Positive donor blood cultures are not associated with worse heart transplant survival.

BACKGROUND: Recent evidence has demonstrated that transplantation of hearts with blood culture positive donors (BCPDs) to pediatric recipients is safe and effective. Few studies have analyzed the effect of BCPD on adult heart transplant recipients. METHODS: The United Network for Organ Sharing (UNOS) database was retrospectively reviewed from September, 1987 to March, 2021. Exclusion criteria included pediatric donors/recipients, donor ejection fraction <10% or >85%, inactive listed recipients, donors missing blood cultures, and recipients missing follow-up time. Outcomes were compared with fully adjusted logistic models. To account for discrepancies in BCPD and non-BCPD covariates, an inverse proportionally weighted model with regression adjustment (IPWRA) was used. RESULTS: A total of 60 592 donors were non-BCPD, while 4009 were BCPD. 7% of hearts not transplanted were BCPD, while 6% of hearts transplanted were BCPD (p = .001). These rates have been nearly constant since 2005. There were no differences in short term survival between the two groups in the adjusted or IPWRA models (p = .103 and .277, respectively). Additionally, the BCPD group had longer ischemic time (3.24 vs. 3.06 h, p < .001), older donor age (32.73 vs. 31.65 years, p < .001), and older recipient age (52.76 vs. 52.09 years, p = .001). The IPWRA revealed an average additional 3.4 years of overall survival and 2.25 years of graft function for BCPD versus non-BCPD recipients, although these results failed to reach statistical significance (p = .387 and .527, respectively). CONCLUSIONS: Given the need for more donor hearts, donors with positive blood cultures should be considered. Great care in evaluating such patients is advised to eliminate donors with untreated infections, while carefully selected donors can be considered and used.

Do vasoactive medications impact donor hearts clinical outcomes in pediatric heart transplantation?

OBJECTIVES: There is limited data examining donor vasopressor and/or inotrope medications (vasoactives) on pediatric orthotopic heart transplant (OHT) outcomes. We aim to evaluate the effects of vasoactives on pediatric OHT outcomes. METHODS: The United Network for Organ Sharing database was retrospectively reviewed from January 2000 to March 2018 for donor hearts. Exclusion criteria included multiorgan transplants and recipient age >18. Donors receiving vasoactives at the time of procurement were compared to donors not on vasoactives, including the number of vasoactives and the type. End-points of interest were survival at 30 days and 1 year as well as post-transplant rejection at 1 year. Logistic and Cox models were used to quantify survival end-points. RESULTS: Of 6462 donors, 3187 (49.3%) were receiving at least one vasoactive. Comparing any vasoactive medication versus none, there was no difference in 30-day survival (p = .27), 1 year survival (p = .89), overall survival (p = .68), or post-transplant rejection (p = .98). There was no difference in 30-day survival for donors receiving 2 or more vasoactive infusions (p = .89), 1 year survival (p = .53), overall survival (p = .75), or post-transplant rejection at 1 year (p = .87). Vasopressin was associated with decreased 30-day mortality (OR = 0.22; p = .028), dobutamine with decreased 1-year mortality (OR = 0.37; p = .036), overall survival (HR = 0.51; p = .003), and decreased post-transplant rejection (HR = 0.63; p = .012). CONCLUSIONS: There is no difference in pediatric OHT outcomes when the cardiac donor is treated with vasoactive infusions at procurement. Vasopressin and dobutamine were associated with improved outcomes. This information can be used to guide medical management and donor selection.

Does donor treatment with inotropes and/or vasopressors impact post-transplant outcomes?

