Multivariate analysis of factors affecting waiting time to heart transplantation

De novo human leukocyte antigen allosensitization patterns in patients bridged to heart transplantation using left ventricular assist devices

INTRODUCTION

We examined the impact and time course of de novo human leukocyte antigen (HLA) allosensitization following left ventricular assist device (LVAD) implantation.

METHODS AND RESULTS

Forty patients had a calculated panel reactive antibody (cPRA) prior to LVAD surgery between January 2014 and December 2018. Of these patients, we retrospectively studied 33 patients who had pre-LVAD cPRA <10%. De novo allosensitization was defined as cPRA ≥10% within 3 months following LVAD surgery, and "persistent allosensitization" was defined as cPRA ≥10% at time of heart transplant or death. One-third (11/33) of our cohort developed de novo allosensitization within 3-months post-LVAD. Median duration of follow-up during LVAD support was 588 days (IQR 337-1071 days), or approximately 19 months. In an adjusted, multivariable analysis, female sex remained associated with de novo allosensitization (adjusted odds ratio [95%CI]: 11 (1.4-85), P = 0.026). De novo allosensitization was subsequently associated with persistent allosensitization (P = 0.024). Both axial-flow and centrifugal-flow LVADs had similar rates of allosensitization. Compared to those with no allosensitization, patients with de novo allosensitization did not appear to have inferior post-transplant outcomes of death or treated rejection.

CONCLUSION

In our single-center experience, one-third of patients developed de novo allosensitization which did not appear to associate with inferior post-transplant outcomes. Female sex was associated with de novo allosensitization.

The Waiting List Mortality of Pediatric Heart Transplantation Candidates in Korea before the Pediatric Ventricular Assist Device Era

BACKGROUND

Despite advancements in heart transplantation for pediatric patients in Korea, the waiting list mortality has not been reported. Therefore, we investigated the waiting list mortality rate and factors associated with patient mortality.

METHODS

We reviewed the medical records of pediatric patients who were registered for heart transplantation at three major hospitals in Korea from January 2000 to January 2020. All patients who died while waiting for heart transplantation were investigated, and we identified the waiting list mortality rate, causes of mortality and median survival periods depending on the variable risk factors.

RESULTS

A total of 145 patients received heart transplantations at the three institutions we surveyed, and the waiting list mortality rate was 26%. The most common underlying diseases were cardiomyopathy (66.7%) and congenital heart disease (30.3%). The leading causes that contributed to death were heart failure (36.3%), multi-organ failure (27.2%), and complications associated with extracorporeal membrane oxygenation (ECMO) (25.7%). The median survival period was 63 days. ECMO was applied in 30 patients. The different waiting list mortality percentages according to age, cardiac diagnosis, use of ECMO, and initial Korean Network of Organ Sharing (KONOS) level were determined using univariate analysis, but age was the only significant factor associated with waiting list mortality based on a multivariate analysis.

CONCLUSION

The waiting list mortality of pediatric heart transplantation candidates was confirmed to be considerably high, and age, underlying disease, the application of ECMO, and the initial KONOS level were the factors that influenced the survival period.

Complications of left ventricular assist devices causing high urgency status on waiting list: impact on outcome after heart transplantation

Aims

Heart transplantation (HTx) represents optimal care for advanced heart failure. Left ventricular assist devices (LVADs) are often needed as a bridge‐to‐transplant (BTT) therapy to support patients during the wait for a donor organ. Prolonged support increases the risk for LVAD complications that may affect the outcome after HTx.

Methods and results

A total of 342 patients undergoing HTx after LVAD as BTT in a 10‐year period in two German high‐volume HTx centres were retrospectively analysed. While 73 patients were transplanted without LVAD complications and with regular waiting list status (T, n = 73), the remaining 269 patients were transplanted with high urgency status (HU) and further divided with regard to the observed leading LVAD complications (infection: HU1, n = 91; thrombosis: HU2, n = 32; stroke: HU3, n = 38; right heart failure: HU4, n = 41; arrhythmia: HU5, n = 23; bleeding: HU6, n = 18; device malfunction: HU7, n = 26). Postoperative hospitalization was prolonged in patients with LVAD complications. Analyses of perioperative morbidity revealed no differences regarding primary graft dysfunction, renal failure, and neurological events except postoperative infections. Short‐term survival, as well as Kaplan–Meier survival analysis, indicated comparable results between the different study groups without disadvantages for patients with LVAD complications.

