Detection of left atrial thrombus by intracardiac echocardiography in patients undergoing ablation of atrial fibrillation

The use of cardiac imaging in patients undergoing atrial fibrillation ablation

Cardiac imaging (CI), including echocardiography, multidetector computed tomography (MDCT), and cardiac magnetic resonance (CMR), is gaining increasing interest to aid atrial fibrillation (AF) ablation procedures, from pre-procedural planning to intra-procedural guidance. Transthoracic echocardiography is widely used for imaging, especially for preprocedural assessment, while transesophageal and intracardiac echocardiography (ICE) are used for intraprocedural guidance during transseptal puncture. Cardiac MDCT, leveraging its high spatial resolution, offers a detailed anatomical visualization of cardiac chambers and adjacent structures; moreover, left atrial wall thickness assessed by MDCT may guide radiofrequency energy titration to enhance procedural safety and efficiency. At the same time, CMR allows for detailed myocardial tissue characterization and the detection of fibrosis. ICE, MDCT, and CMR also permit intra-procedural image integration with electroanatomical maps, allowing to be aware of a greater amount of intra-procedural real-time information regarding the anatomy and the local characteristics of the tissue in contact with the ablation catheter. One of the primary objectives of performing CI-aided AF ablations is to increase procedural safety and to permit more personalized procedures, according to the characteristics of each patient. This review offers a comprehensive overview of the current applications of CI during the different phases of AF ablation and explores the potential future applications of CI in this context.

Review of the Etiology, Diagnosis, and Therapy of Left Atrial Thrombus

Thrombi in the left atrial appendage (LAA) are an important cause of systemic thromboembolism in patients with atrial fibrillation. The gold standard for the diagnosis of LAA thrombi is a transesophageal echocardiogram, although cardiac multidetector computed tomography, intracardiac echocardiogram, and cardiac magnetic resonance imaging are alternative diagnostic imaging modalities. When an LAA thrombus is diagnosed, effective anticoagulation is recommended for at least 3 weeks or until thrombus resolution is confirmed on repeat transesophageal echocardiogram. Recent prospective research shows the efficacy of nonvitamin K oral anticoagulants in the treatment of LAA thrombus, which offers a promising alternative to vitamin K antagonists. As an alternative approach, left atrial aspiration thrombectomy has been described in case reports, though there is limited evidence comparing its efficacy to anticoagulation alone.

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.

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.

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.

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.

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

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 .

Intracardiac echocardiography is a safe and effective alternative to transesophageal echocardiography for left atrial appendage thrombus evaluation at the time of atrial fibrillation ablation: The ICE-TEE study

BACKGROUND

Intracardiac echocardiography (ICE) technology has been increasingly accepted as an integral part of atrial fibrillation (AF) ablation procedures. It is still unknown whether ICE can routinely replace transesophageal echocardiography (TEE) for routine thrombus screening in non-selective AF patients.

OBJECTIVE

To assess whether ICE can routinely replace TEE in screening for left atrial (LA)/left atrial appendage (LAA) thrombus in general patients undergoing catheter ablation for AF.

METHODS

A total of 2003 consecutive patients undergoing AF ablation were included. 1155 patients (ICE group) received intra-procedural ICE examination for LA/LAA thrombus screening, while 848 patients (TEE group) received pre-procedure TEE examination. The incidence of thrombus, peri-procedure complications, and hospital efficiency were assessed.

RESULTS

The LA and LAA were adequately visualized in all patients. Five patients in the ICE group and 15 patients in the TEE group were found to have LAA thrombus. The incidence of major periprocedural thrombo-embolic events was comparable between two groups (0.2% vs. 0.1%, p = .76), none were due to undetected LA/LAA thrombus. Other major periprocedural complications occurred at similar rates in both groups, while post-procedure fever was less common in the ICE group (12.7% vs. 17.4%, p < .001). Procedure times and hospital length of stay were both shorter in the ICE group (142 min [87-197 min] vs. 150 min [95-205 min], and 3[2-4] day vs. 4[3-5] day, respectively, both p < .001).

CONCLUSIONS

ICE can replace TEE for atrial thrombus screening in AF patients undergoing ablation without increased complications. An "ICE replacing TEE" workflow can also reduce the incidence of postoperative fever and improve hospital efficiency.

