Introduction: High cardiovascular mortality primarily limits survival following kidney transplantation (KTx). The increased risk is intrinsically connected to cardiac structural and functional abnormalities. LV volumetric imaging measurements are used to quantify this, such as left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume index (LVEDVi). However, there is an increasing interest in the assessment of myocardial strain. It provides direct information about myocardial function by measuring the deformation of myocardial fibres during the cardiac cycle. An impaired LV diastolic strain is associated with adverse outcomes in end-stage kidney disease (ESKD) patients. Cardiac magnetic resonance imaging (MRI) has emerged as the golden standard for evaluating cardiac structure and function. However, studies investigating the prognostic value of myocardial strain are mainly based on echocardiography, and diastolic strain still needs to be examined in KTx recipients.
Aim: It was hypothesized that myocardial strain has the potential to detect early diastolic dysfunction more effectively when compared to LV volumetric measurements. The primary objective of this thesis was to determine whether it is possible to predict all-cause mortality of KTx recipients on cardiac MRI two weeks post-KTx by diastolic strain.
Methods: Data from patients included in the Amsterdam Leiden GROningen (ALEGRO) trial were used. Medis Suite MR was used to calculate LV volumetric outcomes and identify deformation of the LV during the cardiac cycle. A MATLAB script was developed to obtain diastolic strain rate outcomes from these data. Kaplan-Meier curves were used for survival analysis and Cox regression analysis was performed to identify independent predictors of survival.
Results: 67 patients were included with cardiac MRI at baseline, two weeks post-KTx. The mortality was 27\% (n=18) over a median follow-up of 10 years. Significant differences between survival distributions were found based on longitudinal peak early diastolic strain rate (PEDSR) at baseline. Using LV volumetric outcomes, including LVEF, LVEDVi and left ventricular end-systolic volume index (LVESVi), this was achievable starting from a follow-up of one year. Multivariable analysis showed that longitudinal PEDSR was the strongest independent predictor of mortality at baseline.
Conclusion: It is demonstrated that myocardial strain has the potential to detect early diastolic dysfunction more effectively when compared to LV volumetric outcomes. Longitudinal PEDSR measured two weeks post-KTx by cardiac MRI independently predicts all-cause mortality and provides incremental prognostic information beyond clinical parameters. Further research in cardiovascular therapeutics is an essential next step in improving KTx recipients' prognosis.