Michel Rayar

Dr. Michel Rayar

Service de chirurgie hépatobiliaire et digestive, Universitaire de Rennes, Rennes, France

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 April 2022 in American Journal of Transplantation
Verified
Journal Article
Open access
IBIsabel M.A. Brüggenwirth
Isabel M.A. Brüggenwirth
MMMatteo Mueller
Matteo Mueller
VLVeerle A. Lantinga
Veerle A. Lantinga
SCStefania Camagni
Stefania Camagni
RCRiccardo De Carlis
Riccardo De Carlis
VMVincent E. de Meijer
Vincent E. de Meijer
A short period (1–2 h) of hypothermic oxygenated machine perfusion (HOPE) after static cold storage is safe and reduces ischemia‐reperfusion injury‐related complications after liver transplantation. Machine perfusion time is occasionally prolonged for logistical reasons, but it is unknown if prolonged HOPE is safe and compromises outcomes. We conducted a multicenter, observational cohort study of patients transplanted with a liver preserved by prolonged (≥4 h) HOPE. Postoperative biochemistry, complications, and survival were evaluated. The cohort included 93 recipients from 12 European transplant centers between 2014–2021. The most common reason to prolong HOPE was the lack of an available operating room to start the transplant procedure. Grafts underwent HOPE for a median (range) of 4:42 h (4:00–8:35 h) with a total preservation time of 10:50 h (5:50–20:50 h). Postoperative peak ALT was 675 IU/L (interquartile range 419–1378 IU/L). The incidence of postoperative complications was low, and 1‐year graft and patient survival were 94% and 88%, respectively. To conclude, good outcomes are achieved after transplantation of donor livers preserved with prolonged (median 4:42 h) HOPE, leading to a total preservation time of almost 21 h. These results suggest that simple, end‐ischemic HOPE may be utilized for safe extension of the preservation time to ease transplantation logistics.

3 July 2024 in Journal of Hepatology
Verified
Journal Article
Open access
JEJanina Eden
Janina Eden
IBIsabel M.A. Brüggenwirth
Isabel M.A. Brüggenwirth
GBGabriela Berlakovich
Gabriela Berlakovich
BBBettina M. Buchholz
Bettina M. Buchholz
FBFlorin Botea
Florin Botea
VMVincent E. de Meijer
Vincent E. de Meijer
Despite strong evidence for improved preservation of donor livers by machine perfusion, longer post-transplant follow-up data are urgently needed in an unselected patient population. We aimed to assess long-term outcomes after transplantation of hypothermic oxygenated machine perfusion (HOPE)-treated donor livers based on real-world data (i.e., IDEAL-D stage 4). In this international, multicentre, observational cohort study, we collected data from adult recipients of HOPE-treated livers transplanted between January 2012 and December 2021. Analyses were stratified by donation after brain death (DBD) and donation after circulatory death (DCD), sub-divided by their respective risk categories. The primary outcome was death-censored graft survival. Secondary outcomes included the incidence of primary non-function (PNF) and ischaemic cholangiopathy (IC). We report on 1,202 liver transplantations (64% DBD) performed at 22 European centres. For DBD, a total number of 99 benchmark (8%), 176 standard (15%), and 493 extended-criteria (41%) cases were included. For DCD, 117 transplants were classified as low risk (10%), 186 as high risk (16%), and 131 as futile (11%), with significant risk profile variations among centres. Actuarial 1-, 3-, and 5-year death-censored graft survival rates for DBD and DCD livers were 95%, 92%, and 91%, vs. 92%, 87%, and 81%, respectively (log-rank p = 0.003). Within DBD and DCD strata, death-censored graft survival was similar among risk groups (log-rank p = 0.26, p = 0.99). Graft loss due to PNF or IC was 2.3% and 0.4% (DBD), and 5% and 4.1% (DCD). This study shows excellent 5-year survival after transplantation of HOPE-treated DBD and DCD livers with low rates of graft loss due to PNF or IC, irrespective of their individual risk profile. HOPE treatment has now reached IDEAL-D stage 4, which further supports its implementation in routine clinical practice. ClinicalTrials.gov Identifier: NCT05520320. This study demonstrates the excellent long-term performance of hypothermic oxygenated machine perfusion (HOPE) treatment of donation after circulatory and donation after brain death liver grafts irrespective of their individual risk profile in a real-world setting, outside the evaluation of randomised-controlled trials. While previous studies have established safety, feasibility, and efficacy against the current standard, according to the IDEAL-D evaluation framework, HOPE treatment has now reached the final IDEAL-D stage 4, which further supports its implementation in routine clinical practice.

1 March 2018 in Transplantation
Verified
Journal Article
Closed access
MRMichel Rayar
Michel Rayar
CTCamille Tron
Camille Tron
CJCaroline Jézéquel
Caroline Jézéquel
JBJean Marie Beaurepaire
Jean Marie Beaurepaire
APAntoine Petitcollin
Antoine Petitcollin
FLFlorian Lemaitre
Florian Lemaitre
Background Tacrolimus (TAC) is the cornerstone of immunosuppressive regimen in liver transplantation (LT). Its pharmacokinetics is characterized by a high interpatient and intrapatient variability (IPV) leading to an unpredictable dose-response relationship. The aim of our study was to evaluate the impact of TAC IPV (IPV) on graft and patient outcomes after LT. Methods We retrospectively analyzed 812 LT recipients treated with TAC. The IPV of TAC concentrations was estimated by calculating the coefficient of variation (CV) of whole blood trough concentrations. Patients were categorized in 2 groups: low IPV (CV < 40%) and high IPV (CV ≥ 40%). Results There were significantly more neurologic complications (31.2% vs 16.6%, P < 0.001), cardiovascular complications (19.7% vs 9.7%, P < 0.001), and acute renal failure requiring dialysis (8.5% vs 2.2%, P < 0.001) in the high CV group than in the low CV group. Moreover, graft survival was significantly poorer in the high CV group (hazard ratio, 1.42; 95% confidence interval, 1.04-1.95; P = 0.03). A pretransplantation elevated Model for End-Stage Liver Disease score (P < 0.001) and Child-Pugh grade (P < 0.001) were identified as risk factors for presenting a high CV. Conclusions A high CV of TAC concentrations was found to be predictive of TAC-related toxicity and poorer survival.

