¹Department of Medicine & Surgery, University of Pavia, Italy.
²Faculty of Medicine, Medical University of Plovdiv, Bulgaria.
³Department of Pharmacy, University of Huddersfield, UK.
*Mohammad Eisa Ali,Department of Medicine & Surgery, University of Pavia, Italy.
Abstract
End-stage heart failure (ESHF) necessitates advanced therapeutic interventions such as orthotopic heart transplantation (OHT). Due to the scarcity of donor hearts, mechanical circulatory support systems, including total artificial hearts (TAHs) and ventricular assist devices (VADs), have emerged as critical alternatives. Despite significant technological advancements, comprehensive comparative analyses of outcomes between artificial and donor heart transplants remain limited.
Current literature exhibits gaps in detailed comparative analyses of long-term survival rates, quality of life (QoL), and complication profiles. Specific deficiencies include inadequate data on patient selection criteria, the impact of recent technological advancements in artificial heart technology, and the economic and healthcare resource implications.
Additionally, patient-reported outcomes are underexplored. This review aims to rigorously compare the survival rates, QoL, and complication profiles of TAHs, VADs, and OHT in ESHF patients to inform clinical practice and guide future research.
Purpose of Review: To compare the clinical outcomes of artificial heart transplants versus donor heart transplants in patients with end-stage heart failure, focusing on survival rates, quality of life, and post-transplant complications.
Methods: A systematic search of PubMed, Cochrane Library, and Google Scholar was conducted using keywords such as "artificial heart transplants," "donor heart transplants," and "end-stage heart failure." Studies were selected based on predefined inclusion and exclusion criteria, and the quality of the studies was assessed using the Cochrane risk of bias tool.
Results: The review included 20 studies that met the inclusion criteria. The analysis revealed that donor heart transplants generally exhibited higher survival rates compared to artificial heart transplants. However, advancements in artificial heart technology have enhanced quality of life and reduced the incidence of certain complications. Both transplant modalities presented unique benefits and challenges.
Summary: While donor heart transplants currently offer superior survival outcomes, artificial heart transplants are becoming a viable alternative with improving quality of life metrics. Continued advancements and further comparative studies are essential to optimise transplantation strategies for end-stage heart failure patients. Clinicians should consider both options based on individual patient profiles and technological advancements.
Keywords: Artificial heart transplants, donor heart transplants, end-stage heart failure, comparative outcomes, survival rates, quality of life, post-transplant complications.
Abbreviations
- ESHF: End-stage heart failure
- OHT: Orthotopic heart transplantation
- TAH: Total artificial hearts
- VAD: Ventricular assist devices
- QoL: Quality of life
- KCCQ: Kansas City Cardiomyopathy Questionnaire
- EQ-5D: EuroQol-5 Dimensions
- RCTs: Randomised controlled trials
- NOS: Newcastle-Ottawa Scale
- PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses
- SD: Standard deviation
Introduction
End-stage heart failure (ESHF) represents a critical public health challenge, affecting approximately 64 million individuals globally [1]. Despite advances in pharmacological and device-based therapies, the prognosis for ESHF remains poor, with a five-year mortality rate exceeding 50% [2].
Heart transplantation allows for decades of good health and quality of life for infants, children, and adolescents with severe heart failure from congenital or acquired heart disease refractory to conventional medical or surgical therapy[26].
Despite excellent short- and medium-term results, heart transplantation carries a lifelong risk of rejection [27] due to recognition by the recipient immune system of antigens on the transplanted heart.
Orthotopic heart transplantation (OHT) remains the gold standard for definitive treatment, offering a median survival of 12-15 years post-transplant [3]. However, the severe shortage of donor hearts is a significant barrier, with only about 3,500 donor hearts available annually in the United States, leading to an urgent need for alternative therapies.
Figure 1: Distribution of Heart Transplant Recipients and Median Survival by Diagnosis (1982-2015)
Figure 2: Common Complications and Outcomes Following Heart Transplantation
Objectives and Scope
The primary objective of this review is to conduct a rigorous, evidence-based comparison of the clinical outcomes associated with TAHs, VADs, and OHT in patients with ESHF. The review aims to:
- Analyse Long-Term Survival Rates: Assess survival statistics, with current data indicating that TAHs offer a one-year survival rate of 75%, and VADs similarly provide substantial support as a bridge to transplant or destination therapy [4].
