Myocardial strain and strain rate from speckle-tracking echocardiography are unable to differentiate asymptomatic biopsy-proven cellular rejection in the first year after cardiac transplantation

Background Cellular rejection after cardiac transplantation is treatable with timely diagnosis. Because noninvasive methods for diagnosis are limited, surveillance endomyocardial biopsies are routinely performed in the first year after transplantation. The aim of this study was to test whether myocardial strain and strain rate as assessed by speckle-tracking echocardiography would be a sensitive noninvasive method for the detection of asymptomatic rejection. Methods Surveillance biopsies and echocardiograms obtained in the first year after transplantation were retrospectively reviewed, and patients with asymptomatic biopsy-proven cellular rejection were identified, as well as control transplantation patients without rejection or cardiac complications. Circumferential and longitudinal strain and strain rate were measured using Velocity Vector Imaging software from echocardiograms performed at three time points for patients with rejection - baseline (no rejection), rejection, and resolution (of rejection) - and three time points for control patients - baseline (within the first month after transplantation), 6 months, and 12 months after transplantation. Results Speckle-tracking strain and strain rate measurements were obtained from 30 patients with asymptomatic biopsy-proven rejection and 14 control transplantation patients. There were no significant differences in circumferential and longitudinal strain or strain rate between the baseline, rejection, and resolution studies. Furthermore, there were no significant differences in strain and strain rate in control transplantation patients during the first year after transplantation or compared with patients with rejection. Conclusions Speckle-tracking analysis was unable to detect changes on serial studies from patients with asymptomatic rejection and thus cannot replace biopsy. Other noninvasive methods for the diagnosis of cellular-mediated rejection are needed.