Unraveling the Mechanism of Alkali Metal Fluoride Post-Treatment of SnO2 for Efficient Planar Perovskite Solar Cells.

The facile synthesis and beneficial properties of tin oxide have driven the development of efficient planar perovskite solar cells (PSCs). To increase the PSC performance, alkali salts are used to treat the SnO2 surface to minimize the defect states. However, the underlying mechanism of alkali cations' role in the PSCs needs further exploration. Herein the effect of alkali fluoride salts (KF, RbF, and CsF) on the properties of SnO2 and PSC performance is investigated. The results show different alkali have significant roles depending on their nature. Larger cations Cs+ preferably locate at the SnO2 film surface to passivate surface defects and enhance conductivity, while smaller cations like Rb+ or K+ cations tend to diffuse into the perovskite layer to reduce trap density of the material. The former effect leads to enhanced fill factor while the latter effect increases the open circuit voltage of the device. It is then demonstrated that a dual cation post-treatment of the SnO2 layer with RbF and CsF achieves PSC with a significantly higher power conversion efficiency (PCE) of 21.66% compared to pristine PSC with a PCE of 19.71%. This highlights the significance of defect engineering of SnO2 using selective multiple alkali treatment to improve PSC performance.

Atomically precise nanoclusters predominantly seed gold nanoparticle syntheses.

Seed-mediated synthesis strategies, in which small gold nanoparticle precursors are added to a growth solution to initiate heterogeneous nucleation, are among the most prevalent, simple, and productive methodologies for generating well-defined colloidal anisotropic nanostructures. However, the size, structure, and chemical properties of the seeds remain poorly understood, which partially explains the lack of mechanistic understanding of many particle growth reactions. Here, we identify the majority component in the seed solution as an atomically precise gold nanocluster, consisting of a 32-atom Au core with 8 halide ligands and 12 neutral ligands constituting a bound ion pair between a halide and the cationic surfactant: Au32X8[AQA+•X-]12 (X = Cl, Br; AQA = alkyl quaternary ammonium). Ligand exchange is dynamic and versatile, occurring on the order of minutes and allowing for the formation of 48 distinct Au32 clusters with AQAX (alkyl quaternary ammonium halide) ligands. Anisotropic nanoparticle syntheses seeded with solutions enriched in Au32X8[AQA+•X-]12 show narrower size distributions and fewer impurity particle shapes, indicating the importance of this cluster as a precursor to the growth of well-defined nanostructures.

Are Metal Halide Perovskite Solar Cells Ready for Space Applications?

The appeal of metal halide perovskite solar cells (PSCs) has been widely demonstrated in the field of photovoltaic technology. On account of the excellent optical and electrical properties, as well as compatibility with flexible substrates, the PSCs also hold the highest record of specific power for lightweight solar cell devices, suggesting excellent promise in space applications. Hence, there is increasing interest in the performance of PSCs in space environments where radiation beams and thermal cycling can cause extreme stress on the devices. In this Perspective, we provide a brief summary of the research on PSCs for space applications. The radiation tolerance and thermal stability of PSCs and the fundamental mechanisms are discussed and analyzed. Key challenges facing PSC technology toward future space applications are demonstrated. This Perspective features the prospect of PSCs as the next frontier in space PV technology.

Surface Treatment of Inorganic CsPbI3 Nanocrystals with Guanidinium Iodide for Efficient Perovskite Light-Emitting Diodes with High Brightness.

