Left ventricular remodeling and systolic function changes in patients with obstructive sleep apnea: a comprehensive contrast-enhanced cardiac magnetic resonance study.

Background: A comprehensive assessment of left ventricular (LV) remodeling and systolic function using contrast-enhanced cardiac magnetic resonance (CMR) imaging in patients with obstructive sleep apnea (OSA) has not yet been reported. This retrospective case-control study aimed to explore and assess the myocardial structure, function, and tissue characteristic changes of LV remodeling in patients with OSA using the CMR method. Methods: Fifty-one selected participants 32 OSA and 19 non-OSA underwent overnight polysomnography and CMR examination using T1 mapping and feature tracking techniques. Twenty age- and sex-matched healthy controls were also enrolled for comparison between the groups. Results: Patients were grouped by apnea-hypopnea index (AHI): AHI <5 events/h as non-OSA group (n=19, 40.7±8.0 years), 5-30 events/h as mild-moderate OSA (n=13, 47.8±9.4 years), and >30 events/h as severe OSA (n=19, 39.0±10.0 years). The OSA group had a higher LV mass index (LVMI) to height2.7 than the non-OSA and healthy control groups (21.0±3.8 vs. 16.4±3.1 and 16.3±3.2 mL/m2.7, P<0.001). Compared with healthy controls, OSA patients had lower global circumferential strain values, although the LV ejection fraction was preserved. Late gadolinium enhancement was not detected in all participants, whereas the extracellular volume fraction was lower in patients with OSA than in the non-OSA and healthy control groups (24.4%±1.9% vs. 26.2%±2.5%, P=0.006 and 24.4%±1.9% vs. 26.5%±2.3%, P=0.004, respectively). The indexed cellular volume (iCV) of the myocardium was significantly higher in subjects with mild-to-moderate and severe OSA than in those without OSA (14.2±2.3 and 15.8±3.1 vs. 11.6±2.4 mL/m2.7, P<0.05). On multivariate linear regression analysis of patients with two different models, OSA severity remained significantly associated with increased LVMI (ß=0.348, P=0.004 and ß=0.233, P=0.048, respectively) and iCV (ß=0.337, P=0.004 and ß=0.231, P=0.047, respectively) after adjusting for clinical risk factors. Conclusions: LVMI is elevated in OSA with a normal LV ejection fraction, mainly with cellular hypertrophy. Cellular hypertrophy without focal fibrosis in OSA may be our main finding.

Multiphoton microscopy providing pathological-level quantification of myocardial fibrosis in transplanted human heart.

Multiphoton microscopy (MPM), a high-resolution laser scanning technique, has been shown to provide detailed real-time information on fibrosis assessment in animal models. But the value of MPM in human histology, especially in heart tissue, has not been fully explored. We aimed to evaluate the association between myocardial fibrosis measured by MPM and that measured by histological staining in the transplanted human heart. One hundred and twenty samples of heart tissue were obtained from 20 patients consisting of 10 dilated cardiomyopathies (DCM) and 10 ischemic cardiomyopathies (ICM). MPM and picrosirius red staining were performed to quantify collagen volume fraction (CVF) in explanted hearts postoperatively. Cardiomyocyte and myocardial fibrosis could be clearly visualized by MPM. Although patients with ICM had significantly greater MPM-derived CVF than patients with DCM (25.33  ± 12.65 % vs. 19.82  ± 8.62 %, p = 0.006), there was a substantial overlap of CVF values between them. MPM-derived CVF was comparable to that derived from picrosirius red staining based on all samples (22.58 ± 11.13% vs. 21.19 ± 11.79%, p = 0.348), as well as in DCM samples and ICM samples. MPM-derived CVF was correlated strongly with the magnitude of staining-derived CVF in both all samples and DCM samples and ICM samples (r = 0.972, r = 0.963, r = 0.973, respectively; all p < 0.001). Intra- and inter-observer reproducibility for MPM-derived CVF and staining-derived CVF were 0.995, 0.989, 0.995, and 0.985, respectively. Our data demonstrated that MPM can provide a pathological-level assessment of myocardial microstructure in transplanted human heart.

T1 mapping and feature tracking imaging of left ventricular extracellular remodeling in severe aortic stenosis.

