Medium-term outcome of recipients of marginal donor hearts selected with new stress-echocardiographic techniques over standard criteria

Novel Imaging Technologies for Accurate Assessment of Cardiac Allograft Performance

Purpose of the Review

The current lack of objective and quantitative assessment techniques to determine cardiac graft relative viability results in risk-averse decision-making, which negatively impact the utilization of cardiac grafts. The purpose of this review is to highlight the current deficiencies in cardiac allograft assessment before focusing on novel cardiac assessment techniques that exploit conventional and emerging imaging modalities, including ultrasound, magnetic resonance, and spectroscopy.

Recent Findings

Extensive work is ongoing by the scientific community to identify improved objective metrics and tools for cardiac graft assessment, with the goal to safely increasing the number and proportion of hearts accepted for transplantation.

Summary

This review briefly discusses the in situ and ex vivo tools currently available for clinical organ assessment, before focusing on the individual capabilities of ultrasound, magnetic resonance, and spectroscopy to provide insightful, non-invasive information regarding cardiac graft functional and metabolic status that may be used to predict outcome after transplantation.

The 2-year postoperative left heart function in marginal donor heart recipients assessing by speckle tracking echocardiography

This study analyzed the differences and explored the donor/recipient factors between marginal and standard donor heart recipients after heart transplantation (HT) by speckle tracking echocardiography (STE). Seventy-two HT patients were enrolled: 25 standard and 47 marginal donor heart recipients. Thirty HT patients completed 2-year continuous follow-up (1, 6, 12, 24 months). Thirty healthy volunteers were controls. STE was used to track the strain characteristics of the left ventricle and atrium for detecting early changes in marginal donor heart recipients, including left ventricular global longitudinal, circumferential and radial strain (LVGLS, LVGCS, LVGRS) and left atrial strain in systole (LAS-S) and late diastole (LAS-A). The perioperative parameters were similar between the standard and marginal groups. No significant differences were found in left heart size, systolic and diastolic function parameters. Left ventricular systolic strain (LVGLS, LVGCS, LVGRS) and systolic and late diastolic left atrial strain (LAS-S, LAS-A) were lower in the HT recipients than the control group (P < 0.05), but there was no difference between the marginal and standard groups (P > 0.05). LVGLS, LVGCS, and LAS-S were low in the marginal group 1 month after surgery but recovered gradually at 6 months. The patients with donor/recipient body weight ratio < 0.8 group had lower LVGLS and LAS-S. STE showed no significant difference between marginal and standard donor recipients. The LVGLS and LAS-S were lower in those with a smaller donor/recipient body weight ratio. The cardiac function of HT patients was lower in the early postoperative period but gradually recovered over time.

ADONHERS (Aged DONor HEart Rescue by Stress Echo) National Protocol: Recipient's Survival after 10-Year Follow-Up

Background: The gold-standard treatment for end-stage heart failure is heart transplantation, but the lack of organ donors remains an important limitation in this field. An accurate selection of marginal hearts is fundamental to increase organ availability. Purpose: In our study we analyzed if recipients receiving marginal donor (MD) hearts, selected by dipyridamole stress echocardiography according to the ADOHERS national protocol, had different outcomes compared to recipients with acceptable donor (AD) hearts. Methods: Data were collected and retrospectively analyzed from patients who received an orthotopic heart transplant at our institution between 2006 and 2014. Dipyridamole stress echo was performed on identified marginal donors and selected hearts were eventually transplanted. Clinical, laboratory and instrumental features of the recipients were evaluated and patients with homogenous baseline characteristics were selected. Results: Eleven recipients transplanted with a selected marginal heart and eleven recipients transplanted with an acceptable heart were included. Mean donor age was 41 ± 23. The median follow-up was 113 months (IQR 86-146 months). Age, cardiovascular risk and morpho-functional characteristics of the left ventricle were comparable between the two populations (p > 0.05). Left atrial size was significantly higher in patients with marginal hearts (acceptable atrial volume: 23 ± 5 mL; marginal atrial volume: 38 ± 5 mL; p = 0.003). Acceptable donor recipients showed a higher impact of Cardiac Allograph Vasculopathy (p = 0.019). No rejection differences were found between the two groups. Four patients deceased, three were standard donor recipients and one was from the marginal donor group. Conclusions: Our study shows how cardiac transplant (Htx) from selected marginal donor hearts through a non-invasive bedside technique can alleviate the shortage of organs without a difference in survival compared to acceptable donor hearts.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Impact of using higher-risk donor hearts for candidates with pre-transplant mechanical circulatory support

BACKGROUND

We evaluated post-heart transplant (HTx) outcomes after use of higher-risk donor hearts for candidates supported with pre-HTx mechanical circulatory support (MCS).

METHODS

In this retrospective analysis of the national United Network for Organ Sharing registry, a total of 9,915 adult candidates on MCS underwent HTx from January 1, 2010 to March 31, 2019. Multi-organ, re-transplant, and congenital heart disease patients were excluded. Higher-risk donor organs met at least one of the following criteria: left ventricular ejection fraction <50%, donor to recipient predicted heart mass ratio <0.86, donor age >55 years, or ischemic time >4 hours. Primary outcome was 1 year post-transplant survival.