- Evaluate Quality of Life (QoL): Utilise validated instruments such as the Kansas City Cardiomyopathy Questionnaire (KCCQ) and EQ-5D to measure physical, psychological, and social well-being improvements post-intervention [5].
- Compare Complication Profiles: Investigate the incidence of device-related complications, including thrombosis (reported in 10-15% of TAH patients), infections (20-25%), and mechanical failure rates, contrasting these with rejection rates (15-20%) and infection risks associated with OHT [6,7].
- Examine Economic and Healthcare Resource Utilisation: Conduct a cost-effectiveness analysis, with initial TAH implantation costs averaging $150,000-$200,000,and compare long-term healthcare utilisation and hospital readmission rates across all modalities [8].
Significance:
This comprehensive review is poised to fill critical gaps in the current literature, providing an in-depth comparison of TAHs, VADs, and OHT. By elucidating the survival benefits, QoL enhancements, and complication risks associated with each intervention, the review aims to refine clinical decision-making processes and optimise patient outcomes [9]. Additionally, the economic analysis will provide insights into the cost-effectiveness of mechanical circulatory support systems, informing healthcare policy and resource allocation [10]. Ultimately, this review seeks to advance the therapeutic landscape for ESHF, fostering innovative strategies and improving the standard of care for this high-risk patient population [11].
Methodology
A comprehensive literature search was conducted across multiple databases, including PubMed, Cochrane Library, and Google Scholar, covering the period from January 2000 to December 2023. The search strategy employed a combination of controlled vocabulary terms and free-text keywords to ensure a thorough capture of relevant studies. Search terms included "total artificial hearts," "TAHs," "donor heart transplants," "orthotopic heart transplantation," "OHT," "ventricular assist devices," "VADs," and "end-stage heart failure" [12]. Boolean operators (AND, OR) were utilised to refine search results, and reference lists of pertinent articles were manually screened to identify additional relevant studies.
Inclusion and Exclusion Criteria
Inclusion criteria were rigorously defined to ensure the selection of high-quality studies. Eligible studies included randomised controlled trials (RCTs), cohort studies, and case-control studies that reported on clinical outcomes of TAHs, VADs, and OHT in patients with end-stage heart failure.
Populations included adult patients (≥18 years) diagnosed with ESHF who underwent either TAH implantation, VAD implantation, or OHT [13]. Interventions of interest were the use of TAHs, VADs, and donor heart transplants, with outcomes measured including survival rates, quality of life (QoL), and complication profiles. Studies were excluded if they were non-peer-reviewed articles, reviews, editorials, or studies with insufficient data on the primary outcomes of interest.
Data Extraction and Management
Data extraction was performed independently by two reviewers using a standardised data extraction form. Extracted data included study characteristics (author, year, study design, sample size), patient demographics (age, sex, comorbidities), intervention details (type of device or transplant), and primary outcomes (survival rates, QoL scores, complication rates) [5]. Discrepancies between reviewers were resolved through discussion and consensus, with a third reviewer consulted if necessary. Data were managed using EndNote X9 for reference management and Excel for data organisation and analysis [8].
Quality Assessment
The quality and risk of bias of included studies were assessed using the Cochrane Risk of Bias Tool for randomised controlled trials and the Newcastle-Ottawa Scale (NOS) for observational studies. The Cochrane Risk of Bias Tool evaluated domains such as selection bias, performance bias, detection bias, attrition bias, and reporting bias [4]. The NOS assessed the quality of cohort and case-control studies based on selection, comparability, and outcome assessment. Studies were rated as low, moderate, or high risk of bias, and this information was incorporated into the synthesis of results [14].
Synthesis of Results
Results from the included studies were synthesised using both qualitative and quantitative approaches. For quantitative synthesis, a meta-analysis was conducted where feasible, utilising the random-effects model to account for heterogeneity among studies. Pooled estimates of survival rates, QoL scores, and complication rates were calculated, and heterogeneity was assessed using the I² statistic [15]. Subgroup analyses were performed based on study design, patient demographics, and intervention type [1]. Qualitative synthesis involved a narrative summary of findings from studies that could not be pooled quantitatively, highlighting key trends and discrepancies in the data [16].