Conclusions

Left ventricular assist device therapy can impair the outcome after HTx. However, the occurrence of LVAD complications may not impact on outcome after HTx. Thus, we cannot support the prioritization or discrimination of HTx candidates according to distinct mechanical circulatory support‐associated complications. Future allocation strategies have to respect that device‐related complications may define urgency but do not impact on the outcome after HTx.

Validating patient prioritization in the 2018 Revised United Network for Organ Sharing Heart Allocation System: A single-center experience

The 2018 Revised United Network for Organ Sharing Heart Allocation System (HAS) was proposed to reclassify status 1A candidates into groups of decreasing acuity; however, it does not take into account factors such as body mass index (BMI) and blood group which influence waitlist (WL) outcomes. We sought to validate patient prioritization in the new HAS at our center. We retrospectively evaluated patients listed for heart transplantation (n = 214) at Emory University Hospital from 2011 to 2017. Patients were reclassified into the 6-tier HAS. Multistate modeling and competing risk analysis were used to compare outcomes of transplantation and WL death/deterioration between new tiers. Additionally, a stratified sensitivity analysis by BMI and blood group was performed. Compared with tier 4 patients, there was progressively increasing hazard of WL death/deterioration in tier 3 (HR: 2.52, 95% CI: 1.37-4.63, P = .003) and tier 2 (HR: 5.03, 95% CI: 1.99-12.70, P < .001), without a difference in transplantation outcome. When stratified by BMI and blood group, this hierarchical association was not valid in patients with BMI ≥30 kg/m2 and non-O blood groups in our cohort. Therefore, the 2018 HAS accurately prioritizes the sickest patients in our cohort. Factors such as BMI and blood group influence this relationship and iterate that the system can be further refined.

Sex-mismatch influence on survival after heart transplantation: A systematic review and meta-analysis of observational studies

INTRODUCTION AND OBJECTIVES

Heart transplantation (HT) is the treatment for patients with end-stage heart disease. Despite contradictory reports, survival seems to be worse when donor/recipient sex is mismatched. This systematic review and meta-analysis aims to synthesize the evidence on the effect of donor/recipient sex mismatch after HT.

METHODS

We searched PubMed and EMBASE until November 2017. Comparative cohort and registry studies were included. Published articles were systematically selected and, when possible, pooled in a meta-analysis. The primary endpoint was one-year mortality.

RESULTS

After retrieving 556 articles, ten studies (76 175 patients) were included in the quantitative meta-analysis. Significant differences were found in one-year survival between sex-matched and mismatched recipients (odds ratio (OR) 1.30, 95% confidence interval (CI) 1.25-1.35, P < .001). In female recipients, we found that sex mismatch was not a risk factor for one-year mortality (OR = 0.93, 95% CI = 0.85-1.00, P = .06). However, in male recipients, we found that it was a risk factor for one-year mortality (OR = 1.38, 95% CI = 1.31-1.44, P < .001).

CONCLUSIONS

Sex mismatch increases one-year mortality after HT in male recipients. Its influence in long-term survival should be further explored with high-quality studies.

Using machine learning to estimate survival curves for patients receiving an increased risk for disease transmission heart, liver, or lung versus waiting for a standard organ

Introduction

Over 19% of deceased organ donors are labeled increased risk for disease transmission (IRD) for viral blood‐borne disease transmission. Many potential organ recipients need to decide between accepting an IRD organ offer and waiting for a non–IRD organ.