PURPOSE: The purpose was to evaluate the effects of the most commonly used cardiac donor inotropes/vasopressors on subsequent post-heart transplant survival. METHODS: Adult heart transplant recipients from January 2000 to June 2022 were identified in the United Network for Organ Sharing (UNOS) database. Exclusion criteria included: multiorgan transplants, donor age < 15, and recipient age < 18. Donors receiving vasoactive medications at the time of procurement were compared to donors not receiving these medications. Those on vasoactive medications were stratified by medication: phenylephrine, dopamine, dobutamine, norepinephrine and epinephrine, the combination of these agents, and the concomitant administration of vasopressin with any single agent alone or in combination. The primary area of interest was short-and-long-term survival. Survival at 30 days, 1 year, and long-term (Median = 13.6 years) was compared using logistic and Cox models to quantify survival endpoints. RESULTS: A total of 45,198 donors met inclusion criteria and had data on the use of vasoactive agents available. Mean donor age was 32.3 years with 71% male. Vasoactive medications and potential combinations included phenylephrine in 8156 donors (18.0%), dopamine in 9550 (21.1%), dobutamine in 718 (1.6%), epinephrine in 332 (.73%), and norepinephrine in 4854 (10.7%). A total of 25,856 donors (57.2%) were receiving vasopressin at the time of procurement. There was no impact of donor inotropes on 30-day survival. Donors receiving one inotrope and no vasopressin were associated with increased 1 year mortality (OR 1.14; p = .021), as were donors receiving 2+ inotropes and no vasopressin (OR 1.26; p = .006). For individual agents, 1 year mortality was increased for dopamine (OR 1.11; p = .042) and epinephrine (OR 1.59; p = .004). CONCLUSIONS: There is no difference in heart transplant recipient survival at 30 days when the donor is receiving inotropes without vasopressin at the time of procurement. Inotropic support without vasopressin is associated with greater 1 year mortality. The impact of donor inotropic support on long term heart transplant survival, and the interaction with vasopressin warrants further study.

Functional status of heart transplant recipients predicts survival.

INTRODUCTION: Recipient functional status prior to transplantation can significantly impact post-transplant survival. METHODS: The United Network for Organ Sharing database was queried for adult heart transplants including data on functional capacity and from February 1, 2005 to March 1, 2021; there were 32 875 cases included. The four functional categories studied were based on adult daily activities of living and were separated into total assistance required, some assistance required, no assistance required, and near death. Survival outcomes were compared for recipient's pretransplant level of functional status versus those with near death status. These were compared using adjusted logistic regression (odds of death at 30 days and 1 year) and conditional Cox models (overall survival and time until post-transplant rejection). All models were adjusted for donor age, sex, ethnicity, ischemic time, as well as recipient age, sex, ethnicity, length of stay, UNOS region, ventricular assist device, creatinine, days on the waiting list, and status at transplant. RESULTS: There were 12 953 recipients classified as "near death" or "severely disabled"; 7711 "required total assistance in daily living", 7,328 "needed some", and 4883 "needed none". In adjusted models, the probabilities of death for the lowest functioning groups within 30 days and 1 year were 5% and 10%, respectively. Those "requiring total assistance" had analogous probabilities of 3% (OR = 0.58; p < 0.001) and 9% (OR = 0.81; p < 0.001). Those "requiring some assistance" had probabilities of 3% (OR = 0.56; p < 0.001) and 9% (OR = 0.74; p < 0.001). Lastly, those "requiring no assistance" had probabilities of death of 2% (OR = 0.35; p < 0.001) and 7% (OR = 0.63; p < 0.001). CONCLUSION: Recipient functional status assessed pre-transplant and recorded in the UNOS database is a strong predictor of post-transplant survival.

Ischemic time and patient outcomes after the 2018 UNOS donor heart allocation system change.

BACKGROUND: The allocation system for heart donors in the United States changed on October 18, 2018. The typical distance from donor hospitals to recipient hospitals has increased as has the ischemic time. We investigated patient outcomes with the new allocation system and the differential effects of ischemic time under both the old and new allocation schemas. METHODS: The United Network for Organ Sharing Registry (UNOS) was queried for data regarding heart transplants occurring from October 1, 1987 to March 1, 2021. In total, 62,301 adult heart transplants were examined. Survival outcomes at 30 days and 1 year and ischemic times were compared via adjusted logistic and Cox models (overall survival and time until post-transplant rejection). RESULTS: Mean ischemic time was slightly increased in the new system (3.43 h vs. 3.03 h, p < .001). Survival differences between old versus new systems were not observed in adjusted models (p = .818). However, there was evidence to suggest longer ischemic times are more detrimental to long-term survival under the new system (hazard ratio [HR] = 1.15 per hour increase; p = .001) versus the old system (HR = 1.08 per hour increase; p < .001), although this relationship did not reach statistical significance (p = .150). CONCLUSIONS: Although travel distances have significantly increased under the new allocation system, survival outcomes remain largely unchanged. Ischemic time is an influential factor in recipient survival that should be limited during organ transport. Further studies on the impact of travel distances and ischemic time under the new allocation system are needed.

Donor Utilization in the Recent Era: Effect of Sex, Drugs, and Increased Risk.

