Early detection of myocardial fibrosis in cardiomyopathy in the absence of late enhancement: role of T1 mapping and extracellular volume analysis.

OBJECTIVES: To analyze myocardial fibrosis in dilated cardiomyopathy (DCM) patients with no late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) using T1 mapping and extracellular volume (ECV) and investigate the potential correlation with left ventricular (LV) dilation and dysfunction. METHODS: The study included 41 DCM patients without LGE and 79 healthy controls. T1 and ECV were compared between the two groups using multivariable logistic regression analysis. The correlations between histological and functional parameters were evaluated using Pearson's correlation. RESULTS: Mean native myocardial T1 and ECV were significantly higher in the DCM group compared to controls (p ≤ 0.001, respectively). Multivariable logistic regression revealed that ECV (mean, minimum), LV ejection fraction (LVEF), and LV end-diastolic diameter (LVEDD) were independent discriminators for LGE-negative DCM; the area under the curve (AUC) of LVEF, LVEDD, ECV mean, and ECV minimum were 0.97, 0.96, 0.88, and 0.68, respectively. In the DCM group, LVEDD and LVEF were positively and negatively correlated with ECV, respectively. LVEDV index and LV end-systolic volume (LVESV) index were positively correlated with native-T1 and ECV, and the absolute value of LV global strain had a negative correlation with ECV. CONCLUSIONS: Early myocardial fibrosis in DCM could be detected by prolonged native T1 and elevated ECV despite the absence of LGE on CMR. Moreover, the change of histological characteristics of myocardium in DCM was correlated with LV dilation and dysfunction. KEY POINTS: • At an early stage, patients with DCM may have myocardial fibrosis despite the absence of LGE. • T1 mapping and ECV are efficient methods for early detection of potential myocardial fibrosis. • Increased native T1 and ECV are correlated with left ventricular dilation and dysfunction in LGE-negative DCM patients.

Myocardial infarct size for predicting improvements in cardiac function in patients with ischemic cardiomyopathy following coronary artery bypass grafting.

Background: This study used late gadolinium enhancement-cardiac magnetic resonance (LGE-CMR) to assess myocardial infarct size, with the data being employed to predict whether patients with ischemic cardiomyopathy (ICM) would experience improvements in left ventricular function at 6 months following coronary artery bypass grafting (CABG). Methods: The data of patients with ICM with left ventricular ejection fraction (LVEF) ≤40% who underwent CABG were retrospectively analyzed. All patients underwent preoperative LGE-CMR imaging. Echocardiography results from 6 months post-CABG were used to assess improvements in LVEF, with improvement being defined as ΔLVEF ≥5%. The value of myocardial infarction segments and infarct size as predictors of improved cardiac function following CABG was analyzed. Results: Of the included patients, 66.7% (52/78) exhibited improved cardiac function at 6 months post-CABG. LGE-CMR imaging data revealed that compared to improved group, the improved group had significantly more myocardial infarct segments [improved group: median 1.0, interquartile range (IQR) 0-3; nonimproved group: median 4.0, IQR 3.0-6.0; P<0.001] and significantly greater myocardial infarct size (improved group: 22.4%±8.2%; nonimproved group: 34.7%±5.9%; P<0.001). The area under the receive operating characteristic curve values for myocardial infarct size in predicting cardiac function improvement were significantly higher than those of myocardial infarct segments (0.88 vs. 0.81; P=0.041). The respective sensitivity and specificity values for using a myocardial infarct size cutoff of 26.4% in differentiating between these 2 patient groups were 92.3% and 71.2%, respectively. According to logistic regression analysis, myocardial infarct size was an independent predictor of nonimprovement in cardiac function [odds ratio (OR) =1.244; 95% confidence interval (CI): 1.114-1.389; P<0.001]. A median 1.6-year follow-up interval (range, 0.5-4.1 years) revealed that the incidences of major adverse cerebrovascular events and cardiovascular events were significantly higher in the nonimproved group (5.8% vs. 26.9%; P<0.001), with these individuals having a higher New York Heart Association grading than patients with improved cardiac function (P=0.019). Conclusions: Myocardial infarct size can be measured to reliably predict improvements in cardiac function in patients with ICM following CABG. These results can guide clinicians in their efforts to identify those patients most likely to achieve positive outcomes following CABG.