Methods

Using machine learning and simulation, we built transplant and waitlist survival models and compared the survival for patients accepting IRD organ offers or waiting for non–IRD organs for the heart, liver, and lung. The simulation consisted of generating 20 000 different scenarios of a recipient either receiving an IRD organ or waiting and receiving a non–IRD organ.

Results

In the simulations, the 5‐year survival probabilities of heart, liver, and lung recipients who accepted IRD organ offers increased on average by 10.2%, 12.7%, and 7.2%, respectively, compared with receiving a non–IRD organ after average wait times (190, 228, and 223 days, respectively). When the estimated waitlist time was at least 5 days for the liver, and 1 day for the heart and lung, 50% or more of the simulations resulted in a higher chance of 5‐year survival when the patient received an IRD organ versus when the patient remained on the waitlist. We also developed a simple equation to estimate the benefits, in terms of 5‐year survival probabilities, of receiving an IRD organ versus waiting for a non–IRD organ, for a particular set of recipient/donor characteristics.

Conclusion

For all three organs, the majority of patients are predicted to have higher 5‐year survival accepting an IRD organ offer compared with waiting for a non–IRD organ.

Assessment of Heart Transplant Waitlist Time and Pre- and Post-transplant Failure: A Mixed Methods Approach

BACKGROUND

Over the past two decades, there have been increasingly long waiting times for heart transplantation. We studied the relationship between heart transplant waiting time and transplant failure (removal from the waitlist, pretransplant death, or death or graft failure within 1 year) to determine the risk that conservative donor heart acceptance practices confer in terms of increasing the risk of failure among patients awaiting transplantation.

METHODS

We studied a cohort of 28,283 adults registered on the United Network for Organ Sharing heart transplant waiting list between 2000 and 2010. We used Kaplan-Meier methods with inverse probability censoring weights to examine the risk of transplant failure accumulated over time spent on the waiting list (pretransplant). In addition, we used transplant candidate blood type as an instrumental variable to assess the risk of transplant failure associated with increased wait time.

RESULTS

Our results show that those who wait longer for a transplant have greater odds of transplant failure. While on the waitlist, the greatest risk of failure is during the first 60 days. Doubling the amount of time on the waiting list was associated with a 10% (1.01, 1.20) increase in the odds of failure within 1 year after transplantation.

CONCLUSIONS

Our findings suggest a relationship between time spent on the waiting list and transplant failure, thereby supporting research aimed at defining adequate donor heart quality and acceptance standards for heart transplantation.

Creation of a quantitative score to predict the need for mechanical support in children awaiting heart transplant

BACKGROUND

Due to the availability of new devices, the use of ventricular assist devices (VADs) in children has been increasing; however, patient selection and optimal timing of device implantation in this population remains uncertain.

METHODS

A retrospective review of the United Network for Organ Sharing dataset identified 5,200 listings without mechanical circulatory support (MCS) for isolated pediatric heart transplant, 1995 to 2012. Patients were randomly divided into a derivation and validation cohort. A multivariable logistic regression model predicting the likelihood of death or need for MCS within 60 days was built using the derivation cohort and tested in the validation cohort. A simplified score (PedsMCS score) was developed and evaluated for accuracy.

RESULTS

The predictive model consisted of variables present at listing (age, albumin level, creatinine clearance, serum bilirubin, mechanical ventilation, and inotropic support). It had good predictive ability (C statistic 0.7304) within the validation cohort. The simplified PedsMCS score was also predictive (C statistic 0.7217) and there was a strong correlation between predicted and expected outcomes (r=0.91, p<0.0001). Patients with PedsMCS score 16 or greater had a significantly higher risk of death or MCS within 2 months (36.6%) than those with low scores (<6) (1.5%, p<0.0001). A single point increase in PedsMCS score was associated with a 16.7% increase in the risk of death or MCS with 2 months (p<0.0001).

CONCLUSIONS

We have developed and validated a simplified score to predict the need for MCS based on risk factors present at listing. This will provide more accurate prognostication in children awaiting heart transplant, and may improve patient selection.

