Faculty Bibliography

Over the past several decades, the operation of choice for end-stage lung disease secondary to severe pulmonary hypertension (PH) has shifted from heart-lung transplantation (HLT) to bilateral lung transplantation (BLT). This change has maintained excellent long-term outcomes and is appropriate for the majority of patients presenting with end-stage disease in need of transplantation. However, a distinct subset of patients with severe PH have an excessive early mortality within 90 days of transplantation. Based on the different causes of this early mortality compared to BLT recipients with other indications, right heart failure and refractory primary graft dysfunction (PGD) appear to play a significant role. It is therefore critical to identify this subset of patient during their evaluation for transplant. This distinction would allow specific patient referral for HLT, which may mitigate those causes of early mortality. Similarly, there is a subgroup of BLT recipients for severe PH that fail to recover right ventricular function, with suboptimal long-term functional status that is independent of early survival. Identification and referral for HLT of these patients may also be important. In this manuscript, we describe our institutional approach and consideration for the risks of early mortality from right heart failure and PGD, as well failure of right ventricular recovery long-term. The described evaluation is used to ascertain those patients with severe PH who may benefit from a HLT over BLT.

BACKGROUND:Increased utilization of hepatitis C virus (HCV)-positive donors has increased transplantation rates. However, high levels of viremia have been documented in recipients of viremic donors. There is a knowledge gap in how transient viremia may impact acute cellular rejections (ACRs). METHODS:In this study, 50 subjects received hearts from either viremic or non-viremic donors. The recipients of viremic donors were classified as nucleic acid amplification testing (NAT)+ group, and the remaining were classified as NAT-. All patients were monitored for viremia levels. Endomyocardial biopsies were performed through 180 days, evaluating the incidence of ACRs. RESULTS:A total of 50 HCV-naive recipients received hearts between 2018 and 2019. A total of 22 patients (44%) who received transplants from viremic donors developed viremia at a mean period of 7.2 ± 0.2 days. At that time, glecaprevir/pibrentasvir was initiated. In the viremia period (<56 days), 14 of 22 NAT+ recipients (64%) had ACR vs 5 of 28 NAT- group (18%) (p = 0.001). Through 180 days, 17 of 22 NAT+ recipients (77%) had a repeat rejection biopsy vs 12 of 28 NAT- recipients (43%) (p = 0.02). NAT+ biopsies demonstrated disparity of ACR distribution: negative, low-grade, and high-grade ACR in 84%, 12%, and 4%, respectively, vs 96%, 3%, and 1%, respectively, in the NAT- group (p = 0.03). The median time to first event was 26 (interquartile range [IQR]: 8-45) in the NAT+ group vs 65 (IQR: 44-84) days in the NAT-. Time to first event risk model revealed that NAT+ recipients had a significantly higher rate of ACR occurrences, adjusting for demographics (p = 0.004). CONCLUSIONS:Transient levels of viremia contributed to higher rates and severity of ACRs. Further investigation into the mechanisms of early immune activation in NAT+ recipients is required.

Worldwide, the majority of heart transplant organs are from donation after brain death. However, the shortage of suitable donors places severe limitations on this route. One option to increase the donor pool is to use organs from donation after circulatory death (DCD). Transplant centers for solid organs have been using DCD organs for years. At this time, 40% of solid organ transplantation in the United Kingdom uses organs from DCD. Use of DCD for solid organ transplants in Canada is also rising. Recently, there has been interest in using DCD organs for heart transplantation. The authors will discuss their experience of 4 heart transplants with organs from DCD donors after normothermic regional perfusion (NRP). The authors' first heart transplant using a DCD organ was in January 2020, and the fourth was in March 2020, just before the coronavirus disease 2019 (COVID-19) pandemic. The authors' protocol using NRP allows adequate evaluation of the donor heart to confidently determine organ acceptance. The co-location of the donor and the recipient in neighboring operating rooms limits ischemic times. Avoidance of an expensive ex vivo organ perfusion machine is an additional benefit for programs that may not have the resources required to purchase and maintain the machine. Some hospitals may not have the resources and space to be able to co-locate both the donor and recipient. Use of cold storage may be an option to transport the procured organ, similar to donation after brain death organs. The authors hope that this technique of NRP in DCD donors can help further increase the donor pool for heart transplantation in the United States.