BACKGROUND: Heart transplantation volumes have increased in recent years, yet less than a third of donors are typically accepted for transplantation. Whether donor sex, donor drug use, or perception of increased risk affects utilization for transplantation is unclear. METHODS: The United Network for Organ Sharing database was queried for donors from January 1, 2007, to December 31, 2017. Donor toxicology was collected when available. Multivariate analysis was conducted to examine correlations with donor utilization. RESULTS: Between January 1, 2007, and December 31, 2017, there were 87 816 heart donors aged ≥15 years. The mean age was 42.7±15.8 years, and 24 831 donors (28.3%) were utilized for heart transplantation. Subsequent analyses focused on donors between 15 and 39 years old. The strongest associations with donor acceptance were for male donor sex, blood type, hepatitis C antibody, donor age, left ventricular hypertrophy, and history of donor drug use. After removing hepatitis C, Public Health Service Increased Risk was identified as a strong negative predictor. Most positive drug toxicology results were associated with donor nonuse except for donors between 15 and 19 years of age. Exceptions included alcohol, marijuana, and cocaine. Opiates were associated with less utilization at all donor ages. The Public Health Service Increased Risk status was associated with significantly less utilization in all age groups except 15- to 19-year-old donors. CONCLUSIONS: While male donors were preferentially utilized, donors with drug use or those deemed Public Health Service Increased Risk were significantly less utilized for heart transplantation. Further consideration of such donors would be appropriate particularly as the demand for transplantation continues to increase.

"It Works." Every heart transplant program should have one.

The total artificial heart (TAH) provides full biventricular cardiac replacement, pulsatile perfusion at flows of 7-9 L/min at low filling pressures. This allows organs that are failing to recover and for the potential cardiac recipient to become a better transplant candidate. Postimplant patients are mobile and able to go through physical rehabilitation in a hospital or at home. The risks are acceptable as shown by the authors. TAH use in more transplant centers could save lives in many transplant candidates.

Venoarterial extracorporeal membrane oxygenation is a viable option as a bridge to heart transplant.

OBJECTIVE: Venoarterial extracorporeal membrane oxygenation is a rescue therapy for patients in cardiogenic shock. We hypothesize that patients bridged to heart transplant with extracorporeal membrane oxygenation have decreased survival. METHODS: The United Network of Organ Sharing database was retrospectively reviewed from January 1, 1999, to March 31, 2018, for heart transplant recipients. Recipients bridged with any form of mechanical support and those without support were compared with recipients bridged with extracorporeal membrane oxygenation. The primary end point was restricted mean survival time through 16.7 years. RESULTS: Of 26,918 recipients, 15,076 required no pretransplant mechanical support (56.0%). Support patients included 9321 with left ventricular assist devices (34.6%), 53 with right ventricular assist devices (0.2%), 258 with total artificial hearts (1.0%), 686 with biventricular assist devices (2.6%), 1378 with intra-aortic balloon pumps (5.1%), and 146 who required extracorporeal membrane oxygenation (0.5%). In the first 16.7 years post-transplant, compared with recipients bridged with extracorporeal membrane oxygenation, estimated adjusted restricted mean survival time was higher in patients who required no mechanical support (16.6 months [14.0-19.4]) and patients with a left ventricular assist device (16.5 months [99% confidence interval, 13.9-19.2]), an intra-aortic balloon pump (11.2 months [8.3-14.7]), or a biventricular assist device (6.6 months [3.6-10.3]). Restricted mean survival time in patients with a right ventricular assist device or a total artificial heart was similar to patients with extracorporeal membrane oxygenation. CONCLUSIONS: Recipients bridged with extracorporeal membrane oxygenation were estimated to survive 16.6 months less than nonmechanical circulatory support recipients. Bridge to heart transplant with extracorporeal membrane oxygenation is a viable option, and these patients should be considered transplant candidates.

Better together: a reappraisal of heterotopic heart transplantation.

