Left atrial size and function as assessed by computed tomography in cardiac resynchronization therapy: Association to echocardiographic and clinical outcome

Improving Reproducibility of Volumetric Evaluation Using Computed Tomography in Pediatric Patients with Congenital Heart Disease

The volumetric data obtained from the cardiac CT scan of congenital heart disease patients is important for defining patient's status and making decision for proper management. The objective of this study is to evaluate the intra-observer, inter-observer, and interstudy reproducibility of left ventricular (LV) and right ventricular (RV) or functional single-ventricle (FSV) volume. And compared those between manual and using semi-automated segmentation tool. Total of 127 patients (56 female, 71 male; mean age 82.1 months) underwent pediatric protocol cardiac CT from January 2020 to December 2022. The volumetric data including both end-systolic and -diastolic volume and calculated EF were derived from both conventional semiautomatic region growing algorithms (CM, TeraRecon, TeraRecon, Inc., San Mateo, CA, USA) and deep learning-based annotation program (DLS, Medilabel, Ingradient, Inc., Seoul, Republic of Korea) by three readers, who have different background knowledge or experience of radiology or image extraction before. The reproducibility was compared using intra- and inter-observer agreements. And the usability was measured using time for reconstruction and number of tests that were reconfigured before the reconfiguration time was reduced to less than 5 min. Inter- and intra-observer agreements showed better agreements degrees in DLS than CM in all analyzers. The time used for reconstruction showed significantly shorter in DLS compared with CM. And significantly small numbers of tests before the reconfiguration is needed in DLS than CM. Deep learning-based annotation program can be more accurate way for measurement of volumetric data for congenital heart disease patients with better reproducibility than conventional method.

Left atrium phasic impairments in paroxysmal atrial fibrillation patients assessed by cardiovascular magnetic resonance feature tracking

Atrial fibrillation (AF) is an abnormal and irregular heartbeat caused by uncoordinated electrical impulses in the left atrium (LA), which could induce lasting changes in the heart tissue or could be a consequence of underlying cardiac disease. This study aimed to assess the left atrial phasic function and deformation in paroxysmal AF (PAF) patients—who had not received radiofrequency ablation and had no signs of permanent AF—using the cardiovascular magnetic resonance (CMR) feature-tracking (FT) technique. Fifty subjects (27 PAF patients and 23 controls) were included and examined with CMR. Their LA volume, LA function, LA longitudinal strain (LS) and LA strain rate were assessed in the LA reservoir, conduit, and contractile phases. PAF patients exhibited higher LA volumes than controls, while their LA emptying fraction and LA LS was significantly lower in all three phases. In contrast, the corresponding emptying volumes (total, passive and active) were similar in both groups. The LA volumetric rates from CMR-derived volume curves differed significantly in PAF patients vs controls in the reservoir and contractile phases. In contrast, the equivalent LV volumetric rates were similar. This study suggests that assessing the LA phasic function could offer insight into early LA impairments for PAF patients.

Left Atrial Function Determined by Cardiac Computed Tomography Predicts Device-Detected Atrial High-Rate Episodes in Patients Treated With Cardiac Resynchronization Therapy

OBJECTIVE

The objective of this study was to examine whether left atrial (LA) volumes and function were associated with atrial high-rate episodes (AHREs) in patients with cardiac resynchronization therapy (CRT).

METHODS

Ninety-two consecutive patients without prior atrial fibrillation underwent clinical evaluation, echocardiograms, and cardiac computed tomography (CT) before CRT implantation and after 6 months. Left atrial volumes and LA emptying fraction (LAEF) were derived by CT images reconstructed at 5% phase increments of the cardiac cycle. Cox regression was used to assess associations between AHRE and LA anatomical and functional variables.

RESULTS

Twenty-two patients (24%) developed AHRE during 1.9 years (SD, 1 year) At baseline, higher LAEF was associated with a lower risk of AHRE (hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.91-0.98; P = 0.003), and large LA minimal (LAmin) volume was related to higher risk of AHRE (HR, 1.03; 95% CI, 1.00-1.06; P = 0.04). When combining LAEF and LAmin volume, only LAEF remained associated with occurrence of AHRE. Higher passive LAEF was associated with lower risk of AHRE (HR, 0.95; 95% CI, 0.91-0.98; P = 0.003).

CONCLUSIONS

In patients with CRT, low preimplant LAEF measured by cardiac CT was independently associated with device-detected AHRE.

Improved Left Atrial Function in CRT Responders: A Systematic Review and Meta-Analysis

Cardiac resynchronization therapy (CRT) is associated with reverse left atrial (LA) remodeling. The aim of this meta-analysis was to assess the relationship between clinical response to CRT and LA function changes. We conducted a systematic search of all electronic databases up to September 2019 which identified 488 patients from seven studies. At (mean) 6 months follow-up, LA systolic strain and emptying fraction (EF) were increased in CRT responders, with a -5.70% weighted mean difference (WMD) [95% confidence interval (CI) -8.37 to -3.04, p < 0.001 and a WMD of -8.98% [CI -15.1 to -2.84, p = 0.004], compared to non-responders. The increase in LA strain was associated with a fall in left ventricle (LV) end-systolic volume (LVESV) r = -0.56 (CI -0.68 to -0.40, p < 0.001) and an increase in the LV ejection fraction (LVEF) r = 0.58 (CI 0.42 to 0.69, p < 0.001). The increase in LA EF correlated with the fall in LVESV r = -0.51 (CI -0.63 to -0.36, p < 0.001) and the increase in the LVEF r = 0.48 (CI 0.33 to 0.61, p = 0.002). The increase in LA strain correlated with the increase in the LA EF, r = 0.57 (CI 0.43 to 0.70, p < 0.001). Thus, the improvement of LA function in CRT responders reflects LA reverse remodeling and is related to its ventricular counterpart.