Echocardiography in Percutaneous Left Atrial Appendage Occlusion and Related Complications

Atrial fibrillation (AF) is a devastating disease with a large global prevalence. The left atrial appendage (LAA) is a major source of thrombi in patients with AF. Echocardiography plays an important role in identifying LAA thrombi and has become an invaluable imaging tool in planning for LAA occlusion (LAAO) in patients intolerant to anticoagulation. This review article will discuss the role of echocardiography in selecting patients for LAAO, intraprocedural monitoring, and identifying procedure-related complications.

Detection of left atrial appendage thrombus by dual-energy computed tomography-derived imaging biomarkers in patients with atrial fibrillation

Aims

This study aimed to assess the diagnostic performances of dual-energy computed tomography (CT)-derived iodine concentration and effective atomic number (Z_eff) in early-phase cardiac CT in detecting left atrial appendage (LAA) thrombus and differentiating thrombus from spontaneous echo contrast (SEC) in patients with atrial fibrillation using transesophageal echocardiography (TEE) as the reference standard.

Methods and results

A total of 389 patients with atrial fibrillation were prospectively recruited. All patients underwent a single-phase cardiac dual-energy CT scan using a third-generation dual-source CT. The iodine concentration, Z_eff, and conventional Hounsfield units (HU) in the LAA were measured and normalized to the ascending aorta (AA) of the same slice to calculate the LAA/AA ratio. Of the 389 patients, TEE showed thrombus in 15 (3.9%), SEC in 33 (8.5%), and no abnormality in 341 (87.7%) patients. Using TEE findings as the reference standard, the respective sensitivity, specificity, positive predictive value, and negative predictive value of the LAA/AA HU ratio for detecting LAA thrombus were 100.0, 96.8, 55.6, and 100.0%; those of the LAA/AA iodine concentration ratio were 100.0, 99.2, 83.3, and 100.0%; and those of the LAA/AA Z_eff ratio were 100.0, 98.9, 79.0, and 100.0%. The areas under the receiver operator characteristic curve (AUC) of the LAA/AA iodine concentration ratio (0.978; 95% CI 0.945–1.000) and Z_eff ratio (0.962; 95% CI 0.913–1.000) were significantly larger than that of the LAA/AA HU ratio (0.828; 95% CI 0.714–0.942) in differentiating the thrombus from the SEC (both P < 0.05). Although the AUC of the LAA/AA iodine concentration ratio was larger than that of the LAA/AA Z_eff ratio, no significant difference was found between them (P = 0.259).

Conclusion

The dual-energy CT-derived iodine concentration and the Z_eff showed better diagnostic performance than the conventional HU in early-phase cardiac CT in detecting LAA thrombus and differentiating the thrombus from the circulatory stasis. However, these results need to be validated in large-cohort studies with late-phase images.

Diagnostic Value of Delayed Contrast-Enhanced Cardiac Computed Tomography for Detecting Left Atrial Appendage Thrombus in Patients With Atrial Fibrillation

Objective

Delayed enhancement cardiac CT is a reliable tool for the diagnosis of left atrial appendage thrombus but limited for scanning heterogeneity. We aimed to explore the improvement of the 1 and 3-min delay phase at the diagnostic level to detect left atrial appendage thrombus, in order to set up a reasonable CT scanning scheme.

Materials and Methods

A total of 6,524 patients were continuously retrieved from January 2015 to September 2020 retrospectively. The patients had undergone Transesophageal echocardiography (TEE) and cardiac CT with complete period include the arterial enhancement phase, 1 and 3-min delay phase, TEE were used as the reference standard. The final study included 329 patients. Three experienced radiologists independently assessed each phase of the cardiac CT images for thrombus diagnosis. We explored the improvement of the diagnostic ability of different delayed contrast-enhanced phases for left atrial appendage thrombus detection. Multiple logistic regression analysis were used for further high-risk stratification to avoid an additional 1-min delayed scan.

Results

In total, 29 thrombosis were detected at TEE. For all cardiac CT phases, sensitivity and negative predictive were 100%. The specificity were 0.54, 0.93, and 1.00, respectively; The positive predictive values (PPV) were 0.17, 0.57, and 1.00, respectively; Area under curve (AUC) were 0.75, 0.95, and 0.98, respectively. High risk factors that cannot be clearly diagnosed with 1-min delay phase included reduced cardiac function, increased CHA2DS2-VAScscore and left atrial enlargement. Compared with the arterial enhanced phase, increased radiation doses in the 1 and 3-min delay phases were 1.7 ± 1.3 msv and 1.5 ± 0.8 msv (mean ± standard deviation).

Conclusion

Using TEE as the reference standard, early contrast-enhanced CT scanning with 1 and 3-min delay is necessary for the diagnosis of left appendage thrombus, which could significantly improve the diagnostic efficiency. Patients with high-risk stratification are suitable for direct 3-min delayed scanning.

Imaging of left heart intracardiac thrombus: clinical needs, current imaging, and emerging cardiac magnetic resonance techniques

Intracardiac thrombus in the left atrium and atrial appendage (LA/LAA) and left ventricle (LV) increases the risk of systemic thromboembolism and causes potentially devastating diseases such as ischemic stroke and acute ischemia in abdominal organs and lower extremities. Detecting the presence and monitoring the resolution of left heart intracardiac thrombus are of vital importance for stratifying patients and guiding treatment decisions. Currently, echocardiography is the most frequently used method for the above clinical needs, followed by computed tomography. An increasing number of studies have been performed to investigate the value of cardiac magnetic resonance (CMR) as an alternative imaging modality given its several unique strengths. This article provides an overview of the clinical relevance of the LA/LAA and LV thrombus as well as the diagnostic performance of the current imaging modalities and emerging CMR techniques.