Risk factors for mortality or delisting of patients from the pediatric heart transplant waiting list

OBJECTIVE

Current literature assessing factors associated with outcomes of patients waiting for pediatric heart transplants has focused on survival to transplant and mortality. Our aim was to determine risk factors associated with the outcomes of delisting, transplant, or death while waiting.

METHODS

In this single-center, retrospective study of patients listed for heart transplants, competing risk analysis was used to model survival from listing to 4 competing outcomes (transplant, death, delisting for clinical deterioration, delisting for clinical improvement or surgical intervention).

RESULTS

There were 308 listing episodes in 280 patients. In competing risk analysis, 11% remained listed at 6 months (transplant 62%, dead 13%, delisted worse 6%, delisted improved 8%). Extracorporeal membrane oxygenation and ventricular assist devices were associated both with higher probability of transplant (hazard ratio [HR], 2.8; P < .001) and delisting for clinical deterioration (HR, 2.7; P = .06). Younger age at listing and complex congenital heart disease were shared risk factors for mortality (HR, 1.07; P = .05; HR, 2.9; P = .003) and delisting because of clinical deterioration (HR, 1.17; P = .01; HR, 2.8; P = .02). Younger age at listing and fetal listing were associated with delisting for clinical improvement or surgical intervention (HR, 1.13; P = .01; HR, 2.9; P = .02).

CONCLUSIONS

Overall survival to transplant depends on risk factors including age at listing, cardiac diagnosis, and mechanical circulatory support. Knowledge of risk factors for death and delisting for clinical deterioration or improvement can assist patient selection and timing of transplant listing.

Waiting list mortality among children listed for heart transplantation in the United States

BACKGROUND

Children listed for heart transplantation face the highest waiting list mortality in solid-organ transplantation medicine. We examined waiting list mortality since the pediatric heart allocation system was revised in 1999 to determine whether the revised allocation system is prioritizing patients optimally and to identify specific high-risk populations that may benefit from emerging pediatric cardiac assist devices.

METHODS AND RESULTS

We conducted a multicenter cohort study using the US Scientific Registry of Transplant Recipients. All children <18 years of age who were listed for a heart transplant between 1999 and 2006 were included. Among 3098 children, the median age was 2 years (interquartile range 0.3 to 12 years), and median weight was 12.3 kg (interquartile range 5 to 38 kg); 1294 (42%) were nonwhite; and 1874 (60%) were listed as status 1A (of whom 30% were ventilated and 18% were on extracorporeal membrane oxygenation). Overall, 533 (17%) died, 1943 (63%) received transplants, and 252 (8%) recovered; 370 (12%) remained listed. Multivariate predictors of waiting list mortality include extracorporeal membrane oxygenation support (hazard ratio [HR] 3.1, 95% confidence interval [CI] 2.4 to 3.9), ventilator support (HR 1.9, 95% CI 1.6 to 2.4), listing status 1A (HR 2.2, 95% CI 1.7 to 2.7), congenital heart disease (HR 2.2, 95% CI 1.8 to 2.6), dialysis support (HR 1.9, 95% CI 1.2 to 3.0), and nonwhite race/ethnicity (HR 1.7, 95% CI 1.4 to 2.0).

CONCLUSIONS

US waiting list mortality for pediatric heart transplantation remains unacceptably high in the current era. Specific high-risk subgroups can be identified that may benefit from emerging pediatric cardiac assist technologies. The current pediatric heart-allocation system captures medical urgency poorly. Further research is needed to define the optimal organ-allocation system for pediatric heart transplantation.

Improved Survival of Patients With End-Stage Heart Failure Listed for Heart Transplantation

OBJECTIVES

We sought to investigate the actual survival of patients with end-stage heart failure listed for heart transplantation (HT) in the U.S.

BACKGROUND

The United Network of Organ Sharing (UNOS) reported that the mortality rates on the U.S. HT waiting list have been gradually declining. This suggests that the survival of these patients may have improved.

METHODS

The survival censored on the day of HT or removal from the waiting list was calculated for 18,004 UNOS status 1 and 30,978 status 2 candidates listed in eras I (1990 to 1994), II (1995 to 1999), and III (2000 to 2005) in the U.S. The Cox proportional model was employed for multivariable analysis.

