Skip to main content
NCBI home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2016 May 5.
Published in final edited form as: Heart Rhythm. 2015 Sep 1;13(1):12–19. doi: 10.1016/j.hrthm.2015.09.002

Effectiveness of Integrating Delayed Computed Tomography Angiography Imaging for Left Atrial Appendage Thrombus Exclusion into the Care of Patients Undergoing Ablation of Atrial Fibrillation

Kenneth C Bilchick 1,*, Augustus Mealor *, Jorge Gonzalez 1, Patrick Norton 1,3, David Zhuo 1, Pamela Mason 1, John D Ferguson 1, Rohit Malhotra 1, J Michael Mangrum 1, Andrew E Darby 1, John DiMarco 1, Klaus Hagspiel 1,3, John Dent 1, Christopher M Kramer 1,3, George J Stukenborg 4, Michael Salerno 1,2,3
PMCID: PMC4858349  NIHMSID: NIHMS723328  PMID: 26341605

Abstract

Background

Computed tomography angiography (CTA) can identify and rule out left atrial appendage (LAA) thrombus when delayed imaging is also performed.

Objective

In patients referred for CTA for pulmonary vein anatomy prior to ablation of atrial fibrillation or atypical left atrial flutter (AF), we sought to determine the effectiveness of a novel clinical protocol for integrating results of CTA delayed imaging of the LAA into pre-procedure care.

Methods

After making delayed imaging of the LAA part of our routine pre-ablation CTA protocol, we integrated early reporting of pre-ablation CTA LAA imaging results into clinical practice as part of a formal protocol in June 2013. We then analyzed the effectiveness of this protocol by evaluating 320 AF ablation patients with CTA imaging during 2012–2014.

Results

Among CTA patients with delayed LAA imaging, the sensitivity and negative predictive values for LAA thrombus with intracardiac echocardiography (ICE) or transesophageal echocardiograms (TEEs) as the reference standard were both 100%. ICE during ablation confirmed absence of thrombus in patients with a negative CTA or negative TEE. No patients with either a negative CTA or an equivocal CTA combined with a negative TEE had strokes or transient ischemic attacks. Overall, the need for TEEs decreased from 57.5% to 24.0% during the 3-year period as a result of the CTA protocol.

Conclusions

Clinical integration of CTA with delayed LAA imaging into the care of patients having catheter ablation of AF is feasible, safe, and effective. Such a protocol could be applied broadly to improve patient care.

Keywords: atrial fibrillation, catheter ablation, computed tomography angiography, transesophageal echocardiography, stroke

Introduction

The prevalence of paroxysmal or persistent atrial fibrillation (AF) has been recently estimated to be 2.2 million in the United States,1 and the prevalence of stroke in patients with nonvalvular AF has been estimated to be 5–8%.2 Although catheter ablation for atrial fibrillation3–5 is indicated for most patients with symptomatic paroxysmal and persistent arrhythmia,6 the optimal strategy for ruling out thrombus in the left atrial appendage (LAA) prior to catheter ablation is unclear. Although transesophageal echocardiography (TEE) is currently considered the gold standard,7 it is a semi-invasive procedure associated with patient discomfort and a small risk of complications. Computed tomography angiography (CTA) is commonly utilized to visualize pulmonary vein anatomy prior to left atrial ablation for pulmonary vein isolation for AF. There is growing evidence suggesting that CTA could provide a non-invasive alternative to TEE for evaluation of LAA thrombus in patients who are already having a CTA to evaluate pulmonary vein anatomy prior to ablation, particularly if delayed LAA imaging is performed as part of the CTA imaging protocol.8–18 With these considerations in mind, we hypothesized that among patients undergoing a clinically ordered CTA study for pre-procedure evaluation of pulmonary vein anatomy prior to AF ablation, a clinical protocol with early reporting of the CTA delayed imaging results prior to the procedure and confirmatory intracardiac echocardiography (ICE) evaluation of the LAA during the procedure could improve clinical efficiency, maintain patient safety, and reduce the need for TEE procedures and their corresponding costs prior to catheter ablation of AF.

Methods

Cohort Selection

The study was approved by the Institutional Review Board for Human Subjects Research at the University of Virginia. Patients with ablation of AF (term includes both atrial fibrillation and atypical left atrial flutter in this report) and CTA imaging prior to ablation during the years 2012–2014 at the University of Virginia Health System were identified using a query of the electronic medical record. Patients with TEEs during this period were identified in a similar fashion. The data on these procedures were then merged based on the medical record number using statistical software (SAS 9.4, Carey, NC).