BACKGROUND: Left ventricular (LV) extracellular remodeling is a critical process in aortic stenosis (AS), which is related to functional abnormalities. Data regarding the use of combined T1 mapping and feature tracking (FT) to assess LV extracellular remodeling in severe AS are scarce. This study aimed to investigate the ability of T1-derived and FT-derived parameters to identify and assess the changes in process of LV extracellular remodeling in patients with severe AS. METHODS: A total of 49 patients with severe AS and 20 healthy volunteers were prospectively recruited. Modified look-locker inversion-recovery T1 mapping and FT imaging were performed in all participants using 3.0-T cardiac magnetic resonance imaging. The degree of myocardial fibrosis was quantified using Masson trichrome stain in biopsy specimens obtained intraoperatively from 13 patients and expressed as collagen volume fraction (CVF). Patients were divided into subgroups according to preserved LV ejection fraction (LVEF) (LVEF ≥50%) or reduced LVEF (LVEF <50%). RESULTS: Regarding the diffuse fibrosis burden, extracellular volume (ECV) was statistically insignificant between patients with preserved LVEF) and controls (28.0%±3.3% vs. 26.5%±2.3%, P>0.05). ECV in the reduced LVEF group (n=20) was significantly higher than that in the preserved LVEF group (n=29) (30.4%±3.9% vs. 28.0%±3.3%, P<0.05). Regarding the myocardial strain, global longitudinal strain (GLS) showed increasing impairment from the control group to the preserved LVEF AS group to the reduced LVEF AS group (-23.4%±3.3% vs. -18.6%±3.8% vs. -11.2%±4.8%, P<0.05). A significant correlation was found between ECV and CVF (r=0.64, P=0.020), whereas the correlation between GLS and CVF was insignificant. Significant correlations were observed between GLS and LV mass index (r=0.72, P=0.006) and LVEF (r=0.82, P<0.001). However, no correlations were found between ECV and LV mass index (P=0.172) and between ECV and LVEF (P=0.339). Discrimination of patients with preserved LVEF from controls, GLS yielded the best diagnostic performance as defined by the area of under the curve (-0.83), and GLS, ECV, and post-T1 were significant discriminators after regression analysis. CONCLUSIONS: In the process of LV extracellular remodeling in severe AS, ECV is the structural marker of extracellular fibrosis burden, and GLS is the functional marker before the fibrosis burden intensifies.

ECG-gated CT in Aortic Perivalvular Abscess: Comparison with Transesophageal Echocardiography and Intraoperative Findings.

Background The 2015 European Society of Cardiology guidelines acknowledged similar diagnostic performance of electrocardiography (ECG)-gated CT on perivalvular abscesses compared with transesophageal echocardiography (TEE), but data on ECG-gated CT remain insufficient. Purpose To determine the diagnostic performance of ECG-gated CT for assessing aortic root perivalvular abscesses and to compare it with TEE. Materials and Methods Between January 2008 and June 2019, the imaging records of surgically confirmed infective endocarditis were retrospectively reviewed for presence of aortic perivalvular abscesses, their extension, fistulization, vegetations, and valvular destruction. The diagnostic performance of ECG-gated CT was analyzed in all patients (part A) and in an noninferiority analysis (part B; δ = -10%) in patients undergoing TEE. Results A total of 178 patients (median age, 54 years [interquartile range, 15 years]; 147 men) were evaluated (CT, n = 178; TEE, n = 35). In part A, the sensitivity and specificity of CT were 70 of 71 (99% [95% confidence interval (CI): 96%, 100%]) and 102 of 107 (95% [95% CI: 91%, 99%]) for abscess; 65 of 68 (96% [95% CI: 91%, 100%]) and 107 of 110 (97% [95% CI: 94%, 100%]) for extension, 36 of 36 (100% [95% CI: 100%, 100%]) and 139 of 142 (98% [95% CI: 96%, 100%]) for fistulization, 153 of 160 (96% [95% CI: 93%, 99%]) and five of 18 (28% [95% CI: 7%, 49%]) for vegetations, and 90 of 90 (100% [95% CI: 100%, 100%]) and 24 of 88 (27% [95% CI: 18%, 37%]) for valvular destruction. In part B, ECG-gated CT had noninferior sensitivity compared with TEE for detecting abscess (difference, 14 percentage points [lower one-sided 95% CI: -4 percentage points]), extension (difference, 0 percentage points [lower one-sided 95% CI: 0 percentage points]), fistulization (difference, 0 percentage points [lower one-sided 95% CI: 0 percentage points]), and valvular destruction (difference, 5 percentage points [lower one-sided 95% CI: -4 percentage points]). Specificity of CT was inferior for demonstrating perivalvular abscess (difference, 5 percentage points [lower one-sided 95% CI: -11 percentage points]) and valvular destruction (difference, -62 percentage points [lower one-sided 95% CI: -92 percentage points]). ECG-gated CT had inferior sensitivity in detecting vegetations (difference, -6 percentage points [lower one-sided 95% CI: -14 percentage points]). Conclusion Electrocardiography-gated CT had noninferior sensitivity compared with transesophageal echocardiography for identification of aortic perivalvular abscesses, extension of these abscesses, fistulization, and valvular destruction but had inferior sensitivity in detection of vegetations. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Sakuma in this issue.