Heterotopic heart transplantation (HHT) is rare in the modern era. When used as a biologic left ventricular assist, HHT provides pulsatile flow, supports the left ventricle with a physiologic cardiac output, responds to humoral stimuli, and with modern immunosuppression may offer long-term untethered survival. This study was undertaken to compare survival of HHT with orthotopic heart transplantation (OHT) to assess its viability in the modern era. In the United Network for Organ Sharing database, from January 1999 to December 2020, there were 27691 bicaval OHT, 13836 biatrial OHT, 1271 total OHT, and 51 HHT with sufficient follow-up. Survival was analyzed using restricted mean survival time (RMST) through 4 years as the outcome. In the first 4 years after transplant, compared with HHT, differences in RMST were 0.1 years (99% CI: -0.4 to 0.5 years) for bicaval OHT, 0.0 years (99% CI: -0.4 to 0.5 years) for biatrial OHT, and 0.0 years (99% CI: -0.5 to 0.4 years) for total OHT. In this cohort, survival was indistinguishable between HHT and OHT recipients in the first four years. Thus, HHT might be a viable alternative to durable mechanical circulatory assist particularly with size mismatched grafts or for patients with refractory pulmonary hypertension.

Intoxicated Donors and Heart Transplant Outcomes: Long-Term Safety.

BACKGROUND: The opioid crisis has led to an increase in available donor hearts, although questions remain about the long-term outcomes associated with the use of these organs. Prior studies have relied on historical information without examining the toxicology results at the time of organ offer. The objectives of this study were to examine the long-term survival of heart transplants in the recent era, stratified by results of toxicological testing at the time of organ offer as well as comparing the toxicology at the time of donation with variables based on reported history. METHODS: The United Network for Organ Sharing database was requested as well as the donor toxicology field. Between 2007 and 2017, 23 748 adult heart transplants were performed. United Network for Organ Sharing historical variables formed a United Network for Organ Sharing Toxicology Score and the measured toxicology results formed a Measured Toxicology Score. Survival was examined by the United Network for Organ Sharing Toxicology Score and Measured Toxicology Score, as well as Cox proportional hazards models incorporating a variety of risk factors. RESULTS: The number and percent of donors with drug use has significantly increased over the study period (P<0.0001). Cox proportional hazards modeling of survival including toxicological and historical data did not demonstrate differences in post-transplant mortality. Combinations of drugs identified by toxicology were not associated with differences in survival. Lower donor age and ischemic time were significantly positively associated with survival (P<0.0001). CONCLUSIONS: Among donors accepted for transplantation, neither history nor toxicological evidence of drug use was associated with significant differences in survival. Increasing use of such donors may help alleviate the chronic donor shortage.

Total Artificial Heart Update.

The SynCardia Total Artificial Heart (TAH, SynCardia Systems, Tucson, AZ) is the only biventricular cardiac replacement approved for bridge to transplantation by the U.S. Food and Drug Administration (FDA) and which carries the European Union CE mark. It has been implanted in about 2000 patients. In experienced centers, 60 to 80 % of implanted patients have been transplanted and over 80 % of those transplanted have lived for over 1 year. The SynCardia TAH has supported potential cardiac recipients with irreversible biventricular failure for up to 6 years, providing physiologic pulsatile flows of 6 to 8 L/min at filling pressures of less than 10 mmHg allowing for optimal perfusion and recovery of organs such as the kidneys and liver. It is a tested device that provides a method for recovering potential transplant candidates who rapidly decompensate from biventricular failure or who have chronic cardiac failure from a variety of etiologies. This article covers the history, mechanical function and monitoring, implantation, patient selection and management, and outpatient use. It also reviews outcome data from the original FDA study as well as contemporary data from experienced centers.

The effects of increased donor support time from organ donation referral to donor procurement on heart transplant recipient survival.

INTRODUCTION: Given the known deleterious cardiac effects of brain death (BD) physiology, we hypothesized that time from cardiac donation referral to procurement (donor support time [DST]), would negatively impact cardiac transplant recipient survival. METHODS: The United Network for Organ Sharing database was queried from 2007 to 2018, identifying 22,593 donor hearts for analysis. Multivariate logistic models for 30-day and 1-year survival, as well as Cox models for overall survival and posttransplant rejection, were used to assess adjusted outcomes. RESULTS: median DST was 3 days (interquartile range: 2-5 days). Ischemic time; distance between donor and recipient hospitals; and recipient age, creatinine, waitlist time, and length of stay were adjusted predictors of survival and rejection. DST was not associated with either outcome in aggregate; however, differential association by donor race was identified, with DST in any race recipient associated with 4% higher odds of 1-year mortality (p = .001; p value for interaction .005) but only a trend towards worse overall mortality (p = .064; p value for interaction .046). CONCLUSION: Thus, duration of exposure to BD physiology may have a differential impact on recipient outcomes based on donor race, suggesting that additional research is needed on donor immunologic, socioeconomic, and healthcare access factors that may impact cardiac transplant recipient outcomes.