CTA Clinical Protocol

Prior to the study period, pre-procedure imaging with CTA or cardiac magnetic resonance had become the standard clinical practice for most of our patients undergoing catheter ablation of AF in order to define pulmonary vein anatomy. In October of 2012, we began to perform delayed imaging of the LAA as part of our routine pre-ablation CTA protocol. In June 2013, we integrated prompt reporting of these results into clinical practice according to the clinical protocol described in Figure 1. The choice to utilize the clinical protocol was left to the discretion of the attending electrophysiologist who would be performing the ablation procedure, and patient characteristics including CHA2DS2VASc scores19 were also integrated as shown in the figure.

Figure 1.

Figure 1

Open in a new tab

CTA Protocol for Patients Undergoing Catheter Ablation of Atrial Fibrillation. A flowchart demonstrating the clinical protocol for pre-procedure imaging is shown.

According to the clinical protocol, an outpatient pre-procedure visit was scheduled before 9:00 am on the pre-procedure day, and a CTA was performed at 9:00 am to follow the office visit while the patient was still in the fasting state. The imager interpreting the study then provided an early read of the CTA for LAA thrombus and reported these results to our clinical nursing staff prior to 12:00 noon. Patients were instructed to remain in the hospital in a fasting state until noon and informed that they may need a TEE later that day depending on the results of the CTA.

If the early read of the CTA was negative for LAA thrombus, the nursing staff communicated this to the patients and let them know that they no longer needed to remain fasting, that they could return home, and that the ablation procedure would proceed as scheduled the following day. If the early read of the CTA was positive or equivocal for LAA thrombus, the nursing staff activated the add-on TEE appointment slot at 3:00 pm that day and told the patients that they should continue fasting. If the TEE was positive for LAA thrombus or another concerning finding, the ablation procedure would be cancelled.

Intraprocedural Intracardiac Echocardiography

In all ablation procedures, ICE examinations of the LAA were performed to confirm the results of the CTA. ICE is a standard part of our ablation procedures, and we routinely visualize the LAA in all patients as standard of care. Phased-array ICE (Acunav or Soundstar, Biosense Webster) was used in the majority of patients, while rotational ICE (Boston Scientific) was used in other patients. All EP operators are highly experienced with ICE, and the protocol for LAA imaging with each type of ICE is standardized. When phased array ICE is used, the catheter is positioned just beyond the tricuspid valve to image the LAA and the ridge between the appendage and left superior pulmonary vein. With rotational ICE, the catheter is positioned in the left atrium at the base of the left atrial appendage and carefully rotated and advanced to visualize the appendage completely. We believed this was preferable to performing TEEs routinely in all patients in the Electrophysiology Laboratory after induction of general anesthesia for several reasons, including: 1) TEEs performed as part of the procedure add additional time to the procedure and require coordination with echocardiography staff; 2) performance of routine TEEs is associated with some additional risk of complications, particularly in AF ablation patients, in whom protection of the esophagus is of high importance; and 3) aborting an ablation procedure after the patient has been taken to the electrophysiology laboratory and has had induction of general anesthesia subjects the patients to additional risk and is more inefficient than cancelling the procedure prior to the procedure day.

CTA Imaging Protocol

CTAs were performed using a non-gated Siemens FLASH sequence with high-pitched acquisition mode, ref mAs 200, ref Kv 120kVp, and care kV mode, which selects actual mAs and kVp based on the CT topogram. Using a bolus tracking technique and a 60cc bolus of IV contrast, imaging of the left atrial volume commenced 4 seconds after contrast enhancement reached 150 Hounsfield units (HU) in a region of interest in the left atrium. A delayed image volume tailored to the region of the left-atrial appendage was acquired 40 seconds after the initial CTA. Non-contrast images were not acquired because they do not contribute significantly to diagnostic utility.

Interpretation of CTA Results

Four dedicated attending cardiac imagers (MS, CMK, PN, KH) each with 6–8 years of experience interpreting cardiac CTAs, including level III training in CTA, read the CTA images in this study. CTAs are read daily by our cardiac imaging service, which includes one of these attending cardiac imager and several other physicians. All equivocal or positive CTAs in the present series were also read by at least one other cardiac imaging attending (MS, CMK, PN, or KH), and agreement was achieved in all cases. With respect to image viewing, we use both axial planar viewing and MPR 3-D reconstruction. Regarding the latter, the method used was iterative reconstruction (SAFIRE) with SAFIRE level set to 3, and images were reconstructed at 0.5mm with a 0.4mm increment. A CTA was read as negative if there were no filling defects in the LAA with delayed imaging and positive if there was a definite filling defect on delayed imaging of the LAA that had typical appearance of thrombus. A CTA was read as equivocal if there was a hypointensity in the LAA on delayed imaging that could not be definitively differentiated from a trabeculation or appeared to be possibly caused by an artifact.

