A low-dose, dual-phase cardiovascular CT protocol to assess left atrial appendage anatomy and exclude thrombus prior to left atrial intervention

Left Atrial Appendage Pseudothrombus Is Associated With Stroke History in Patients With Atrial Fibrillation Undergoing Cardiac Computed Tomography

BACKGROUND

In nonvalvular atrial fibrillation (NVAF), the left atrial appendage (LAA) is the source of thrombus in up to 90% of patients. LAA pseudothrombus (LAAPT), defined as a filling defect on the initial but not the 60-second delayed acquisition on cardiovascular computed tomography scan (CCT), is a recognized phenomenon in NVAF, with unknown clinical relevance. We aimed to determine the relationship between LAAPT and history of stroke in patients with NVAF.

METHODS AND RESULTS

The study included 213 consecutive patients with NVAF undergoing CCT who were assessed for LAAPT. LA and LAA dimensions and LAA morphology correlated with clinical demographics including cardiovascular risk factors, history of stroke, thromboembolic stroke, and transient ischemic attack. Mean age (±SD) was 65.1±10.5 years (range 31-89) and 150 of 213 (70.4%) were men. LAAPT was present in 59 of 213 (27.7%) patients. Greater mean LAA ostium area (5.7 versus 4.5, P<0.001), greater mean LAA ostium area:curved length (0.11 versus 0.08, P<0.001), increased LAA volume (14.0 versus 10.2, P<0.001), and lower mean LAA tortuosity index (1.17 versus 1.38, P<0.001) were all associated with the presence of LAAPT. On multivariable analysis, LAAPT on CCT (odds ratio [OR], 3.20 [95% CI, 1.40-7.20]; P<0.006) and higher CHA2DS2-VASc score (OR, 1.65 [95% CI, 1.16-2.35]; P=0.01) were associated with all strokes, with LAAPT remaining a statistically significant risk factor even after adjustment for CHA2DS2-VASc score.

CONCLUSIONS

LAAPT on CCT is common in patients with NVAF. It has a strong positive association with stroke prevalence, even after adjustment for CHA2DS2-VASc score. LAAPT on CCT may potentially allow further stratification for stroke risk, additive to the CHA2DS2-VASc score.

Cardiac Masses and Pseudomasses: An Overview about Diagnostic Imaging and Clinical Background

A cardiac lesion detected at ultrasonography might turn out to be a normal structure, a benign tumor or rarely a malignancy, and lesion characterization is very important to appropriately manage the lesion itself. The exact relationship of the mass with coronary arteries and the knowledge of possible concomitant coronary artery disease are necessary preoperative information. Moreover, the increasingly performed coronary CT angiography to evaluate non-invasively coronary artery disease leads to a rising number of incidental findings. Therefore, CT and MRI are frequently performed imaging modalities when echocardiography is deemed insufficient to evaluate a lesion. A brief comprehensive overview about diagnostic radiological imaging and the clinical background of cardiac masses and pseudomasses is reported.

Left lateral decubitus computed tomography before catheter ablation in patients with atrial fibrillation

Aim    The study aimed to determine the efficacy of cardiac computed tomography angiography (CCTA) for diagnosing left atrial appendage (LAA) thrombus before catheter ablation with the patient in the left lateral decubitus position and, also, to evaluate the risk factors for thrombus formation.Material and methods    This retrospective, cohort study included 101 patients with atrial fibrillation. All patients underwent transthoracic echocardiography (TTE) and left lateral decubitus CCTA. Transesophageal echocardiography (TEE) was performed to confirm or exclude LAA thrombus. Patients with allergic reactions to iodinated contrast media, increased serum creatinine, hyperthyroidism, pregnancy, and age&lt;18 years were excluded. The CHA2‑DS2‑VASc and HAS-BLED scores were calculated for each patient.Results    All LAA thrombi detected on CCTA were confirmed by TEE. Higher CHA2‑DS2‑VASc, HAS-BLED scores, enlarged LA, and the anteroposterior dimension of the left atrium were significantly associated with the presence of LAA thrombus. A LAA cauliflower shape was a predictor of thrombus. An increase of LAA volume by 1 ml increased the chances of LAA thrombus and cerebral ischemic infarct by 2 %. The growth of the LAA anteroposterior diameter by 1 cm increased the risk of LAA thrombus by 190 % and of cerebral infarct by 78 %. An increase in the CHA2DS2‑VASc score by 1 point increased the risk of thromboembolism and cerebral infarction by 12 %.Conclusions    CCTA performed in the left lateral decubitus position of the patient is an optimal screening tool to detect or exclude LAA thrombus before catheter ablation because of atrial fibrillation. CCTA has predictive value for risk of thrombosis formation in LAA.