Cardiac Computed Tomography Versus Transesophageal Echocardiography for the Detection of Left Atrial Appendage Thrombus: A Systemic Review and Meta-Analysis

Background Transesophageal echocardiography (TEE) has been considered the gold standard for left atrial appendage (LAA) thrombus detection. Nevertheless, TEE may sometimes induce discomfort and cause complications. Cardiac computed tomography has been studied extensively for LAA thrombus detection. We performed this systemic review and meta-analysis to assess the diagnostic accuracy of cardiac computed tomography for LAA thrombus detection compared with TEE. Methods and Results A systemic search was conducted in the PubMed, Embase, and Cochrane Library databases from January 1977 to February 2021. Studies performed for assessment diagnostic accuracy of cardiac computed tomography on LAA thrombus compared with TEE were included. Summary sensitivity, specificity, and posterior probability of LAA thrombus was calculated by using bivariate random-effects model. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used for the quality assessment. A total of 27 studies involving 6960 patients were included in our study. The summary sensitivity of early imaging studies was 0.95 (95% CI, 0.79-0.99), and the specificity was 0.89 (95% CI, 0.85-0.92). The positive posterior probability was 19.11%, and the negative posterior probability was 0.16%. The summary sensitivity of delayed imaging studies was 0.98 (95% CI, 0.92-1.00), and the specificity was 1.00 (95% CI, 0.98-1.00). The positive posterior probability was 95.76%, and the negative posterior probability was 0.12%. The delayed imaging method significantly improved the specificity (1.00 versus 0.89; P<0.05) and positive posterior probability (95.76% versus 19.11%; P<0.05). Conclusions Cardiac computed tomography with a delayed imaging is a reliable alternative to TEE. It may save the patient and health care from an excess TEE. Registration URL: https://www.crd.york.ac.uk/PROSPERO; Unique identifier: CRD42021236352.

Feasibility of the Big 5-Jena eCS Protocol : First Experience Implementing a New Extended CT Protocol in the Initial Diagnostics of Ischemic Stroke

PURPOSE

The most common protocols in the initial diagnostic of acute ischemic stroke do not assess cardiogenic or aortic causes of embolism. These are usually evaluated later by transthoracic (TTE) or transesophageal (TEE) echocardiography. This study aimed to evaluate the feasibility of a diagnostic tool for thoracic cardiovascular thrombi according to the first experience with a new extended cardio-stroke protocol (Big 5-Jena eCS protocol) in acute stroke patients.

METHODS

Retrospective analyses of the tomography scans database of the Jena University Hospital were performed. We included a total of 67 patients in the feasibility analyses, based on the evaluation of three outcomes.

RESULTS

Primary outcome: the Big 5-Jena eCS protocol was able to detect thoracic cardiovascular thrombi in a total of 20 patients in different locations including the arch of the aorta, the aortic valve, the left atrium, the left atrial appendage, the left ventricle, and the pulmonary arteries. Secondary outcome: implementating the protocol did not result in a significant elevation of the radiation exposure compared to traditional protocols. Tertiary outcome: the new protocol identified seven cases that were considered negative by echocardiography.

CONCLUSION

The implementation of an extended cardio-stroke protocol is feasible, no significantly time-consuming, acquiring assessable imaging, and maintaining radiation exposure acceptable. The Big 5-Jena eCS protocol was also able to detect some thrombi not reported by TTE or TEE; however, due to our data's explorative character, a conclusive comparison with cardiac ultrasound is not possible. A prospective pilot study and clinical trials should be conducted to assess the diagnostic accuracy of this protocol compared to echocardiography and determine the potential impact on diagnostic and treatment decisions.

EACVI recommendations on cardiovascular imaging for the detection of embolic sources: endorsed by the Canadian Society of Echocardiography

Cardioaortic embolism to the brain accounts for approximately 15-30% of ischaemic strokes and is often referred to as 'cardioembolic stroke'. One-quarter of patients have more than one cardiac source of embolism and 15% have significant cerebrovascular atherosclerosis. After a careful work-up, up to 30% of ischaemic strokes remain 'cryptogenic', recently redefined as 'embolic strokes of undetermined source'. The diagnosis of cardioembolic stroke remains difficult because a potential cardiac source of embolism does not establish the stroke mechanism. The role of cardiac imaging-transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE), cardiac computed tomography (CT), and magnetic resonance imaging (MRI)-in the diagnosis of potential cardiac sources of embolism, and for therapeutic guidance, is reviewed in these recommendations. Contrast TTE/TOE is highly accurate for detecting left atrial appendage thrombosis in patients with atrial fibrillation, valvular and prosthesis vegetations and thrombosis, aortic arch atheroma, patent foramen ovale, atrial septal defect, and intracardiac tumours. Both CT and MRI are highly accurate for detecting cavity thrombosis, intracardiac tumours, and valvular prosthesis thrombosis. Thus, CT and cardiac magnetic resonance should be considered in addition to TTE and TOE in the detection of a cardiac source of embolism. We propose a diagnostic algorithm where vascular imaging and contrast TTE/TOE are considered the first-line tool in the search for a cardiac source of embolism. CT and MRI are considered as alternative and complementary tools, and their indications are described on a case-by-case approach.

Prevalence of intracardiac thrombi on cardiac computed tomography angiography: Outcome and impact on consequent management

Objective

Intracardiac thrombi are intermittently come across on cardiac computed tomography angiography (CCTA). This study aimed to examine the prevalence, outcome, and prognosis in patients with incidental found left-sided cardiac thrombi on CCTA.

Material and Methods

The Ethics Committee approved the present study of the Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. A retrospective review of CCTA was performed for incidental left-sided cardiac thrombi.