Assessment of Procedure-Related Stroke/TIA Events

Procedure-related strokes and TIAs were defined as events occurring within one month of the procedure. This clinical endpoint was assessed at routine clinical follow-up one month after the procedure in all patients.

Statistical Methods

Statistical analyses were performed using SAS 9.4 (SAS, Cary, NC). Distributional characteristics of continuous variables were described using medians and interquartile ranges, and differences between groups for these variables were compared using the Wilcoxon rank sum test. Categorical variable distributions were described based on the number and percentage of each value of the variable in each group, and differences between groups were compared using the Fisher exact test. Correlations were described using the Pearson correlation coefficient, and the associated p-value was reported. Characteristics of patients based on CHA2DS2VASc scores and whether TEEs were performed were determined based on review of the patient’s electronic medical record.

Results

Characteristics of Ablation Patients with CTA Imaging

We evaluated 320 consecutive patients with delayed imaging of the LAA performed within one week of the catheter ablation during the time period 2012–2014. As shown in the Table, the median age of patients in the entire cohort with and without TEEs during the entire evaluation period was not different (66.8 v. 63.7 years; p=0.13). The proportion of females was also similar between these two groups (p=0.80). Patients with pre-ablation CTAs were more likely to have TEEs if they had persistent atrial fibrillation (37.2% v. 15.4%; p<0.001) or hypertension (70.8% v. 56.0%; p=0.01).

Table.

No TEE (n=207) TEE (n=113) P-value
Age [yrs; median(IQR)] 63.7 (57.1–70.8) 66.8 (57.9–72.8) 0.13
Female [n (%)] 61 (29.4%) 31 (27.4%) 0.80
Persistent AF [n (%)] 32 (15.4%) 42 (37.2%) <0.001
Heart Failure [n (%)] 34 (16.4%) 24 (21.2%) 0.29
Hypertension [n (%)] 116 (56.0%) 80 (70.8%) 0.01
Diabetes [n (%)] 28 (13.5%) 17 (15.0%) 0.74
Stroke [n (%)] 9 (4.3%) 9 (8.0%) 0.21
Vascular Disease [n (%)] 33 (16.0%) 19 (16.8%) 0.87
CHA2DS2_VASc 0.22
0–2 [n (%)] 141 (68.1%) 67 (59.3%)
3–4 [n (%)] 54 (26.1%) 40 (35.4%)
>5 [n (%)] 12 (5.8%) 6 (5.3%)
Open in a new tab

Performance of Delayed CTA Imaging

In this cohort, delayed CTA imaging had an excellent performance for identification of LAA abnormalities, and all positive or equivocal CTAs were confirmed by two experienced attending cardiac imaging physicians, as described in the Methods. Two patients with positive CTAs and confirmed LAA thrombus had their procedures postponed. Both of these patients had persistent AF and CHA2DS2VASc scores of 2. An example of the filling defects seen clearly on one of these patients and the thrombus seen on TEE is shown in Figure 2. Six CTAs had equivocal findings on delayed imaging of the LAA, and all subsequently had TEEs that were negative for LAA thrombus. Of these patients, three had prominent trabeculations, and two had significant spontaneous echo contrast in the left atrium. These patients went on to have the ablation procedures performed. During the ablation procedures, absence of left atrial appendage thrombus was confirmed by intracardiac echocardiography, as per our usual protocol. No peri-procedure strokes or transient ischemic attacks occurred in these patients, and there were also no esophageal complications in any patients. No patients with negative CTAs had thrombus on TEEs (if performed) or intraprocedural intracardiac echocardiography, and none of these patients with negative CTAs had procedural-related strokes or transient ischemic attacks, either. Overall, the sensitivity and negative predictive value of negative delayed CTA imaging result for LAA thrombus using ICE as the reference standard was 100% (Figure 3). The specificity of the test when grouping positive and equivocal CTA results together and comparing versus a negative CTA result was 98%.

Figure 2.

