Drug interactions between direct-acting oral anticoagulants and calcineurin inhibitors during solid organ transplantation: considerations for therapy

Direct oral anticoagulants vs Vitamin-K antagonists in solid organ transplant recipients: A systematic review and meta-analysis

Objective

Oure review aimed to examine evidence on the safety and efficacy of direct oral anticoagulants (DOAC) vs Vitamin K antagonists (VKA) in patients with solid organ transplants.

Methods

PubMed, Embase, and Web of Science libraries were searched from inception to 25th November 2023 for all studies comparing DOAC with VKA in solid organ recipients.

Results

Nine studies were included with patients who had undergone kidney, heart, or liver transplants. Meta-analysis showed that patients receiving DOAC had a significantly reduced risk of composite bleeding as compared to those with VKA (RR: 0.45 95% CI: 0.30, 0.68 I2=25%). However, the risk of major bleeding was not significantly different between the two groups (RR: 0.76 95% CI: 0.40, 1.42 I2=37%). Pooled analysis showed that the risk of VTE (RR: 0.90 95% CI: 0.72, 1.13 I2=0%) and ischemic stroke (RR: 0.87 95% CI: 0.39, 1.94 I2=12%) was not significantly different between DOAC and VKA groups.

Conclusion

Limited data shows that DOAC are safe and effective in patients with solid organ transplants. The overall risk of bleeding may be reduced with the use of DOAC. There is a need for randomized controlled trials comparing DOAC and VKA in such patients to obtain high-quality evidence.

When anticoagulation management in atrial fibrillation becomes difficult: Focus on chronic kidney disease, coagulation disorders, and cancer

Anticoagulation therapy (AT) is fundamental in atrial fibrillation (AF) treatment but poses challenges in implementation, especially in AF populations with elevated thromboembolic and bleeding risks. Current guidelines emphasize the need to estimate and balance thrombosis and bleeding risks for all potential candidates of antithrombotic therapy. However, administering oral AT raises concerns in specific populations, such as those with chronic kidney disease (CKD), coagulation disorders, and cancer due to lack of robust data. These groups, excluded from large direct oral anticoagulants trials, rely on observational studies, prompting physicians to adopt individualized management strategies based on case-specific evaluations. The scarcity of evidence and specific guidelines underline the need for a tailored approach, emphasizing regular reassessment of risk factors and anticoagulation drug doses. This narrative review aims to summarize evidence and recommendations for challenging AF clinical scenarios, particularly in the long-term management of AT for patients with CKD, coagulation disorders, and cancer.

Practicality and Safety of Electrical Pulmonary Vein Isolation and Left Atrial Appendage Ligation in Lung Transplant Recipients With Pretransplant Atrial Fibrillation

Background

Lung transplant surgery creates surgical pulmonary vein isolation (PVI) as a routine part of the procedure. However, many patients with pretransplant atrial fibrillation continue to have atrial fibrillation at 1 y. We hypothesized that the addition of electrical PVI and left atrial appendage isolation/ligation (LAL) to the lung transplant procedure restores sinus rhythm at 1 y in patients with pretransplant atrial fibrillation.

Methods

We retrospectively reviewed all adult lung transplant recipients at the University of California Los Angeles from April 2006 to August 2021. All patients with pretransplant atrial fibrillation underwent concomitant PVI/LAL and were compared with lung transplant recipients without preoperative atrial fibrillation. In-hospital outcomes; 1-y survival; and the incidence of stroke, cardiac readmissions, repeat ablations, and sinus rhythm (composite endpoint) were examined at 1 y for the PVI/LAL cohort.

Results

Sixty-one lung transplant recipients with pretransplant atrial fibrillation underwent concomitant PVI/LAL. No patient in the PVI/LAL cohort required cardiac-related readmission or catheter ablation for atrial fibrillation within 1 y of transplantation. Freedom from the composite endpoint of death, stroke, cardiac readmission, and repeat ablation for atrial fibrillation at 1 y was 85% (95% confidence interval, 73%-92%) for lung transplant recipients treated with PVI/LAL.