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.

Prevalence and characteristics of transesophageal echocardiography-related esophageal mucosal injury in patients with atrial fibrillation who underwent pulmonary vein isolation

BACKGROUND

Transesophageal echocardiography (TEE) is the gold standard for detecting thrombi in the left atrium (LA) and left atrial appendage (LAA) prior to pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). Although TEE has a good safety profile, it was recently reported that TEE preceding PVI can cause esophageal mucosal injuries (EMIs). The exact mechanism remains to be elucidated. In the present study, we investigated the incidence and risk factors of TEE-related EMI (TEE-EMI) among patients who underwent PVI for AF.

METHODS AND RESULTS

This study included 262 consecutive patients who underwent PVI with preoperative TEE using a 3D TEE probe and postoperative esophagogastroduodenoscopy. TEE-EMIs were observed in 16 (6.1%) patients (18 lesions), whereas PVI-related EMIs were found in 5 (1.9%) patients (8 lesions). All TEE-EMIs were observed in the upper or middle esophagus and occurred more frequently in the right region of the upper esophagus and the left anterior region of the middle esophagus; only one patient experienced mild chest discomfort. In the multivariate analysis, advanced age was an independent risk factor for TEE-EMIs (odds ratio 1.08, 95% confidence interval 1.01-1.16; P = 0.0274).

CONCLUSIONS

The incidence of TEE-EMIs with 3D TEE probes was relatively high in the upper or middle esophagus, anatomically close to the LA, among patients who underwent PVI. Advanced age could pose a significant risk. These findings may warrant consideration of other methods to rule out LA/LAA thrombi, especially in elderly patients.

Applications of multimodality imaging for left atrial catheter ablation

Atrial arrhythmias, including atrial fibrillation and atrial flutter, may be treated through catheter ablation. The process of atrial arrhythmia catheter ablation, which includes patient selection, pre-procedural planning, intra-procedural guidance, and post-procedural assessment, is typically characterized by the use of several imaging modalities to sequentially inform key clinical decisions. Increasingly, advanced imaging modalities are processed via specialized image analysis techniques and combined with intra-procedural electrical measurements to inform treatment approaches. Here, we review the use of multimodality imaging for left atrial ablation procedures. The article first outlines how imaging modalities are routinely used in the peri-ablation period. We then describe how advanced imaging techniques may inform patient selection for ablation and ablation targets themselves. Ongoing research directions for improving catheter ablation outcomes by using imaging combined with advanced analyses for personalization of ablation targets are discussed, together with approaches for their integration in the standard clinical environment. Finally, we describe future research areas with the potential to improve catheter ablation outcomes.

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.

Coronary CTA to Investigate Predictive Value of Left Atrial Appendage for Cardiogenic Stroke in Patients with Nonvalvular Atrial Fibrillation

PURPOSE

To investigate the predictive value of changes in LAA size and function for cardiogenic stroke (CS) in patients with NVAF by coronary CTA examination. Materials and Method. 179 patients with NVAF were selected and grouped according to the outbreak of acute ischemic stroke and TIA within 2 years after coronary CTA examination. Those who met the criteria for CS were selected as cases (87 patients), and those neither stroke nor TIA as controls (92 patients). LAA size of selected patients was measured and data postprocessing was performed. The differences of baseline data and LAA parameters between groups were analyzed. The impacts of BMI, hyperlipidemia, the duration of AF, the LAAOA Index, and the LAAEF on CS were assessed by binary logistic regression. The predictive abilities of LAAOA Index, LAAEF, and the combined predictor were assessed by ROC curves.