Figure 2

Open in a new tab

Examples of Normal and Abnormal CTA Imaging of the Left Atrial Appendage. Filling defects in the left atrial appendage are seen with CTA (yellow arrows). For the case in which the filling defect was seen on both early and delayed imaging (row C), the findings were confirmed by TEE (true positive). For the case in which the filling defect was seen on early but not delayed imaging (row B), the finding was not confirmed by TEE (false positive).

Figure 3.

Figure 3

Open in a new tab

Performance of CTA with Delayed Imaging with Respect to the Reference Standard of TEE. The sensitivity, specificity, positive predictive value, and negative predictive value for CTA with delayed imaging relative to TEE as the reference standard are shown. In determining the specificity, equivocal CTA results may be grouped with the positive CTA results or the negative CTA results. Specificity results based on both methods are shown in the example.

Radiation Dose

The radiation dose was low, with an average/median DLP of 257.5/264 mGy-cm (which corresponds to an effective dose of 3.6 mSv using a coefficient of 0.014 mSv/mGy-cm).

CTA Results, TEE Results, and Protocol Participation by Patient Subgroup

As shown in Figure 4, 232 of the 320 patients had CTAs performed during the protocol period. Of these 232 patients, 216 were in the low-intermediate risk category, and 213/216 had negative CTAs. The majority of these patients (163/216, or 75.4%) went through the protocol process for determination of the need for TEEs. Among the remaining 24.6% of patients, 53 low-intermediate risk patients with negative CTAs had TEEs performed, anyway, at the ordering physician’s discretion (allowed because the protocol was optional), and 11 high-risk patients with negative CTAs (in whom the protocol recommended TEEs regardless of the CTA results) did not have TEEs ordered. The latter observation reflects increasing physician confidence in the protocol even for high-risk patients, which was validated by the fact that none of these 11 high-risk patients had evidence of LAA thrombus on ICE or strokes/TIAs during the postoperative period. Of note, all patients with equivocal or positive CTAs had TEEs performed as recommended by the protocol.

Figure 4.

Figure 4

Open in a new tab

CTA and TEE Results by Patient Subgroup and Time Period. The number of patients having different CTA and TEE results are shown by patient subgroup and time period. LAA=left atrial appendage. LAAT=left atrial appendage thrombus. SEC=spontaneous echo contrast.

Temporal Trends in Pre-Ablation CTA Results and TEE Imaging

Figure 5 shows that the proportion of patients with pre-ablation CTAs with delayed imaging who had TEEs also significantly decreased from 57.5% in the first half of 2012 to an ending value of 24.0% in the second half of 2014. As shown in the figure, the marked additional reduction in the number of TEEs that were performed after this optional protocol was made available to our patients after June 2013 were mostly in patients for whom the protocol was not used, most commonly for one of the reasons listed in Figure 1. Interestingly, the decrease in the need for TEEs was associated with a progressive increase in the distribution of CHA2DS2VASc scores of patients during the study period, as discussed also in the subsequent section.

Figure 5.

Figure 5

Open in a new tab

Temporal Trends in Pre-Procedure TEE Imaging Prior to Catheter Ablation of Atrial Fibrillation. The proportion of patients with TEEs after pre-procedure CTA imaging has markedly decreased since the institution of the CT protocol in June 2013.

With respect to temporal trends in patients meeting protocol criteria for TEE before and after protocol initiation in mid-2013, 3/81 low-intermediate risk patients prior to protocol initiation would have met protocol criteria for TEEs based on the CTA results, while 3/216 low-intermediate risk patients after protocol initiation met protocol criteria for CTA results. If the protocol were extended to high-risk patients, 0/7 high-risk patients would have met protocol criteria for TEEs prior to protocol initiation, and 2/14 high-risk patients would have met protocol criteria for TEEs after protocol initiation. Overall, only 1–3% of the TEEs performed during each 6-month time period after June 2013 in patients with preoperative CTA with delayed LAA imaging were associated with positive or equivocal LAA findings on the CTA. Considering that there were no perioperative strokes or TIAs in any of these patients, these findings suggest the proportion of patients who need TEE prior to ablation is even lower. Of note, there were no significant differences before and after CT protocol initiation in patients with a prior ablation in the preceding year (8.1% versus 10.3%; p=0.48).