RESULTS

The 1-year survival on the HT waiting list improved from 49.5% to 69.0% for status 1 and from 81.8% to 89.4% for status 2 candidates between eras I and III. The predictors of death within 2 months from listing of status 1 candidates included UNOS status 1A, mechanical ventilation, inotropic and intra-aortic balloon pump support, pulmonary capillary wedge pressure >20 mm Hg and serum creatinine >1.5 mg/dl, failed HT, valvular cardiomyopathy, age >60 years, Caucasian ethnicity, and weight < or =70 kg, as well as the lack of intracardiac cardioverter-defibrillator on the day of listing.

CONCLUSIONS

Survival of HT candidates on the waiting list has significantly improved. Survival of status 1 candidates continues to depend on urgent HT. Predictors of 2-month mortality may help identify status 1 candidates who warrant the highest priority for HT and/or mechanical circulatory support. The 1-year survival of status 2 candidates approaches outcomes of HT, thus raising the question of whether early listing of some of these patients is justified.

Influence of Blood Group on Mortality and Waiting Time Before Heart Transplantation in the United Kingdom: Implications for Equity of Access

BACKGROUND

We examined waiting time for adult heart transplantation in the UK and sought to determine whether recipients with particular ABO blood groups were disadvantaged.

METHODS

Data were obtained from the National Transplant Database. Registration outcome data were analyzed for 622 new, non-urgent, adult, heart-only registrations from April 1, 1999 to March 31, 2003. Unadjusted waiting times of the 618 first registrations were summarized using Kaplan-Meier estimates.

RESULTS

Death rates were relatively low, with no significant difference in the proportions of patients among the different blood groups who died while waiting. A smaller proportion of blood group O patients were transplanted at 1 year after registration, with a significant difference in waiting time to transplant between blood groups (p < 0.0001). Blood group A and AB patients were generally transplanted sooner than O and B patients, with median waiting times of 81 days (95% CI: 67 to 114) and 76 days (95% CI: 52 to 178) vs 214 days (95% CI: 162 to 308) and 174 days (95% CI: 78 to 249), respectively.

CONCLUSIONS

Although no particular blood group was disadvantaged in terms of mortality on the heart transplant list, blood group O and B patients waited significantly longer for transplantation. The difference was at least partly due to a large proportion of blood group O hearts being used for non-O patients. To address this imbalance, the UK Transplant Cardiothoracic Advisory Group (CTAG) changed the allocation protocol, so that "out-of-zone" offers of blood group O donors for non-urgent patients are now restricted to O and B recipients.

The use of quantile regression in health care research: a case study examining gender differences in the timeliness of thrombolytic therapy

Investigators are frequently interested in determining patient and system characteristics associated with delays in the provision of essential medical treatment. Investigators have typically used either multiple linear regression or Cox proportional hazards models to assess the impact of patient and system characteristics on the timeliness of medical treatment. A drawback to the use of these two methods is that they allow, at best, a partial exploration of how a distribution of delays in treatment or of waiting times changes with patient characteristics. In contrast, quantile regression models allow one to assess how any quantile of a conditional distribution changes with patient characteristics. We illustrate the utility of quantile regression by examining gender differences in the delivery of thrombolysis in patients with an acute myocardial infarction. We demonstrate that richer inferences can be drawn through the use of quantile regression. Females were more likely to experience delays in treatment compared to males. Furthermore, gender had a greater impact upon those patients who had the greatest delays in treatment. Investigators who want to determine how a distribution of delays in treatment or of waiting times changes with patient or system characteristics should consider complementing their analyses with the use of quantile regression.

Should stable UNOS Status 2 patients be transplanted?

BACKGROUND

Improved outcomes with contemporary medical therapy in patients with advanced heart failure brings into question the survival advantage of transplantation for patients in stable United Network for Organ Sharing (UNOS) Status 2.