RESULTS

Proportions of BMI ≥ 25, prevalence of hyperlipidemia, duration of AF, and LAAODmax, LAAODmin, LAAOA, LAAVmax, and LAAVmin with their correction index were greater in cases than controls. The LAAEF was lower in cases than that in controls. The binary logistic regression model showed an increase in LAAOA Index (P = 0.005) and a decrease in LAAEF (P < 0.001) were independent risk factors for CS. ROC curve analysis showed that the optimal cutoff values of LAAOA Index and LAAEF to predict CS were 3.16 cm²/m² and 38.71%, with AUC value of 0.712 and 0.734, respectively. The LAAOA Index-LAAEF combined predictor (AUC value = 0.786) was likely superior to either LAAOA Index or LAAEF.

CONCLUSIONS

Coronary CTA can provide additional valuable parameters, as a by-product of coronary artery assessment without additional radiation dose, for the risk assessment of CS in patients with NVAF. Coronary CTA may make up for the limitation of single indicator of CHA₂DS₂-VASc in guiding anticoagulation program, to reduce the incidence of embolism and bleeding events.

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.

Cardio-Oncology in the Era of the COVID-19 Pandemic and Beyond

Coronavirus disease 2019 (COVID-19) has emerged as a global pandemic and public health crisis. Increasing waves of intermittent infectious outbreaks have dramatically influenced care among broad populations. Over the past 2 decades, there has been a rapid increase in cancer survival, with >400 000 new survivors each year. The increasingly common presence of cardiovascular disease in patients during or after cancer treatment led to the rapid growth of the field of cardio-oncology with a mandate of identifying, treating, and preventing the various forms of cardiovascular disease seen among this population. This review evaluates the implications of the pandemic on the practice and study of cardio-oncology. The evolving understanding of the relationship between comorbid disease and clinical outcomes among this population is assessed. With the impetus of the pandemic, cardio-oncology can be deliberate in embracing changes to cardiac screening, monitoring, and intervention during oncology care. Bridging 2 specialties, consideration of the lessons learned in cancer and cardiovascular may pivotally inform ongoing therapeutic efforts. Further, the development of multicenter registries focused on understanding and optimizing outcomes among these patients should be considered. Together, these insights may critically inform strategies for the care of cardio-oncology patients in future phases of the COVID-19 pandemic and beyond.

Diagnosis of left atrial appendage thrombus in patients with atrial fibrillation: delayed contrast-enhanced cardiac CT

Objectives

The current reference standard for diagnosing LAA thrombi is transesophageal echocardiography (TEE), a semi-invasive technique. We aimed to devise an optimal protocol for cardiac computed tomography (CCT) in diagnosing left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF), using TEE as reference standard.

Methods

Two hundred sixty consecutive patients referred for radiofrequency ablation for AF were prospectively enrolled. All patients underwent CCT and TEE within 2 hours. The CCT protocol included one standard angiographic phase and three delayed acquisitions at 1-, 3-, and 6-min after contrast injection. Thrombi were defined as persisting defects at 6-min delayed acquisition.

Results

TEE demonstrated spontaneous contrast in 52 (20%) patients and thrombus in 10 (4%). In 63 patients (24%), CCT demonstrated LAA early filling defects at angiographic phase. Among them, 15 (6%) had a persistent defect at 1-min, 12 (5%) at 3-min, and 10 (4%) at 6-min. All 10 thrombi diagnosed on TEE were correctly identified by delayed CCT, without any false positives. For all phases, sensitivity and negative predictive were 100%. Specificity increased from 79% for the angiographic phase to 100% at 6-min. Positive predictive value increased from 16% to 100%. Estimated radiation exposure was 2.08 ± 0.76 mSv (mean ± standard deviation) for the angiographic phase and 0.45 ± 0.23 mSv for each delayed phase.

