Regional Distribution of Extracellular Volume Quantified by Cardiac CT in Aortic Stenosis: Insights Into Disease Mechanisms and Impact on Outcomes.

BACKGROUND: Extracellular volume fraction (ECV) is a marker for myocardial fibrosis and infiltration, can be quantified using cardiac computed tomography (ECVCT), and has prognostic utility in several diseases. This study aims to map out regional differences in ECVCT to obtain greater insights into the pathophysiological mechanisms of ECV expansion and its clinical implications. METHODS: Three prospective cohorts were included: patients with aortic stenosis (AS) and coexisting AS and transthyretin cardiac amyloidosis were referred for a transcatheter aortic valve replacement and had ECG-gated CT angiography and Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy to differentiate between the 2 cohorts. Controls had CT angiography and cardiac magnetic resonance demonstrating no significant coronary artery disease or infarction. Global and regional ECVCT was analyzed, and its association with mortality was assessed for patients with AS. RESULTS: In 199 patients, controls (n=65; 66% male), AS (n=115), and coexisting AS and transthyretin cardiac amyloidosis (n=19) had a global ECVCT of 26.1 (25.0-27.8%) versus 29.1 (27.5-31.1%) versus 37.4 (32.5-46.6%), respectively; P<0.001. Across cohorts, ECVCT was higher at the base (versus apex), the inferoseptum (versus anterolateral wall), and the subendocardium (versus subepicardium); P<0.05 for all. Among patients with AS, epicardial ECVCT, rather than any other regional value or global ECVCT, was the strongest predictor of mortality at a median of 3.9 (max 6.3) years (adjusted hazard ratio, 1.21 [95% CI, 1.08-1.36]; P=0.002). CONCLUSIONS: Regional differences in ECVCT suggest a predilection for fibrosis and amyloid infiltration at the base, subendocardium, inferior wall, and septum more than the anterior and lateral myocardium. ECVCT can predict long-term mortality with the subepicardium demonstrating the strongest discriminatory power. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03029026 and NCT03094143.

Cardiac Computed Tomography: Application in Valvular Heart Disease.

The incidence and prevalence of valvular heart disease (VHD) is increasing and has been described as the next cardiac epidemic. Advances in imaging and therapeutics have revolutionized how we assess and treat patients with VHD. Although echocardiography continues to be the first-line imaging modality to assess the severity and the effects of VHD, advances in cardiac computed tomography (CT) now provide novel insights into VHD. Transcatheter valvular interventions rely heavily on CT guidance for procedural planning, predicting and detecting complications, and monitoring prosthesis. This review focuses on the current role and future prospects of CT in the assessment of aortic and mitral valves for transcatheter interventions, prosthetic valve complications such as thrombosis and endocarditis, and assessment of the myocardium.

Right Ventricular Volume and Function Assessment in Congenital Heart Disease Using CMR Compressed-Sensing Real-Time Cine Imaging.

BACKGROUND AND OBJECTIVE: To evaluate the reliability of compressed-sensing (CS) real-time single-breath-hold cine imaging for quantification of right ventricular (RV) function and volumes in congenital heart disease (CHD) patients in comparison with the standard multi-breath-hold technique. METHODS: Sixty-one consecutive CHD patients (mean age = 22.2 ± 9.0 (SD) years) were prospectively evaluated during either the initial work-up or after repair. For each patient, two series of cine images were acquired: first, the reference segmented multi-breath-hold steady-state free-precession sequence (SSFPref), including a short-axis stack, one four-chamber slice, and one long-axis slice; then, an additional real-time compressed-sensing single-breath-hold sequence (CSrt) providing the same slices. Two radiologists independently assessed the image quality and RV volumes for both techniques, which were compared using the Wilcoxon test and paired Student's t test, Bland-Altman, and linear regression analyses. The visualization of wall-motion disorders and tricuspid-regurgitation-related signal voids were also analyzed. RESULTS: The mean acquisition time for CSrt was 22.4 ± 6.2 (SD) s (95% CI: 20.8-23.9 s) versus 442.2 ± 89.9 (SD) s (95% CI: 419.2-465.2 s) for SSFPref (p < 0.001). The image quality of CSrt was diagnostic in all examinations and was mostly rated as good (n = 49/61; 80.3%). There was a high correlation between SSFPref and CSrt images regarding RV ejection fraction (49.8 ± 7.8 (SD)% (95% CI: 47.8-51.8%) versus 48.7 ± 8.6 (SD)% (95% CI: 46.5-50.9%), respectively; r = 0.94) and RV end-diastolic volume (192.9 ± 60.1 (SD) mL (95% CI: 177.5-208.3 mL) versus 194.9 ± 62.1 (SD) mL (95% CI: 179.0-210.8 mL), respectively; r = 0.98). In CSrt images, tricuspid-regurgitation and wall-motion disorder visualization was good (area under receiver operating characteristic curve (AUC) = 0.87) and excellent (AUC = 1), respectively. CONCLUSIONS: Compressed-sensing real-time cine imaging enables, in one breath hold, an accurate assessment of RV function and volumes in CHD patients in comparison with standard SSFPref, allowing a substantial improvement in time efficiency.