Results

A total of 1080 CCTAs were enrolled with the prevalence of incidental left-sided cardiac thrombi is 4.53%. Of the 49 patients with CCTA incidental left-sided cardiac thrombi, 16 had left atrial thrombi, and 33 had left ventricular thrombi. All thrombi were undetermined before the CCTA, and their identification subsequently generated anticoagulation treatment. In 10 patients, embolic complications happened, 4 of which were fatal. Patients with incidental detected left-sided intracardiac thrombi seen by CCTA had more embolic event than patients who did not discover left-sided intracardiac thrombi by CCTA (HR = 8.07; 95% CI 1.48-44.06; p = 0.016).

Conclusions

Incidental left-sided cardiac thrombi on CCTA guided to management adjustments and seemed to present substantial mortality and morbidity in the present study. Physicians who interpret CCTA should ensure a dedicated effort not to disregard these prospective pitfalls.

Use of radiomics to differentiate left atrial appendage thrombi and mixing artifacts on single-phase CT angiography

To assess if radiomics can differentiate left atrial appendage (LAA) contrast-mixing artifacts and thrombi on early-phase CT angiography without the need for late-phase images. Our study included 111 patients who underwent early- and late-phase, contrast-enhanced cardiac CT. Of these, 79 patients had LAA filling defects from thrombus (n = 46, mean age: 72  ±  12 years, M:F 26:20) or contrast-mixing artifact (n = 33, mean age: 71  ±  13 years, M:F 21:12) on early-contrast-enhanced phase. The remaining 32 patients (mean age: 66  ±  10 years, M:F 19:13) had homogeneous LAA opacification without filling defects. The entire LAA volume on early-phase CT images was manually segmented to obtain radiomic features (Frontier, Siemens). A radiologist assessed for the presence of LAA filling defects and recorded the size and mean CT attenuation (HU) of filling defects and normal LAA. The data were analyzed using multiple logistic regression with receiver operating characteristics area under the curve (AUC) as an output. The radiologist correctly identified all 32 patients without LAA filling defects, 42/46 LAA with thrombi, and 23/33 contrast mixing artifacts. Although HU of LAA thrombi and contrast mixing artifacts was significantly different, with the lowest AUC (0.66), it was inferior to both radiologist assessment and radiomics (p = 0.05). Combination of radiologist assessment and radiomics (AUC 0.92) was superior to HU (0.66), radiomics (0.85), and radiologist (0.80) alone (p < 0.008). Radiomics can differentiate between LAA filling defects from thrombi and contrast mixing artifacts on early-phase contrast-enhanced CT images without the need for late-phase CT.

High rate of cardiac thrombus diagnosed by adding cardiac imaging in acute stroke computed tomography protocol

BACKGROUND

Detection of left atrial appendage thrombus (LAAt) in acute stroke patients can be improved by cardiac computed tomography using prospective electrocardiogram-gated volume acquisition, which was added to the acute stroke computed tomography protocol in our institution in 2018.

AIMS

To evaluate the factors and clinical management associated with LAAt in patients with acute ischemic stroke.

METHODS

We retrospectively included 324 consecutive patients with ischemic stroke from November 2018 to October 2019. Clinical data and post-stroke management were compared in LAAt and no-LAAt patients.

RESULTS

Thirty-five patients (10.8%; 95%CI 7.4-14.2) had LAAt and 289 had no-LAAt. LAAt patients were significantly older (82 ± 12 vs. 74 ± 14 yo for no-LAAt, p = 0.002), predominantly female (71% vs. 45%, p = 0.004), and were more likely to have previous atrial fibrillation (63% vs. 15%, p < 0.001) and previous stroke (32% vs. 14%, p = 0.005). There was no significant difference between groups in stroke localization or severity scales at admission or at hospital discharge. After multivariable analysis, female sex (odds ratio 2.51; 95%CI 1.09-5.77, p = 0.031), previous atrial fibrillation (odds ratio 4.87; 95%CI 2.11-11.22, p < 0.001), and left atrial volume >86 ml (odds ratio 5.33; 95%CI 1.70-16.69, p = 0.004) were independently associated with LAAt. More than a third of LAAt patients (37%) received acute heparin therapy compared to 13% of no-LAAt patients (p < 0.001). Moreover, despite comparable stroke severity at admission, the mortality rate was markedly higher in the LAAt group than in the no-LAAt group (37% vs. 13%, p < 0.001).

CONCLUSIONS

Cardiac computed tomography for left atrial appendage thrombus evaluation in routine acute stroke imaging protocol could be beneficial for decision-making with regard to the initiation of early anticoagulation.

CT Angiography of the Heart and Aorta in TIA and Ischaemic Stroke: Cardioembolic Risk Sources and Clinical Implications

BACKGROUND

Cardiac emboli are important causes of (recurrent) ischaemic stroke. Aorta atherosclerosis might also be associated with an increased risk of stroke recurrence. This study aimed to evaluate the yield and clinical implications of CT-angiography (CTA) of the heart and aorta in the diagnostic workup of transient ischaemic attack (TIA) or ischaemic stroke.

METHODS

CTA of the heart and aortic arch was performed in TIA/ischaemic stroke patients, in addition to routine diagnostic workup. Occurrence of cardioembolic (CE) risk sources and complex aortic plaques were assessed. Implications of cardiac CTA for therapeutic management were evaluated RESULTS: Sixty-seven patients were included (TIA n = 33, ischaemic stroke n = 34) with a mean age of 68 years (range 51-89) and median NIHSS of 0 (interquartile range 0-2). CE risk sources were detected in 29 (43%) patients. An intracardiac thrombus was present in 2 patients (3%; TIA 0%; ischaemic stroke 6%). Medium/low-risk CE sources included mitral annular calcification (9%), aortic valve calcification (18%) and patent foramen ovale (18%). Complex aortic plaque was identified in 16 patients (24%). In two patients with an intracardiac thrombus, therapeutic management changed from antiplatelet to oral anticoagulation.

CONCLUSIONS

CTA of the heart and aorta has a high yield for detection of embolic risk sources in TIA/ischaemic stroke, with clinical consequences for 6% of ischaemic stroke patients. Implementation of CTA of the heart and aorta in the acute stroke setting seems valuable, but cost-effectiveness of this approach remains to be determined.