METHODS

Between January 1999 and June 2001, a total of 7,539 adult patients were listed for heart transplantation. Of those, 4,255 (56.4%) patients were listed as UNOS Status 2. Using a competing risk method, we computed probabilities of events while on the waiting list. Additionally, we used a time-dependent proportional hazards model to determine predictors of death before and after transplantation.

RESULTS

Demographics included age >60 (72%), female sex (23%), ischemic causes for transplantation (49%), white race (85%), and median time on the waiting list (544 days). Laboratory and hemodynamic values included mean serum albumin of 3.9 g/dl, serum creatinine of 1.4 mg/dl, mean pulmonary artery pressure of 28 mm Hg, mean pulmonary capillary wedge pressure of 19 mm Hg, and mean cardiac output of 4.5 liter/min. Final outcomes on the waiting list for patients initially listed as UNOS Status 2 were transplantation (48%), removal from the list (11.5%), death (11.4%), and continued listing (29%). At 30 months after transplantation, survival was 81% for patients undergoing transplantation as Status 1A, 77% as Status 1B, and 83% as Status 2, and showed no difference among groups. At 365 days, survival analysis showed no difference for patients listed and undergoing transplantation as UNOS Status 2 compared with those still waiting as Status 2.

CONCLUSION

In the current era of advances in medical and surgical therapies for heart failure, we found no survival benefit of cardiac transplantation at 1 year for patients initially listed as UNOS Status 2.

Influence of UNOS status on chance of heart transplantation and posttransplant survival

This study was designed to compare the chance of heart transplantation (HTx) and survival among patients in different UNOS statuses in Taiwan.

METHODS AND RESULTS

From 1996 to 2002, among 203 patients on the heart transplant waiting list, 127 patients had undergone HTx up to December 2002 with 71 dead while waiting, and 5 still alive without transplantation. This study included those 198 patients who had either undergone HTx or who died. At the time of registry, 40 patients were at status IA, 57 at IB, and 101 at II. Nineteen (47.5%) of 40 status IA patients underwent HTx with a mean waiting time of 92 +/- 116 days and median waiting time of 35 days. The 1-month survival was 84%, and 1-year survival was 58%. Seven (64.9%) of 57 status IB patients underwent HTx with a mean waiting time of 85 +/- 100 days and a median waiting time of 40 days. Both 1-month and 1-year survivals were 92%. Seventy-one (70.3%) patients among 101 status II patients underwent HTx. Their mean waiting time was 134 +/- 135 days and median waiting time was 86 days. Their 1-month survival was 95%, and 1-year survival was 85%.

CONCLUSION

Although UNOS status IA patients had a shorter waiting time, their chance to undergo HTx was lower than those in either status IB or status II. The UNOS status IA heart-waiting patients showed lower posttransplant 1-month and 1-year survival rates.

Sensitivity, ventricular assist devices, and the waiting game in heart transplantation: what's new?

Orthotopic heart transplantation became more successful with the introduction of cyclosporine in the late 1970s. Although congestive heart failure has become a significant public health issue and the proportion of patients with advanced heart failure has increased, the number of heart transplants performed has not increased substantially in the past decade. Transplant waiting times have been related to many different factors. Unfortunately, implantation of ventricular assist devices (VADS) may provoke antibody responses. These result in the sensitization of patients and increased waiting time prior to transplantation. The purpose of this article is to explore etiologies of waiting times for pre heart transplant and left ventricular assist device pre heart transplant candidates, explain new theories of sensitization, define current methods to detect sensitization, and discuss nursing care implications.

On the allocation of cardiac allografts from blood group-O donors

An organ allocation policy, in which hearts from blood group-O donors are used to transplant recipients with other blood groups (ABO-compatible, non-identical transplantations), may affect blood group-O patients on the waiting list. We investigated how blood group affiliation influences potential recipients on the waiting list. In the case of patients with blood group O, fewer patients were transplanted, waiting list mortality was higher and waiting time to transplantation was longer. Patients with blood group O awaiting cardiac transplantation are affected considerably by an organ allocation policy in which ABO-compatible, non-identical transplantations are performed.

