Clinical and cost-effectiveness of left ventricular assist devices as a bridge to heart transplantation for people with end-stage heart failure: a systematic review and economic evaluation

A Systematic Review of Cost-Effectiveness Analyses of Left Ventricular Assist Devices: Issues and Challenges

BACKGROUND

Advanced heart failure (HF) can be treated conservatively or aggressively, with left ventricular assist devices (LVADs) and heart transplant (HT) being the most aggressive strategies.

OBJECTIVE

The goal of this review was to identify, describe, critique and summarize published cost-effectiveness analyses on LVADs for adults with HF.

METHODS

We conducted a literature search using PubMed and ProQuest DIALOG databases to identify English-language publications from 2006 to 2017 describing cost-effectiveness analyses of LVADs and reviewed them against inclusion criteria. Those that met criteria were obtained for full-text review and abstracted if they continued to meet study requirements.

RESULTS

A total of 12 cost-effectiveness studies (13 articles) were identified, all of which described models; they were almost evenly split between those examining LVADs as destination therapy (DT) or as bridge to transplant (BTT). Studies were Markov or semi-Markov models with one- or three-month cycles that followed patients until death. Inputs came from a variety of sources, with the REMATCH trial and INTERMACS registry common clinical data sources, although some publications also used data from studies at their own institutions. Costs were derived from standard sources in many studies but from individual hospital data in some. Inputs for health utilities, which were used in 11 of 12 studies, were generally derived from two studies. None of the studies reported a societal perspective, that is, included non-medical costs such as caregiving.

CONCLUSIONS

No study found LVADs to be cost effective for DT or BTT with base case assumptions, although incremental cost-effectiveness ratios met thresholds for cost effectiveness in some probabilistic analyses. With constant improvements in LVADs and expanding indications, understanding and re-evaluating the cost effectiveness of their use will be critical to making treatment decisions.

The In-Hospital Cost of Ventricular Assist Device Therapy: Implications for Patient Selection

Ventricular assist device (VAD) therapy is increasingly utilized to support patients in end-stage heart failure. However, VAD programs are resource intensive and demand active monitoring to ensure long-term sustainability. The purpose of this study was to analyze total cost trends of the VAD program at our academic medical center. Retrospective analysis of University of California - Los Angeles's VAD program between 2013 and 2014 was performed. Total in-hospital costs from the date of VAD surgery admission were queried and normalized to a z score. Multivariable linear regression analysis with step-wise elimination was used to model total costs. Overall, 42 patients received a VAD during the study period, with 19 (45%) receiving biventricular support. On univariate analysis, high body mass index, biventricular support, time between VAD implantation and discharge, and total length of hospital stay were correlated with higher costs (all p < 0.02). On multivariable analysis, time between VAD implantation and discharge and biventricular support remained significantly related to total costs (overall R = 0.831, p < 0.001). The time between VAD implantation and discharge and the use of biventricular support were the most predictive factors of total cost in our VAD population. Reducing hospital stay post-VAD implantation is important in minimizing the cost of VAD care.

Voluntary Exercise Improves Cardiac Function and Prevents Cardiac Remodeling in a Mouse Model of Dilated Cardiomyopathy

Objective: Despite the indubitable beneficial effect of exercise to prevent of cardiovascular diseases, there is still a lack of studies investigating the impact of exercise in non-ischemic dilated cardiomyopathy. Here, we investigated the impact of voluntary exercise on cardiac function in a mouse model of non-ischemic dilated cardiomyopathy (αMHC-MerCreMer:Sf/Sf), induced by cardiac-specific inactivation of the Serum Response Factor.

Materials and Methods: Seven days after tamoxifen injection, 20 αMHC-MerCreMer:Sf/Sf mice were assigned to sedentary (n = 8) and exercise (n = 12) groups. Seven additional αMHC-MerCreMer:Sf/Sf mice without tamoxifen injection were used as control. The exercise group performed 4 weeks of voluntary running on wheel (1.8 ± 0.12 km/day). Cardiac function, myocardial fibrosis, and mitochondrial energetic pathways were then blindly assessed.