CT angiography vs echocardiography for detection of cardiac thrombi in ischemic stroke: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Cardiac thrombi are an important cause of embolic stroke. We studied the diagnostic yield and diagnostic accuracy of cardiac CT angiography (CTA) compared to echocardiography for detection of cardiac thrombi in ischemic stroke patients.

METHODS

We performed a systematic review and meta-analysis of the literature on cardiac CTA versus echocardiography for detection of cardiac thrombi in ischemic stroke patients. We included studies (N ≥ 20) in which both cardiac CTA (index test) and echocardiography (reference test) were performed and data on cardiac thrombi were reported. Results were stratified for type of echocardiography: transesophageal (TEE) vs transthoracic (TTE).

RESULTS

Out of 1530 studies, 14 were included (all single center cohort studies), with data on 1568 patients. Mean age varied between 52 and 69 years per study and 66% were men. Reported time intervals ranged from 0 to 21 days between stroke and first test, and from 0 to 199 days between tests. In ten studies that compared CTA to TEE, CTA detected cardiac thrombi in 87/1385 (6.3%) patients versus 68/1385 (4.9%) on TEE (p < 0.001). In four studies comparing CTA to TTE, CTA detected thrombi in 23/183 (12.5%) patients versus 12/183 (6.6%) on TTE (p = 0.010). Pooled sensitivity and specificity of CTA versus TEE were 86.0% (95% CI 65.6-95.2) and 97.4% (95% CI 95.0-98.7), respectively.

CONCLUSIONS

CTA may be a promising alternative to echocardiography for detection of cardiac thrombi in patients with ischemic stroke, especially now that CTA is standard care for patient selection for endovascular treatment. However, studies were too heterogeneous and of insufficient methodological quality to draw firm conclusions. Large, prospective studies on this topic are warranted.

Detection of left atrial appendage thrombi by third-generation dual-source dual-energy CT: Iodine concentration versus conventional enhancement measurements

BACKGROUND

Dual-energy computed tomography (DECT) can differentiate iodine from other materials through the material decomposition technique. The purpose of this study was to compare the diagnostic performance of DECT-derived iodine concentration (mg/ml) with conventional enhancement measurements (HU), in detecting left atrial appendage (LAA) thrombi and differentiating thrombi from circulatory stasis in atrial fibrillation (AF) patients referred for catheter ablation.

METHODS

Consecutive patients were prospectively recruited and scanned using a third-generation dual-source CT system in dual-energy mode. Regions of interest were placed inside the filling defect in the LAA and ascending aorta (AA) of the same sections, to determine iodine concentration and the LAA/AA HU ratio. The diagnostic performance of iodine concentration and LAA/AA HU ratios were compared using transesophageal echocardiography (TEE) as the reference standard.

RESULTS

Among 302 patients, 10 thrombi and 27 cases with spontaneous echo contrast (SEC) were detected by TEE. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of iodine concentration were superior to those of LAA/AA HU ratios (iodine concentration: 99.7%, 100%, 99.7%, 90.9%, and 100% vs. LAA/AA HU ratios: 96.0%, 100%, 95.9%, 45.5%, and 100%) in detecting LAA thrombi. The area under the receiver operating characteristic curve of iodine concentration (0.996; 0.898-1.000) was significantly larger than that of the LAA/AA HU ratio (0.881; 0.733-0.964) in differentiating thrombi from circulatory stasis (p < 0.05).

CONCLUSIONS

DECT-derived iodine concentration was associated with improved diagnostic accuracy compared with conventional enhancement measurements in detecting LAA thrombi and differentiating thrombi from circulatory stasis in AF patients.

Circulatory Stasis or Thrombus in Left Atrial Appendage, An Easy Diagnostic Solution

OBJECTIVE

The purpose of this study was to assess the diagnostic performance of prone position cardiac multidetector computed tomography (MDCT) in the detection of left atrial appendage (LAA) thrombi and to make differentiate between thrombus and circulatory stasis using transesophageal echocardiography (TEE) as the criterion-standard imaging modality.

METHODS

From December 2014 to April 2016, 53 consecutive patients were admitted to the hospital because of circulatory stasis or/and thrombus. All patients underwent prone-position MDCT and TEE. Prone-position MDCT and TEE sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

For the MDCT scan in the prone position, the sensitivity, specificity, positive predictive value, and negative predictive value results were 100%, 100%, 100%, and 100%, respectively.

CONCLUSIONS

Multidetector computed tomography scanning in the prone position differentiates circulatory stasis and LAA thrombus, is clinically useful for detecting and ruling out LAA thrombus, and may be an alternative to TEE as a diagnostic tool.

A Case of Cardiogenic Stroke After Thoracoscopic Left Atrial Appendectomy

Thoracoscopic left atrial appendectomy is a minimally invasive procedure for left atrial appendage occlusion in patients with non-valvular atrial fibrillation, particularly those at a great risk for both stroke and bleeding despite appropriate oral anticoagulant therapy. It serves as an alternative strategy for stroke risk reduction. Moreover, the oral anticoagulant therapy can be discontinued after the operation. However, we encountered a 74-year old male patient who developed cardiogenic stroke after thoracoscopic left atrial appendectomy. We report this case to introduce how we evaluate the risk of postoperative cardiogenic stroke by means of contrast-enhanced cardiac computed tomography (CT), and how we formulate the postoperative patient management strategy including short-term oral anticoagulation therapy by using results of cardiac CT.

Nongated Cardiac Computed Tomographic Angiograms for Detection of Embolic Sources in Acute Ischemic Stroke

Background and Purpose—

We assessed the feasibility of obtaining diagnostic quality images of the heart and thoracic aorta by extending the z axis coverage of a non–ECG-gated computed tomographic angiogram performed in the primary evaluation of acute stroke without increasing the contrast dose.