Prediction of left ventricular ejection fraction improvement in patients with ischemic cardiomyopathy after coronary artery bypass grafting based on cardiac magnetic resonance.

Background: To investigate the risk factors of left ventricular ejection fraction (LVEF) improvement in patients with ischemic cardiomyopathy (ICM) after coronary artery bypass grafting (CABG), and to construct a model that predicts LVEF improvement. Methods: A retrospective analysis was performed on 106 ICM patients who received CABG and underwent cardiac magnetic resonance (CMR) at Beijing Anzhen Hospital, Capital Medical University from January 2017 to June 2022. Patients were divided into two groups with improved LVEF and no improved LVEF based on the results of postoperative 6-month transthoracic echocardiography. To analyze the risk factors affecting the LVEF non-improvement after CABG and establish a prediction model. Results: There was LVEF non-improvement in 30.2% (32/106) of patients. Multivariate analysis showed that the number of transmural scar segments and left ventricular end-systolic volume index (LVESVI) were independent risk factors in LVEF non-improvement after CABG [odds ratio (OR) =2.398, 95% confidence interval (CI): 1.607-3.579, P<0.001; OR =1.036, 95% CI: 1.009-1.063, P=0.008]. The model is built and internally verified. ROC showed that the area under the curve (AUC) was 0.866 (95% CI: 0.792-0.940), calibration curve showed that the probability predicted by the model matched well with the clinical results, and decision curve analysis (DCA) showed that the model had good clinical applicability. During the mean follow-up time of 1.5 years, the incidence of major adverse cardiovascular and cerebrovascular events (MACCE) in the LVEF non-improvement group was higher (5.4% vs. 25.0%, P=0.009), and the NYHA grading was higher (P=0.016), when compared to the LVEF improvement group. Conclusions: The prediction model based on the number of transmural scar segments and LVESVI has good diagnostic efficacy. Our findings help to identify patients with improved LVEF and thus guide the selection of clinical treatment strategies.

Influence of MRI-based boundary conditions on type B aortic dissection simulations in false lumen with or without abdominal aorta involvement.

Most computational hemodynamic studies of aortic dissections rely on idealized or general boundary conditions. However, numerical simulations that ignore the characteristics of the abdominal branch arteries may not be conducive to accurately observing the hemodynamic changes below the branch arteries. In the present study, two men (M-I and M-II) with type B aortic dissection (TBAD) underwent arterial-phase computed tomography angiography and four-dimensional flow magnetic resonance imaging (MRI) before and after thoracic endovascular aortic repair (TEVAR). The finite element method was used to simulate the computational fluid dynamic parameters of TBAD [false lumen (FL) with or without visceral artery involvement] under MRI-specific and three idealized boundary conditions in one cardiac cycle. Compared to the results of zero pressure and outflow boundary conditions, the simulations with MRI boundary conditions were closer to the initial MRI data. The pressure difference between true lumen and FL after TEVAR under the other three boundary conditions was lower than that of the MRI-specific results. The results of the outflow boundary conditions could not characterize the effect of the increased wall pressure near the left renal artery caused by the impact of Tear-1, which raised concerns about the distal organ and limb perfused by FL. After TEVAR, the flow velocity and wall pressure in the FL and the distribution areas of high time average wall shear stress and oscillating shear index were reduced. The difference between the calculation results for different boundary conditions was lower in M-II, wherein FL did not involve the abdominal aorta branches than in M-I. The boundary conditions of the abdominal branch arteries from MRI data might be valuable in elucidating the hemodynamic changes of the descending aorta in TBAD patients before and after treatment, especially those with FL involving the branch arteries.