Results: Exercised mice exhibited a smaller decrease of left ventricular (LV) fractional shortening and ejection fraction compared to control mice. This was associated with a lower degree of LV remodeling in exercised mice, as shown by a lower LV end-systolic intrerventricular septal and posterior wall thickness decrease from baseline values compared to sedentary mice. Moreover, exercised mice displayed a reduced gene expression of atrial and brain natriuretic factors. These benefits were associated by a reduced level of myocardial fibrosis. In addition, exercised mice exhibited a higher mitochondrial aconitase, voltage-dependent anion-selective channel 1 and PPAR gamma coactivators-1 alpha proteins levels suggesting that the increase of mitochondrial biogenesis and/or metabolism slowed the progression of dilated cardiomyopathy in exercised animals.

Conclusions: In conclusion, our results support the role of voluntary exercise to improve outcomes in non-ischemic dilated heart failure (HF) and also support its potential for a routine clinical use in the future.

A Systematic Review of the Cost-Effectiveness of Long-Term Mechanical Circulatory Support

BACKGROUND

Mechanical circulatory support (MCS) is an option for the treatment of medically intractable end-stage heart failure. MCS therapy, however, is resource intensive.

OBJECTIVE

The purpose of this report was to systematically review the MCS cost-effectiveness literature as it pertains to the treatment of adult patients in end-stage heart failure.

METHODS

We conducted a systematic search and narrative review of available cost- effectiveness and cost-utility analyses of MCS in adult patients with end-stage heart failure.

RESULTS

Eleven studies analyzing the cost-effectiveness or cost-utility of MCS were identified. Seven studies focused on bridge to transplantation, three studies focused on destination therapy, and one study presented analyses of both strategies. Two articles evaluated the cost-effectiveness of the HeartMate II (Thoratec Corp., Pleasanton, CA). Incremental cost-effectiveness ratios between MCS and medical management ranged between $85,025 and $200,166 for bridge to transplantation and between $87,622 and $1,257,946 for destination therapy (2012 Canadian dollars per quality-adjusted life-year). Sensitivity analyses indicated that improvements in survival and quality of life and reductions in device and initial hospital-stay costs may improve the cost-effectiveness of MCS.

CONCLUSIONS

Current studies suggest that MCS is likely not cost-effective with reference to generally accepted or explicitly stated thresholds. Refined patient selection, complication rates, achieved quality of life, and device/surgical costs, however, could modify the cost-effectiveness of MCS.

Efficacy of epicardially delivered adipose stroma cell sheets in dilated cardiomyopathy

AIMS

Few studies have assessed the effects of cell therapy in non-ischaemic cardiomyopathies which, however, contribute to a large number of cardiac failures. Assuming that such conditions are best suited for a global delivery of cells, we assessed the effects of epicardially delivered adipose tissue-derived stroma cell (ADSC) sheets in a mouse model of dilated cardiomyopathy based on cardiac-specific and tamoxifen-inducible invalidation of serum response factor.

METHODS AND RESULTS

Three weeks after tamoxifen administration, the function of the left ventricle (LV) was assessed by echocardiography. Twenty-nine mice were then allocated to control (n = 9, non-transgenic), sham (n = 10, transgenic non-treated), and treated (n = 10, transgenic) groups. In the treated group, 3 × 10(6) allogeneic ADSCs were cultured for 2 days onto temperature-responsive polymers and the generated sheets were then transplanted over the surface of the heart. In 10 additional mice, the sheet was made of green fluorescent protein (GFP)-labelled ADSCs to track cell fate. Function, engraftment, and fibrosis were blindly assessed after 3 weeks. In the non-treated group, fractional shortening declined compared with baseline, whereas the sheet application resulted in its stabilization. This correlated with a lesser degree of LV remodelling, as LV end-diastolic and end-systolic diameters did not differ from baseline values. Many GFP(+) cells were identified in the epicardial graft and in the myocardium. Treated animals also displayed a reduced expression of the stress-induced atrial natriuretic factor and beta-myosin heavy chain genes. These protective effects were also accompanied by a reduction of myocardial fibrosis.