We conducted a retrospective review of thoracic transplant recipients (22 heart and 16 lung transplant recipients) prospectively enrolled in a single-center observational study of HCV NAT+ organ transplantation in HCV NAT- recipients. All recipients were treated with 8 weeks of glecaprevir-pibrentasvir (GP) for HCV viremia in addition to standard triple immunosuppression post-transplant. Thoracic transplant recipients of HCV NAT- organs were used as a control (24 heart and 22 lung transplant recipients). Our primary outcome was to assess the effect of GP on tacrolimus dose requirements. Secondary objectives included assessing drug interactions with common post-transplant medications, adverse effects, and the need to hold or discontinue GP therapy. The median tacrolimus concentration-to-dose (CDR) in the cohort was 184 (99-260) during GP therapy and 154 (78-304) over the first month after GP (p=0.79). Trends in median tacrolimus CDR were similar on a per-week basis and per-patient basis. In three instances, concomitant posaconazole and GP led to hyperbilirubinemia and interruption of posaconazole. GP therapy was held in one heart transplant recipient, and discontinued in another, due to unresolving hyperbilirubinemia. Utilization of GP to treat HCV viremia post-thoracic transplant is feasible and safe, but requires modifications to post-transplant pharmacotherapy and careful monitoring for adverse effects.