The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material. In particular, nanocrystals (NCs) of inorganic perovskites have demonstrated excellent performance for light-emitting and display applications. However, the presence of surface defects on the NCs negatively impacts their performance in devices. Herein, we report a compatible facial post-treatment of CsPbI3 nanocrystals using guanidinium iodide (GuI). It is found that the GuI treatment effectively passivated the halide vacancy defects on the surface of the NCs while offering effective surface protection and exciton confinement thanks to the beneficial contribution of iodide and guanidinium cation. As a consequence, the film of treated CsPbI3 nanocrystals exhibited significantly enhanced luminescence and charge transport properties, leading to high-performance light-emitting diode with maximum external quantum efficiency of 13.8% with high brightness (peak luminance of 7039 cd m-2 and a peak current density of 10.8 cd A-1). The EQE is over threefold higher than performance of untreated device (EQE: 3.8%). The operational half-lifetime of the treated devices also was significantly improved with T50 of 20 min (at current density of 25 mA cm-2), outperforming the untreated devices (T50 ~ 6 min).

Low-Dimensional-Networked Perovskites with A-Site-Cation Engineering for Optoelectronic Devices.

Low-dimensional-networked (LDN) perovskites denote materials in which the molecular structure adopts 2D, 1D, or 0D arrangement. Compared to conventional 3D structured lead halide perovskite (chemical formula: ABX3 where A: monovalent cations, B: divalent cations, X: halides) that have been studied widely as light absorber and used in current state-or-the-art solar cells, LDN perovskite have unique properties such as more flexible crystal structure, lower ion transport mobility, robust stability against environmental stress such as moisture, thermal, etc., making them attractive for applications in optoelectronic devices. Since 2014, reports on LDN perovskite materials used in perovskite solar cells, light emitting diodes (LEDs), luminescent solar concentrators (LSC), and photodetectors have been reported, aiming to overcome the obstacles of conventional 3DN perovskite materials in these optoelectronic devices. In this review, the variable ligands used to make LDN perovskite materials are summarized, their distinct properties compared to conventional 3D perovskite materials. The research progress of optoelectronic devices including solar cells, LEDs, LSCs, and photodetectors that used different LDNs perovskite, the roles and working mechanisms of the LDN perovskites in the devices are also demonstrated. Finally, key research challenges and outlook of LDN materials for various optoelectronic applications are discussed.

Characteristics and outcome of ambulatory heart failure patients receiving a left ventricular assist device.

AIMS: Despite regularly updated guidelines, there is still a delay in referral of advanced heart failure patients to mechanical circulatory support and transplant centres. We aimed to analyse characteristics and outcome of non-inotrope-dependent patients implanted with a left ventricular assist device (LVAD). METHODS AND RESULTS: The ASSIST-ICD registry collected LVAD data in 19 centres in France between February 2006 and December 2016. We used data of patients in Interagency Registry for Mechanically Assisted Circulatory Support Classes 4-7. The primary endpoint was survival analysis. Predictors of mortality were searched with multivariable analyses. A total of 303 patients (mean age 61.0 ± 9.9 years, male sex 86.8%) were included in the present analysis. Ischaemic cardiomyopathy was the leading heart failure aetiology (64%), and bridge to transplantation was the main implantation strategy (56.1%). The overall likelihood of being alive while on LVAD support or having a transplant at 1, 2, 3, and 5 years was 66%, 61.7%, 58.7%, and 55.1%, respectively. Age [hazard ratio (HR) 1.03, 95% confidence interval (CI) 1.00-1.05; P = 0.02], a concomitant procedure (HR 2.32, 95% CI 1.52-3.53; P < 0.0001), and temporary mechanical right ventricular support during LVAD implantation (HR 2.94, 95% CI 1.49-5.77; P = 0.002) were the only independent variables associated with mortality. Heart failure medications before or after LVAD implantation were not associated with survival. CONCLUSION: Ambulatory heart failure patients displayed unsatisfactory survival rates after LVAD implantation. A better selection of patients who can benefit from LVAD may help improving outcomes.

Comparison of Outcomes and Mortality in Patients Having Left Ventricular Assist Device Implanted Early -vs- Late After Diagnosis of Cardiomyopathy.