Methods—

Twenty consecutive patients with acute ischemic stroke within the 4.5 hours of symptom onset were prospectively recruited. We increased the longitudinal coverage to the domes of the diaphragm to include the heart. Contrast administration (Omnipaque 350) remained unchanged (injected at 3–4 mL/s; total 60–80 mL, triggered by bolus tracking). Images of the heart and aorta, reconstructed at 5 mm slice thickness in 3 orthogonal planes, were read by a radiologist and cardiologist, findings conveyed to the treating neurologist, and correlated with the transthoracic or transesophageal echocardiogram performed within the next 24 hours.

Results—

Of 20 patients studied, 3 (15%) had abnormal findings: a left ventricular thrombus, a Stanford type A aortic dissection, and a thrombus of the left atrial appendage. Both thrombi were confirmed by transesophageal echocardiography, and anticoagulation was started urgently the following day. None of the patients developed contrast-induced nephropathy on follow-up. The radiation dose was slightly increased from a mean of 4.26 mSV (range, 3.88–4.70 mSV) to 5.17 (range, 3.95 to 6.25 mSV).

Conclusions—

Including the heart and ascending aorta in a routine non–ECG-gated computed tomographic angiogram enhances an existing imaging modality, with no increased incidence of contrast-induced nephropathy and minimal increase in radiation dose. This may help in the detection of high-risk cardiac and aortic sources of embolism in acute stroke patients.

Impact of Implementing Cardiac CT in Evaluating Patients Suspected of Cardioembolic Stroke

BACKGROUND AND OBJECTIVES

In practice, clinical and logistic hurdles may hamper performing transesophageal echocardiography in stroke patients. Cardiac computed tomography (CT) is a recently introduced noninvasive modality able to detect various embolic causes. Thus, we retrospectively assessed possible added values of applying cardiac CT in the real-world work-up of suspected cardioembolic stroke cases.

METHODS

Forty-seven patients were neurology service referrals for suspected cardioembolic stroke. The CT images and clinical reports of our cardiac CT radiologists were retrospectively evaluated. Cardiac CT was assessed in terms of detecting major embolic potential findings, potentially significant stroke-unrelated findings, and coronary arterial disease (CAD). Computed tomography results were correlated with echocardiographic reports.

RESULTS

Cardiac CT showed findings of major embolic potential in 10 patients (21%, 5 thrombi cases, 2 vasculitis cases, 1 case of metastasis invading the left superior pulmonary artery, 1 myocardial infarction case, and 1 pulmonary arteriovenous malformations case), none of which were documented in echocardiography reports. Two cases (4%) with findings of major embolic potential where identified on echocardiography but not on CT (1 left atrial appendage thrombus and 1 mitral valve vegetation). Computed tomography of 13 patients (28%) showed 16 potentially significant stroke-unrelated findings. Twenty-one patients (47%) had unexpected CAD on CT, 11 (52%) of which were obstructive.

CONCLUSIONS

Implementing cardiac CT in assessing patients suspected of cardioembolic stroke added value to echocardiographic evaluation, by detecting major embolic potential findings. In addition, cardiac CT revealed additional potentially significant stroke-unrelated findings and CAD.

Characteristics of pulmonary vein enlargement in non-valvular atrial fibrillation patients with stroke

PURPOSE

The association between pulmonary vein (PV) dilatation and stroke in non-valvular atrial fibrillation (AF) patients remains unknown.

MATERIALS AND METHODS

We examined the left atrium (LA) and PV in control (n=138) and non-valvular AF patients without (AF group, n=138) and with non-hemorrhagic stroke (AF with stroke group, n=138) using computed tomography.

RESULTS

The LA, LA appendage (LAA), and all PVs were larger in the AF than control patients. The orifice areas of the LAA (5.6±2.2 cm² vs. 4.7±1.7 cm², p<0.001), left superior PV (3.8±1.5 cm² vs. 3.4±1.2 cm², p=0.019), and inferior PV (2.3±1.0 cm² vs. 1.8±0.7 cm², p<0.001) were larger in the AF with stroke than in the AF only group. However, right PVs were not different between the two groups. In a multivariate analysis, the orifice areas of the left superior PV [odds ratio (OR) 1.25, 95% confidence interval (CI) 1.03-1.51, p=0.02], left inferior PV (OR 1.97, 95% CI 1.41-2.75, p<0.001), and LAA (OR 1.30, 95% CI 1.13-1.50, p<0.001) were independent predictors of stroke.

CONCLUSION

Compared to the right PVs, the left PVs and LAA exhibited more significant enlargement in patients with AF and stroke than in patients with AF only. This finding suggests that the remodeling of left-sided LA structures might be related to stroke.

Dual-enhancement cardiac computed tomography for assessing left atrial thrombus and pulmonary veins before radiofrequency catheter ablation for atrial fibrillation

Noninvasive imaging that provides anatomic information while excluding intracardiac thrombus would be of significant clinical value for patients referred for catheter ablation of atrial fibrillation (AF). This study assessed the diagnostic performance of a dual-enhancement single-phase cardiac computed tomography (CT) protocol for thrombus and circulatory stasis detection in AF patients before catheter ablation. We studied 101 consecutive symptomatic AF patients (71 men and 30 women; mean age, 61.8 years) who were scheduled to have catheter ablation. All patients had undergone pre-AF ablation CT imaging and transesophageal echocardiography on the same day. CT was performed with prospective electrocardiographic gating, and scanning began 180 seconds after the test bolus. Mean left atrial appendage (LAA)/ascending aorta Hounsfield unit (HU) ratios were measured on CT images. Among the 101 patients, 9 thrombi and 18 spontaneous echo contrasts were detected by transesophageal echocardiography. The overall sensitivity, specificity, positive predictive value, and negative predictive value of CT for the detection of thrombi in the LAA were 89%, 100%, 100%, and 99%, respectively. The mean LAA/ascending aorta HU ratios were significantly different between thrombus and circulatory stasis (0.17 vs 0.33, p = 0.002). Dual-enhancement single-scan cardiac CT is a sensitive modality for detecting and differentiating LAA thrombus and circulatory stasis.