PURPOSE: Passive transmission of hepatitis C (HCV) viremia from actively infected donors to uninfected recipients at the time of heart transplantation may modulate response to alloantigens and risk of allograft rejection. We evaluated the one-year incidence of acute cellular rejection (ACR) in patients transplanted from nucleic amplification testing positive (NAT+) HCV donors compared to those from NAT negative (NAT-) donors.
METHOD(S): Since January 2018, 25 patients completed one-year follow-up. All recipients underwent right ventricular endomyocardial biopsy (EMB) per our institution protocol. ACR was graded according to both the 1990 and the revised 2004 International Society for Heart and Lung Transplantation (ISHLT) criteria. All NAT+ donor recipients developed viremia detected by RT-PCR. Mixed models were used to assess the association between donor HCV NAT status, recipient viremia, tacrolimus levels and ACR in the first year post-transplant.
RESULT(S): Twelve NAT+ recipients (mean age 60, 67% male) and 13 NAT- recipients (mean age 54, 77% male) completed one-year follow-up; 182 and 191 EMB were performed, respectively. NAT+ recipients were associated with higher grade rejection compared with NAT- recipients (p=0.041). At least one episode of high grade rejection (2R/3A) occurred in 4 NAT+ recipients (33%) compared with 2 NAT- recipients (15%). At least one episode of low grade rejection (1R/1B or 1R/2) occurred in 11 NAT+ recipients (92%) compared with 7 NAT- recipients (54%). These findings were independent of the presence and magnitude of viremia and tacrolimus levels. No episodes of ACR 3R or antibody mediated rejection were detected during one-year follow-up in either group. There was no allograft dysfunction or mortality related to ACR in either group.
CONCLUSION(S): One year data from our institution demonstrate increased ACR in heart transplant recipients from NAT+ donors. Most of the rejection episodes in the NAT+ group were low grade and did not translate into any adverse outcomes through one-year follow-up.
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PURPOSE: Heart transplantation from Hepatitis C (HCV) viremic donors is becoming increasingly used due to advent of direct acting antiviral drugs with almost 100% cure. There are limited data about its impact on cardiac allograft vasculopathy (CAV). We report the incidence of CAV in heart transplant recipients from HCV viremic donors (nucleic amplification test positive; NAT+) compared to non-HCV infected donors (NAT-).
METHOD(S): We retrospectively reviewed coronary angiograms with intravascular ultrasound (IVUS) of heart transplant recipients at our institution from January 5, 2018 to September 17, 2019. The presence of CAV was graded according to ISHLT guidelines. IVUS was performed as per our lab protocol on the left main and left anterior descending arteries. Maximal intimal thickness (MIT) was measured with advanced quantification software as per protocol. MIT >= 5mm was considered significant for future adverse outcomes.
RESULT(S): LHC and IVUS was performed on 24 heart transplant recipients (mean age 56; 70% male) at 1- year post transplant. Eleven of these patients were transplanted from NAT+ donors. Thirteen patients received a NAT- donor heart. Two recipients (18.7%) of NAT+ donors had CAV grade >= 1 compared to 2 (16.7%) from NAT- donors (p=1). MIT >= 5mm was seen in 88.9% of NAT+ vs 50% of NAT- recipients (p=0.14) (Figure). The mean MIT was 76mm and 65mm for NAT+ and NAT- group, respectively. Both NAT+ and NAT- donor recipients exhibit mostly eccentric (84.2%) and few (15.7%) demonstrated concentric plaques. There was no heterogeneity in the data after adjusting for risk factors for CAD and donor LHC.
CONCLUSION(S): Our data show no difference in the presence of (CAV >= grade 1) or subclinical atherosclerosis at 1 year among NAT+ donor recipients. HCV viremia is a known risk factor for accelerated atherosclerosis and the consequence of prolonged donor viremia on the recipient is not known. A larger cohort and further longitudinal follow-up is needed to assess the validity of this trend and its prognostic implications.
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PURPOSE: Thoracic organ transplantation from Hepatitis C (HCV) viremic donors is a promising strategy due to curative therapies for HCV. Currently, there is no consensus on the best time to initiate HCV therapy relative to time of transplantation. We assessed the difference in magnitude of viremia and time to clearance in recipients of heart (HT) and lung (LT) transplant, based on timing of starting antiviral HCV therapy.
METHOD(S): From January 2018 to October 2019, 42 patients received thoracic organs from viremic donors. All recipients were treated with Mavyret (glecaprevir/pibrentasvir) for 8 weeks. HT recipients received therapy at the time of detectable viremia, while LT recipients were preemptively treated within 3 days post-transplant. HCV viral load was monitored by RT-PCR.
RESULT(S): 23 patients received HT (mean age 59 +/- 9 years) and 19 patients received LT (mean age 60 +/- 9 years). HCV serologic testing was performed in HT recipients at a mean of 7 +/- 1 days and in LT recipients at a mean of 4 +/- 3 days post-transplant. At the time of testing, all HT and 14 LT patients had detectable viremia. Five LT patients never developed viremia. The mean viral load f HT was 4.5 logIU/mL and for LT was 1.6 logIU/ml. Viremia clearance was obtained at a mean of 28 +/- 13 days in HT and 21+/-11 days in LT recipients (p=0.13) (Fig). The mean time to HCV antibody (AB) clearance was 130 +/- 145 days in HT and 225 +/- 103 days in LT recipients (p=0.058). There was no correlation between the 2 groups in either the duration of viremia or HCV AB clearance.
CONCLUSION(S): Our study suggests that the magnitude and conversion to detectable viremia depends on the time of initiation of HCV therapy relative to time of transplant with complete conversion to HCV viremia in the HT group. Interestingly, there was no significance in time to viremia or HCV AB clearance between the two groups. This may be an organ specific response, but larger sample size studies need to be conducted to define the optimal time of starting HCV therapy.
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BACKGROUND:The use of direct acting antivirals (DAA) has expanded transplantation from hepatitis C viremic donors (HCV-VIR). Our team has conducted an open-label, prospective trial to assess outcomes transplanting HCV-viremic hearts. Glecaprevir/Pibrentasvir (GLE/PIB) was our sole DAA. METHODS:Serial quantitative hepatitis C virus (HCV) RNA PCR was obtained to assess HCV viral titers. Between January 2018 to June 2019, a total of 50 recipients were transplanted. Of these, 22/50 (44%) were from HCV-VIR, the remaining 28 from non-viremic (HCV NON-VIR) donors. An 8 week course of GLE/PIB was initiated at 1 week post-transplant. RESULTS:There was no difference in demographic or clinical parameters between groups. All 22 recipients of HCV-VIR transplants became viremic. GLE/PIB was effective in decreasing viremia to undetectable levels by 6 weeks post-transplant in all patients. The median time to first undetectable HCV quantitative PCR was (4.3 weeks, IQR: 4-5.7 weeks). All patients demonstrated sustained undetectable viral load through 1 year follow up. There was no difference in survival at one year between HCV NON-VIR 28/28: (100%) vs. HCV-VIR 21/22 (95%) recipients. CONCLUSIONS:Our center reports excellent outcomes in transplanting utilizing hearts from HCV-VIR donors. No effect on survival or co-morbidity was found. An 8 week GLE/PIB course was safe and effective when initiated approximately 1 week post-transplant.