Conclusion

A CCT protocol adding a 6-min delayed phase to the angiographic phase can be considered optimized for the diagnosis of LAA thrombi, with a low radiation dose.

Key Points

• In patients with persistent atrial fibrillation referred for ablation procedures, a cardiac CT examination comprising an angiographic-phase acquisition and, in case of filling defects, a 6-min delayed phase may help reduce the need for transesophageal echocardiography.

• Cardiac CT would provide morphological and volumetric data, along with the potential to exclude the presence of thrombi in the left atrial appendage.

Preoperative Planning for Structural Heart Disease

Preoperative assessment with computed tomography (CT) is critical before transcatheter interventions for structural heart disease. CT provides information for device selection, device sizing, and vascular access approach. The interpreting radiologist must have knowledge of appropriate CT protocols, how and where to obtain the important measurements, and know additional imaging characteristics that are important to describe for optimal support of the interventionalist. CT is the modality of choice for pre-operative evaluation in patients undergoing transcatheter aortic valve replacement and left atrial appendage occlusion, and is also useful before transcatheter mitral valve replacement, which is an ongoing area of research.

Predicting Left Atrial Appendage Thrombus from Left Atrial Volume and Confirmation by Computed Tomography with Delayed Enhancement

Assessing thromboembolic risk is crucial for proper management of patients with atrial fibrillation. Left atrial volume is a promising predictor of cardiac thrombosis. To determine whether left atrial volume can predict left atrial appendage thrombus in patients with atrial fibrillation, we conducted a prospective study of 73 patients. Left atrial and ventricular volumes were evaluated by cardiac computed tomography with retrospective electrocardiographic gating and then indexed to body surface area. Left atrial appendage thrombus was confirmed or excluded by cardiac computed tomography with delayed enhancement. Seven patients (9.6%) had left atrial appendage thrombus; 66 (90.4%) did not. Those with thrombus had a significantly higher mean left atrial end-systolic volume index (139 ± 55 vs 101 ± 35 mL/m2; P =0.0097) and mean left atrial end-diastolic volume index (122 ± 45 vs 84 ± 34 mL/m2; P =0.0077). On multivariate logistic regression analysis, left atrial end-systolic volume index (per 10 mL/m2 increase) was significantly associated with left atrial appendage thrombus (odds ratio [OR]=1.24; 95% CI, 1.03-1.50; P =0.02); so too was the left atrial end-diastolic volume index (per 10 mL/m2 increase) (OR=1.29; 95% CI, 1.05-1.60; P =0.02). These findings suggest that increased left atrial volume increases the risk of left atrial appendage thrombus. Therefore, patients with atrial fibrillation and an enlarged left atrium should be considered for cardiac computed tomography with delayed enhancement to confirm whether thrombus is present.

Computed Tomography of the Left Atrium and Left Atrial Appendage: A Pictorial Essay on the Anatomy, Normal Variants, and Pathology

전산화단층촬영(이하 CT) 영상 기술의 발전으로 박동하는 심장에 대한 섬세한 영상의학적 평가가 가능해졌다. 심초음파 및 MRI에 비해 심장 CT의 강점은 대부분의 의료기관에 보급되어 있고 고품질 이미지의 빠른 생산이 가능하며 해부학적 묘사가 뛰어나다는 것이다. 좌심방과 좌심방이에서 생기는 대부분의 변이 혹은 병리적 상태들은 CT 상의 소견만으로도 추정진단을 내릴 수 있다. 또한 CT 영상은 성공적인 카테터 기반 시술 또는 수술에 중요한 해부학적 정보들을 제공한다. 특히 좌심방과 좌심방이는 심방세동 환자들의 치료 및 관리에 중요한데, 이는 다양한 카테터 기반 시술들이 두 구조물의 기계적 혹은 전기적 차단을 목표로 하기 때문이다. 따라서 임상적으로 의미 있는 판독을 위해서는 병리적 상태의 CT 소견 기술과 함께 좌심방 및 좌심방이의 모양, 크기 및 주변 구조물과의 상대적 위치 관계 등에 대한 포괄적인 검토를 해야 한다.