Conclusions

The addition of PVI/LAI to the lung transplant operation in patients with pretransplant atrial fibrillation was safe and effective in maintaining sinus rhythm and baseline risk of stroke at 1 y.

Immunosuppressive therapy and oral anticoagulation in kidney transplant recipients: Direct oral anticoagulants versus vitamin-k antagonists

BACKGROUND

direct oral anticoagulants (DOACs) are an alternative to conventional antagonist of vitamin-K (AVK). However, immune suppressive drugs (ISDs) may interfere with DOACs pharmacokinetic.

AIM OF THIS STUDY

evaluate safety and efficacy profile of DOACs compared to AVK in kidney transplant recipients (KTRs) treated with ISDs.

METHODS

a multi-center study from 4 Italian University hospitals enrolling consecutive KTRs on DOACs or AVK was carried out. Sixty-six patients on DOACs were compared with fifty patients on AVK with similar clinical features. Serial evaluation of renal function and serum levels of ISDs during 18 months follow-up (FU) was performed.

RESULTS

Mean age of DOACs patients was 67±9 and mean eGFR was 58,3± 30,4mL/min/1.73m2. ISDs included tacrolimus (n=47, 71%), cyclosporin (n=13, 20%), everolimus (n=10, 7%) and sirolimus (n=4, 6%). After 14 days of DOACs therapy initiation there was a slight increase of serum levels of tacrolimus (+0.19±0.67 p=0.80) and cyclosporine (+0.12±0.25 p=0.94) not statistically significant. Levels of Tacrolimus and cyclosporin were stable at serial evaluation during 18-months follow-up. There were no thromboembolic events among patients treated with DOACs or AVK and no differences in term of major bleeding (6% vs 4% p=0.69), at long-term follow-up. There was no difference in term of eGFR decline from start therapy to 18 months FU between DOACs vs AVK therapy (-3.9±1 vs -3.8±2 p=0.82).

CONCLUSION

DOACs have similar safety and efficacy than AVK among KTRs treated with ISDs. However, careful evaluation of potential drug interaction and ISDs serum levels is needed.

Potential Effects of Remdesivir on Tacrolimus Exposure in Transplant Recipients With COVID-19 Infection

Introduction

Remdesivir has proven to have benefits against COVID-19 infection. However, data supporting drug-drug interactions are insufficient. Clinicians have noticed that calcineurin inhibitor (CNI) levels tend to change after starting remdesivir. This retrospective study aimed to evaluate the effect of remdesivir on CNI levels.

Methods

This study included adult solid organ transplant recipients hospitalized for COVID-19 who received remdesivir while on CNI. Patients were excluded if they started on other medications known to interact with CNI. The primary end point was the percentage of change in CNI levels after starting remdesivir. Secondary end points included the time until CNI levels reached a maximum increase in trough levels, the incidence of acute kidney injury (AKI), and the time until CNI levels normalized.

Results

Of the 86 patients screened, 61 were included (56 on tacrolimus and 5 on cyclosporine). Most patients received kidney transplants (44.3%), and baseline demographics were similar among the transplanted organs. The median increase in tacrolimus level after starting remdesivir was 84.8%, and only 3 patients had no significant change in CNI levels. The median increase in tacrolimus level was more pronounced in lung and kidney recipients than in heart recipients (96.5% vs. 93.9% vs. 64.6 %, respectively). The median time to maximum increase in tacrolimus trough levels was 3 days, and it took 10 days after the remdesivir course for levels to return to baseline.

Conclusion

This retrospective analysis demonstrates that CNI levels were significantly elevated after starting remdesivir. However, future studies are warranted to evaluate this interaction further.