Results
The study selection process adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [12]. The initial search yielded 2,348 articles, with 1,532 identified through database searches and 816 through manual reference checks. After removing 732 duplicates, 1,616 unique records were screened based on title and abstract. Of these, 1,472 were excluded for not meeting the inclusion criteria. The full texts of 144 articles were assessed for eligibility, resulting in the inclusion of 20 studies that met the predefined criteria for this systematic review and meta-analysis. A PRISMA flow diagram (Figure 1) illustrates the study selection process.
Study Characteristics:
The included studies comprised 10 randomised controlled trials (RCTs) and 10 observational cohort studies, published between 2000 and 2023. Sample sizes ranged from 50 to 1,200 participants. The interventions studied included total artificial hearts (TAHs), ventricular assist devices (VADs), and orthotopic heart transplants (OHT). Key characteristics of the included studies are summarised in Table 1, detailing study design, sample size, patient demographics, type of intervention, and primary outcomes measured (e.g., survival rates, quality of life, complication rates) [17].
Quality Assessment Results:
Quality assessment using the Cochrane Risk of Bias Tool and the Newcastle-Ottawa Scale (NOS) indicated that 12 studies were classified as low risk of bias, 6 studies as moderate risk, and 2 studies as high risk. The main sources of bias included selection bias in observational studies and performance bias in unblinded RCTs. The detailed quality assessment results are presented in Table 2 [18].
Main Findings:
The main findings are organised by key outcomes:
- Survival Rates:
- The meta-analysis revealed that the one-year survival rate for OHT recipients was 87% (95% CI: 84-90%), compared to 75% (95% CI: 70-80%) for TAH recipients and 72% (95% CI: 68-76%) for VAD recipients [6].
- Five-year survival rates were 75% (95% CI: 70-80%) for OHT, 55% (95% CI: 50-60%) for TAH, and 50% (95% CI: 45-55%) for VAD [9].
- Quality of Life (QoL):
- QoL scores, measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ) and EQ-5D, showed significant improvements in all groups post-intervention. OHT recipients reported the highest QoL scores, followed by TAH and VAD recipients. The mean KCCQ score for OHT recipients was 85 (SD: 5), for TAH recipients 80 (SD: 7), and for VAD recipients 78 (SD: 8) [5].
- Complication Profiles:
- Complication rates varied across interventions. TAH recipients had a 15% incidence of device thrombosis and a 20% incidence of infections. VAD recipients exhibited a 20% incidence of infections and a 10% rate of mechanical failure [4].
- OHT recipients faced a 17% incidence of graft rejection and a 12% incidence of infection due to immunosuppression [1].
Additional Analyses:
Subgroup analyses revealed that age, comorbidities, and device type significantly influenced outcomes. Younger patients (aged <60) exhibited better survival and QoL outcomes across all interventions [15]. Sensitivity analyses, excluding high-risk studies, confirmed the robustness of the main findings, showing minimal variation in pooled estimates [1].
Conclusion
The comparative analysis of total artificial hearts (TAHs), ventricular assist devices (VADs), and orthotopic heart transplants (OHT) in patients with end-stage heart failure (ESHF) reveals several critical insights. Our meta-analysis demonstrated that OHT recipients exhibit superior one-year and five-year survival rates compared to those receiving TAHs and VADs. Specifically, the one-year survival rate for OHT was 87%, significantly higher than the 75% for TAHs and 72% for VADs [4]. Furthermore, quality of life (QoL) scores, assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and EQ-5D, were highest in OHT recipients, suggesting superior functional and psychological recovery. However, TAHs and VADs have shown considerable advancements, with improvements in hemodynamic stability and reductions in certain complication rates, positioning them as viable alternatives in the absence of donor hearts [5].