Contrast-enhanced CMR is equally effective as TEE in the evaluation of left atrial appendage thrombus in patients with atrial fibrillation undergoing pulmonary vein isolation procedure

BACKGROUND

Patients with atrial fibrillation (AF) routinely undergo transesophageal echocardiography (TEE) for the evaluation of the left atrial appendage (LAA) to rule out thrombus prior to undergoing pulmonary vein isolation (PVI). Cardiac magnetic resonance (CMR) is now increasingly used for the evaluation of patients with AF to define pulmonary vein (PV) anatomy prior to PVI.

OBJECTIVE

To hypothesize that a retrospective comparison of 2-dimensional/3-dimensional (2D/3D) contrast-enhanced CMR sequences with TEE for the evaluation of LAA thrombus in patients with AF selected for PVI will demonstrate equivalence.

METHODS

Ninety-seven (N = 97) consecutive patients with AF underwent near-simultaneous TEE and noncontrast and contrast CMR prior to undergoing an initial PVI procedure. The CMR images were analyzed in 2 categories: (1) the 2D noncontrast cine images and early gadolinium enhancement images showing LAA and (2) 3D contrast source images acquired during PV magnetic resonance angiography. CMR variables evaluated were the presence or absence of LAA thrombus and the quality of images, and they were compared with the results of TEE in a blinded fashion.

RESULTS

All subjects were analyzed for the presence or absence of LAA thrombus. Thrombus was absent in 98% of the patients on both TEE and CMR and present in 2% on both studies (100% correlation). In 6 subjects, 2D cine CMR images were indeterminate whereas all 2D early gadolinium enhancement images and 3D contrast images were successful in excluding LAA thrombus. There was 100% concordance between CMR and TEE for the final diagnosis of LAA thrombus.

CONCLUSIONS

In one single examination, CMR offers a comparable alternative to TEE for the complete noninvasive evaluation of LAA thrombus and PV anatomy in patients with AF referred for PVI without obligate need for TEE.

Evaluation of the aortic and mitral valves with cardiac computed tomography and cardiac magnetic resonance imaging

Cardiac computed tomography (CT) produces high-quality anatomical images of the cardiac valves and associated structures. Cardiac magnetic resonance imaging (MRI) provides images of valve morphology, and allows quantitative evaluation of valvular dysfunction and determination of the impact of valvular lesions on cardiovascular structures. Recent studies have demonstrated that cardiac CT and MRI are important adjuncts to echocardiography for the evaluation of aortic and mitral valvular heart diseases (VHDs). Radiologists should be aware of the technical aspects of cardiac CT and MRI that allow comprehensive assessment of aortic and mitral VHDs, as well as the typical imaging features of common and important aortic and mitral VHDs on cardiac CT and MRI.

Severity of pseudofilling defect in the left atrial appendage on cardiac computed tomography is a simple predictor of the degree of left atrial emptying dysfunction in patients with chronic atrial fibrillation

OBJECTIVES

The purpose of our study was to investigate the clinical relevance of a pseudofilling defect in the left atrial appendage (LAA) detected on coronary computed tomography (CT) angiography (CCTA) as an indicator of impaired left atrial (LA) volumetric function in patients with chronic atrial fibrillation (CAF).

METHODS

Forty-two patients with CAF underwent CCTA. Quantitative and visual measurements of contrast enhancement of the LAA were performed, and they were correlated with results of CT volumetric functional analysis of the LA. Four volumetric parameters representing LA function were measured: maximum (LAVmax) and minimum volumes of the LA (LAVmin) through the entire cardiac cycle; LA emptying volume (LAEV); and LA emptying fraction (LAEF). All volumetric parameters were standardized by body surface area to adjust for variation in LA size among patients. For quantitative measurement, the CT attenuation was measured at the LAA and the LA to calculate an LAA/LA attenuation ratio. For visual measurement, contrast enhancement of the LAA was categorized into 3 groups; no filling defect, mild-to-moderate pseudofilling defect, and severe pseudofilling defect group. The Spearman correlation coefficient and the Kruskal-Wallis test were used for statistical analysis.

RESULTS

The LAA/LA ratio showed a strong positive correlation with LAEV (r = 0.52; P < 0.001) and LAEF (r = 0.69; P < 0.001). The LAEV in the no pseudofilling defect group and the mild-to-moderate and severe pseudofilling defect groups were 16.1 ± 8.4, 10.8 ± 3.1, and 6.7 ± 4.9 mL/m², respectively (P < 0.001). The LAEF in each group were 24.2 ± 13.8%, 12.0 ± 3.4%, and 6.9 ± 3.1%, respectively (P < 0.001).

CONCLUSIONS

The severity of pseudofilling defect in the LAA on CCTA could predict the degree of LA emptying dysfunction in patients with CAF.