Compressed sensing real-time cine imaging for assessment of ventricular function, volumes and mass in clinical practice.

OBJECTIVES: This study was conducted in order to evaluate the accuracy of a compressed sensing (CS) real-time single-breath-hold cine sequence for the assessment of left and right ventricular functional parameters in daily practice. METHODS: Cardiac magnetic resonance (CMR) cine images were acquired from 100 consecutive patients using both the reference segmented multi-breath-hold steady-state free precession (SSFP) acquisition and a prototype single-breath-hold real-time CS sequence, providing the same slice number, position, and thickness. For both sequences, the left (LV) and right ventricular (RV) ejection fractions (EF) and end-diastolic volumes (EDV) were assessed as well as LV mass (LVM). The visualization of wall-motion disorders (WMD) and signal void related to mitral or tricuspid regurgitation was also analyzed. RESULTS: The CS sequence mean scan time was 23 ± 6 versus 510 ± 109 s for the multi-breath-hold SSFP sequence (p < 0.001). There was an excellent correlation between the two sequences regarding mean LVEF (r = 0.995), LVEDV (r = 0.997), LVM (r = 0.981), RVEF (r = 0.979), and RVEDV (r = 0.983). Moreover, inter- and intraobserver agreements were very strong with intraclass correlations of 0.96 and 0.99, respectively. On CS images, mitral or tricuspid regurgitation visualization was good (AUC = 0.85 and 0.81, respectively; ROC curve analysis) and wall-motion disorder visualization was excellent (AUC ≥ 0.97). CONCLUSION: CS real-time single-breath-hold cine imaging reduces CMR scan duration by almost 20 times in daily practice while providing reliable measurements of both left and right ventricles. There was no clinically relevant information loss regarding valve regurgitation and wall-motion disorder depiction. KEY POINTS: • Compressed sensing single-breath-hold real-time cine imaging is a reliable sequence in daily practice. • Fast CS real-time imaging reduces CMR scan time and improves patient workflow. • There is no clinically relevant information loss with CS regarding heart valve regurgitation or wall-motion disorders.

Left circumflex coronary artery from the pulmonary artery in scimitar syndrome.

BACKGROUND: Scimitar syndrome is a rare combination of cardiopulmonary abnormalities found in 1-3 per 1000 live births. Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is only found in 1 in 250-400 congenital heart disease patients. OBJECTIVE: We aimed to investigate the incidence of left circumflex ALCAPA within our referral center's cohort of scimitar syndrome patients. MATERIALS AND METHODS: A review of medical records, cardiac imaging and operative notes from all patients diagnosed with scimitar syndrome at our center between 1992 and 2016 was undertaken and all imaging reviewed. RESULTS: Fifty-four patients with scimitar syndrome and imaging were identified. Of these, 3 patients (1 male and 2 female) with ALCAPA were identified, representing an incidence of 5.5% (95% confidence interval [CI] 0-11.67%). In all three cases, the anomalous coronary arising from the pulmonary artery was the left circumflex coronary artery (LCx) and the point of origin was close to the pulmonary arterial bifurcation. CONCLUSION: We hypothesize that the prevalence of LCx-ALCAPA, in the setting of scimitar syndrome, may be greater than previously thought. We suggest that any patient with scimitar syndrome, especially with evidence of ischaemia, should be investigated for ALCAPA. Given its noninvasive nature and simultaneous imaging of the lungs, we suggest that cardiovascular CT is the most appropriate first-line investigation for these patients.