Temporal Trends in Stroke Risk Score

With respect to temporal trends in the risk of stroke, the mean CHA2DS2VASc score of patients in 2013 was lower than that of the patients in 2014 (1.75 v. 2.27; p=0.0016), and the frequency distribution for the percentage of TEEs in each CHA2DS2VASc score group was also significantly shifted toward higher scores (p=0.05 by Fisher exact test) in 2014. The decrease in TEEs in CTA patients in 2014 with the CTA protocol is very interesting considering that, if anything, patients in 2014 had a higher stroke risk. TEEs were more commonly performed in patients with higher CHA2DS2VASc scores in 2013 (r=0.88 for the correlation between CHA2DS2VASc score versus the percent of TEEs ordered by CHA2DS2VASc group in 2013; p=0.047), while the corresponding correlation was not significant in 2014 (r=0.76; p=0.13) (Figure 6). The weaker relationship in the later time period between the CHA2DS2VASc score and the decision to perform a TEE may reflect increasing physician confidence in negative CTA imaging of the LAA after institution of the clinical protocol even in patients with higher CHA2DS2VASc scores.

Figure 6.

Figure 6

Open in a new tab

TEEs Performed Prior to Catheter Ablation by CHA2DS2VASc Score and Year. The proportion of patients with pre-procedure CTA imaging who also received TEEs is shown by CHA2DS2VASc score and by time period (2014 versus prior to 2014).

Discussion

The key findings of this analysis are: 1) a novel clinical protocol with early reporting of the results of CTA delayed imaging of the LAA to inform the need for TEEs prior to AF ablation is feasible; 2) there is excellent agreement among CTA results, transesophageal echocardiography (TEE) findings (when performed), and intraprocedural intracardiac echocardiography findings; 3) CTA was associated with very low radiation doses; 4) the clinical protocol markedly reduced the number of TEEs in patients with pre-ablation CTAs from 57.5% to 24%; and 5) the protocol had an excellent safety profile, with no peri-procedural strokes/TIAs or esophageal complications.

While previous studies have shown that CTA has a high negative predictive value for left atrial appendage thrombus,8–18 we provide the first report of how the pre-procedure CTA results can be integrated with other ultrasound imaging modalities for the patient undergoing AF ablation to improve clinical efficiency, promote patient safety, reduce the need for TEEs, and reduce costs. Prior to initiating this program, patients would typically be NPO for much of the pre-procedure day until after they completed their pulmonary vein imaging study and TEE in the early afternoon, and then would fast again for a significant proportion of the procedure day until they had recovered enough from sedation. In addition, the TEE probe represented another potential irritant to the oropharynx in addition to the endotracheal tube placed during the procedure, as well as a potential source of esophageal injury for patients in whom esophageal protection is of major concern because of the left posterior wall ablation performed in proximity to the esophagus during the ablation procedure. Considering that CTA with delayed imaging has a very high negative predictive value for LAA thrombus, the TEE was providing redundant information in many cases, such that the ratio of risks to benefits associated with the TEE was no longer favorable in many patients. In other words, although TEE imaging is very powerful and very useful for a number of clinical applications, the protocol helped to reduce the use of TEE imaging when a negative evaluation for LAA thrombus had already been achieved using another imaging modality (CTA).

CTA provides excellent definition of pulmonary vein anatomy prior to AF ablation, which can be helpful in defining the presence of a left common os, a right middle vein, an accessory vein, or other variant anatomical findings, as well as pulmonary vein and left atrial dimensions. In addition, the relationship between the left atrium and esophagus are defined well with CTA, and relevant other extracardiac structures are visualized well. With the addition of delayed imaging, CTA now can also provide high-quality imaging of filling defects in the LAA. Although cardiac magnetic resonance is an alternative to CTA for definition of pulmonary vein anatomy, and late gadolinium enhancement and cine findings may be desired in some patients for whom evaluation of myocardial scar and/or valvular function is needed, CTA is generally recognized as being superior to cardiac magnetic resonance for exclusion of LAA thrombus, as current cardiac magnetic resonance protocols for exclusion of LAA thrombus are not adequate in most cases. Furthermore, although it is true that there is no radiation association with CMR, the radiation dose is quite low with the current CTA protocol, so this should not be a deterrent to its use. The CTA dose could also be further reduced by using 100 kVp in the majority of patients.

