Does Heart Transplantation Confer Survival Benefit in All Risk Groups?

Dynamic Metabolic Changes During Prolonged Ex Situ Heart Perfusion Are Associated With Myocardial Functional Decline

Ex situ heart perfusion (ESHP) was developed to preserve and evaluate donated hearts in a perfused beating state. However, myocardial function declines during ESHP, which limits the duration of perfusion and the potential to expand the donor pool. In this research, we combine a novel, minimally-invasive sampling approach with comparative global metabolite profiling to evaluate changes in the metabolomic patterns associated with declines in myocardial function during ESHP. Biocompatible solid-phase microextraction (SPME) microprobes serving as chemical biopsy were used to sample heart tissue and perfusate in a translational porcine ESHP model and a small cohort of clinical cases. In addition, six core-needle biopsies of the left ventricular wall were collected to compare the performance of our SPME sampling method against that of traditional tissue-collection. Our state-of-the-art metabolomics platform allowed us to identify a large number of significantly altered metabolites and lipid species that presented comparable profile of alterations to conventional biopsies. However, significant discrepancies in the pool of identified analytes using two sampling methods (SPME vs. biopsy) were also identified concerning mainly compounds susceptible to dynamic biotransformation and most likely being a result of low-invasive nature of SPME. Overall, our results revealed striking metabolic alterations during prolonged 8h-ESHP associated with uncontrolled inflammation not counterbalanced by resolution, endothelial injury, accelerated mitochondrial oxidative stress, the disruption of mitochondrial bioenergetics, and the accumulation of harmful lipid species. In conclusion, the combination of perfusion parameters and metabolomics can uncover various mechanisms of organ injury and recovery, which can help differentiate between donor hearts that are transplantable from those that should be discarded.

Usefulness of speckle tracking echocardiography and biomarkers for detecting acute cellular rejection after heart transplantation

BACKGROUND

Acute cellular rejection (ACR) is a major complication after heart transplantation. Endomyocardial biopsy (EMB) remains the gold standard for its diagnosis, but it has concerning complications. We evaluated the usefulness of speckle tracking echocardiography (STE) and biomarkers for detecting ACR after heart transplantation.

METHODS

We prospectively studied 60 transplant patients with normal left and right ventricular systolic function who underwent EMB for surveillance 6 months after transplantation. Sixty age- and sex-matched healthy individuals constituted the control group. Conventional echocardiographic parameters, left ventricular global longitudinal, radial and circumferential strain (LV-GLS, LV-GRS and LV-GCS, respectively), left ventricular systolic twist (LV-twist) and right ventricular free wall longitudinal strain (RV-FWLS) were analyzed just before the procedure. We also measured biomarkers at the same moment.

RESULTS

Among the 60 studied patients, 17 (28%) had severe ACR (grade ≥ 2R), and 43 (72%) had no significant ACR (grade 0 - 1R). The absolute values of LV-GLS, LV-twist and RV-FWLS were lower in transplant patients with ACR degree ≥ 2 R than in those without ACR (12.5% ± 2.9% vs 14.8% ± 2.3%, p=0.002; 13.9° ± 4.8° vs 17.1° ± 3.2°, p=0.048; 16.6% ± 2.9% vs 21.4%± 3.2%, p < 0.001; respectively), while no differences were observed between the LV-GRS or LV-GCS. All of these parameters were lower in the transplant group without ACR than in the nontransplant control group, except for the LV-twist. Cardiac troponin I levels were significantly higher in patients with significant ACR than in patients without significant ACR [0.19 ng/mL (0.09-1.31) vs 0.05 ng/mL (0.01-0.18), p=0.007]. The combination of troponin with LV-GLS, RV-FWLS and LV-Twist had an area under curve for the detection of ACR of 0.80 (0.68-0.92), 0.89 (0.81-0.93) and 0.79 (0.66-0.92), respectively.

CONCLUSION

Heart transplant patients have altered left ventricular dynamics compared with control individuals. The combination of troponin with strain parameters had higher accuracy for the detection of ACR than the isolated variables and this association might select patients with a higher risk for ACR who will benefit from an EMB procedure in the first year after heart transplantation.

