15.2; p = 0.0001), diabetes (HR: 2.39; 95% CI: 1.41 to 4.09; LRχ(2): 10.3; p = 0.001), a history of heart failure (HR: 1.78; 95% CI: 1.09 to 2.91; LRχ(2): 5.37; p = 0.02), left atrial dimension (HR: 1.04; 95% CI: 1.01 to 1.08; LRχ(2): 6.47; p = 0.01), presence of LGE (HR: 5.08; 95% CI: 3.08 to 8.36; LRχ(2): 28.8; p < 0.0001), and LGE extent (HR: 1.15; 95% CI: 1.10 to 1.21; LRχ(2): 35.6; p < 0.0001) provided the strongest associations with mortality. The mortality rate was 8.1% per patient-year in patients with LGE compared with 2.3% patients without LGE. In the best overall multivariate model for mortality, age and the extent of LGE were independent predictors of mortality. Indeed, each 1% increase in the extent of LGE was associated with a 15% increased risk for death.

CONCLUSIONS

In patients with AF, LV LGE is a frequent finding and is a powerful predictor of mortality.

Pulmonary vein morphology by free-breathing whole heart magnetic resonance imaging at 3 Tesla versus breathhold multi-detector computed tomography

PURPOSE

To compare pulmonary vein and left atrial anatomy using three-dimensional free-breathing whole-heart magnetic resonance imaging (MR) at 3 Tesla (T) and multi-detector computed tomography (MDCT).

MATERIALS AND METHODS

Thirty-three subjects (19 male, age 49 ± 12 years) underwent free-breathing 3T MR and contrast-enhanced MDCT during inspiratory breath hold. Pulmonary vein parameters (ostial areas, diameters, angles) were measured.

RESULTS

All pulmonary veins and anomalies were identified by 3T MR and by MDCT. The right-sided pulmonary veins were directed more posteriorly, the right superior pulmonary vein more inferiorly, and the right inferior pulmonary vein more superiorly by 3T MR when compared with MDCT. The cross-sectional area, perimeters and minimum diameters of right-sided pulmonary vein ostia were significantly larger by MR, as were the maximum diameters of right and left inferior pulmonary veins. There were no significant differences between techniques in distance to first pulmonary vein branch.

CONCLUSION

Pulmonary vein measurements demonstrated significant differences in angulations and dimensions when 3T MR is compared with MDCT. These differences likely represent hemodynamic and respiratory variation during free-breathing with MR versus breath-holding with MDCT. MR imaging at 3T during free-breathing offers an alternate method to define pulmonary vein and left atrial anatomy without exposure to radiation.

Precision of pulmonary vein diameter measurements assessed by CE-MRA and steady-state-free precession imaging

OBJECTIVE

Pulmonary vein (PV) diameter assessment is important for planning and follow-up of PV ablation in atrial fibrillation. Therefore, the aim of our study was to evaluate inter- and intraobserver reliability of PV diameter measurements by contrast-enhanced magnetic resonance angiography (CE-MRA) and ECG-gated 2D multislice unenhanced steady-state-free precession sequences (multislice SSFP).

METHODS

Sixty PV diameters in 17 consecutive patients were measured in transverse and coronal orientation with CE-MRA and multislice SSFP by two observers. Statistics to evaluate inter- and intraobserver reliability included Bland-Altman analysis and F-test.

RESULTS

Intraobserver limits of agreement (LAG) ranged between ±0.50 cm (transverse) and ±0.86 cm (coronal) for CE-MRA versus ±0.40 cm (transverse) and ±0.67 cm (coronal) for multislice SSFP. Interobserver agreement showed LAG ranging between ±0.59 cm (transverse) and ±0.83 cm (coronal) for CE-MRA versus ±0.34 cm (transverse) and ±0.75 cm (coronal) for multislice SSFP. Intra- and interobserver variances did not reveal significant differences between CE-MRA and multislice SSFP in any orientation (all p-values >0.05).

CONCLUSION

Multislice SSFP and CE-MRA enable comparable precision of PV diameter measurements. However, both methods reveal a wide range of intra- and interobserver agreement, which has to be thoroughly considered in clinical use.

KEY POINTS

• Unenhanced magnetic resonance imaging can now provide measurement of pulmonary vein diameters • Steady-state-free precession offers a new method of performing unenhanced MR imaging • Both unenhanced and enhanced MRI measurements show wide intra- and interobserver variation • PV diameter measurements assessed by MRI have to be interpreted with care • Nevertheless, unenhanced MRI might replace some CT examinations for pulmonary vein demonstration.