Looking at cardiac transplantation through a 20-year retrospective study-invited commentary.

The authors present an excellent large cohort review and complete analysis of long-term heart transplant survival including multiple institutions. Most studies on long-term heart transplant survival have single-center institutional experience. The authors present a comprehensive national review of the United Network for Organ Sharing Database (UNOS). The paper reflects the early transplant era through 1998 and demonstrates the long-term survival of this time.

Does pediatric heart transplant survival differ with various cardiac preservation solutions?

BACKGROUND: Few studies directly compare outcomes between the most commonly used preservation solutions in pediatric heart transplantation in a large cohort of recipients. The purpose of this study is to investigate the effect of cardiac preservation solution on survival in pediatric heart transplant recipients. METHODS: The United Network for Organ Sharing (UNOS) database was retrospectively reviewed from 01/2004-03/2018 for pediatric donor hearts. Saline, University of Wisconsin (UW), "cardioplegia," Celsior, and Custodiol preservation solutions were evaluated. The primary endpoints were recipient survival at 30 days, 1 year, and long term. RESULTS: After exclusion criteria, 3012 recipients had preservation solution data available. The most common preservation solution used was UW in 1203 patients (40%), followed by Celsior in 542 (18%), cardioplegia in 461 (15%), saline in 408 (14%), and Custodiol in 398 (13%). Survival of recipients whose donor hearts were procured with UW was as follows: 97%-30 day, 92%-1 year; Celsior: 97%-30 day, 92%-1 year; cardioplegia: 97%-30 day, 91%-1 year; saline: 97%-30 day, 91%-1 year; and Custodiol: 96%-30 day and 92%-1 year. Analysis of Cox models for 30-day and long-term survival revealed no statistical differences when comparing UW to Celsior (p = .333), cardioplegia (p = .914), saline (p = .980), or Custodiol (p = .642) in adjusted models. CONCLUSIONS: There were no significant differences in 30-day or 1-year survival detected between commonly used preservation solutions in the pediatric heart transplant population.

Donor heart and lung procurement: A consensus statement.

Heart and lung procurements are multiphased processes often accompanied by an array of complex logistics. Approaches to donor evaluation and management, organ procurement, and organ preservation vary among individual procurement teams. Because early graft failure remains a major cause of mortality in contemporary thoracic organ transplant recipients, we sought to establish some standardization in the procurement process. This paper, in this vein, represents an international consensus statement on donor heart and lung procurement and is designed to serve as a guide for physicians, surgeons, and other providers who manage donors to best optimize the clinical status for the procurement of both heart and lungs for transplantation. Donation after brain death (DBD) and donation after circulatory determination death (referred to as donation after circulatory death [DCD] for the remainder of the paper) for both heart and lung transplantation will be discussed in this paper. Although the data available on DCD heart donation are limited, information regarding the surgical technique for procurement is included within this consensus statement. Furthermore, this paper will focus on adult DBD and DCD heart and lung procurement. Currently, no certification, which is either recognized and/or endorsed by the transplant community at large, exists for the training of a cardiothoracic procurement surgeon. Nevertheless, establishing a training curriculum and credentialing requirements are beyond the scope of this paper.

What Number Are We?

Background In 2007, the United Network for Organ Sharing changed the way centers were notified of possible organ donors. In the new system, a donor sequence number (DSN) was provided signifying the position of a recipient on the list for a particular donor. Whether high DSN donors have equivalent outcomes is unknown. Methods and Results The United Network for Organ Sharing database was queried between May 2007 and March 2014. DSNs were divided into cohorts of 5 (sequence 1-5, 6-10, and so forth). Survival was analyzed by Kaplan-Meier method. In this dataset, 12 363 adult de novo heart transplants were performed, and the median DSN was 3 with 58.3% of donors allocated locally. The distance from donor to transplant hospital was ≤500 miles in 93.8% of cases. With increasing DSN group, recipients were older, with longer ischemic time, and higher distance ( P <0.001 for all comparisons). As well, with increasing DSN, donors were increasingly older, female sex, mismatched gender (female donor with a male recipient), lower ejection fraction, hypertensive, and had a history of smoking, alcohol, or cocaine use. For the whole cohort, the 1-year and 5-year survivals were 89.7% and 74.8%, respectively. Survival based on various cut points of DSN was investigated; there was no difference regardless of DSN. Conclusions Most donors since 2007 were allocated within a close geographic range. DSN functions as a crowdsourced rank with most donors being selected within low numbers. Given the similar survival of donors at higher DSN, this represents an opportunity to increase transplant volumes.