Retrospective, observational analysis of cardiac function associated with global preoperative myocardial scar in patients with ischemic cardiomyopathy after coronary artery bypass grafting.

Background: Drawing on accumulated patient data from a hospital database, the goal of this retrospective study was to analyze cardiac function associated with global preoperative myocardial scarring assessed by cardiac magnetic resonance with late gadolinium enhancement (CMR-LGE) in patients with ischemic cardiomyopathy (ICM) after coronary artery bypass grafting (CABG). Methods: A total of 57 patients diagnosed with ICM who underwent isolated CABG at Beijing Anzhen Hospital between September 2017 and September 2019 were enrolled in this retrospective study. All these patients underwent a preoperative CMR-LGE examination. Based on postoperative echocardiography results at 6 months, cases were divided into the following 2 groups: improved cardiac function [a difference of left ventricular ejection fraction (LVEF) greater than or equal to 5%] and unimproved cardiac function. The factors contributing to these patients' unimproved cardiac function were investigated. Results: At 6 months after surgery, 64.9% (37/57) of cases had improved cardiac function, and 35.1% (20/57) had no improvement. There was no statistical difference between the 2 groups in the Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) score (41.7±7.6 vs. 42.8±8.3; P=0.603), but compared to the improved group, preoperative myocardial scarring was significantly enlarged in the unimproved group (41.9%±6.4% vs. 27.8%±8.5%; P<0.001). In regression analysis, only preoperative myocardial scarring [odds ratio (OR) =1.44; 95% confidence interval (CI): 1.13-1.83; P=0.003] was associated with no change in cardiac function evaluated by echocardiography after CABG. The median follow-up of 1.6 years (range, 0.6-4.1 years) found that the unimproved group had a higher incidence of major adverse cardiovascular and cerebrovascular events (MACCEs) (8.1% vs. 25.0%; P=0.044), and that the New York Heart Association (NYHA) classification of the unimproved group was higher than that of the improved group (P=0.018). Conclusions: In ICM patients, a greater amount of preoperative myocardial scarring is associated with unimproved cardiac function after CABG. The measurement of preoperative myocardial scarring may aid clinicians in identifying patients who would benefit from CABG.

The number of myocardial infarction segments connected to papillary muscle is associated with the improvement in moderate ischemic mitral regurgitation.

Background: We evaluated whether the number of myocardial infarction (MI) segments connected to the papillary muscle (PM), as assessed using cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE), predicts whether moderate ischemic mitral regurgitation (IMR) improves after isolated coronary artery bypass grafting (CABG) to guide the choice of surgical strategy. Methods: A total of 54 patients diagnosed with coronary heart disease (CHD) complicated with moderate IMR who underwent isolated CABG were selected continuously in this retrospective study at Beijing Anzhen Hospital. All patients underwent preoperative LGE. The patients were divided into the IMR improved group (37 patients) and the unimproved group (17 patients) according to 1-year postoperative echocardiography. The factors associated with no IMR improvement after isolated CABG were analyzed. There was no trial registration and no publication of the study protocol. Results: The number of MI segments connected to PM was an independent risk factor for no IMR improvement after isolated CABG [odds ratio 4.39; 95% confidence interval (CI): 1.93-9.98; P<0.001]. The optimal receiver operating characteristic (ROC) curve cut-off value for no IMR improvement was ≥2 (sensitivity: 82.4%; specificity: 83.8%). Follow-up at 1-5 years (median, 2.8 years) showed that the incidences of major adverse cardiovascular and cerebrovascular events (5.4% vs. 23.5%; P=0.041) and New York Heart Association (NYHA) grade (P=0.026) were higher in the unimproved group. Conclusions: In patients with CHD complicated with moderate IMR, the number of MI segments connected to PM is an independent risk factor for no IMR improvement after isolated CABG. Mitral valve surgery should be performed simultaneously with CABG in patients with ≥2 MI segments connected to the PM.