Intracardiac echocardiography Chinese expert consensus

In recent years, percutaneous catheter interventions have continuously evolved, becoming an essential strategy for interventional diagnosis and treatment of many structural heart diseases and arrhythmias. Along with the increasing complexity of cardiac interventions comes ever more complex demands for intraoperative imaging. Intracardiac echocardiography (ICE) is well-suited for these requirements with real-time imaging, real-time monitoring for intraoperative complications, and a well-tolerated procedure. As a result, ICE is increasingly used many types of cardiac interventions. Given the lack of relevant guidelines at home and abroad and to promote and standardize the clinical applications of ICE, the members of this panel extensively evaluated relevant research findings, and they developed this consensus document after discussions and correlation with front-line clinical work experience, aiming to provide guidance for clinicians and to further improve interventional cardiovascular diagnosis and treatment procedures.

Can intracardiac echocardiography completely replace transesophageal echocardiography to guide left atrial appendage closure?-The comparisons of intracardiac echocardiography with transesophageal echocardiography

Left atrial appendage closure (LAAC) is an effective means of preventing ischemic stroke in patients with nonvalvular atrial fibrillation. Transesophageal echocardiography (TEE) is the primary imaging technique to guide LAAC. Its shortcomings, namely the use of general anesthesia and tracheal intubation, inevitably increase procedural risks. Intracardiac echocardiography (ICE), a novel imaging modality for guiding LAAC, has proven more advantageous over TEE due to use of local anesthesia, shortened procedural time, and reduced radiation exposure. This review highlights the differences between ICE and TEE guided LAAC, aiming to provide a reference for clinical decision-making.

Cardiac Tomography and Cardiac Magnetic Resonance to Predict the Absence of Intracardiac Thrombus in Anticoagulated Patients Undergoing Atrial Fibrillation Ablation

Background: Pulmonary veins isolation (PVI) is a standard treatment for recurrent atrial fibrillation (AF). Uninterrupted anticoagulation for a minimum of 3 weeks before ablation and exclusion of left atrial (LA) thrombus with transesophageal echography (TEE) immediately before or during the procedure minimize peri-procedural risk. We aimed to demonstrate the utility of cardiac tomography (CT) and cardiac magnetic resonance (CMR) to rule out LA thrombus prior to PVI. Methods: Patients undergoing PVI for recurrent AF were retrospectively evaluated. Only patients that started anticoagulation at least 3 weeks prior to the CT/CMR and subsequently uninterrupted until the ablation procedure were selected. An intracardiac echo (ICE) catheter was used in all patients to evaluate LA thrombus. The results of CT/CMR were compared to ICE imaging. Results: We included 272 consecutive patients averaging 54.5 years (71% male; 30% persistent AF). Average CHA2DS2VASC score was 0.9 ± 0.83 and mean LA diameter was 42 ± 5.7 mm, 111 (41%) patients were on Acenocumarol and 161 (59%) were on direct oral anticoagulants. Anticoagulation was started 227 ± 392 days before the CT/CMR, and 291 ± 416 days before the ablation procedure. CT/CMR diagnosed intracardiac thrombus in two cases, both in the LA appendage. A new CT/CMR revealed resolution of thrombus after six additional months of uninterrupted anticoagulation. No macroscopic thrombus was observed in any patients with ICE (negative predictive value of 100%; p < 0.01). Conclusions: CT and MRI are excellent surrogates to TEE and ICE to rule out intracardiac thrombus in patients adequately anticoagulated prior AF ablation. This is true even for delayed procedures as long as anticoagulation is uninterrupted.

Intracardiac versus transesophageal echocardiography for diagnosis of left atrial appendage thrombosis in atrial fibrillation: A meta-analysis

INTRODUCTION

Left atrial appendage (LAA) thrombus in patients with atrial fibrillation is usually detected by transesophageal echocardiography (TEE). Intracardiac echocardiography (ICE) can be a suitable alternative to detect thrombosis. However, the effectiveness of the two methods for detecting LAA thrombus is still unclear, we performed a meta-analysis that compared ICE versus TEE for LAA thrombosis.

METHODS

We searched PubMed, Cochrane Library, and Embase for published abstracts and manuscripts on June 1, 2020. The analysis was performed using RevMan 5.3, STATA 15, and Meta-Disc 1.4.

RESULTS

Eight studies consists of 1108 patients (TEE = 558 vs. ICE = 550) were included. The average sensitivity of ICE and TEE to diagnose LAA thrombus is 1.0 (95% CI: 0.91-1.00) versus 0.68 (95% CI: 0.49-0.83), and specificity of ICE and TEE to diagnosis of LAA thrombus is 1.0 (95% CI: 0.99-1.00) versus 0.98 (95% CI: 0.96-0.99). The AUC of ICE and TEE is 0.9846 (SEAUC = 0.0196) and 0.9655 (SEAUC = 0.0401), and the Q* statistics is 0.9462 (SEQ* = 0.0406) and 0.9127 (SEQ * = 0.0616), respectively. Z test was performed on Q* statistics (Z = 0.45, p > .05).