LVAD implantation in patients with a recently diagnosed cardiomyopathy has been poorly investigated. This work aims at describing the characteristics and outcomes of patients receiving a LVAD within 30 days following the diagnosis of cardiomyopathy. Patients from the ASSIST-ICD study was divided into recently and remotely diagnosed cardiomyopathy based on the time from initial diagnosis of cardiomyopathy to LVAD implantation using the cut point of 30 days. The primary end point of the study was all-cause mortality at 30-day and during follow-up. A total of 652 patients were included and followed during a median time of 9.1 (2.5 to 22.1) months. In this population, 117 (17.9%) had a recently diagnosed cardiomyopathy and had LVAD implantation after a median time of 15.0 (9.0 to 24.0) days following the diagnosis. This group of patients was significantly younger, with more ischemic cardiomyopathy, more sudden cardiac arrest (SCA) events at the time of the diagnosis and were more likely to receive temporary mechanical support before LVAD compared with the remotely diagnosed group. Postoperative in-hospital survival was similar in groups, but recently diagnosed patients had a better long-term survival after hospital discharge. SCA before LVAD and any cardiac surgery combined with LVAD implantation were identified as 2 independent predictors of postoperative mortality in recently diagnosed patients. In conclusion, rescue LVAD implantation for recently diagnosed severe cardiomyopathy is common in clinical practice. Such patients experience a relatively low postoperative mortality and have a better long-term survival compared with remotely diagnosed patients.

Septuagenarian population has similar survival and outcomes to younger patients after left ventricular assist device implantation.

BACKGROUND: Left ventricular assist device (LVAD) implantation may be an attractive alternative therapeutic option for elderly patients with heart failure who are ineligible for heart transplantation. AIM: We aimed to describe the characteristics and outcomes of elderly patients (i.e. aged≥70 years) receiving an LVAD. METHODS: This observational study was conducted in 19 centres between 2006 and 2016. Patients were divided into two groups-younger (aged<70 years) and elderly (aged≥70 years), based on age at time of LVAD implantation. RESULTS: A total of 652 patients were included in the final analysis, and 74 patients (11.3%) were aged≥70 years at the time of LVAD implantation (maximal age 77.6 years). The proportion of elderly patients receiving an LVAD each year was constant, with a median of 10.6% (interquartile range 8.0-15.4%) per year, and all were implanted as destination therapy. Elderly and younger patients had similar durations of hospitalization in intensive care units and total lengths of hospital stays. Both age groups experienced similar rates of LVAD-related complications (i.e. stroke, bleeding, driveline infection and LVAD exchange), and the occurrence of LVAD complications did not impact survival in the elderly group compared with the younger group. Lastly, when compared with younger patients implanted as destination therapy, the elderly group also exhibited similar mid-term survival. CONCLUSION: This work strongly suggests that selected elderly adults can be scheduled for LVAD implantation.

Relation of Body Mass Index to Outcomes in Patients With Heart Failure Implanted With Left Ventricular Assist Devices.

We aimed at characterizing the impact of low and high body mass index (BMI) on outcomes after left-ventricular assist device (LVAD) surgery and define the predictors of mortality in patients with abnormal BMI (low/high). This study was conducted in 19 centers from 2006 to 2016. Patients were divided based on their baseline BMI into 3 groups of BMI: low (BMI ≤18.5 kg/m²); normal (BMI = 18.5 to 24.99 kg/m²) and high (BMI ≥25 kg/m²) (including overweight (BMI = 25 to 29.99 kg/m²), and obesity (BMI ≥30 Kg/m²)). Among 652 patients, 29 (4.4%), 279 (42.8%) and 344 (52.8%) had a low-, normal-, and high BMI, respectively. Patients with high BMI were significantly more likely men, with more co-morbidities and more history of ventricular/supra-ventricular arrhythmias before LVAD implantation. Patients with abnormal BMI had significantly lower survival than those with normal BMI. Notably, those with low BMI experienced the worst survival whereas overweight or obese patients had similar survival. Four predictors of mortality for LVAD candidates with abnormal BMI were defined: total bilirubin ≥16 µmol/L before LVAD, hypertension, destination therapy, and cardiac surgery with LVAD. Depending on the number of predictor per patients, those with abnormal BMI may be divided in 3 groups of 1-year mortality risk, i.e., low (0 to 1 predictor: 29% and 31%), intermediate (2 to 3 predictors, 51% and 52%, respectively), and high (4 predictors: 83%). In conclusion, LVAD recipients with abnormal BMI experience lower survival, especially underweight patients. Four predictors of mortality have been identified for LVAD population with abnormal BMI, differentiating those a low-, intermediate-, and high risks of death.