Pretransplant cachexia and morbid obesity are predictors of increased mortality after heart transplantation

BACKGROUND

Extremes in body weight are a relative contraindication to cardiac transplantation.

METHODS

We retrospectively reviewed 474 consecutive adult patients (377 male, 97 female, mean age 50.3+/-12.2 years), who received 444 primary and 30 heart retransplants between January of 1992 and January of 1999. Of these, 68 cachectic (body mass index [BMI]<20 kg/m2), 113 overweight (BMI=>27-30 kg/m2), and 55 morbidly obese (BMI>30 kg/m2) patients were compared with 238 normal-weight recipients (BMI=20-27 kg/m2). We evaluated the influence of pretransplant BMI on morbidity and mortality after cardiac transplantation. Kaplan-Meier survival distribution and Cox proportional hazards model were used for statistical analyses.

RESULTS

Morbidly obese as well as cachectic recipients demonstrated nearly twice the 5-year mortality of normal-weight or overweight recipients (53% vs. 27%, respectively, P=0.001). An increase in mortality was seen at 30 days for morbidly obese and cachectic recipients (12.7% and 17.7%, respectively) versus a 30-day mortality rate of 7.6% in normal-weight recipients. Morbidly obese recipients experienced a shorter time to high-grade acute rejection (P=0.004) as well as an increased annual high-grade rejection frequency when compared with normal-weight recipients (P=0.001). By multivariable analysis, the incidence of transplant-related coronary artery disease (TCAD) was not increased in morbidly obese patients but cachectic patients had a significantly lower incidence of TCAD (P=0.05). Cachectic patients receiving oversized donor hearts had a significantly higher postoperative mortality (P=0.02).

CONCLUSIONS

The risks of cardiac transplantation are increased in both morbidly obese and cachectic patients compared with normal-weight recipients. However, the results of cardiac transplantation in overweight patients is comparable to that in normal-weight patients. Recipient size should be kept in mind while selecting patients and the use of oversized donors in cachectic recipients should be avoided.

Heart transplant center practice patterns affect access to donors and survival of patients classified as status 1 by the United Network of Organ Sharing

OBJECTIVE

To determine the effect of adult cardiac transplant center practice patterns within a single organ procurement organization on access to donors and survival for patients listed as United Network of Organ Sharing (UNOS) status 1.

METHODS

A total of 662 patients listed (January 1, 1992, through December 31, 1995) as UNOS status 1 for heart transplantation by the 4 adult cardiac transplant centers in an organ procurement organization were analyzed in a retrospective cohort study to determine differences in clinical outcomes.

RESULTS

The specific center at which an individual was listed as UNOS status 1 was a significant independent predictor of receiving a transplant (odds ratios for 3 centers vs center with highest likelihood = 0.73, 0.64, 0.35, respectively; P <. 01). Only 1 center had a significantly increased mortality rate compared with the other centers (odds ratio 2.03, P <.01).

CONCLUSION

Within a single regional organ procurement organization, cardiac transplant centers demonstrate significant variability in the likelihood of transplantation and survival for patients listed as UNOS status 1.

Milrinone for long-term pharmacologic support of the status 1 heart transplant candidates

BACKGROUND

We determined the efficacy of long-term therapy with milrinone alone or in combination with inotropic agents in status 1 heart transplant candidates as a pharmacological support until heart transplantation.

METHODS

Hemodynamic and biochemical variables were recorded in 29 status 1 men with symptoms of severe congestive heart failure, who received continuous intravenous milrinone alone (group 1, n = 21) or in combination with inotropic agents (group 2, n = 8) while awaiting heart transplantation.

RESULTS

Symptomatic relief was noted in all patients of both groups without any preoperative deaths. One patient (4.8%) of group 1 died on the second day and 1 patient of group 2 died 16.4 months after transplantation. Although pulmonary capillary wedge pressure (group 1, p = 0.021; group 2, p = 0.0002), mean pulmonary artery pressure (group 1, p = 0.051; group 2, p = 0.004), and pulmonary vascular resistance (group 1, p = 0.0026; group 2, p = 0.056) were reduced by 1 hour after the onset of treatment and maintained unchanged until transplantation, the changes in mean pulmonary artery pressure in group 1 and pulmonary vascular resistance in group 2 were statistically insignificant except in the posttransplantation period.