CONCLUSION

These results strongly suggest the functional relevance of epicardially delivered cell-seeded biomaterials to non-ischaemic heart failure.

Variability in infection control measures for the percutaneous lead among programs implanting long-term ventricular assist devices in the United States

Ventricular assist devices (VADs) are a surgical treatment for heart failure. These devices may be implanted as a bridge to transplant or as destination therapy. After surgical recovery and education regarding device care, patients are discharged home. Meticulous care of the driveline must be taken to prevent infection and trauma of the site throughout the perioperative event and for the duration of support. Currently a standardized protocol for care of the driveline and exit site does not exist. VAD coordinators from across the country discussed the variability in care at different centers in the United States through a series of conference calls. A survey consisting of 16 questions was developed. The survey included questions on preoperative antibiotic recommendations, driveline placement and exit site suturing, frequency of dressing changes, and showering practices. VAD coordinators shared center-specific dressing protocols and any driveline success stories. This survey was sent to 73 centers; 38 centers (52%) responded. The purpose of the survey was to define current practice in order to move toward a standard of practice or protocol based on expert opinion for VAD driveline care and to assess the need for future studies.

Cost-effectiveness of the implantable HeartMate II left ventricular assist device for patients awaiting heart transplantation

BACKGROUND

Left ventricular assist devices (LVADs) are being proposed as a life-saving therapeutic alternative to conventional medical management for people with end-stage heart failure awaiting transplantation. However, cost-effectiveness assessments of first-generation LVADs have not been encouraging. The cost-effectiveness of the enhanced second-generation LVAD HeartMate II (Thoratec, Pleasanton, CA) is estimated here.

METHODS

A probabilistic Markov model was developed to extrapolate survival, utility, and resource use over the total lifetime of a hypothetic cohort of patients with end-stage heart failure under the 2 competing therapeutic strategies, using the most robust and recently published evidence about their performance. Cost data are based on UK activity to consider reimbursement in the UK National Health Service setting.

RESULTS

HeartMate II had a mean cost per quality-adjusted life-year (QALY) of £258,922 ($414,275). The sensitivity analysis showed that 2 factors mainly explain why HeartMate II is not a cost-effectiveness strategy as a bridge-to-transplant: (1) the survival of heart transplant candidates treated conventionally while on the waiting list has significantly improved in recent years, and (2) the high acquisition cost of the device, £94,200 ($150,720).

CONCLUSIONS

Although HeartMate II LVAD implantation significantly increases survival compared with conventional medical management, it does not provide good value for the money spent according to established thresholds of cost-effectiveness in the UK. HeartMate II is unlikely to become cost-effective unless the additional survival gained by its use raises and/or the device is given free of charge. Therefore, its implantation to transplant candidates lacks justification in terms of cost-effectiveness.

Chronic left ventricular failure: the role of imaging in diagnosis and planning of conventional and novel therapies

Heart failure is the leading cause of hospitalisation in the UK, and its prevalence is expected to increase further in the future due partly to an aging population. Although pharmacological agents remain the mainstay of therapy, an increasing number of surgical and novel minimally invasive interventions have been developed for the treatment of both acute and chronic heart failure. Imaging is essential for diagnosis, guiding therapeutic options, and monitoring therapy and its complications. As a result, radiologists should be familiar with the pathogenesis, treatment options, and imaging-related issues pertaining to the management of these patients.