An alternative to our approach would be to perform risk stratification based on the likelihood of LAA thrombus using baseline patient characteristics or risk scores such as the 20,21 and not integrate CTA into the pre-ablation protocol. This approach CHA2DS2VASc score, is limited by the lower accuracy of risk stratification based on patient characteristics alone as compared with the present protocol based both patient characteristics and CTA delayed imaging of the LAA, which is integrated into a CTA exam that would be performed, anyway, for pulmonary vein anatomy. Notably, in our study, none of the patients with a negative CTA had a thrombus identified by TEE regardless of whether they were considered high risk or not using baseline characteristics, offering the possibility of extending the protocol to patients with a higher risk of thrombus. One exception may be patients with prior interventional closure of the LAA, who would likely benefit from a TEE in addition to the CTA because of the possibility of incomplete closure and the complexity of evaluating the LAA in this setting. A TEE may also provide important information with respect to flow and spontaneous echo contrast in selected high-risk patients and those with equivocal CTA findings of the LAA.18

Limitations

The present report is designed to show the impact of a novel clinical protocol on clinical efficiency, patient outcomes, and patient safety. It is not a randomized study of one intervention versus another for a couple of reasons. First, clinical practice varies from physician to physician, there is significant experience with TEEs, and we did not want to prevent our EP physicians from ordering a TEE if they thought it was indicated. Second, we wished to evaluate the effect of this optional clinical protocol on clinical practice without mandating its use, and we believe the popularity of this clinical protocol among our physicians is a testament its utility. As our electrophysiologists became more comfortable with the protocol, we saw increased utilization of this protocol. Another limitation of this study is that although patient satisfaction with the new clinical protocol appeared to be qualitatively improved, we did not formally conduct patient satisfaction surveys. Finally, characteristics of patients referred for AF ablation vary from institution to institution.

Conclusion

A novel clinical protocol employing CTA with delayed LAA imaging improves clinical efficiency. In our cohort, we have also demonstrated excellent agreement between CTA and ultrasound-based imaging of the LAA, very low radiation doses with CTA imaging, a reduced need for additional pre-ablation procedures such as TEEs when LAA filling defects had been ruled out with CTA, and an excellent safety profile with no procedure-related cerebrovascular or esophageal complications. Such a protocol could be widely adopted by electrophysiology practices and have very positive impact on patient care and patient satisfaction.

Clinical Perspectives.

This manuscript presents new medical knowledge regarding how delayed imaging of the left atrial appendage (LAA) with computed tomography angiography (CTA) can improve the clinical care of patients undergoing catheter ablation of atrial fibrillation and left atrial flutter (AF) as part of a novel clinical protocol, particularly when a CTA has already been ordered for pulmonary vein anatomy. Although delayed imaging with CTA requires only one extra sequence during the study, and current CTA protocols involve very low radiation doses, delayed CTA imaging of the LAA is not routinely performed and/or not integrated into pre-procedure care in many practices. Furthermore, there have been no published reports outlining a blueprint for integration and demonstrating associated clinical outcomes. The present manuscript describes application of a novel clinical protocol in 320 patients at a major academic medical center and demonstrates the following key findings: 1) excellent agreement among CTA results, transesophageal echocardiography (TEE) findings (when performed), and intraprocedural intracardiac echocardiography findings; 2) very low radiation doses; 3) marked reduction in the need for semi-invasive (TEEs) with such a protocol; and 4) an excellent safety profile, with no peri-procedural strokes/TIAs. These findings show that this novel protocol can greatly improve and streamline pre-ablation care, reduce the need for TEEs when the information would be superfluous based on negative CTA results, and maintain an excellent safety profile with no cerebrovascular or esophageal complications. Dissemination of our findings will hopefully encourage other electrophysiology practices to implement similar protocols to promote optimal clinical care for pre-ablation patients.

Acknowledgments

We would like to acknowledge Cherie Parks, RN, Karen Coleman, RN, Felicia Murphy, RN, Susan Gionakos, RN, and our other nurses in the Cardiac Transition Unit for their great help in implementing this protocol. We also acknowledge Anita Barber and Gregory Megginson for their help with the database queries.

Funding Sources: This research was supported by Dr. Bilchick’s NIH K23 grant HL094761 and Dr. Salerno’s NIH K23 HL112910.

Abbreviations

AF

atrial fibrillation

CTA

computed tomography angiography

HU

Hounsfield units

ICE

intracardiac echocardiography

LAA

left atrial appendage

LAAT

left atrial appendage thrombus

LVEF

left ventricular ejection fraction

SEC

spontaneous echo contrast

TEE

transesophageal echocardiography

TIA

transient ischemic attack

Footnotes

Disclosures: Dr. Mason receives research grants from Johnson and Johnson, Boston Scientific, and Medtronic. Dr. Malhotra receives consulting fees and research grants from Medtronic. Dr. Darby receives consulting fees from Biosense Webster and Medtronic and research grants from Boston. Dr. DiMarco receives consulting fees from Novartis, Medtronic, and Boston Scientific. Dr. Mangrum receives research grants from Hansen Medical, St. Jude Medical, CardioFocus, Inc., and Medtronic. Dr. Ferguson receives consulting fees from St. Jude Medical and Biosense Webster, and research grants from Boston Scientific and Medtronic. Dr. Kramer receives consulting fees from St. Jude Medical and research support from Siemens Healthcare. Dr. Salerno receives grant support from Astra-Zeneca and research support from Siemens Healthcare. Dr. Bilchick has received consulting fees from Biosense Webster.