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.

Patient Safety Analysis in Radiation Burden of Head Computed Tomography Imaging in 1185 Neurosurgical Inpatients

OBJECTIVE

We performed a retrospective analysis in a cohort of 1185 patients at our institution who were identified as undergoing ≥1 head computed tomography (CT) examinations during their inpatient stay on the neurosurgery service, to quantify the number, type, and associated radiation burden of head CT procedures performed by the neurosurgery service.

METHODS

CT procedure records and radiology reports were obtained via database search and directly validated against records retrieved from manual chart review. Next, dosimetry data from the head CT procedures were extracted via automated text mining of electronic radiology reports.

RESULTS

Among 4510 identified adult head CT procedures, 88% were standard head CT examinations. A total of 3.65 ± 3.60 head CT scans were performed during an average adult admission. The most common primary diagnoses were neoplasms, trauma, and other hemorrhage. The median cumulative effective dose per admission was 5.66 mSv (range, 1.06-84.5 mSv; mean, 8.56 ± 8.95 mSv). The median cumulative effective dose per patient was 6.4 mSv (range, 1.1-127 mSv; mean, 9.26 ± 10.0 mSv).

CONCLUSIONS

The median cumulative radiation burden from head CT imaging in our cohort equates approximately to a single chest CT scan, well within accepted limits for safe CT imaging in adults. Refined methods are needed to characterize the safety profile of the few pediatric patients identified in our study.

Role of imaging in diagnosis and management of left ventricular assist device complications

Heart failure is a clinical condition that is associated with significant morbidity and mortality. With the advent of left ventricular assist device (LVAD), an increasing number of patients have received an artificial heart both as a bridge-to-therapy and as a destination therapy. Clinical trials have shown clear survival benefits of LVAD implantation. However, the increased survival benefits and improved quality of life come at the expense of an increased complication rate. Common complications include perioperative bleeding, infection, device thrombosis, gastrointestinal bleeding, right heart failure, and aortic hemodynamic changes. The LVAD-associated complications have unique pathophysiology. Multiple imaging modalities can be employed to investigate the complications, including computed tomography (CT), positron emission tomography-computed tomography (PET-CT), catheter angiography and echocardiography. Imaging studies not only help ascertain diagnosis and evaluate the severity of disease, but also help direct relevant clinical management and predict prognosis. In this article, we aim to review the common LVAD complications, present the associated imaging features and discuss the role of imaging in their management.

Cardiac computed tomography previous to atrial fibrillation ablation - effects of technological improvements and protocol optimization

BACKGROUND

Cardiac computed tomography (CT) can provide a precise tridimentional anatomic map and exclude intra-cardiac thrombus. We aimed to access the impact of CT protocol optimization and technological evolution on the contrast and radiation dose as well as on image quality previous to atrial fibrillation (AF) ablation.

METHODS

From a prospective registry of consecutive patients who underwent cardiac CT in a single center, we selected 270 patients in whom the CT was done for evaluation prior to AF ablation and they were distributed in 3 groups: Group1: the first 150 patients included; Group2: the last 60 patients performed with the same CT scanner; Group3: the first 60 exams performed with the new CT scanner. Quality of the protocol was access based on radiation dose, contrast volume used, the use of a second (delayed) acquisition, and on quantitative image quality analisis (signal to noise and contrast to noise ratios; density homogeneity racio between LA and LAA).

RESULTS

We found a significant radiation dose as well as contrast dose reduction between the first and last subgroups (G1: 5,6mSv and 100ml; G2: 1,3mSv and 90ml; G3: 0,6mSv and 65ml). Even though group 3 had less radiation and contrast used it still had better quantitative image quality (signal/noise of 13,5; contrast/noise 14,8; density homogeneity racio of 0,92).

CONCLUSION

Protocol optimization and technology both contributed to significant lower radiation dose and contrast volume used on cardiac CTs prior to AF ablation, without compromising image quality.

