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.