Study design and rationale of the pAtients pResenTing with cOngenital heaRt dIseAse Register (ARTORIA-R).

AIM: Due to improved therapy in childhood, many patients with congenital heart disease reach adulthood and are termed adults with congenital heart disease (ACHD). ACHD often develop heart failure (HF) as a consequence of initial palliative surgery or complex anatomy and subsequently require advanced HF therapy. ACHD are usually excluded from trials evaluating heart failure therapies, and in this context, more data about heart failure trajectories in ACHD are needed to guide the management of ACHD suffering from HF. METHODS AND RESULTS: The pAtients pResenTing with cOngenital heaRt dIseAse Register (ARTORIA-R) will collect data from ACHD evaluated or listed for heart or heart-combined organ transplantation from 16 countries in Europe and the Asia/Pacific region. We plan retrospective collection of data from 1989-2020 and will include patients prospectively. Additional organizations and hospitals in charge of transplantation of ACHD will be asked in the future to contribute data to the register. The primary outcome is the combined endpoint of delisting due to clinical worsening or death on the waiting list. The secondary outcome is delisting due to clinical improvement while on the waiting list. All-cause mortality following transplantation will also be assessed. The data will be entered into an electronic database with access to the investigators participating in the register. All variables of the register reflect key components important for listing of the patients or assessing current HF treatment. CONCLUSION: The ARTORIA-R will provide robust information on current management and outcomes of adults with congenital heart disease suffering from advanced heart failure.

Overcoming non-specific binding to measure the active concentration and kinetics of serum anti-HLA antibodies by surface plasmon resonance.

Human leukocyte antigen (HLA) donor-specific antibodies are key serum biomarkers for assessing the outcome of transplanted patients. Measuring their active concentration, i.e. the fraction that really interacts with donor HLA, and their affinity could help deciphering their pathogenicity. Surface plasmon resonance (SPR) is recognized as the gold-standard for measuring binding kinetics but also active concentrations, without calibration curves. SPR-based biosensors often suffer from non-specific binding (NSB) occurring with the sensor chip surface and the immobilized targets, especially for complex media such as human serum. In this work we show that several serum treatments such as dialysis or IgG purification reduce NSB but insufficiently for SPR applications. We then demonstrate that the NSB contribution to the SPR signal can be eliminated to determine precisely and reliably the active concentration and the affinity of anti-HLA antibodies from patients' sera. This was achieved even at concentrations close to the limit of quantification of the method, in the 0.5-1 nM range. The robustness of the assay was demonstrated by using a wide range of artificially generated NSB and by varying the density of the targets captured onto the surface. The assay is of general interest and can be used with molecules generating strong NSB, as far as a non-cognate target structurally close to the target can be captured on the same flow cell, in a different binding cycle. Compared with current fluorescence-based methods that are semi-quantitative, we expect this SPR-based assay to help better understanding anti-HLA antibodies pathogenicity and improving organ recipients' management.