Exclusion of left atrial thrombus by dual-source cardiac computed tomography prior to catheter ablation for atrial fibrillation

OBJECTIVES

Thromboembolic complications during atrial fibrillation (AF) ablation due to mobilisation of a pre-existing thrombus formation (TF) in the left atrium (LA) are devastating. The gold standard to exclude LA TF is transesophageal echocardiography (TEE). The present study compares sensitivity and specificity of a dual-source cardiac-computed tomography (DS-CT) with TEE for TF exclusion prior to AF ablation. In addition, CT protocols with and without ECG synchronized were evaluated.

METHODS

In 622 patients, DS-CT as well as TEE to exclude TF was performed less than 48 h prior to AF ablation. Mean age of patients was 60 ± 10 years (69% males, 61% paroxysmal AF). During DS-CT, 280 patients (45%) were in AF. An ECG-synchronized DS-CT was performed in 332 patients, whereas 290 patients underwent DS-CT without ECG synchronization.

RESULTS

In all patients without suspected TF on DS-CT (n = 552; 88.7%), no thrombus was found on TEE. A TF was suspected on DS-CT in 70 patients, of whom only three patients showed TF on TEE. No TF was detected in the other 67 patients (Fig. 1). Overall, sensitivity for TF detection in DS-CT was 100% and specificity was 89.2% (positive predictive value 4.3%, negative predictive value 100%). The CT protocol (ECG-synchronized versus non-ECG-synchronized) had no significant influence on diagnostic accuracy. Mean dose length product during DS CT was 282 ± 287 mGy cm (synchronized) versus 136 ± 55 mGy cm (non-synchronized) with p < 0.0001.

CONCLUSIONS

DS-CT is a highly sensitive method for LA thrombus detection in patients undergoing AF ablation. It delivers additional anatomic details of pulmonary veins and LA anatomy with an acceptable radiation exposure. Non-ECG-synchronized DS-CT showed a significantly lower radiation exposure, whereas diagnostic accuracy was comparable. Therefore, DS-CT might serve as primary method to exclude LA TF in patients undergoing AF ablation.

Accuracy of cardiac CT in evaluating severity of left atrial appendage spontaneous echo contrast: comparison with transesophageal echocardiography

To investigate the capacity of biphasic cardiac CT (CCT) for qualitative and quantitative evaluation of different grades of left atrial appendage spontaneous echo contrast (LAASEC). The study included 267 inpatients with confirmed atrial fibrillation who underwent both CCT and transesophageal echocardiography (TEE). CT numbers for LAA, ascending aorta (AA), and left atrium (LA) were identified, and ROC curves for LAA, LAA/AA, and LAA/LA were plotted. With TEE as the standard, the sensitivity, specificity, PPV, NPV, and accuracy of CCT for LAASEC grade ≥ 1 were 60.3, 92.9, 92.4, 64.8, and 75.7%; and for grade ≥ 2 were 100.0, 84.4, 71.4, 100.0, and 88.8% respectively. The values of LAA, LAA/AA, and LAA/LA were significantly larger in LAASEC grade 0 versus 1 and in grade 1 versus 2, but were similar in grades 2 and 3 or in grades 3 and 4. The values of LAA/AA were larger in grade 2 versus 4. When the cutoff value for LAA/AA = 0.897, sensitivity, specificity, PPV, NPV, and accuracy of CCT for LAASEC grade ≥ 1 was 89.6, 83.2, 87.9, 85.5, and 86.9% and with a cutoff for LAA/AA of 0.524, the sensitivity, specificity, PPV, NPV, and accuracy for LAASEC grade ≥ 2 was 98.7, 92.7, 84.1, 99.4, and 94.4%. Although CCT showed limited diagnostic accuracy for grade 1 LAASEC, grade ≥ 2 LAASEC could be excluded when there was no LAA filling defect on first-phase CCT, and TEE can be avoided. CCT has an excellent accuracy in diagnosing LAASEC, and quantitative analysis (in particular LAA/AA) is superior.