New Strategies to Expand and Optimize Heart Donor Pool: Ex Vivo Heart Perfusion and Donation After Circulatory Death: A Review of Current Research and Future Trends

Heart transplantation remains the definitive management for end-stage heart failure refractory to medical therapy. While heart transplantation cases are increasing annually worldwide, there remains a deficiency in organ availability with significant patient mortality while on the waiting list. Attempts have therefore been made to expand the donor pool and improve access to available organs by recruiting donors who may not satisfy the standard criteria for organ donation because of donor pathology, anticipated organ ischemic time, or donation after circulatory death. "Ex vivo" heart perfusion (EVHP) is an emerging technique for the procurement of heart allografts. This technique provides mechanically supported warm circulation to a beating heart once removed from the donor and before implantation into the recipient. EVHP can be sustained for several hours, facilitate extended travel time, and enable administration of pharmacological agents to optimize cardiac recovery and function, as well as allow assessment of allograft function before implantation. In this article, we review recent advances in expanding the donor pool for cardiac transplantation. Current limitations of conventional donor criteria are outlined, including the determinants of organ suitability and assessment, involving transplantation of donation after circulatory death hearts, extended criteria donors, and EVHP-associated assessment, optimization, and transportation. Finally, ongoing research relating to organ optimization and functional ex vivo allograft assessment are reviewed.

Peripartum Cardiomyopathy: Current Options for Treatment and Cardiovascular Support

Peripartum cardiomyopathy is a rare form of acute heart failure but the major cause of all deaths in pregnant patients with heart failure. Improved survival rates in recent years, however, emphasize the importance of early recognition and initiation of heart failure treatment. This article, therefore, attempts to raise awareness among cardiac and obstetric anesthesiologists as well as intensivists of this often fatal diagnosis. This review summarizes theories of the pathophysiology and outcome of peripartum cardiomyopathy. Based on the most recent literature, it further outlines diagnostic criteria and treatment options including medical management, mechanical circulatory support devices, and heart transplantation. Earlier recognition of this rare condition and a new generation of mechanical circulatory devices has contributed to the improved outcome. More frequently, patients in cardiogenic shock who fail medical management are successfully bridged to recovery on extracorporeal circulatory devices or survive with a long-lasting implantable ventricular assist device. The outcome of transplanted patients with peripartum cardiomyopathy, however, is worse compared to other recipients of heart transplants and warrants further investigation in the future.

Successful heart transplantation after prolonged cardiac arrest and extracorporeal life support in organ donor-a case report

BACKGROUND

Although heart transplantation is a successful therapy for patients suffering from end-stage heart failure, the therapeutic is limited by the lack of organs. Donor cardiac arrest is a classic hindrance to heart retrieval as it raises issues on post-transplant outcomes.

CASE PRESENTATION

The present case reports a successful heart transplantation after prolonged donor cardiac arrest (total lowflow time of 95 minutes) due to anaphylactic shock necessitating extracorporeal life support. We further provide an overview of the current evidence and outcomes of heart transplantation in cases of donor cardiac arrest.

CONCLUSION

Providing that donor and recipient criteria are respected, donor cardiac arrest does not seem to be an adverse predictor in heart transplantation.

Heart transplantation outcomes from cardiac arrest-resuscitated donors

BACKGROUND

The aim of this study was to compare the outcomes of heart transplantation from cardiopulmonary-resuscitated donors (CPR(+)) to those who received hearts from donors who did not require cardiopulmonary resuscitation (CPR(-)).

METHODS

This investigation was a retrospective analysis of UNOS adult heart transplantation donor and recipient data from May 1994 through July 2012. Discrete variables were compared using the chi-square test. Continuous variables were compared using the t-test. Patient and graft survival rates were calculated using the actuarial method and compared using Wilcoxon's test.

RESULTS

Of the 29,242 adult heart transplantations performed in USA during the study period, 1,396 patients (4.7%) received hearts from CPR(+) donors. The patients in the CPR(+) group were younger (25.5 ± 15 years vs 28.5 ± 14 years; p < 0.0001) and more likely to be female (31% vs 27%; p = 0.001). Mean duration of CPR in these donors was 20 minutes. UNOS listing status at the time of transplantation was Status 1A for 54.3% of those in the CPR(+) group and 46.9% in the CPR(-) group (p < 0.0001). More recipients were hospitalized and were in the intensive care unit at transplantation in the CPR(+) group (56% vs 51%; p = 0.0008). Recipient survival at 30 days, 1 year and 5 years was 95.2%, 88.2% and 72.9% in CPR(+) group, and 94.7%, 87.7% and 74.4% in the CPR(-) group, respectively. Similarly, graft survival at 30 days, 1 year and 5 years was 94.7%, 87.6% and 71.9% in the CPR(+) donor hearts, and 94.4%, 87.3% and 73.2% in the CPR(-) donor hearts, respectively.