Usefulness of cardiac computed tomographic delayed contrast enhancement of the left atrial appendage before pulmonary vein ablation

Left atrial appendage (LAA) contrast filling defects are commonly found in patients undergoing multidetector cardiac computed tomography (CCT) before catheter ablation of atrial fibrillation. Delayed CCT allows quantification of the LAA delayed/initial attenuation ratio and improves accuracy for LAA thrombus detection, which may obviate routine transesophageal echocardiography (TEE) before ablation. CCT with contrast-enhanced scans (initial CCT) and with noncontrast-enhanced scans (delayed CCT) was performed in 176 patients. LAA was evaluated for filling defects. LAA apex, left atrial (LA) body, and ascending aorta (AA) attenuations (Hounsfield units) were measured on initial and delayed cardiac computed tomograms to calculate LAA, LA, LAA/LA, and LAA/AA attenuation ratios. LAA, initial LAA/LA, and initial LAA/AA attenuation ratios differed significantly in patients with versus without filling defects on cardiac computed tomogram, those with atrial fibrillation versus normal sinus rhythm, and those with abnormal left ventricular ejection fraction versus larger LA volumes (p <0.05). In 70 patients (40%) who underwent TEE, 13 LAA filling defects were seen on initial cardiac computed tomogram. Two defects persisted on delayed cardiac computed tomogram and thrombus was confirmed on transesophageal echocardiogram. Sensitivity, specificity, and positive and negative predictive values of initial CCT for LAA thrombi detection were 100%, 84%, 15%, and 100%, respectively. With delayed CCT these values increased to 100%. Intraobserver and interobserver reproducibilities for cardiac computed tomographic measurements were good (intraclass correlation 0.72 to 0.97, kappa coefficients 0.93 to 1.00). In conclusion, delayed CCT provided an increase in diagnostic accuracy of CCT for detection of LAA thrombus in patients with atrial fibrillation before ablation, which may decrease the need for routine TEE before the procedure.

Dual-enhanced cardiac CT for detection of left atrial appendage thrombus in patients with stroke: a prospective comparison study with transesophageal echocardiography

BACKGROUND AND PURPOSE

A noninvasive method with high reliability and accuracy comparable to transesophageal echocardiography for identification of left atrial appendage thrombus would be of significant clinical value. The aim of this study was to assess the diagnostic performance of a dual-enhanced cardiac CT protocol for detection of left atrial appendage thrombi and for differentiation between thrombus and circulatory stasis in patients with stroke.

METHODS

We studied 83 consecutive patients with stroke (56 men and 27 women; mean age, 62.6 years) who had high risk factors for thrombus formation and had undergone both dual-source CT and transesophageal echocardiography within a 3-day period. CT was performed with prospective electrocardiographic gating, and scanning began 180 seconds after the test bolus.

RESULTS

Among the 83 patients, a total of 13 thrombi combined with spontaneous echo contrast and 14 spontaneous echo contrasts were detected by transesophageal echocardiography. All 13 thrombi combined with spontaneous echo contrast were correctly diagnosed on CT. Using transesophageal echocardiography as the reference standard, the overall sensitivity and specificity of CT for the detection of thrombi and circulatory stasis in the left atrial appendage were 96% (95% CI, 78% to 99%), and 100% (95% CI, 92% to 100%), respectively. On CT, the mean left atrial appendage/ascending aorta Hounsfield unit ratios were significantly different between thrombus and circulatory stasis (0.15 Hounsfield unit versus 0.27 Hounsfield unit, P=0.001). The mean effective radiation dose was 3.11 mSv.

CONCLUSIONS

Dual-enhanced cardiac CT with prospective electrocardiographic gating is a noninvasive and sensitive modality for detecting left atrial appendage thrombus with an acceptable radiation dose.

Surgical treatment of atrial fibrillation: a review

Atrial fibrillation is the most commonly sustained arrhythmia in man. While it affects millions of patients worldwide, its incidence will markedly increase with an aging population. Primary goals of AF therapy are to (1) reduce embolic complications, particularly stroke, (2) alleviate symptoms, and (3) prevent long-term heart remodelling. These have been proven to be a challenge as there are major limitations in our knowledge of the pathological and electrophysiological mechanisms underlying AF. Although advances continue to be made in the medical management of this condition, pharmacotherapy is often unsuccessful. Because of the high recurrence rate of AF despite antiarrhythmic drug therapy for maintenance of sinus rhythm and the adverse effects of these drugs, there has been growing interest in nonpharmacological strategies. Surgery for treatment of AF has been around for some time. The Cox-Maze procedure is the gold standard for the surgical treatment of atrial fibrillation and has more than 90% success in eliminating atrial fibrillation. Although the cut and sew maze is very effective, it has been superseded by newer operations that rely on alternate energy sources to create lines of conduction block. In addition, the evolution of improved ablation technology and instrumentation has facilitated the development of minimally invasive approaches. In this paper, the rationale for surgical ablation for atrial fibrillation and the different surgical techniques that were developed will be explored. In addition, it will detail the new approaches to surgical ablation of atrial fibrillation that employ alternate energy sources.

Usefulness of transoesophageal echocardiography before circumferential pulmonary vein ablation in patients with atrial fibrillation: is it really mandatory?

AIMS

Transoesophageal echocardiography (TEE) is recommended prior to circumferential pulmonary vein ablation (CPVA) in patients with atrial fibrillation (AF) to identify left atrial (LA) or left atrial appendage (LAA) wall thrombi. It is not clear whether all patients undergoing CPVA should receive pre-procedural TEE. We wanted to assess the incidence of LA thrombus in these patients and to identify factors associated with its presence.

METHODS AND RESULTS

Consecutive patients referred for CPVA from 2004 to 2009 underwent TEE within 48 h prior to the procedure. Of 408 patients included in the study, 6 patients (1.47%) had LA thrombi, persistent AF, and LA dilation. Compared with patients without thrombus, these six patients had larger LA diameter (P = 0.0001) and more frequently were women (P = 0.002), had persistent AF (P = 0.04), and had underlying structural cardiac disease (P = 0.014). The likelihood of presenting LA thrombus increased with the number of these four risk factors present (P < 0.001). None of the patients with paroxysmal AF and without LA dilation had LA thrombus. A cut-off value of 48.5 mm LA diameter yielded 83% sensitivity, 92% specificity, and a 10.1 likelihood ratio to predict LA thrombus appearance.

CONCLUSION

The incidence of LA thrombus prior to CPVA is low. Persistent AF, female sex, structural cardiopathy, and LA dilation were associated with the presence of LA thrombus. Our data suggest that the use of TEE prior to CPVA to detect LA thrombi might not be needed in patients with paroxysmal AF and no LA dilation or structural cardiopathy.

