Altered Regional Myocardial Mechanics in Transplanted Hearts: Influence of Time and Transplantation

Background Global longitudinal strain is reduced in heart transplant recipients, but little is known about regional contractility of the transplanted heart. Moreover, it is unclear if factors such as time after transplant and ischemic time have an influence on regional contractility. To test for regional changes in myocardial deformation, we assessed regional myocardial deformation using three-dimensional speckle tracking echocardiography in heart transplant recipients and controls. Methods Global and regional longitudinal, circumferential, and radial strain was assessed in 51 heart transplant recipients and a control group of healthy individuals (n = 26). Moreover, we correlated regional contractility with clinical characteristics and compared subgroups of heart transplant recipients with normal (n = 32) and reduced left ventricular ejection fraction (n = 32). Results Global longitudinal and circumferential strain was significantly reduced in all heart transplant recipients, as well as in the transplant group with normal ejection fraction compared with the control group (p < 0.001). Global radial strain (GRS) was elevated in both transplant groups, but was significantly higher in transplant recipients with normal ejection fraction compared with the control group (p < 0.01). Both transplant groups revealed lower longitudinal and circumferential strain values in the mid- and apical regions (p < 0.001), whereas longitudinal and circumferential strain was higher in the basal region (p < 0.01). In both groups, transplanted hearts showed increased radial strain in the basal (p < 0.05, p < 0.01) and midregions (p = 0.22; p < 0.01) and did not differ in the apical regions. Cold ischemic time (150 ± 12.6 minutes) was independently associated with reduction in circumferential strain. Time since transplantation ranging from 18 days to 21 years had no effect on myocardial deformation parameters. Conclusion Left ventricular mechanics in transplanted hearts display significantly different systolic deformation patterns than native hearts. Strain capability forms a regional gradient from the base toward the apex. The presence of a time-independent deformation pattern and the correlation with cold ischemic time suggest damage induced by the transplantation itself. These findings might be important for understanding pseudo-abnormal echocardiograms in heart transplant patients.