CONCLUSIONS

This large, multicenter adult heart transplant database from across the USA did not show inferior outcomes in recipients of heart transplantation from selected CPR(+) donors. Recipient and graft survival were similar over 5 years of follow-up.

Ethical issues in organ transplantation

We discuss ethical issues of organ transplantation including the stewardship tension between physicians' duty to do everything possible for their patients and their duty to serve society by encouraging organ donation. We emphasize consideration of the role of the principles of justice, utility and equity in the just distribution of transplantable organ as scarce resources. We then consider ethical issues of determining death of the organ donor including the remaining controversies in brain death determination and the new controversies raised by circulatory death determination. We need uniformity in standards of death determination, agreement on the duration of asystole before death is declared, and consensus on the allowable circulatory interventions on the newly declared organ donor that are intended to improve organ function. We discuss the importance of maintaining the dead donor rule, despite the argument of some scholars to abandon it.

Who is the high-risk recipient? Predicting mortality after heart transplant using pretransplant donor and recipient risk factors

BACKGROUND

In this study we sought the following: (1) To objectively assess the risk related to various pretransplant recipient and donor characteristics; (2) to devise a preoperative risk stratification score (RSS) based on pretransplant recipient and donor characteristics predicting graft loss at 1 year; and (3) to define different risk strata based on RSS.

METHODS

The United Network for Organ Sharing provided de-identified patient-level data. Analysis included 11,703 orthotopic heart transplant recipients aged 18 years or greater and transplanted between January 1, 2001 and December 31, 2007. The primary outcome was 1-year graft failure. Multivariable logistic regression analysis (backward p value<0.20) was used to determine the relationship between pretransplant characteristics and 1-year graft failure. Using the odds ratio for each identified variable, an RSS was devised. The RSS strata were defined by calculating receiver operating characteristic curves and stratum specific likelihood ratios.

RESULTS

The strongest negative predictors of 1-year graft failure included the following: right ventricular assist device only, extracorporeal membrane oxygenation, renal failure, extracorporeal left ventricular assist device, total artificial heart, and advanced age. Threshold analysis identified 5 discrete RSS strata: low risk (LR, RSS: <2.55; n=3242, 27.7%), intermediate risk (IR, RSS: 2.55-5.72; n=6,347, 54.2%), moderate risk (MR, RSS: 5.73-8.13; n=1,543, 13.2%), elevated risk (ER, RSS: 8.14-9.48; n=310, 2.6%), and high risk (HR, RSS: >9.48; n=261, 2.2%). The 1-year actuarial survival (%) in the LR, IR, MR, ER, and HR groups were 93.8, 89.2, 81.3, 67.0, and 47.0, respectively.

CONCLUSIONS

Pretransplant recipient variables significantly influence early and late graft failure after heart transplantation. The RSS may improve organ allocation strategies by reducing the potential negative impact of transplanting candidates who are at a high risk for poor postoperative outcomes.

Effect of heart transplantation on survival in ambulatory and decompensated heart failure

BACKGROUND

In the absence of randomized trials comparing heart transplantation (HTx) with medical therapy for the treatment of advanced heart failure (HF), the role of HTx remains uncertain. Using data from a national audit, we examined the effect of HTx on HF mortality in the United Kingdom.

METHODS

Two thousand two hundred nineteen adults listed for HTx from April 1995 to October 2003 and followed to June 2007 were analyzed. In a substudy of 627 patients from two centers, ambulatory patients were risk-stratified by the heart failure survival score. A time-dependent nonproportional hazards model was used to estimate the effect of HTx.

RESULTS

Fourteen percent of patients were nonambulatory at listing. Death while waiting was higher among nonambulatory patients (19% vs. 14% in the ambulatory group, P<0.001 with 76% vs. 71% being transplanted). Posttransplant survival to 3 years was 78% and 75% in nonambulatory and ambulatory groups, respectively (P=0.68). HTx was found to benefit all groups. For nonambulatory patients, the risk of dying after HTx fell below the risk of dying while waiting after 10 days (95% CI 2-18) with a net survival benefit after 26 days (95% CI 5-53); for the ambulatory group the estimates were 42 days (95% CI 36-47) and 274 days (95% CI 214-359), respectively. In the substudy cohort net survival benefit was seen after 20, 124, 291, and 729 days for the nonambulatory, high, moderate, and low heart failure survival score risk groups, respectively.

CONCLUSION

HTx remains an effective treatment of advanced HF. Prioritization of patients with refractory HF is rational, because they are the first to benefit.