Analysis of left atrial appendix by dual-source CT coronary angiography: morphologic classification and imaging by volume rendered CT images

AIM

We investigated the evaluability of left atrial appendix by dual source coronary CT angiography and analyzed morphologic features.

MATERIALS AND METHODS

We included 106 consecutive patients who underwent coronary CT angiography for various indications. Technical parameters were slice thickness 0.6 mm, reconstruction interval 0.3mm, gantry rotation time 165 ms. Images were reconstructed from 10% to 100% R-R intervals at 10% intervals to evaluate the left atrial appendix and 4-D inspace software was used for analysis. We recorded the R-R intervals when the left atrial appendix was at maximum and minimum volume. We also evaluated visibility of appendix at R-R intervals. Maximum appendix volume was calculated. Atrial appendices were classified morphologically based on number of chambers (types 1-3) seen on volume rendered images.

RESULTS

There were 60 male and 46 female patients in the study group and, mean age was 55±13. Mean heart rate was 72 (ranges 47-110). Left atrial was evaluable at maximum and minimum volume by coronary CT angiography in all patients. We noted types 1-3 appendix in 29 (27%), 73 (69%), and 4 (4%) patients, respectively. Mean R-R intervals at maximum and minimum volume were 40%±6 (95% CI; 28-52%) and 95%±5 (95% CI; 85-5%), respectively. Mean appendix maximum volume was 7±4 cm3. Appendix contours were mildly, moderately and severely irregular in 10 (9%), 58 (55%), 38 (36%) patients, respectively.

CONCLUSION

Left atrial appendix was visualized in all patients independent of heart rate at maximum and minimum volumes. Volume rendered CT images can allow excellent depiction of left atrial appendix morphology and classification. Presence of moderate and severe irregularity of appendix contour in most of the patients may be the cause of slow flow. This morphologic appearance may be the underlying reason for the propensity to atrial appendix thrombus formation.

Ischemic stroke: etiologic work-up with multidetector CT of heart and extra- and intracranial arteries

PURPOSE

To assess the potential of a single-session multidetector computed tomography (CT) protocol, as compared with established methods, for the etiologic work-up of acute ischemic stroke.

MATERIALS AND METHODS

Patients found to have recently experienced an ischemic stroke were recruited for this prospective study after institutional review board approval was obtained. Each patient was scheduled for two evaluation strategies: (a) a standard approach involving transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), duplex ultrasonography (US) of the neck vessels, and magnetic resonance (MR) angiography of the neck and brain vessels; and (b) a protocol involving single-session multidetector CT of the heart, neck, and brain vessels. The authors sought to determine the major etiologic factors of stroke, including cardiac sources of embolism and atheroma of the aortic arch and the extra- and intracranial vessels, by using both strategies.

RESULTS

Multidetector CT, MR imaging, and duplex US were performed in 46 patients, 39 of whom also underwent TEE. The sensitivity and specificity of multidetector CT were 72% (18 of 25 cases) and 95% (20 of 21 cases), respectively, for detection of cardiac sources and 100% (24 of 24 cases) and 91% (20 of 22 cases), respectively, for detection of major arterial atheroma. For the 46 cases of stroke, the final etiologic classifications determined by using the standard combination approach were cardiac sources in 20 (44%) cases, major arterial atheroma in nine (20%), multiple sources in four (9%), and cryptogenic sources in 13 (28%). Multidetector CT facilitated correct etiologic classification for 38 (83%) of the 46 patients.

CONCLUSION

Multidetector CT is a promising tool for etiologic assessment of ischemic stroke, although the identification of minor cardiac sources with this examination requires the establishment of robust criteria.

Differentiation between spontaneous echocardiographic contrast and left atrial appendage thrombus in patients with suspected embolic stroke using two-phase multidetector computed tomography

The detection of a thrombus at the left atrial appendage (LAA) is an important step for management in a patient with a suspected embolic infarction. However, spontaneous echocardiographic contrast (SEC), which can mimic thrombus, can confuse clinicians in many cases. We examined electrocardiographic-gated 64-slice multidetector computed tomography with a 2-phase scan and transesophageal echocardiography in 314 patients with suspected embolic stroke. The transesophageal echocardiographic findings were classified using a 5-grade scale and the multidetector computed tomographic findings were categorized as no filling defect, an early filling defect (a filling defect seen on early-phase images without considering the late-phase images), and a persistent filling defect (a filling defect seen on added late-phase images, as well as on early-phase images). For quantitative analysis, the ratio of Hounsfield units in the LAA to the ascending aorta (AA) was calculated for each early-phase and late-phase image (LAA/AA(L)). Using transesophageal echocardiography as the reference standard, for no filling defect seen on early-phase images, the presence of a thrombus, including severe SEC, could be ruled out with 100% sensitivity and a 100% negative predictive value. When considering the addition of late-phase images, all persistent filling defects had resulted from the presence of a thrombus and severe SEC. However, using the optimal cutoff value of 0.5 for the LAA/AA(L) ratio, thrombi could be distinguished from severe SEC where all thrombi had a LAA/AA(L) ratio < 0.5. In conclusion, our findings suggest that 2-phase multidector computed tomography is useful for the detection and differentiation of a thrombus from SEC at the LAA in patients with suspected embolic stroke.

Heart as a source of stroke: imaging evaluation with computed tomography

Stroke from cardiac sources is a major cause of cerebral infarctions and ischemia. Cardiac sources of stroke include intracardiac thrombus, right-to-left shunts, tumors, and slow-flow states resulting from hemodynamic compromise. Computed tomography angiography of the neck is currently used for the evaluation of a suspected stroke. The availability of longer multidetector computed tomography detector arrays and prospective echocardiography triggering techniques could permit evaluation of the chest, head, and neck during the same examination, streamlining patient evaluation and management.