Paradoxical Increase of Stroke in Patients with Defect of High Molecular Weight Multimers of the von Willebrand Factors following Transcatheter Aortic Valve Replacement.

BACKGROUND: Stroke is a major cause of disability after transcatheter aortic valve replacement (TAVR) and stroke prediction models and data are crucially needed. Following TAVR, high molecular weight (HMW) multimers defect of von Willebrand factor (VWF) as assessed by closure time of adenosine diphosphate (CT-ADP) value > 180 seconds is an independent predictor of bleeding events. This study sought to identify predictors of ischemic neurological events in patients who underwent TAVR and the specific impact of HMW multimers defect of VWF. METHODS: Patients were prospectively enrolled between November 2012 and May 2018 at our institution. The CT-ADP, a point-of-care measure of hemostasis, was assessed the day before and 24 hours after the procedures. The rate of ischemic stroke and transient ischemic attack (TIA) was recorded up to 30 days after the procedures. RESULTS: Of 565 TAVR patients, ischemic stroke/TIA was observed in 21 (3.7%) patients within 30 days. Ischemic stroke/TIA was associated with major/life-threatening bleeding complications (MLBCs) (9 [43%] vs. 88 [16%], p = 0.002) and postprocedure CT-ADP > 180 seconds (10 [48%] vs. 116 [21%], p = 0.01). By multivariate analysis, MLBCs (odds ratio [OR]: 3.58; 95% confidence interval [CI]: 1.45-8.84; p = 0.006) and postprocedure CT-ADP > 180 seconds (OR: 3.38; 95% CI: 1.38-8.25; p = 0.008) were evidenced as independent predictors of ischemic stroke/TIA. CONCLUSION: MLBCs and CT-ADP > 180 seconds were identified as predictors for ischemic stroke or TIA. The present study suggests that the defects of HMW multimers of the VWFs may contribute not only to bleeding events but also to thrombotic events.

Minimally invasive surgery for left ventricular assist device implantation is safe and associated with a decreased risk of right ventricular failure.

BACKGROUND: Right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation is associated with significant mortality and morbidity. The objective of this study was to determine pre- and postoperative risk factors associated with the occurrence of RVF after LVAD implantation. METHODS: This retrospective study included 68 patients who received LVADs between 2010 and 2018 either for bridge to transplant (40 patients, 58.8%) or bridge to destination therapy (28 patients, 41.2%). RVF after LVAD implantation was defined according to the INTERMACS classification. The primary endpoint was the occurrence of RVF. The secondary endpoints were hospital mortality and morbidity and long-term survival. RESULTS: The majority of patients (61.8%) had an INTERMACS profile 1 (36.8%) or 2 (25.0%). The LVAD was implanted either by sternotomy (37 patients, 54.4%) or thoracotomy (31 patients, 45.6%). RVF after LVAD implantation was observed in 32 patients (47.1%). In univariate analysis, an elevated serum glutamic oxaloacetic transaminase (SGOT) (P=0.028) and a high preoperative vasoactive inotropic score (VIS) (P=0.028) were significantly associated with an increased risk of RVF, whereas the implantation of LVAD through a thoracotomy approach was associated with a significant reduction in this risk (P=0.006). The multivariate analysis demonstrated that only the thoracotomy approach was significantly associated with decreased risk of RVF (odds ratio =0.33, 95% confidence interval: 0.17-0.96; P=0.042). Hospital mortality was 53.1% and 5.6% in the RVF and control groups, respectively (P<0.0001). The incidence of stroke and postoperative acute renal failure were significantly increased in the RVF group compared with the control group. The survival after LVAD implantation was 33.5%±9.0% and 85.4%±6.0% at 1 year in the RVF and control groups, respectively (P<0.0001). CONCLUSIONS: LVAD implantation by thoracotomy significantly reduced the risk of postoperative RVF. This surgical approach should, therefore, be favored.