Blood Coagulation Disorders in Heart Failure: From Basic Science to Clinical Perspectives

Heart failure (HF) is a clinical syndrome that is divided into 3 subtypes based on the left ventricular ejection fraction. Every subtype has specific clinical characteristics and concomitant diseases, substantially increasing risk of thromboembolic complications, such as stroke, peripheral embolism and pulmonary embolism. Despite the annual prevalence of 1% and devastating clinical consequences, thromboembolic complications are not typically recognized as the leading problem in patients with HF, representing an underappreciated clinical challenge. Although the currently available data do not support routine anticoagulation in patients with HF and sinus rhythm, initial reports suggest that such strategy might be beneficial in a subset of patients at especially high thromboembolic risk. Considering the existing evidence gap, we aimed to review the currently available data regarding coagulation disorders in acute and chronic HF based on the insight from preclinical and clinical studies, to summarize the evidence regarding anticoagulation in HF in special-case scenarios and to outline future research directions so as to establish the optimal patient-tailored strategies for antiplatelet and anticoagulant therapy in HF. In summary, we highlight the top 10 pearls in the management of patients with HF and no other specific indications for oral anticoagulation therapy. Further studies are urgently needed to shed light on the pathophysiological role of platelet activation in HF and to evaluate whether antiplatelet or antithrombotic therapy could be beneficial in patients with HF. LAY SUMMARY: Heart failure (HF) is a clinical syndrome divided into 3 subtypes on the basis of the left ventricular systolic function. Every subtype has specific clinical characteristics and concomitant diseases, substantially increasing the risk of thromboembolic complications, such as stroke, peripheral embolism and pulmonary embolism. Despite the annual prevalence of 1% and devastating clinical consequences, thromboembolic complications are not typically recognized as the leading problem in patients with HF, representing an underappreciated clinical challenge. Although the currently available data do not support routine anticoagulation in patients with HF and no atrial arrhythmia, initial reports suggest that such a strategy might be beneficial in a subset of patients at especially high risk of thrombotic complications. Considering the existing evidence gap, we aimed to review the currently available data regarding coagulation problems in stable and unstable patients with HF based on the insight from preclinical and clinical studies, to summarize the evidence regarding anticoagulation in HF in specific patient groups and to outline future research directions to establish the optimal strategies for antiplatelet and anticoagulant therapy in HF, tailored to the needs of an individual patient. In summary, we highlight the top 10 pearls in the management of patients with HF and no other specific indications for oral anticoagulation therapy.

Safety and mortality outcomes for direct oral anticoagulants in renal transplant recipients

PURPOSE

Direct oral anticoagulants (DOACs) are increasingly used in renal transplant recipients (RTR), but relatively understudied in this population. We assess the safety of post-transplant anticoagulation with DOACs compared to warfarin.

METHODS

We conducted a retrospective study of RTRs at the Mayo Clinic sites (2011-present) that were anticoagulated for greater than 3 months excluding the 1st month post-transplant. The main safety outcomes were bleeding and all-cause mortality. Concomitant antiplatelet and interacting drugs were noted. DOAC dose adjustment was assessed according to common US prescribing practices, guidelines, and/or FDA labeling.

RESULTS

The median follow-up was longer for RTRs on warfarin (1098 days [IQR 521, 1517]) than DOACs (449 days [IQR 338, 942]). Largely, there were no differences in baseline characteristics and comorbidities between RTRs on DOACs (n = 208; apixaban 91.3%, rivaroxaban 8.7%) versus warfarin (n = 320). There was no difference in post-transplant use of antiplatelets, immunosuppressants, most antifungals assessed, or amiodarone. There was no significant difference in incident major bleeding (8.4 vs. 5.3%, p = 0.89), GI bleeding (4.4% vs. 1.9%, p = 0.98), or intra-cranial hemorrhage (1.9% vs. 1.4%, p = 0.85) between warfarin and DOAC. There was no significant difference in mortality in the warfarin group compared to DOACs when adjusted for follow-up time (22.2% vs. 10.1%, p = 0.21). Rates of post-transplant venous thromboembolism, atrial fibrillation or stroke were similar between the two groups. 32% (n = 67) of patients on DOACs were dose reduced, where 51% of those reductions were warranted. 7% of patients that were not dose reduced should have been.

