Diastolic strain imaging: a new non-invasive tool to detect subclinical myocardial dysfunction in early cardiac allograft rejection

Acute cellular rejection (ACR) remains a significant contributor to increased morbidity and mortality in heart transplant recipients. Early detection of ACR by non-invasive imaging is of potential clinical benefit. This study sought to investigate the use of non-invasive early global diastolic strain rate (GDSRe) and global longitudinal strain (GLS) in the detection of biopsy proven ACR. We retrospectively analysed 31 heart transplant patients (Mean age 52 +/- 14 years) with biopsy proven ACR who underwent serial transthoracic echocardiographic examination and 2D strain analysis. Traditional echocardiographic systolic and diastolic parameters and novel systolic and diastolic strain imaging were measured during (1) early rejection free period (0R); (2) pre-rejection period (pre-1R); and (3) grade 1R acute cellular rejection (1R-ACR). GDSRe was significantly reduced (p = 0.0001) during the pre-rejection period (pre-1R) (0.74/s) when compared with 0R (0.97/s). GLS was only significantly reduced during 1R-ACR (17.7%), p = 0.001 but could not detect pre-1R (19.9%). Global diastolic strain rate at isovolumic relaxation showed no significant differences between any of the rejection periods. Traditional systolic and diastolic indices showed no significant differences. In conclusion, early global diastolic strain rate is the most sensitive parameter to detect subclinical myocardial dysfunction during early periods of pre-1R prior to biopsy confirmed 1R-ACR. GDSRe is a potential new tool for non-invasive screening of early post-transplant cardiac allograft rejection.