Impact of Setting up an "Endocarditis Team" on the Management of Infective Endocarditis.

BACKGROUND: Infective endocarditis (IE) remains a severe disease with a high mortality rate. Therefore, guidelines encourage the setup of a multidisciplinary group in reference centers. The present study evaluated the impact of this "Endocarditis Team" (ET). METHODS: We conducted a monocentric observational study at Strasbourg University Hospital, Strasbourg, France, between 2012 and 2017. The primary end point was in-hospital mortality. Secondary end points were 6-month and 1-year mortality, surgery rate, time to surgical procedure, duration of effective antibiotic therapy, length of in-hospital stay, and sequelae. We also assessed predictors of in-hospital mortality. RESULTS: We analyzed 391 episodes of IE. In the post-ET period, there was a nonsignificant decrease in in-hospital mortality (20.3% vs 14.7%, respectively; P = .27) and sequelae, along with a significant reduction in time to surgery (16.4 vs 10.3 days, respectively; P = .049), duration of antibiotic therapy (55.2 vs 47.2 days, respectively; P < .001), and length of in-hospital stay (40.6 vs 31.9 days, respectively; P < .01). In a multivariate analysis, the post-ET period was positively associated with survival (odds ratio, 0.45; 95% confidence interval, 0.20-0.96; P = .048). CONCLUSIONS: This multidisciplinary approach exerted a positive impact on the management of IE and should be considered in all hospitals managing IE.

Interface Engineering to Eliminate Hysteresis of Carbon-Based Planar Heterojunction Perovskite Solar Cells via CuSCN Incorporation.

A carbon electrode with low cost and high stability exhibited competitiveness for its practical application in organic-inorganic hybrid perovskite solar cells (PSCs). Nonetheless, issues such as poor interface contact with an adjacent perovskite layer and obvious hysteresis phenomenon are bottlenecks that need to be overcome to make carbon-based PSCs (C-PSCs) more attractive in practice. Herein, we report an effective method to enhance the interfacial charge transport of C-PSCs by introducing the CuSCN material into the device. Two types of CuSCN-assisted devices were studied in this work. One was based on the deposition of an ultrathin CuSCN layer between the perovskite absorber layer and the carbon cathode (PSK/CuSCN/C), and the other was by infiltrating CuSCN solution into the carbon film (PSK/C-CuSCN) by taking advantage of the macroporous structure of the carbon. We have found that the CuSCN incorporation by both methods can effectively address the hysteretic feature in planar C-PSCs. The origin for the hysteresis evolution was unraveled by the investigation of the energy alignment and the kinetics of interfacial charge transfer and hole trap-state density. The results have shown that both types of CuSCN-containing devices showed improved interfacial charge carrier extraction, suppressed carrier recombination, reduced trap-state density, and enhanced charge transport, leading to negligible hysteresis. Furthermore, the CuSCN-incorporated C-PSCs demonstrated enhanced device stability. The power conversion efficiency remained 98 and 91% of the initial performance (13.6 and 13.4%) for PSK/CuSCN/C and PSK/C-CuSCN, respectively, after being stored under a high humidity (75-85%) environment for 10 days. The devices also demonstrated extraordinary long-term stability with a negligible performance drop after being stored in air (relative humidity: 33-35%) for 90 days.

