Cardiac Magnetic Resonance Feature Tracking Analysis for Change in Right Ventricular Function After Cardioplegic Arrest.

BACKGROUND: Using echocardiography to assess right ventricular (RV) function after cardioplegic arrest is challenging. Cardiac magnetic resonance (CMR) imaging is a superior alternative, with the feature tracking technique enabling quantitative assessment of myocardial deformation. METHODS: This single-centre, prospective study from 2020 to 2022 assessed RV function in 42 patients who underwent open heart surgery with cardioplegic arrest. CMR data were collected preoperatively, one week postoperatively, and at follow-up (6-12 months after surgery), and assessed using the CMR feature tracking technique. RESULTS: Postoperatively, there was no significant change in RV end-diastolic volume, but RV end-systolic volume significantly decreased, leading to a notable increase in RV ejection fraction. By follow-up, both RV end-diastolic and end-systolic volumes had significantly reduced compared with the preoperative values. Right ventricular longitudinal contractility decreased after surgery but recovered to the preoperative values by follow-up, while RV circumferential contractility improved postoperatively and remained superior to the preoperative levels at follow-up. CONCLUSION: On CMR imaging, significant changes in RV systolic motion were observed after cardioplegic arrest, with decreased longitudinal but increased circumferential contractility. At follow up, these changes had reverted to the preoperative patterns by the mid-term (6-12 months).

Early longitudinal changes in left ventricular function and morphology in diabetic pigs: evaluation by 3.0T magnetic resonance imaging.

BACKGROUND: Previous researches on large animal models of diabetic cardiomyopathy were insufficient. The aim of this study was to evaluate early changes in left ventricular (LV) function and morphology in diabetic pigs using a cardiac magnetic resonance (CMR) time-volume curve and feature tracking technique. METHODS: Streptozotocin (STZ) was used to induce diabetic in sixteen pigs. 3.0T MRI scanned the pig's heart before and 2, 6, 10 and 16 months after modelling. CMR biomarkers, including time-volume curve and myocardial strain, were compared to analyse the longitudinal changes in LV function and morphology. Pearson correlation was used to evaluate the relationship between LV strain and remodelling. Cardiac specimens were obtained at 6, 10, and 16 months after modelling to observe the myocardial ultrastructural and microstructure at different courses of diabetes. RESULTS: Twelve pigs developed diabetes. The 80% diastolic volume recovery rate (DVR) at 6 months after modelling was significantly higher than that before modelling (0.78 ± 0.08vs. 0.67 ± 0.15). The LV global longitudinal peak strain (GLPS) (- 10.21 ± 3.15 vs. - 9.74 ± 2.78 vs. - 9.38 ± 3.71 vs. - 8.71 ± 2.68 vs. - 6.59 ± 2.90%) altered gradually from the baseline data to 2, 6, 10 and 16 months after modelling. After 16 months of modelling, the LV remodelling index (LVRI) of pigs increased compared with that before modelling (2.19 ± 0.97 vs. 1.36 ± 0.45 g/ml). The LVRI and myocardial peak strain were correlated in diabetic pigs (r= - 0.40 to - 0.54), with GLPS being the most significant. Electron microscopy and Masson staining showed that myocardial damage and fibrosis gradually increased with the progression of the disease. CONCLUSION: Intravenous injection of STZ can induce a porcine diabetic cardiomyopathy model, mainly characterized by decreased LV diastolic function and strain changes accompanied by myocardial remodelling. The changes in CMR biomarkers could reflect the early myocardial injury of diabetic cardiomyopathy.

Impact of apical and mid-ventricular transmural infarcts in patients with acute myocardial infarction determined by using late gadolinium enhancement combined with feature tracking magnetic resonance.

Background: To analyze the relationship between left ventricular (LV) myocardial strain and transmurality of myocardial infarction at three circular sections (basal, mid-ventricular, apical) by a combined analysis of cardiac magnetic resonance feature tracking (CMR-FT) and late gadolinium enhancement (LGE) information in a cohort of ST-elevation acute myocardial infarction (STEMI) patients after primary percutaneous coronary intervention (PPCI). Methods: In all, 136 patients with STEMI who underwent PPCI within 12 hours of symptom onset were included. CMR-FT and LGE-MRI were performed 5±2 days after PCI for measuring regional and global myocardial strain indexes and transmural extent. Multivariate regression analysis and Kaplan-Meier survival analysis were performed. Results: Regional radial and circumferential strain decreased with increasing transmurality of myocardial infarction irrespective of basal, mid-ventricular, or apical segments. Segmental longitudinal strain was significantly decreased in the transmural infarcted segments only at the apical and mid-ventricular levels. A significant correlation was found between the number of transmural infarcts and global strain parameters in the apical and mid-ventricular portions. Transmural infarcted segments in apical + mid-ventricular portions >2 was related to an increased risk of cardiac events in patients with STEMI following PPCI than those ≤2. GLS was found to be an independent predictor of cardiac events in these patients. Conclusions: The number of transmural infarcted segments in apical + mid-ventricular portions affects LV global function and prognosis. Global longitudinal strain (GLS) is a significant predictor of adverse events after PPCI for STEMI. Morphologic and functional data fused to study complex pathophysiologic processes of LV early after STEMI may help in risk stratification of patients.

Correlating transmural extent of acute myocardial infarction to left ventricular stain by mrifeature tracking / 中国介入心脏病学杂志

Objective The left ventricular myocardial strain of acute myocardial infarction on cardiac magnetic resonance cine imaging was measured by feature tracking technique. The relationship between left ventricular myocardial strain and the transmural extent of Myocardial Infarction was evaluated. Methods 74 patients with acute ST segment elevation myocardial infarction were included. All theses patients received primary PCI within 12 hours. After 2 to 5 days. ECG gated steady-state free precession sequences were collected. Gadolinium contrast enhanced imaging was performed on short axis. 20 patients repeated same scan after 3 to 5 months. TomTec 2D CPA and Segment software were used to analyze the images. The peak values of the regional myocardial strain indexes. The transmural extent of myocardial infarction of segment in left ventricular was measured. Results There was no significant difference of longitudinal strain in non-infarction,non-transmural infarction and transmural infarction segments at the basal and middle segments. The circumferential strain peak and the radial strain peak of non-transmural infarction segments were lower than those of the non-infarction segments. The circumferential strain of transmural infarction segments were the lowest(basal level:-14.24％±9.05％,P<0.05;middle level:-12.71％±8.92％,P<0.05;apical level:-13.81％±11.13％, P<0.05). GLS was improved while LVDd was increased when compared the acute phase of myocardial infarction to that of 3-5 months after primary PCI. The circumferential strain and longitudinal strain of the non-transmural infarction segments was improved. The circumferential strain and radial strain of the transmural infarction segments 3-5 months later was improved as compared to the acute phase. Conclusions There was differences in myocardial strain in non-infarction,non-transmural infarction and transmural infarction segments from patients with acute ST segment elevation myocardial infarction who had accepted primary PCI. The circumferential strain and longitudinal strain of the non-transmural infarction segments were improved after 3-5 months. The circumferential strain and radial strain of the transmural infarction segments after 3-5 months was improved as compared to the acute phase. Cardiac Magnetic resonance could combine feature tracking technique with gadolinium contrast delayed enhancement technique,giving both function and tissue characteristic evaluation to the myocardial damages after acute myocardial infarction.