CONCLUSION

The ICE and TEE have similar diagnostic efficacy for LAA thrombosis, but the ICE has higher sensitivity. Compared with TEE, ICE may be more advantages and prospects for clinical application.

Catheter ablation of atrial fibrillation: cardiac imaging guidance as an adjunct to the electrophysiological guided approach

Catheter ablation is increasingly utilized to treat patients with atrial fibrillation (AF). Despite progress in technology and procedural strategy, there remain significant limitations with suboptimal outcomes. The role of imaging has continued to evolve, and multimodality imaging now presents an important opportunity to make substantial progress in the safety and efficacy of ablation. In this review, we discuss the history of imaging in the ablation of AF with a specific focus on the ability of cardiac computed tomography and magnetic resonance imaging to characterize anatomy, arrhythmogenic substrate, and guide ablation strategy. We will review the progress that has been made and highlight many of the limitations as well as future directions for the field.

Prone-position computed tomography in the late phase for detecting intracardiac thrombi in the left atrial appendage before catheter ablation for atrial fibrillation

BACKGROUND

Contrast computed tomography (CT) is a useful tool for the detection of intracardiac thrombi. We aimed to assess the accuracy of the late-phase prone-position contrast CT (late-pCT) for thrombus detection in patients with persistent or long-standing persistent atrial fibrillation (AF).

METHODS

Early and late-phase pCT were performed in 300 patients with persistent or long-standing AF. If late-pCT did not show an intracardiac contrast defect (CD), catheter ablation (CA) was performed. Immediately before CA, intracardiac echocardiography (ICE) from the left atrium was performed to confirm thrombus absence and the estimation of the blood velocity of the left atrial appendage (LAA). For patients with CDs on late-pCT, CA performance was delayed, and late-pCT was performed again after several months following oral anticoagulant alterations or dosage increases.

RESULTS

Of the 40 patients who exhibited CDs in the early phase of pCT, six showed persistent CDs on late-pCT. In the remaining 294 patients without CDs on late-pCT, the absence of a thrombus was confirmed by ICE during CA. In all six patients with CD-positivity on late-pCT, the CDs vanished under the same CT conditions after subsequent anticoagulation therapy, and CA was successfully performed. Furthermore, the presence of residual contrast medium in the LAA on late-pCT suggested a decreased blood velocity in the LAA ( ≤ 15 cm/s) (sensitivity = 0.900 and specificity = 0.621).

CONCLUSIONS

Late-pCT is a valuable tool for the assessment of intracardiac thrombi and LAA dysfunction in patients with persistent or long-standing persistent AF before CA.

Epicardial and Coronary Sinus Echocardiography

Catheter-based ultrasonography is a widely used tool in cardiac electrophysiology practice, and intracardiac echocardiography is supplanting other forms of imaging to become the dominant imaging modality. Given advances in pericardial access, intrapericardial echocardiography can be performed using ultrasound catheters as well. Intrapericardial echocardiography and echocardiography from the coronary sinus, also an epicardial structure, allows interventionalists to obtain unique views from virtually any vantage point, compared with other forms of echocardiography. Both intrapericardial echocardiography and coronary sinus echocardiography are safe and important alternatives that can be used during complex procedures in the electrophysiology laboratory.

Sympathetic responses induced by radiofrequency catheter ablation of atrial fibrillation