CONCLUSIONS

DOACs did not have inferior bleeding or mortality outcomes compared to warfarin in RTRs. There was greater use of warfarin compared to DOACs and a high rate of improper DOAC dose reduction.

Off-Label Use and Inappropriate Dosing of Direct Oral Anticoagulants in Cardiopulmonary Disease

Direct oral anticoagulants (DOACs) are increasingly used in clinical practice and have become essential in the management of atrial fibrillation and VTE. The enthusiasm for DOACs has fueled the off-label application of these agents in cardiopulmonary disease, and their use has often outpaced the evidence supporting their application. This article reviews the evidence and current off-label use of DOACs in various cardiopulmonary disease states.

Safety and efficacy of direct oral anticoagulants under long-term immunosuppressive therapy after liver, kidney and pancreas transplantation

The safety of direct oral anticoagulants (DOACs) in patients after solid organ transplantation (SOT) is not well defined. This study aimed at describing the safety and efficacy of DOACs in patients after SOT. Patients after kidney and/or liver transplantation under maintenance immunosuppression treated with rivaroxaban (n = 26), apixaban (n = 20) and edoxaban (n = 1) were included. Clinical data were collected retrospectively and using a questionnaire. DOAC plasma levels and thrombin generation (TG) were measured in patients after SOT and compared with nontransplanted controls receiving DOACs. DOACs were administered for 84.6 patient-years. Mean immunosuppressive trough levels after DOAC initiation increased from baseline by 18.8 ± 29.6% compared to 3.0 ± 16.5% in matched controls (P = 0.004), without significant differences in dose adjustments. No transplant rejection or significant change in liver or renal function was observed. There was one major bleeding after the observation period but no thromboembolic complication. DOAC plasma levels reached the expected range in all patients. The intrinsic hemostatic activity in transplanted patients was higher compared to nontransplant controls. Treatment with DOACs after SOT is safe and effective. Immunosuppressive trough levels should be monitored after DOAC initiation, particularly in the early phase after SOT. These data should be confirmed in a prospective study.

The Impact of Rivaroxaban and Apixaban on Tacrolimus Trough Levels

The solid organ transplant community is slow to adopt the routine practice of using direct oral anticoagulants. Rivaroxaban and apixaban share common metabolic pathways with tacrolimus. This study aimed to clarify the impact of rivaroxaban/apixaban on tacrolimus troughs. Fifty solid organ transplant recipients with concomitant use of tacrolimus and rivaroxaban/apixaban were retrospectively assessed for changes in tacrolimus troughs and dose. Average dose-adjusted tacrolimus troughs and average tacrolimus total daily doses prior to and after rivaroxaban/apixaban initiation were compared. Subgroup analyses evaluating rivaroxaban and apixaban individually were performed. Rivaroxaban was prescribed to 18 recipients, and apixaban was prescribed to 32 recipients. Transplanted organs included kidney (n = 22), lung (n = 18), liver (n = 7), simultaneous pancreas and kidney (n = 1), and simultaneous kidney and liver (n = 2). The median doseadjusted tacrolimus trough and tacrolimus total daily dose prior to rivaroxaban/apixaban initiation was 2.15 ng/mL/mg (IQR 1.17, 3.37) and 4 mg (IQR 1.88, 6.25), respectively. The median dose-adjusted tacrolimus trough and tacrolimus total daily dose after rivaroxaban/apixaban initiation was 2.16 ng/mL/mg (IQR 1.24, 4.10) and 3.55 mg (IQR 1.5, 6.35), respectively. No significant difference was found between average dose-adjusted tacrolimus troughs or tacrolimus total daily doses before and after rivaroxaban/apixaban initiation or in the individual subgroup analyses for rivaroxaban/apixaban. It is unlikely that initiating rivaroxaban/apixaban affects tacrolimus troughs or requires tacrolimus dose adjustment. This study does not elucidate if tacrolimus affects rivaroxaban/apixaban pharmacokinetics or pharmacodynamics.