CONCLUSIONS

Long-term therapy with milrinone in combination with inotropic agents is safe and effective when only milrinone infusion is inadequate for pharmacologic support in status 1 candidates.

Permanent ventricular assist device support versus cardiac transplantation

BACKGROUND

Although cardiac transplantation provides excellent therapy for some patients with terminal heart failure, the results are limited by the scarcity of donor organs, reduced long-term survival, and comorbid conditions. Current experience with temporary left ventricular assist devices suggest that a permanent, totally, or near totally implantable device may be a viable alternative.

METHODS

We analyzed data from the 1997 International Society for Heart and Lung Transplantation (ISHLT) Registry and other literature on heart transplantation and compared survival and complication rates with our experience and that of others with temporary ventricular assist devices. From these data, we attempted to identify those patients who would benefit most from permanent left ventricular assist systems (LVASs).

RESULTS

Among heart transplant candidates, United Network for Organ Sharing (UNOS) status II, O blood type, weight >180 lb, older age, and preformed antibodies are negative factors for receipt of donor hearts. Of patients transplanted, women and nonwhites have poorer outcomes. Success with wearable LVAS's suggest some of these patients might be better served with an LVAS than with cardiac transplantation.

CONCLUSIONS

Because LVAS's could be made readily available without the need for a waiting list, they might compete well with the strategy of cardiac transplantation.

The ventricular assist device as a bridge to cardiac transplantation

Congestive heart failure is occurring in the United States at an increasing rate. Transplantation remains the treatment of choice for end-stage heart failure. Prolonged waiting time and decreased availability of suitable organs has increased the necessity for a device to act as a bridge to transplantation to keep patients alive during the waiting period. Ventricular assist devices have become an accepted and proven option for patients whose condition deteriorates to the point that waiting for an available donor organ is a mortal risk. With proper patient selection and timely device insertion, these patients can remain stable until a donor organ becomes available.

In vivo evaluation of the miniaturized Gyro centrifugal pump as an implantable ventricular assist device

A miniaturized Gyro centrifugal pump has been developed to be incorporated into a totally implantable artificial heart. The Gyro PI (permanently implantable) model is a pivot bearing supported centrifugal pump with a priming volume of 20 ml. With the miniaturized actuator, the pump-actuator package has a height of 53 mm, a diameter of 65 mm, and a displacement volume of 145 ml. To evaluate the hemocompatibility and efficiency of the Gyro PI pump system, a plastic prototype (Gyro PI-601) was implanted into a bovine model as a left or right ventricular assist device (LVAD or RVAD), bypassing from the left ventricular apex to the descending aorta or from the right ventricular infundibulum to the main pulmonary artery. The calves were anticoagulated with heparin to maintain activated clotting times from 150 to 200 s. Four calves were supported for 23, 24, and 50 days in the LVAD studies, and 40 days in the RVAD study. The first calf died due to intrathoracic bleeding associated with sepsis. The second calf was euthanized for a low flow rate less than 2 L/min due to an obstructed inflow with growing pannus. The third and fourth calves were euthanized as scheduled. Renal and hepatic functions remained normal, and plasma free hemoglobin values were less than 8 mg/dL throughout the experiments. The fourth case showed flow rates of 4.83 +/- 0.57 L/min, input power of 6.16 +/- 0.49 W, and the inside temperature of the actuator of 43.5 +/- 0.52 degrees C. The pumps implanted in the fourth calf demonstrated no thrombus formation at the autopsy. These in vivo experiments revealed that the Gyro PI pump can provide adequate flow as an easily implantable, efficient, antithrombogenic, and nonhemolytic centrifugal LVAD or RVAD with miniaturized actuators.