Cardiopulmonary exercise testing in repaired tetralogy of Fallot: a valuable tool for pulmonary regurgitation severity assessment

Funding Acknowledgements

Type of funding sources: None.

Introduction and purpose

The optimal timing for pulmonary valve replacement (PVR) in asymptomatic patients with repaired tetralogy of Fallot (TOF) and pulmonary regurgitation (PR) remains uncertain but is often guided by imaging characterization of the right ventricle. As cardiopulmonary exercise testing (CPET) performance is an accessible prognostic indicator, we assessed which CPET parameters best correlate with pulmonary regurgitation severity to potentially improve identification of high-risk patients.

Methods

A retrospective chart review was done from 2009 to 2018 on adult patients with repaired TOF who underwent maximal effort cardiopulmonary exercise testing with cycle ergometry and with concurrent pulmonary function testing. Demographics, standard measures of CPET interpretation, and major cardiovascular outcomes were collected.

Results

Cardiopulmonary exercise testing was performed in 54 adult repaired TOF patients (59% male), with a mean follow-up of 60 ± 33 months. The mean age was 34 ± 9 years. 30 patients (56%) had severe pulmonary regurgitation and 26 patients (48%) were submitted to PVR, with a 0% mortality rate. PVR was performed a mean 28 ± 7 years after TOF repair surgery. There was moderate to severe right ventricular dysfunction in 11 patients (20%). 12 patients (22%) had a hospitalization for heart failure. Arrhythmic events occurred in 9 patients (17%), mainly atrial fibrillation or atrial flutter (67%). 2 patients (4%) received an implantable cardioverter-defibrillator for secondary prevention of sudden cardiac death.

Peak VO2 consumption (pVO2) showed no statistically significant correlation with severity of pulmonary regurgitation (HR 0.26, 95% CI 0.879-1.036, p= 0.262) or PVR (HR 0.92, 95% CI 0.829-1.028, p = 0.914), while percent of predicted pVO2 significantly correlated with severity of pulmonary regurgitation (HR 0.95, 95% CI 0.918-0.993, p = 0.020) and PVR (HR 0.94, 95% CI 0.886-0.992, p = 0.025).

VE/VCO2 slope was not a significant predictor of severity of pulmonary regurgitation (HR 1.03, 95% CI 0.929-1.130, p = 0.622) or PVR (HR 1.04, 95% CI 0.952-1.128, p = 0.414) or) and neither cardiorespiratory optimal point (HR 0.94, 95% CI 0.786-1.120, p = 0.480) nor maximum end-tidal carbon dioxide pressure (PETCO2) (HR 0.93, 95% CI 0.846-1.037, p = 0.213) correlated with severity of pulmonary regurgitation or PVR.

Conclusion

Percent of predicted peak VO2 had the highest predictive power of all CPET parameters analysed in adult repaired TOF patients. Preoperative CPET could be an accessible way to identify high-risk patients earlier for PVR and should therefore be included in the routine assessment of these patients.

Use of Sysmex XN-10 red blood cell parameters for screening of hereditary red blood cell diseases and iron deficiency anaemia

Introduction

In daily practice in haematology laboratories, red blood cell (RBC) abnormalities are frequent and their management is a real challenge. The aim of this study is to establish a “decision tree” using RBC and reticulocyte parameters from the SYSMEX XN‐10 analyser to distinguish between patients with a hereditary RBC disease from iron deficiency anaemia and other patients.

Methods

We analysed results of complete RBC counts in a cohort composed of 8217 adults divided into 5 different groups: iron deficiency anaemia (n = 120), heterozygous haemoglobinopathy (n = 92), sickle cell disease syndrome (n = 56), hereditary spherocytosis (n = 18) and other patients (n = 7931). A Classification And Regression Tree (CART) analysis was used to obtain a two‐step decision tree in order to predict these previous groups.

Results

Five parameters and the calculated RBC score were selected by the CART method: mean corpuscular haemoglobin concentration, percentage of microcytes, distribution width of the RBC histogram, percentage of nucleated red blood cells, immature reticulocytes fraction and finally RBC Score. When applying the tree and recommended flowchart, 158/166 of the RBC hereditary disease patients and 114/120 iron deficiency anaemia patients are detected. Overall, the correct classification rate reached 99.4%. Sensitivity and specificity for RBC disease detection were 95.2% and 99.9%, respectively. These results were confirmed in an independent validation cohort.

Conclusion

Based on the XN‐10 RBC and reticulocyte parameters, we propose a two‐step decision tree delivering a good prediction and classification of hereditary RBC diseases. These results can be used to optimize additional reticulocyte analysis and microscopy review.

Retrovirus-mediated gene transfer in human primary T lymphocytes induces an activation- and transduction/selection-dependent TCR-B variable chain repertoire skewing of gene-modified cells

In a clinical trial that we recently reported, a suicide gene transfer in human primary T cells required 12 days of ex vivo culture, including activation of peripheral blood mononuclear cells (PBMC) with CD3 monoclonal antibody (CD3 mAb), retrovirus-mediated transduction, and selection of gene-modified cells (GMC) by G418. The aim of the present study was to determine the impact of the initial T cell activation and of the transduction/selection on T cell receptor beta variable chain (TCRBV) repertoire of GMC by using the spectratyping method. The TCRBV repertoires of nontransduced, nonselected control (Co) cells and of GMC generated after an initial stimulation with CD3 mAb, CD3/CD28 beads, or allogeneic PBMC or Epstein-Barr virus-transformed B (B-EBV) cells were compared to the ones of their corresponding PBMC. The TCRBV repertoires were skewed in Co cells generated after CD3 mAb or after allogeneic stimulation, and even more so in their corresponding GMC, demonstrating that both culture-dependent and transduction/selection-dependent events led to TCRBV repertoire alterations. However, TCRBV repertoires were not altered, or to a lesser extent, in Co cells or GMC produced after CD3/CD28 bead activation, demonstrating a protective effect on both culture-dependent and transduction/selection-dependent repertoire alterations. Thus, we suggest to replace the initial CD3 mAb stimulation by CD3/CD28 beads for the production of clinical-grade GMC in the setting of future gene therapy trials.