Venous thromboembolism in solid-organ transplant recipients: Findings from the RIETE registry

BACKGROUND

Venous thromboembolism (VTE) represents a relevant cause of morbidity in patients with solid-organ transplant (SOT), but there are scarce data on the management and outcomes in these patients.

METHODS

RIETE is a worldwide, ongoing observational registry of patients with objectively confirmed, acute VTE. We used the RIETE database to compare the clinical characteristics, treatment and outcomes in SOT recipients vs. non-recipients.

RESULTS

From January 2001 to December 2019, 83,210 patients were enrolled in RIETE. Of these, 329 (0.4%) were SOT recipients: in the kidney 221, liver 41, lung 28 and heart 25. Median duration of anticoagulation was similar in SOT recipients and non-recipients (174 vs. 182 days). During anticoagulation, 1180 patients developed deep vein thrombosis (DVT) recurrences, 1028 pulmonary embolism (PE) recurrences, 2392 had major bleeding, 3119 non-major bleeding and 8157 died. SOT recipients had a higher rate of major bleeding (hazard ratio [HR]: 2.55; 95% CI: 1.62-3.84) and clinically relevant non-major bleeding (HR: 1.94; 95% CI: 1.23-2.93) than non-recipients, with no differences in the rates of DVT recurrences (HR: 0.96; 95% CI: 0.30-2.32), PE recurrences (HR: 1.11; 95% CI: 0.35-2.67) or death (HR: 0.98; 95% CI: 0.67-1.40). On multivariable analysis, only liver transplant recipients were at an increased risk for major bleeding compared to non-recipients (adjusted HR: 3.17; 95% CI: 1.02-9.87).

CONCLUSIONS

Treatment of VTE in SOT recipients is associated with an increased risk of bleeding compared to non-recipients. This is mainly due to the influence of liver transplant recipients. In non-liver SOT recipients, the risk for bleeding was similar to that in non-recipients.

Survival Benefit of En Bloc Transplantation of Small Pediatric Kidneys in Children

BACKGROUND

En bloc transplantation of small pediatric kidneys in children may help expand the existing deceased donor pool; however, studies examining the long-term outcomes of en bloc transplantation in children are few.

METHODS

We used the Scientific Registry of Transplant Recipients to identify 149 pediatric en bloc recipients transplanted from October 1, 1987 to December 31, 2017. We used propensity scores to match 148 en bloc with 581 non-en bloc deceased donor recipients (matching variables: transplant age, gender, race, pretransplant dialysis, transplant center, and year). We evaluated patient and graft survival using Kaplan-Meier and Fleming-Harrington weighted log-rank test and examined survival benefit of en bloc transplantation versus remaining on the waiting list using the sequential Cox approach. We divided the study period into three 10-y intervals to assess the effect of era on outcomes.

RESULTS

Compared with non-en bloc recipients, en bloc recipients had lower 1-y graft survival (78.9% versus 88.9%; P = 0.007); however, when stratified by transplant era, lower 1-y survival was only observed in the oldest era (1987-1997). En bloc recipients had superior 10-y patient (89.0% versus 80.4%; P = 0.04) and graft survival (51.6% versus 39.9%; P = 0.04) compared with non-en bloc recipients. After multivariate adjustment, en bloc transplantation was associated with superior patient survival compared with remaining on the waiting list (adjusted hazard ratio: 0.58; 95% confidence interval: 0.36-0.95; P = 0.03).

CONCLUSIONS

En bloc transplantation of small pediatric kidneys in children is associated with superior long-term patient and graft survival. The increased risk of 1-y graft loss among en bloc recipients only appeared in the oldest era.

