Changes in circumferential strain can differentiate pediatric heart transplant recipients with and without graft rejection

Clinical Predictors of Subacute Myocardial Dysfunction in Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19

Multisystem Inflammatory Syndrome in Children (MIS-C) often involves a post-viral myocarditis and associated left ventricular dysfunction. We aimed to assess myocardial function by strain echocardiography after hospital discharge and to identify risk factors for subacute myocardial dysfunction. We conducted a retrospective single-center study of MIS-C patients admitted between 03/2020 and 03/2021. Global longitudinal strain (GLS), 4-chamber longitudinal strain (4C-LS), mid-ventricular circumferential strain (CS), and left atrial strain (LAS) were measured on echocardiograms performed 3-10 weeks after discharge and compared with controls. Among 60 MIS-C patients, hypotension (65%), ICU admission (57%), and vasopressor support (45%) were common, with no mortality. LVEF was abnormal (< 55%) in 29% during hospitalization but only 4% at follow-up. Follow-up strain abnormalities were prevalent (GLS abnormal in 13%, 4C-LS in 18%, CS in 16%, LAS in 5%). Hypotension, ICU admission, ICU and hospital length of stay, and any LVEF < 55% during hospitalization were factors associated with lower strain at follow-up. Higher peak C-reactive protein (CRP) was associated with hypotension, ICU admission, total ICU days, and with lower follow-up GLS (r = - 0.55; p = 0.01) and CS (r = 0.41; p = 0.02). Peak CRP < 18 mg/dL had negative predictive values of 100% and 88% for normal follow-up GLS and CS, respectively. A subset of MIS-C patients demonstrate subclinical systolic and diastolic function abnormalities at subacute follow-up. Peak CRP during hospitalization may be a useful marker for outpatient cardiac risk stratification. MIS-C patients with hypotension, ICU admission, any LVEF < 55% during hospitalization, or a peak CRP > 18 mg/dL may warrant closer monitoring than those without these risk factors.

Multimodality Imaging to Detect Rejection, and Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients—An Illustrative Review

The three most common modalities of graft surveillance in pediatric heart transplant (HT) recipients include echocardiography, coronary angiography, and endomyocardial biopsy (EMB). The survival outcomes after HT in children have improved considerably in recent years. However, allograft rejection and cardiac allograft vasculopathy remain the leading cause of death or re-transplantation. The routine surveillance by EMB and coronary angiography are invasive and risky. Newer noninvasive echocardiographic techniques, including tissue Doppler imaging (TDI), 2-D speckle tracking echocardiography, CT coronary angiography (CTCA), cardiovascular magnetic resonance (CMR), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) and invasive techniques such as intravascular ultrasound (IVUS), functional flow reserve (CFR) of coronary arteries, optical coherence tomography (OCT), have emerged as powerful tools which may help early recognition of sub-clinical rejection, response to treatment, early detection, and progression of CAV. The multimodality imaging approach, including noninvasive and invasive tests, is the future for the transplanted heart to detect dysfunction, rejections, and early CAV. This review illustrates noninvasive and invasive imaging techniques currently used or could be considered for clinical use in detecting heart transplant rejection, dysfunction, and CAV in children.