The Effect of Cardiac Preservation Solutions on Heart Transplant Survival.

BACKGROUND: Limited data exist that compare the predominant cardiac preservation solutions (CPSs). MATERIALS AND METHODS: The United Network for Organ Sharing database was retrospectively reviewed from January 1, 2004 to March 31, 2018, for donor hearts. Of 34,614 potential donors, 21,908 remained after applying the exclusion criteria. The CPS analyzed included saline, the University of Wisconsin (UW), cardioplegia, Celsior, and Custodiol. The primary endpoints were recipient survival and posttransplant rejection. Logistic and Cox models were used to quantify survival endpoints. RESULTS: Saline was used as the CPS in 2549 patients (12%), UW in 10,549 (48%), cardioplegia in 1307 (6%), Celsior in 5081 (23%), and Custodiol in 2422 (11%). Donor age ranged from 15 to 68 y (mean = 32.0 y, median = 30.0 y), and 71% were male. Adjusted survival probabilities of recipients whose donor hearts were procured with saline was 96% 30 d, 90% 1 y, UW: 97% 30 d, 92% 1 y, cardioplegia: 95% 30 d, 87% 1 y, Celsior: 96% 30 d, 90% 1 y, and Custodiol: 97% 30 d, 92% 1 y. When these comparisons were adjusted for donor age, sex, ethnicity, ischemic time, recipient age, sex, ethnicity, creatinine, ventricular assist device (VAD), length of stay, region and days on waiting list, cardioplegia solution was demonstrated to have a higher risk of death (30 d, 1 y, overall) and posttransplant rejection versus UW (odds ratio 1.70, P = 0.001; odds ratio 1.63, P < 0.001; hazard ratio 1.22, P < 0.001; hazard ratio 1.21, P < 0.001, respectively). CONCLUSIONS: Cardioplegia solutions for cardiac preservation are associated with a higher mortality in heart transplant recipients.

Anticoagulation and Antiplatelet Strategies After On-X Mechanical Aortic Valve Replacement.

BACKGROUND: The burden oral anticoagulation is a limitation of mechanical valve prostheses. OBJECTIVES: The aim of this study was to test whether patients could be safely managed with dual-antiplatelet therapy (DAPT) (aspirin 325 mg and clopidogrel 75 mg) or lower warfarin after On-X mechanical aortic valve replacement (mAVR). METHODS: PROACT (Prospective Randomized On-X Anticoagulation Trial) (n = 576) is a multicenter (41 sites) noninferiority trial. From June 2006 through February 2014, 201 patients ≥18 years of age without thromboembolic risk factors undergoing mAVR were randomized to receive DAPT (n = 99) or standard warfarin plus aspirin (n = 102) 3 months after mAVR (low-risk arm). From June 2006 through October 2009, 375 patients with 1 or more thromboembolic risk factors were also randomized to lower intensity warfarin plus aspirin (international normalized ratio 1.5 to 2.0; n = 185) or standard warfarin plus aspirin (international normalized ratio 2.0 to 3.0; n = 190) 3 months after mAVR (high-risk arm). RESULTS: The low-risk arm was terminated for excess cerebral thromboembolic events (3.12% per patient-year vs. 0.29% per patient-year, p = 0.02) in the DAPT group at up to 8.8-year follow-up (631.6 patient-years), with no differences in bleeding or all-cause mortality. High-risk arm patients experienced significantly lower major (1.59% per patient-year vs. 3.94% per patient-year, p = 0.002) and minor (1.27% per patient-year vs. 3.49% per patient-year, p = 0.002) bleeding up to 8.7-year follow-up (2,035.2 patient-years), with no differences in thromboembolism (0.42% per patient-year vs. 0.09% per patient-year, p = 0.20) and all-cause mortality. CONCLUSIONS: DAPT was associated with higher rates of thromboembolism and valve thrombosis compared with control in the low-risk arm. International normalized ratios were safely maintained at 1.5 to 2.0 in high-risk patients, without differences in mortality or thromboembolic complications. (Randomized On-X Anticoagulation Trial [PROACT]; NCT00291525).