High-pitch versus conventional cardiovascular CT in patients being assessed for transcatheter aortic valve implantation: a real-world appraisal.

OBJECTIVE: High-pitch protocols are increasingly used in cardiovascular CT assessment for transcatheter aortic valve implantation (TAVI), but the impact on diagnostic image quality is not known. METHODS: We reviewed 95 consecutive TAVI studies: 44 (46%) high-pitch and 51 (54%) standard-pitch. Single high-pitch scans were performed regardless of heart rate. For standard-pitch acquisitions, a separate CT-aortogram and CT-coronary angiogram were performed with prospective gating, unless heart rate was ≥70 beats/min, when retrospective gating was used. The aortic root and coronary arteries were assessed for artefact (significant artefact=1; artefact not limiting diagnosis=2; no artefact=3). Aortic scans were considered diagnostic if the score was >1; the coronaries, if all three epicardial arteries scored >1. RESULTS: There was no significant difference in diagnostic image quality for either the aorta (artefact-free high-pitch: 31 (73%) scans vs standard-pitch: 40 (79%), p=0.340) or the coronary tree as a whole (10 (23%) vs 15 (29%), p=0.493). However, proximal coronary arteries were less well visualised using high-pitch acquisitions (16 (36%) vs 30 (59%), p=0.04). The median (IQR) radiation dose was significantly lower in the high-pitch cohort (dose-length product: 347 (318-476) vs 1227 (1150-1474) mGy cm, respectively, p<0.001), and the protocol required almost half the amount of contrast. CONCLUSIONS: The high-pitch protocol significantly reduces radiation and contrast doses and is non-inferior to standard-pitch acquisitions for aortic assessment. For aortic root assessment, the high-pitch protocol is recommended. However, if coronary assessment is critical, this should be followed by a conventional standard-pitch, low-dose, prospectively gated CT-coronary angiogram if the high-pitch scan is non-diagnostic.

Variants of the scimitar syndrome.

UNLABELLED: Introduction The scimitar syndrome comprises hypoplastic right pulmonary artery and lung, anomalous right pulmonary venous drainage to the inferior caval vein, aortopulmonary collateral(s) to the right lung, and bronchial anomalies. Aim The aim of this study was to describe the morphological and clinical spectrum of variants from the classical scimitar syndrome in a single institution over 22 years. RESULTS: In total, 10 patients were recognised. The most consistent feature was an aortopulmonary collateral to the affected lung (90%), but there was considerable variation in the site and course of pulmonary venous drainage. This was normal in 3 (one with meandering course), anomalous right to superior caval vein in 1, to the superior caval vein and inferior caval vein in 2, and to the superior caval vein and the left atrium in 1; one patient had a right pulmonary (scimitar) vein occluded at the insertion into the inferior caval vein but connected to the right upper pulmonary vein via a fistula. There were two left-sided variants, one with anomalous left drainage to the coronary sinus and a second to the innominate vein. Among all, three patients had an antenatal diagnosis and seven presented between 11 and 312 months of age; 90% of the patients were symptomatic at first assessment. All the patients underwent cardiac catheterisation; collateral embolisation was performed in 50% of the patients. Surgical repair of the anomalous vein was carried out in two patients, one patient had a right pneumonectomy, and one patient was lost to follow-up. There was no mortality reported in the remainder of patients during the study period. CONCLUSION: The heterogeneity of this small series confirms the consistent occurrence of an anomalous arterial supply to the affected lung but considerable variation in pulmonary venous drainage.