Cardiac Computed Tomography for Left Atrial Appendage Occlusion: Acquisition, Analysis, Advantages, and Limitations

Transcatheter left atrial appendage occlusion is increasingly used for stroke prevention in atrial fibrillation. The technique has proven effective and safe in randomized trials and multiple observational studies. The procedure is challenging due to the complex anatomy of the left atrial appendage; accurate cardiac imaging is essential for procedural guidance. Transesophageal echocardiography is the gold standard, but cardiac computed tomography (CT) has gained increasing interest within recent years. Cardiac CT offers high-resolution imaging allowing for preprocedural anatomic evaluation and device sizing, but may also be useful for exclusion of left atrial appendage thrombus, and follow-up assessment of residual peri-device leaks.

Transoesophageal echocardiography prior to catheter ablation could be avoided in atrial fibrillation patients with a low risk of stroke and without filling defects in the late-phase MDCT scan: A retrospective analysis of 783 patients

OBJECTIVES

To test whether multidetector computed tomography (MDCT) could completely replace transoesophageal echocardiography (TEE) to detect left atrial appendage (LAA) thrombi in atrial fibrillation (AF) patients using a large sample size.

METHODS

783 patients with AF who underwent MDCT and TEE before catheter ablation were retrospectively included. Demographic data were obtained. Two radiologists blinded to clinical data made the imaging diagnosis.

RESULTS

Most of the patients (96.2 %) had a CHA₂DS₂-VASc score (congestive heart failure, hypertension, age ≥ 75 years old (doubled), diabetes, stroke/transient ischaemic attack/thromboembolism (doubled), vascular disease, age 65-74 years, female sex) ≤ 3. Eight thrombi were identified by TEE, all of which were detected by MDCT; no thrombus was observed with TEE without the observation of filling defects by late-phase MDCT scanning in any of the patients. Using TEE as reference standard, the sensitivity, specificity, positive predictive value and negative predictive value of MDCT for thrombus detection were 100 %, 95.74 % (95 % CI 94.33 %-97.15 %), 19.51 % (95 % CI 16.73 %-22.29 %) and 100 %, respectively.

CONCLUSIONS

For AF patients with low risk of stroke, when MDCT images showed no filling defect in the late phase, TEE prior to catheter ablation can be avoided.

KEY POINTS

• MDCT can help detect the presence of LAA thrombus. • TEE can be avoided when late-phase MDCT shows no filling defect. • TEE is required in patients whose MDCT images indicate thrombus.

A prospective national survey of coronary CT angiography radiation doses in the United Kingdom

BACKGROUND

Little real-world radiation dose data exist for the majority of cardiovascular CT. Some data have been published for coronary CT angiography (coronary CTA) specifically, but they invariably arise from high-volume centres with access to the most recent technology.

OBJECTIVE

The aim of this study was to document real-world radiation doses for coronary CTA in the United Kingdom, and to establish their relationship to clinical protocol selection, acquisition heart rate, and scanner technology.

METHODS

A dose survey questionnaire was distributed to members of the British Society of Cardiovascular Imaging and other UK cardiac CT units. All participating centres collected data for consecutive coronary CTA cases over one month. The survey captured information about the exam conducted, patient demographics, pre-scan details such as beta-blocker administration, acquisition heart rate and scan technique, and post-scan dose indicators - series volumetric CT dose index (CTDI_vol), series dose-length product (DLP), and exam DLP.

RESULTS

Fifty centres provided data on a total of 1341 coronary CTA exams. Twenty-nine centres (58%) performed at least 20 coronary CTA scans in the collection period. The median BMI, acquisition heart rate and exam DLP were 28 kg/m², 60 bpm and 209 mGycm respectively. The corresponding effective dose was estimated as 5.9 mSv using a conversion factor of 0.028 mSv/mGycm. There was no statistically significant difference in radiation dose between low and high-volume centres. Median exam DLP increased with the acquisition heart rate due to the selection of wider temporal windows. The highest exam DLPs were obtained on the older scanner technology.

CONCLUSION

This study provides baseline data for benchmarking practice, optimizing radiation dose and improving service quality locally.