Does Transcatheter Aortic Valve Replacement Modulate the Kinetic of Superoxide Anion Generation?

Reactive oxygen species (ROS) are central bioenergetic markers linked to aortic stenosis (AS) development and severity. We sought to evaluate the time course and impact of ROS assessed by plasmatic superoxide anion (SA) among patients undergoing transcatheter aortic valve replacement (TAVR). Among 106 patients, SA significantly decreased after TAVR. Dropped values were measured 10 min after TAVR (0.590 ± 0.181 vs. 0.648 ± 0.193; p < 0.001) and persistent at 3 days (0.611 ± 0.0.228 vs. 0.646 ± 0.199; p = 0.033) and 30 days follow-up (0.572 ± 0.207 vs. 0.639 ± 0.199; p = 0.005). Increased baseline SA (>75 percentile) was continuously associated with higher postprocedural SA values 10 min after valve expansion (p < 0.001), at 3 days (p < 0.001) and 30 days (p < 0.001). Higher baseline SA was linked to higher inflammatory response assessed by higher C-reactive protein values at day 1 and day 3. The composite endpoint of all-cause mortality and/or stroke and/or pacemaker implantation and/or significant paravalvular aortic regurgitation ≥mild at 30 days did not differ significantly according to SA baseline values (p = 0.055). This is the first report identifying a decrease in oxidative stress level after TAVR. Our observation leads to the hypothesis that oxidative stress biomarkers may survive the journey from bench to bedside in AS and TAVR and become new biomarkers with both diagnostic and prognostic values. Antioxid. Redox Signal. 31, 420-426.

Primary Hemostatic Disorders and Late Major Bleeding After Transcatheter Aortic Valve Replacement.

BACKGROUND: Periprocedural and late (>30 days) bleedings represent major complications after transcatheter aortic valve replacement and have been identified as potential areas for improved patient care. OBJECTIVES: The authors sought to evaluate the impact of ongoing primary hemostasis disorders on late major/life-threatening bleeding complications (MLBCs). METHODS: Bleedings were assessed according to the VARC-2 (Valve Academic Research Consortium-2) criteria. Closure time of adenosine diphosphate (CT-ADP), a surrogate marker of high molecular weight von Willebrand multimers proteolysis was assessed 24 h after the procedure. Ongoing primary hemostasis disorder was defined by a CT-ADP >180 s. RESULTS: Among 372 patients who survived at 30 days, MLBCs occurred in 42 patients (11.3%) at a median follow-up of 383 days (interquartile range: 188 to 574 days). MLBCs were mainly of gastrointestinal origin (42.8%) and were associated with increased overall mortality (hazard ratio [HR]: 5.66; 95% confidence interval [CI]: 3.10 to 10.31; p < 0.001) and cardiac mortality (HR: 11.62; 95% CI: 4.59 to 29.37; p < 0.001). A 2.5-fold elevation of MLBCs could be evidenced in patients with a CT-ADP > 180 s (27.4% vs. 11.5%; p < 0.001). Multivariate regression analysis identified paravalvular leak (PVL) (HR: 6.31; 95% CI: 3.43 to 11.60; p < 0.0001) and CT-ADP > 180 s (HR: 3.08; 95% CI: 1.62 to 5.81; p = 0.0005) as predictor of MLBCs. CONCLUSIONS: MLBCs after transcatheter aortic valve replacement are frequent and associated with an increased morbidity and mortality. PVL and CT-ADP >180 s were identified as strong predictors for MLBCs. These findings strongly suggest that persistent HMW defects contribute to enhanced bleeding risk in patients with residual PVL.

CT-ADP Point-of-Care Assay Predicts 30-Day Paravalvular Aortic Regurgitation and Bleeding Events following Transcatheter Aortic Valve Replacement.