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

References

  • 1.Chugh SS, Blackshear JL, Shen WK, Hammill SC, Gersh BJ. Epidemiology and natural history of atrial fibrillation: clinical implications. J Am Coll Cardiol. 2001;37:371–8. doi: 10.1016/s0735-1097(00)01107-4. [DOI] [PubMed] [Google Scholar]
  • 2.Flegel KM, Shipley MJ, Rose G. Risk of stroke in non-rheumatic atrial fibrillation. Lancet. 1987;1:526–9. doi: 10.1016/s0140-6736(87)90174-7. [DOI] [PubMed] [Google Scholar]
  • 3.Pappone C, Augello G, Sala S, et al. A randomized trial of circumferential pulmonary vein ablation versus antiarrhythmic drug therapy in paroxysmal atrial fibrillation: the APAF Study. J Am Coll Cardiol. 2006;48:2340–7. doi: 10.1016/j.jacc.2006.08.037. [DOI] [PubMed] [Google Scholar]
  • 4.Packer DL, Kowal RC, Wheelan KR, Irwin JM, Champagne J, Guerra PG, Dubuc M, Reddy V, Nelson L, Holcomb RG, Lehmann JW, Ruskin JN. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol. 2013;61:1713–23. doi: 10.1016/j.jacc.2012.11.064. [DOI] [PubMed] [Google Scholar]
  • 5.Jais P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation: the A4 study. Circulation. 2008;118:2498–505. doi: 10.1161/CIRCULATIONAHA.108.772582. [DOI] [PubMed] [Google Scholar]
  • 6.January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the Heart Rhythm Society. Circulation. 2014;130:2071–104. doi: 10.1161/CIR.0000000000000040. [DOI] [PubMed] [Google Scholar]
  • 7.Manning WJ, Weintraub RM, Waksmonski CA, Haering JM, Rooney PS, Maslow AD, Johnson RG, Douglas PS. Accuracy of transesophageal echocardiography for identifying left atrial thrombi. A prospective, intraoperative study. Ann Intern Med. 1995;123:817–22. doi: 10.7326/0003-4819-123-11-199512010-00001. [DOI] [PubMed] [Google Scholar]
  • 8.Romero J, Husain SA, Kelesidis I, Sanz J, Medina HM, Garcia MJ. Detection of left atrial appendage thrombus by cardiac computed tomography in patients with atrial fibrillation: a meta-analysis. Circ Cardiovasc Imaging. 2013;6:185–94. doi: 10.1161/CIRCIMAGING.112.000153. [DOI] [PubMed] [Google Scholar]
  • 9.Sawit ST, Garcia-Alvarez A, Suri B, Gaztanaga J, Fernandez-Friera L, Mirelis JG, D’Anca M, Fuster V, Sanz J, Garcia MJ. Usefulness of cardiac computed tomographic delayed contrast enhancement of the left atrial appendage before pulmonary vein ablation. Am J Cardiol. 2012;109:677–84. doi: 10.1016/j.amjcard.2011.10.028. [DOI] [PubMed] [Google Scholar]
  • 10.Martinez MW, Kirsch J, Williamson EE, Syed IS, Feng D, Ommen S, Packer DL, Brady PA. Utility of nongated multidetector computed tomography for detection of left atrial thrombus in patients undergoing catheter ablation of atrial fibrillation. JACC Cardiovasc Imaging. 2009;2:69–76. doi: 10.1016/j.jcmg.2008.09.011. [DOI] [PubMed] [Google Scholar]
  • 11.Tang RB, Dong JZ, Zhang ZQ, Li ZA, Liu XP, Kang JP, Yu RH, Long dY, Ma CS. Comparison of contrast enhanced 64-slice computed tomography and transesophageal echocardiography in detection of left atrial thrombus in patients with atrial fibrillation. J Interv Card Electrophysiol. 2008;22:199–203. doi: 10.1007/s10840-008-9243-0. [DOI] [PubMed] [Google Scholar]
  • 12.Singh NK, Nallamothu N, Zuck VP, Issa ZF. Left atrial appendage filling defects on 64-slice multidetector computed tomography in patients undergoing pulmonary vein isolation: predictors and comparison to transesophageal echocardiography. J Comput Assist Tomogr. 2009;33:946–51. doi: 10.1097/RCT.0b013e31819cabc3. [DOI] [PubMed] [Google Scholar]