RESULTS

Among HTx recipients, 3688 (37.2%) received higher-risk donor hearts. Candidates supported with pre-HTx extracorporeal membrane oxygenation or biventricular assist device (n = 374, 3.8%) who received higher-risk donor hearts had comparable 1 year survival (HR: 1.14, 95% CI: [0.67-1.93], p = 0.64) to recipients of standard-risk donor hearts, when adjusted for recipient age and sex. In candidates supported with intra-aortic balloon pump (n = 1391, 14.6%), transplantation of higher-risk donor hearts did not adversely affect 1 year survival (HR: 0.80, 95% CI: [0.52-1.22], p = 0.30). Patients on durable left ventricular assist devices (LVAD) who received higher-risk donor hearts had comparable 1 year survival to continued LVAD support on the waitlist, but mortality was increased compared to those who received standard-risk donor hearts (HR: 1.37, 95% CI: [1.11-1.70], p = 0.004).

CONCLUSIONS

Patients requiring pre-HTx temporary MCS who received higher-risk donor hearts had comparable 1 year post-transplant survival to those who received standard-risk donor hearts. Stable patients on durable LVADs may benefit from waiting for standard-risk donor hearts.

Stress Echo 2030: The Novel ABCDE-(FGLPR) Protocol to Define the Future of Imaging

With stress echo (SE) 2020 study, a new standard of practice in stress imaging was developed and disseminated: the ABCDE protocol for functional testing within and beyond CAD. ABCDE protocol was the fruit of SE 2020, and is the seed of SE 2030, which is articulated in 12 projects: 1-SE in coronary artery disease (SECAD); 2-SE in diastolic heart failure (SEDIA); 3-SE in hypertrophic cardiomyopathy (SEHCA); 4-SE post-chest radiotherapy and chemotherapy (SERA); 5-Artificial intelligence SE evaluation (AI-SEE); 6-Environmental stress echocardiography and air pollution (ESTER); 7-SE in repaired Tetralogy of Fallot (SETOF); 8-SE in post-COVID-19 (SECOV); 9: Recovery by stress echo of conventionally unfit donor good hearts (RESURGE); 10-SE for mitral ischemic regurgitation (SEMIR); 11-SE in valvular heart disease (SEVA); 12-SE for coronary vasospasm (SESPASM). The study aims to recruit in the next 5 years (2021-2025) ≥10,000 patients followed for ≥5 years (up to 2030) from ≥20 quality-controlled laboratories from ≥10 countries. In this COVID-19 era of sustainable health care delivery, SE2030 will provide the evidence to finally recommend SE as the optimal and versatile imaging modality for functional testing anywhere, any time, and in any patient.

[Left ventricle myocardium hypertrophy of donor heart: the results and outlook]

Left ventricular hypertrophy - is one of the most frequent structural changes in the heart. This article is devoted to the assessment of modern views on the causes of myocardial hypertrophy of the donor heart, indications and contraindications for the heart trans‑ plantation, the outlook of expanding the pool of effective donors through the use of these hearts. Here are considered the issues of post-transplantation remodeling of the donor heart myocardium, The pathogenesis features, the nascence risk and possibilities of drug regulation of the transplanted heart's myocardial hypertrophy of the left ventricle.

The donor heart and organ perfusion technology

Recent advancement in organ perfusion technology has led to increase clinical transplantation of marginal donor organs and allow for distant procurement of cardiac allograft beyond the time limitation of cold static storage. Ex-situ heart perfusion also provides essential nutrients to maintain cell integrity, thereby reducing the risk of ischaemic injury for functional preservation and provides a platform to assess organ viability and feasibility, with the potential for pharmacotherapy to recover these hearts. Notably, the use of NMP has led to the first distant procurement cardiac transplantation from a donation after circulatory death (DCD) in 2014, which resulted in the adoption of DCD heart transplantation in 4 centres between the United Kingdom and Australia. To date, over 100 DCD heart transplants have been performed utilising cardiac perfusion system with an estimated 10-15% increase in transplant activity in the individual units. This review aims to provide an overview of current experience and outcomes using cardiac perfusion technology, including future technologies and recent advancement within the field.

Combined mitral valve repair and heart transplantation

In times of donor organ shortage, organs with extended allocation criteria, for example, valve pathologies, have to be taken into consideration for transplantation. The donor pool can be extended to hearts with mitral valve insufficiency. Mitral valve repair can rapidly be performed in the donor heart on the back table with excellent results.

Donor selection in the modern era

The growing disparity between the supply of donor hearts for transplantation and the demand for such organs has led to liberalization of the criteria for donor heart acceptance over the past few decades. The upper age limit and size restrictions for donor heart acceptance continue to be revised and hearts are being routinely used from donors with left ventricular dysfunction, left ventricular hypertrophy (LVH), cocaine use, multiple medical co-morbidities and after cardiopulmonary resuscitation. This article reviews recent data for use of such "expanded criteria" donor hearts and suggests ways to further increase the donor pool, including use of hearts from donors with hepatitis C and after circulatory determination of death. Donor biomarkers and risk scores may eventually aid in heart acceptance decisions, while ethical issues surrounding information sharing with transplant recipients remain a topic of great debate.

Role of cardiovascular imaging in selection of donor hearts

AIM: To perform a systematic review of literature on use of cardiovascular imaging in assessment of donor hearts.

METHODS: A systematic search of current literature from January 1965 to August 2015 was performed using PubMed and Google Scholar to investigate the different imaging modalities used to assess donor hearts.

RESULTS: Recent literature still estimates only a 32% utilization of available donor hearts in the United States. Most common imaging modality used is transthoracic echocardiography. Use of advanced imaging modalities such as 3D echocardiography, cardiac computer tomography and cardiac magnetic resonance to evaluate donor hearts is not reported in literature. This review attempts to highlight the relevant imaging modalities that can be used to assess cardiac function in a time-efficient manner. The algorithm suggested in this review would hopefully pave the way to standardized protocols that can be adopted by organ procuring organizations to increase the donor pool.

CONCLUSION: Use of advanced imaging techniques for a thorough assessment of organs will likely increase the donor pool.