Radiofrequency catheter ablation (RFCA) is a frequently performed procedure in patients with atrial fibrillation. Prior studies have shown that the RFCA may directly stimulate vagal afferents during the procedure, whereas the vagal tone assessed by heart rate variability (HRV) is lowered weeks after the RFCA procedure. The effects of RFCA performed in the left atrium on sympathetic nerve activity have not been assessed. In the present study, we hypothesized that RFCA would lower muscle sympathetic nerve activity (MSNA) during ablation and would raise MSNA 1 day postablation. A total of 18 patients were studied. In protocol 1 ( n = 10), electrocardiogram, blood pressure, and MSNA in the peroneal nerve were recorded through the RFCA procedure performed in the electrophysiology laboratory. In protocol 2, eight patients were studied before the procedure and 1 day postablation. RFCA led to a decrease in MSNA immediately after the procedure (25.4 ± 3.2 to 17.2 ± 3.8 bursts/min, P < 0.05). Cardiac parasympathetic activity was determined using indexes of HRV and increased during the procedure. One day postablation, MSNA was above baseline values (21.3 ± 3.7 to 35.7 ± 2.6 bursts/min, P < 0.05). HRV indexes of cardiac parasympathetic activity fell, and the HRV index of sympathovagal balance was not significantly altered. The results show that RFCA raised cardiac parasympathetic activity and decreased MSNA during the procedure. One day postablation, MSNA rose and cardiac parasympathetic activity fell. In addition, RFCA evokes differentiated sympathetic responses directed to the heart and skeletal muscles. NEW & NOTEWORTHY The effects of radiofrequency catheter ablation performed in the left atrium on muscle sympathetic nerve activity (MSNA) have not been assessed. The results of this study show that radiofrequency catheter ablation raised cardiac parasympathetic activity and decreased MSNA during the procedure. One day postablation, MSNA rose and cardiac parasympathetic activity fell. We speculate that the partial autonomic afferent denervation induces these effects on autonomic activity.

A standardized protocol to reliably visualize the left atrial appendage with intracardiac echocardiography: Importance of multiple imaging sites

BACKGROUND

Currently, there is no accepted protocol for left atrial appendage (LAA) imaging with intracardiac echocardiography (ICE).

OBJECTIVE

This study aimed to assess the utility of ICE to reliably visualize the entire cavity of the LAA and propose a specific procedural protocol to achieve the above objective.

METHODS

We created a three-dimensional reconstruction of the LAA, using two-dimensional ICE sections obtained from three different location (the right atrium [RA], right ventricle inflow [RVI], and right ventricular outflow [RVOT]). We then compared the three-dimensional LAA reconstruction by ICE with one obtained by cardiac computed tomography angiography (CCTA) for morphological and volume differences.

RESULTS

Three-dimensional reconstruction with ICE could reliably reproduce the LAA as visualized with CCTA but only when ICE sampling was performed from at least two catheter positions. There was no statistically significant difference between LAA volumes obtained with ICE and CCTA (P = 0.33). The contribution of each anatomical location to the total volume was 17% ± 16.6%, 74% ± 13.3%, and 33% ± 26% for RA, RVI, and RVOT, respectively.

CONCLUSION

In comparison with CCTA, the LAA can be reliably visualized in its entity by ICE, but only if multiple imaging positions (RA, RV inflow, and RVOT) are used.

Intracardiac echocardiography for verification for left atrial appendage thrombus presence detected by transesophageal echocardiography: the ActionICE II study

BACKGROUND

Transesophageal echocardiography (TEE) remains the gold standard for exclusion of left atrial appendage (LAA) thrombus in patients scheduled for direct electrical cardioversion (DEC) or atrial fibrillation (AF) ablation. Recently, intracardiac echocardiography (ICE) of the pulmonary artery (PA) has been shown to provide excellent LAA images and to be useful in verification of equivocal TEE findings.

HYPOTHESIS

ICE of the PA may have a role in detecting false-positive TEE results.

METHODS

Twenty-one patients (12 male, age 65 ± 8 years, CHADS2VASC2 score [congestive heart failure, hypertension, age ≥ 75, age 65-74, diabetes mellitus, stroke/TIA/thrombo-embolism, vascular disease, sex female] = 2.2; HAS-BLED score [hypertension, abnormal renal and liver function, stroke, bleeding, labile International Normalized Ratio, elderly, drugs or alcohol] = 1.1), in whom a thrombus in the LAA was detected during TEE before DEC or AF ablation, underwent ICE of the PA.

RESULTS

On TEE, in 7 (33%) patients, the LAA thrombus was described as "solid" and in the remaining 14 (67%) as "soft." Disagreement between the TEE and ICE (thrombus in TEE and no thrombus in ICE) was found in 9 (43%) patients. In the solid thrombus group, ICE confirmed thrombi existence in 6 and excluded thrombi in 1 patient. In the soft thrombus group, ICE confirmed thrombi in 6 patients and excluded thrombi in the remaining 8 patients. Of the demographic and clinical variables, only the longstanding persistent type of AF was significantly associated with the presence of an LAA thrombus detected both by TEE and ICE.

CONCLUSIONS

With TEE, a false positive of an LAA thrombus may be indicated, especially when a thrombus is described as soft rather than solid. Our study suggests that ICE may be a valuable option for verification of a TEE-based diagnosis of a thrombus.