  • 13.Kapa S, Martinez MW, Williamson EE, Ommen SR, Syed IS, Feng D, Packer DL, Brady PA. ECG-gated dual-source CT for detection of left atrial appendage thrombus in patients undergoing catheter ablation for atrial fibrillation. J Interv Card Electrophysiol. 2010;29:75–81. doi: 10.1007/s10840-010-9505-5. [DOI] [PubMed] [Google Scholar]
  • 14.Dorenkamp M, Sohns C, Vollmann D, Luthje L, Seegers J, Wachter R, Puls M, Staab W, Lotz J, Zabel M. Detection of left atrial thrombus during routine diagnostic work-up prior to pulmonary vein isolation for atrial fibrillation: role of transesophageal echocardiography and multidetector computed tomography. Int J Cardiol. 2013;163:26–33. doi: 10.1016/j.ijcard.2011.06.124. [DOI] [PubMed] [Google Scholar]
  • 15.Jaber WA, White RD, Kuzmiak SA, Boyle JM, Natale A, Apperson-Hansen C, Thomas JD, Asher CR. Comparison of ability to identify left atrial thrombus by three-dimensional tomography versus transesophageal echocardiography in patients with atrial fibrillation. Am J Cardiol. 2004;93:486–9. doi: 10.1016/j.amjcard.2003.10.052. [DOI] [PubMed] [Google Scholar]
  • 16.Kim YY, Klein AL, Halliburton SS, Popovic ZB, Kuzmiak SA, Sola S, Garcia MJ, Schoenhagen P, Natale A, Desai MY. Left atrial appendage filling defects identified by multidetector computed tomography in patients undergoing radiofrequency pulmonary vein antral isolation: a comparison with transesophageal echocardiography. Am Heart J. 2007;154:1199–205. doi: 10.1016/j.ahj.2007.08.004. [DOI] [PubMed] [Google Scholar]
  • 17.Feuchtner GM, Dichtl W, Bonatti JO, Jodocy D, Muller S, Hintringer F, Gradl J, Klauser A, Cury RC. Diagnostic accuracy of cardiac 64-slice computed tomography in detecting atrial thrombi. Comparative study with transesophageal echocardiography and cardiac surgery. Invest Radiol. 2008;43:794–801. doi: 10.1097/RLI.0b013e318184cd6c. [DOI] [PubMed] [Google Scholar]
  • 18.Maltagliati A, Pontone G, Annoni A, Formenti A, Galli CA, Tamborini G, Alimento M, Andreini D, Tondo C, Pepi M. Multidetector computed tomography vs multiplane transesophageal echocardiography in detecting atrial thrombi in patients candidate to radiofrequency ablation of atrial fibrillation. Int J Cardiol. 2011;152:251–4. doi: 10.1016/j.ijcard.2011.07.086. [DOI] [PubMed] [Google Scholar]
  • 19.Chao TF, Lin YJ, Tsao HM, et al. CHADS(2) and CHA(2)DS(2)-VASc scores in the prediction of clinical outcomes in patients with atrial fibrillation after catheter ablation. J Am Coll Cardiol. 2011;58:2380–5. doi: 10.1016/j.jacc.2011.08.045. [DOI] [PubMed] [Google Scholar]
  • 20.Wallace TW, Atwater BD, Daubert JP, Voora D, Crowley AL, Bahnson TD, Hranitzky PM. Prevalence and clinical characteristics associated with left atrial appendage thrombus in fully anticoagulated patients undergoing catheter-directed atrial fibrillation ablation. J Cardiovasc Electrophysiol. 2010;21:849–52. doi: 10.1111/j.1540-8167.2010.01729.x. [DOI] [PubMed] [Google Scholar]
  • 21.Herring N, Ahmed M, Burg M, Hunter R, Earley MJ, Sporton SC, Bashir Y, Betts TR, Schilling R, Rappan K. The prevalence of left atrial appendage thrombus in patients undergoing catheter ablation for atrial fibrillation maintained on warfarin (abstr) Heart. 2012;98:A32. [Google Scholar]

RESOURCES