25 November 2020 in Liver Transplantation
Verified
Journal Article
Closed access
PDF file
MRMichel Rayar
Michel Rayar
JBJean‐Marie Beaurepaire
Jean‐Marie Beaurepaire
EBEmma Bajeux
Emma Bajeux
SHStéphanie Hamonic
Stéphanie Hamonic
TRThomas Renard
Thomas Renard
BMBernard Meunier
Bernard Meunier

7 March 2023 in BJS Open
Verified
Journal Article
Open access
PDF file
FHFrederik J.H. Hoogwater
Frederik J.H. Hoogwater
HKHendrien Kuipers
Hendrien Kuipers
VMVincent E. de Meijer
Vincent E. de Meijer
CMCharlotte Maulat
Charlotte Maulat
FMFabrice Muscari
Fabrice Muscari
RPRobert Porte
Robert Porte
The Mayo protocol for liver transplantation in patients with unresectable perihilar cholangiocarcinoma is based on strict selection and neoadjuvant chemoradiotherapy. The role of neoadjuvant chemoradiotherapy in this scenario remains unclear. The aim of this study was to compare outcomes after transplantation for perihilar cholangiocarcinoma using strict selection criteria, either with or without neoadjuvant chemoradiotherapy. This was an international, multicentre, retrospective cohort study of patients who underwent transplantation between 2011 and 2020 for unresectable perihilar cholangiocarcinoma using the Mayo selection criteria and receiving neoadjuvant chemoradiotherapy or not receiving neoadjuvant chemoradiotherapy. Endpoints were post-transplant survival, post-transplant morbidity rate, and time to recurrence. Of 49 patients who underwent liver transplantation for perihilar cholangiocarcinoma, 27 received neoadjuvant chemoradiotherapy and 22 did not. Overall 1-, 3-, and 5-year post-transplantation survival rates were 65 per cent, 51 per cent and 41 per cent respectively in the group receiving neoadjuvant chemoradiotherapy and 91 per cent, 68 per cent and 53 per cent respectively in the group not receiving neoadjuvant chemoradiotherapy (1-year hazards ratio (HR) 4.55 (95 per cent c.i. 0.98 to 21.13), P = 0.053; 3-year HR 2.07 (95 per cent c.i. 0.78 to 5.54), P = 0.146; 5-year HR 1.71 (95 per cent c.i. 0.71 to 4.09), P = 0.229). Hepatic vascular complications were more frequent in the group receiving neoadjuvant chemoradiotherapy compared with the group not receiving neoadjuvant chemoradiotherapy (nine of 27 versus two of 22, P = 0.045). In multivariable analysis, tumour recurrence occurred less frequently in the group receiving neoadjuvant chemoradiotherapy (HR 0.30 (95 per cent c.i. 0.09 to 0.97), P = 0.044). In selected patients undergoing liver transplantation for perihilar cholangiocarcinoma, neoadjuvant chemoradiotherapy resulted in a lower risk of tumour recurrence, but was associated with a higher rate of early hepatic vascular complications. Adjustments in neoadjuvant chemoradiotherapy reducing the risk of hepatic vascular complications, such as omitting radiotherapy, may further improve the outcome in patients undergoing liver transplantation for perihilar cholangiocarcinoma.

5 October 2016 in Liver Transplantation
Verified
Journal Article
Open access
PDF file
MRMichel Rayar
Michel Rayar
GSGiovanni B. Levi Sandri
Giovanni B. Levi Sandri
CCCaterina Cusumano
Caterina Cusumano
CLClara Locher
Clara Locher
PHPauline Houssel‐Debry
Pauline Houssel‐Debry
KBKarim Boudjema
Karim Boudjema
During orthotopic liver transplantation (OLT), clamping of the portal vein induces splanchnic venous congestion and accumulation of noxious compounds. These adverse effects could increase ischemia/reperfusion injury and subsequently the risk of graft dysfunction, especially for grafts harvested from extended criteria donors (ECDs). Temporary portocaval shunt (TPCS) could prevent these complications. Between 2002 and 2013, all OLTs performed in our center were retrospectively analyzed and a propensity score matching analysis was used to compare the effect of TPCS in 686 patients (343 in each group). Patients in the TPCS group required fewer intraoperative transfusions (median number of packed red blood cells—5 versus 6; P = 0.02; median number of fresh frozen plasma—5 versus 6; P = 0.02); had improvement of postoperative biological parameters (prothrombin time, Factor V, international normalized ratio, alkaline phosphatase, and gamma‐glutamyltransferase levels); and showed significant reduction of biliary complications (4.7% versus 10.2%; P = 0.006). Survival analysis revealed that TPCS improved 3‐month graft survival (94.2% versus 88.6%; P = 0.01) as well as longterm survival of elderly (ie, age > 70 years) donor grafts (P = 0.02). In conclusion, the use of TPCS should be recommended especially when considering an ECD graft. Liver Transplantation 23 174–183 2017 AASLD