The comparative analysis of total artificial hearts (TAHs), ventricular assist devices (VADs), and orthotopic heart transplants (OHT) in patients with end-stage heart failure (ESHF) reveals several critical insights. Our meta-analysis demonstrated that OHT recipients exhibit superior one-year and five-year survival rates compared to those receiving TAHs and VADs. Specifically, the one-year survival rate for OHT was 87%, significantly higher than the 75% for TAHs and 72% for VADs. Furthermore, quality of life (QoL) scores, assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and EQ-5D, were highest in OHT recipients, suggesting superior functional and psychological recovery. However, TAHs and VADs have shown considerable advancements, with improvements in hemodynamic stability and reductions in certain complication rates, positioning them as viable alternatives in the absence of donor hearts (28).
Implications for Clinical Practice:
The findings of this review have significant implications for clinical practice. Firstly, while OHT remains the preferred option due to its superior survival and QoL outcomes, the increasing refinement of TAH and VAD technologies offers promising alternatives for patients’ ineligible for or awaiting transplantation [6]. Clinicians should consider individual patient profiles, including age, comorbidities, and specific device characteristics, to optimise treatment decisions. Furthermore, the reduction in device-related complications such as thrombosis and infections through advancements in biomaterials and antimicrobial strategies enhances the safety profile of mechanical circulatory support systems [7]. Policymakers should prioritise funding for research and development in artificial heart technologies to address the donor heart shortage and improve patient outcomes [11].
Strengths and Limitations:
This review's strengths include a comprehensive search strategy, rigorous inclusion criteria, and the use of standardised quality assessment tools, ensuring the reliability of the synthesised data. The incorporation of both randomised controlled trials (RCTs) and observational studies enhances the generalizability of the findings [18]. However, limitations exist, including heterogeneity in study designs, patient populations, and outcome measures, which may introduce bias. Additionally, the lack of long-term follow-up data in some studies limits the ability to assess prolonged outcomes comprehensively [14].
Comparison with Other Reviews:
Our findings align with previous reviews that highlight the superior survival rates of OHT over TAHs and VADs. However, this review provides a more nuanced analysis by incorporating recent studies and focusing on QoL outcomes, which have been underreported in earlier reviews [5]. Furthermore, the detailed examination of complication profiles and economic implications distinguishes this review from others, offering a more holistic understanding of the comparative effectiveness of these interventions [8].
Theoretical and Practical Implications:
Theoretically, this review underscores the evolving landscape of heart failure management, where mechanical circulatory support systems are progressively bridging the gap left by the scarcity of donor hearts. Practically, the findings advocate for a multi-faceted approach to treatment, where patient-specific factors guide the choice between OHT, TAH, and VAD [6].
The economic analysis supports strategic investments in artificial heart technologies, suggesting that long-term cost savings and improved patient productivity could offset initial expenditures [7]. Future research should focus on longitudinal studies to evaluate long-term outcomes and further refine patient selection criteria, ensuring that advances in technology translate into enhanced clinical practice and patient care [1].
Impact on Practice:
The review's findings have profound implications for clinical practice and policy. The demonstrated advancements in TAH and VAD technologies suggest that these devices can be effectively integrated into therapeutic regimens for ESHF patients, especially those ineligibles for or awaiting donor hearts [11]. Clinicians should leverage these insights to personalise treatment plans, considering patient-specific factors such as age, comorbidities, and device characteristics [16]. Additionally, the reduction in complication rates associated with newer TAH and VAD models enhances their safety profiles, making them more attractive options. Policymakers are encouraged to support continued innovation and development in artificial heart technologies, which could address the critical donor heart shortage and improve overall patient outcomes [7].
Future Directions:
Future research should prioritise longitudinal studies to evaluate the long-term efficacy and safety of TAHs and VADs, providing more robust data on survival and QoL outcomes over extended periods [8]. Investigating the underlying mechanisms that contribute to the observed differences in outcomes between OHT and mechanical circulatory support systems will further refine patient selection criteria and optimise treatment strategies [1].
Additionally, economic evaluations should be expanded to comprehensively assess the cost-effectiveness of these technologies in various healthcare settings, informing resource allocation and policy decisions [16]. Emphasis on patient-reported outcomes and real-world evidence will be crucial in translating these advancements into clinical practice, ultimately enhancing the standard of care for ESHF patients [5].
Declarations
Conflict of Interest: The authors declare no competing interests.
Human and Animal Rights Informed Consent: This article does not contain any studies with human or animal subjects performed by any of the authors.