The Role of Atrial Structural Remodeling in Atrial Fibrillation Ablation:An Imaging Point of View for Predicting Recurrence

Atrial fibrillation (AF) is the most common arrhythmia and is associated with a significant morbidity and mortality. Invasive catheter ablation of AF has emerged as an effective therapy for patients with symptomatic AF. Atrial remodeling, particularly structural remodeling, is important not only for AF persistence but also for AF recurrence after ablation. Atrial dilation and fibrosis are two of the core processes involved in atrial structural remodeling. Increased automaticity and triggered activity occur in atrial structural remodeling, which may cause difficulty in maintaining sinus rhythm after ablation. Furthermore, an enlarged left atrium (LA) may increase the difficulty in achieving catheter stability and thereby require more energy to complete AF ablation. AF causes similar remodeling in both the left and right atria (RA), and myocardial changes in both atria influence AF recurrence. A non-invasive assessment of fibrotic structural remodeling helps predict the outcome of AF ablation. A varie ty of cardiac imaging modalities, such as two- or three-dimensional echocardiography or multi-detector row computed tomography, have been used to estimate the magnitude of atrial structural remodeling by measuring atrial volume or LA function. Furthermore, delayed enhanced cardiac magnetic resonance imaging has been used to detect not only atrial fibrosis but also the effect of the ablation point. Thus, atrial remodeling, particularly structural remodeling, plays an important role in AF recurrence. These non-invasive imaging modalities are significant tools for estimating atrial enlargement to improve patient selection for AF ablation at the point of paroxysmal AF, and for estimating atrial fibrosis to select the AF treatment including ablation strategy at the point of development to persistent or permanent AF.

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

Intracardiac Echocardiography during Catheter-Based Ablation of Atrial Fibrillation

Accurate delineation of the variable left atrial anatomy is of utmost importance during anatomically based ablation procedures for atrial fibrillation targeting the pulmonary veins and possibly other structures of the atria. Intracardiac echocardiography allows real-time visualisation of the left atrium and adjacent structures and thus facilitates precise guidance of catheter-based ablation of atrial fibrillation. In patients with abnormal anatomy of the atria and/or the interatrial septum, intracardiac ultrasound might be especially valuable to guide transseptal access. Software algorithms like CARTOSound (Biosense Webster, Diamond Bar, USA) offer the opportunity to reconstruct multiple two-dimensional ultrasound fans generated by intracardiac echocardiography to a three-dimensional object which can be merged to a computed tomography or magnetic resonance imaging reconstruction of the left atrium. Intracardiac ultrasound reduces dwell time of catheters in the left atrium, fluoroscopy, and procedural time and is invaluable concerning early identification of potential adverse events. The application of intracardiac echocardiography has the great capability to improve success rates of catheter-based ablation procedures.

Pulmonary venous anatomy imaging with low-dose, prospectively ECG-triggered, high-pitch 128-slice dual-source computed tomography

BACKGROUND

The efforts to reduce radiation from cardiac computed tomography (CT) are essential. Using a prospectively triggered, high-pitch dual-source CT protocol, we aim to determine the radiation dose and image quality in patients undergoing pulmonary vein (PV) imaging.

METHODS AND RESULTS

In 94 patients (61±9 years; 71% male) who underwent 128-slice dual-source CT (pitch 3.4), radiation dose and image quality were assessed and compared between 69 patients with sinus rhythm and 25 patients with atrial fibrillation. Radiation dose was compared in a subset of 19 patients with prior retrospective or prospectively triggered CT PV scans without high pitch. In a subset of 18 patients with prior magnetic resonance imaging for PV assessment, PV anatomy and scan duration were compared with high-pitch CT. Using the high-pitch protocol, total effective radiation dose was 1.4 (1.3, 1.9) mSv, with no difference between sinus rhythm and atrial fibrillation (1.4 versus 1.5 mSv; P=0.22). No high-pitch CT scans were nondiagnostic or had poor image quality. Radiation dose was reduced with high-pitch (1.6 mSv) compared with standard protocols (19.3 mSv; P<0.0001). This radiation dose reduction was seen with sinus rhythm (1.5 versus 16.7 mSv; P<0.0001) but was more profound with atrial fibrillation (1.9 versus 27.7 mSv; P=0.039). There was excellent agreement of PV anatomy (κ 0.84; P<0.0001) and a shorter CT scan duration (6 minutes) compared with magnetic resonance imaging (41 minutes; P<0.0001).

CONCLUSIONS

Using a high-pitch dual-source CT protocol, PV imaging can be performed with minimal radiation dose, short scan acquisition, and excellent image quality in patients with sinus rhythm or atrial fibrillation. This protocol highlights the success of new cardiac CT technology to minimize radiation exposure, giving clinicians a new low-dose imaging alternative to assess PV anatomy.

Intracardiac echocardiography: clinical utility and application

Intracardiac echocardiography (ICE) broadens the spectrum of available echocardiographic techniques and provides the operator direct visualization of cardiac structures in real time. ICE has clear advantages over fluoroscopy, transthoracic echocardiography, and transesophageal echocardiography as the imaging modality of choice in the cardiac catheterization and electrophysiological laboratories. With the development of steerable phased array catheters with low frequency and Doppler qualities, there is marked improvement in visualization of left-sided structures from the right heart. Appropriate utilization of ICE is likely to maximize safety and efficacy of complex interventional procedures and may improve patient outcomes. Future advances in ICE imaging will further improve the ease of device guidance and, in combination with new imaging modalities, could dramatically improve other applications of echocardiography which may result in improved patient outcomes. This review describes the technical evolution of ICE, the use of ICE in guiding percutaneous interventional procedures and possible future applications of ICE in the ever-growing field of interventional cardiology.