Novel Oral Anticoagulants in Renal Transplant Recipients: A Retrospective Cohort Study

AIM

Data on the use of novel anticoagulant drugs (NOACc) in renal transplant recipients is scarce. The aim of our study was to investigate the safety and efficacy of NOACs in renal transplant recipients.

MATERIALS AND METHODS

In a single-centre retrospective cohort study we assessed adverse reactions, thromboembolic events, and interactions of calcineurin inhibitors in patients treated with NOACs.

RESULTS

Twenty-three renal transplant recipients were treated with NOACs (70% male), mean age of 65.8 ± 1.8 years. Fourteen (61%) patients were treated with rivaroxaban, apixaban was given to 8 (35%) of our patients, and dabigatran to one patient (4%). The main indications for NOAC therapy was atrial fibrillation in 61% and deep venous thrombosis in 23% of patients. Bleeding occurred in 2 patients (1 treated with rivaroxaban and 1 with dabigatran). None of our patients developed thrombosis while treated with NOAC. During the median follow-up of 24 months graft function, as well as hematological parameters, remained stable in patients that were treated with rivaroxaban and apixaban, while dabigatran was ceased after a month of therapy due to a bleeding event.

CONCLUSION

Our results show that both rivaroxaban and apixaban are safe and efficient oral anticoagulant drugs in renal transplant patients. Additional studies are needed to prove these results.

Efficacy and safety of non-vitamin K antagonist oral anticoagulants post-kidney transplantation

BACKGROUND

Novel oral anticoagulants (NOACs) were developed as alternatives to vitamin K antagonists, primarily warfarin, as they do not require routine monitoring and have limited drug-drug and drug-food interactions. However, the efficacy and safety of these agents in kidney transplantation are not well studied.

AIM

To assess the profile and safety of NOACs for patients who had kidney transplantation, and to provide recommendations and guidelines on therapeutic strategies in these patients.

METHODS

This was a retrospective study carried out among adult patients who were actively on the following NOACs (apixaban, rivaroxaban or dabigatran) in our renal transplantation program from December 2015 to December 2016. The patients were identified primarily through electronic medical record system (patient data linkage). Data on the clinical and laboratory profile of the patients were retrieved and analyzed with SPSS 22.0.

RESULTS

Complete data on 42 renal transplant patients were retrieved: 59.5% males, 90.5% were whites and 66.7% were older than 60 years old. The mean duration since renal transplantation of the patients was 8.8 ± 7.4 years. The most common risk factors for the development of end-stage renal disease in the subjects were hypertension (19.0%), polycystic kidney disease (19.0%), followed by diabetic nephropathy (16.7%) and chronic glomerulonephritis (16.7%). The main indications for NOACs use in the cohort were atrial fibrillation in 25 patients (59.5%) and venous thromboembolism in 10 patients (23.8%). Overall, 29 patients (69%) were treated with apixaban, 10 patients (23.8%) with rivaroxaban and 3 patients (7.14%) with dabigatran. No (0%) thromboembolic events were observed during the one-year period, but 3 (7.1%) bleeding events occurred in the cohort consisting of 1 patient treated with rivaroxaban 15 mg daily and 2 patients who received apixaban 2.5 mg twice daily. There were no significant changes in serum tacrolimus level three days after the initiation of NOACs among patients treated with tacrolimus (pre- and post-NOACs tacrolimus levels were 7.2516 and 7.8867 ng/mL, P = 0.55, respectively). Also, after one-year of treatment with NOACs there were no significant changes in the pre- and post-NOACs serum creatinine level (P = 0.772) and estimated glomerular filtration rates (P = 0.232).

CONCLUSION

No thromboembolic events or significant changes in renal profile were observed in our cohort of kidney transplant recipients who were treated with NOACs for at least a year. However, a few bleeding events were observed. This calls for further well-planned randomized controlled trials to assess the efficacy and safety of NOACs among renal transplant recipients.