BACKGROUND: Paravalvular aortic regurgitation (PVAR) remains a frequent postprocedural concern following transcatheter aortic valve replacement (TAVR). Persistence of flow turbulence results in the cleavage of high-molecular-weight von Willebrand multimers, primary haemostasis dysfunction and may favour bleedings. Recent data have emphasized the value of a point-of-care measure of von Willebrand factor-dependent platelet function (closure time [CT] adenosine diphosphate [ADP]) in the monitoring of immediate PVAR. This study examined whether CT-ADP could detect PVAR at 30 days and bleeding complications following TAVR. METHODS: CT-ADP was assessed at baseline and the day after the procedure. At 30 days, significant PVAR was defined as a circumferential extent of regurgitation more than 10% by transthoracic echocardiography. Events at follow-up were assessed according to the Valve Academic Research Consortium-2 consensus classification. RESULTS: Significant PVAR was diagnosed in 44 out of 219 patients (20.1%). Important reduction of CT-ADP could be found in patients without PVAR, contrasting with the lack of CT-ADP improvement in significant PVAR patients. By multivariate analysis, CT-ADP > 180 seconds (hazard ratio [HR]: 5.1, 95% confidence interval [CI]: 2.5-10.6; p < 0.001) and a self-expandable valve were the sole independent predictors of 30-day PVAR. At follow-up, postprocedural CT-ADP >180 seconds was identified as an independent predictor of major/life-threatening bleeding (HR: 1.7, 95% CI [1.0-3.1]; p = 0.049). Major/life-threatening bleedings were at their highest levels in patients with postprocedural CT-ADP > 180 seconds (35.2 vs. 18.8%; p = 0.013). CONCLUSION: Postprocedural CT-ADP > 180 seconds is an independent predictor of significant PVAR 30 days after TAVR and may independently contribute to major/life-threatening bleedings.

Adjusted calculation model of heparin management during cardiopulmonary bypass in obese patients: A randomised controlled trial.

BACKGROUND: Anticoagulation during cardiopulmonary bypass (CPB) is usually adapted to total body weight (TBW). This may be inaccurate in obese patients and lead to heparin overdose with a risk of bleeding. OBJECTIVES: To validate the efficacy and safety of an adjusted calculation model of heparin dosing based on ideal body weight (IBW) rather than TBW in obese CPB patients, with an expected target mean plasma heparin concentration of 4.5 IU ml after onset of CPB in the experimental group. DESIGN: Randomised controlled study. SETTING: University hospital. PATIENTS: Sixty obese patients (BMI ≥ 30 kg m) scheduled for CPB were included from January to June 2016. INTERVENTIONS: Patients received a bolus dose of unfractionated heparin of either 300 IU kg of TBW or 340 IU kg of IBW before onset of CPB. Additional adjusted boluses were injected to maintain an activated clotting time (ACT) of at least 400 s. MAIN OUTCOME MEASURES: Plasma heparin concentration and ACT were measured at different time points. Total heparin doses and transfusion requirements were recorded. RESULTS: The target heparin concentration of 4.5 IU ml was reached in the IBW group at the onset of CPB and maintained at all time points during CPB. Heparin concentrations were significantly higher in the TBW group after the bolus (6.52 ±â€Š0.97 vs. 4.54 ±â€Š1.13 IU ml, P < 0.001) and after cardioplegia (5.10 ±â€Š1.03 vs. 4.31 ±â€Š1.00 IU ml, P = 0.02). Total heparin doses were significantly higher in the TBW group. Mean ACT was significantly lower in the IBW group but remained over 400 s during CPB. The correlation between heparin and ACT was poor. Peri-operative bleeding and transfusion requirements were comparable. No thrombotic event occurred in the CPB circuit. CONCLUSION: The current IBW-adjusted regimen of heparin administration may be used efficiently in obese CPB patients, thereby avoiding overdose which cannot be accurately assessed by ACT monitoring alone. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02675647.