The strong financial case for regenerative medicine and the regen industry

Although the therapeutic promise of regenerative medicine is immensely exciting, the cost of product development, and particularly of clinical trials, for the more demanding applications will be high. For this reason it is vital for scientists and start-ups who wish to see their ideas implemented to be able to convince established major pharmaceutical or device companies with the necessary 'deep pockets' that the expenditure can yield an appropriate return. It also means that governments and health insurance companies must see a gain in funding regenerative medicine for patients. To address this issue the costs of five major medical conditions that could benefit from regenerative medicine have been defined for the USA as an illustration. This choice of country was made as potentially the largest initial market and one where the billing system for healthcare allows access to individual direct and some indirect costs. The data are complemented by a number of relevant examples of costs per quality-adjusted life year to indicate where current treatment methods are weak or strong. Finally, the relationship of the nascent regen* industry to the pharma and medical device sectors is summarized to assess the challenge of encouraging their involvement.

Role and possible mechanisms of clenbuterol in enhancing reverse remodelling during mechanical unloading in murine heart failure

Aims

Combined left ventricular assist device (LVAD) and pharmacological therapy has been proposed to favour myocardial recovery in patients with end-stage heart failure (HF). Clenbuterol (Clen), a β₂-adrenoceptor (β₂-AR) agonist, has been used as a part of this strategy. In this study, we investigated the direct effects of clenbuterol on unloaded myocardium in HF.

Methods and results

Left coronary artery ligation or sham operation was performed in male Lewis rats. After 4–6 weeks, heterotopic abdominal transplantation of the failing hearts into normal recipients was performed to induce LV unloading (UN). Recipient rats were treated with saline (Sal) or clenbuterol (2 mg/kg/day) via osmotic minipumps (HF + UN + Sal or HF + UN + Clen) for 7 days. Non-transplanted HF animals were treated with Sal (Sham + Sal, HF + Sal) or clenbuterol (HF + Clen). LV myocytes were isolated and studied using optical, fluorescence, and electrophysiological techniques. Clenbuterol treatment improved in vivo LV function measured with echocardiography (LVEF (%): HF 35.9 ± 2 [16], HF + Clen 52.1 ± 1.4 [16]; P < 0.001; mean ± SEM [n]). In combination with unloading, clenbuterol increased sarcomere shortening (amplitude (µm): HF + UN + Clen 0.1 ± 0.01 [50], HF + UN + Sal 0.07 ± 0.01 [38]; P < 0.001) by normalizing the depressed myofilament sensitivity to Ca²⁺ (slope of the linear relationship between Ca²⁺ transient and sarcomere shortening hysteresis loop during relaxation (μm/ratio unit): HF + UN + Clen 2.13 ± 0.2 [52], HF + UN + Sal 1.42 ± 0.13 [38]; P < 0.05).

Conclusion

Clenbuterol treatment of failing rat hearts, alone or in combination with mechanical unloading, improves LV function at the whole-heart and cellular levels by affecting cell morphology, excitation–contraction coupling, and myofilament sensitivity to calcium. This study supports the use of this drug in the strategy to enhance recovery in HF patients treated with LVADs and also begins to elucidate some of the possible cellular mechanisms responsible for the improvement in LV function.

Evaluation of the clinical effectiveness of the Ventricular Assist Device Program in the United Kingdom (EVAD UK)

BACKGROUND

The UK Government funds ventricular assist device (VAD) implantation as bridge to transplantation (BTT) at three centers. Results from this program have not been published.

METHODS

All 70 VAD implants for BTT, 71 inotrope-dependent and 179 non-VAD transplant candidates, accepted for transplantation between April 2002 and December 2004, were prospectively monitored for survival to transplantation, survival overall and quality of life.

RESULTS

Of the 70 VAD patients, 31 (44%) survived to heart transplantation, 4 (6%) were bridged to recovery and 5 remained on support at the end of the study. Thirty patients (43%) died while on support. Overall survival from VAD implant was 52% at 1 year. Ten percent of non-VAD inotrope-dependent patients and 9% of routine transplant candidates died while on the waiting list. For transplant recipients, 12-month post-operative survival was 84%, 85% and 84%, respectively, for VAD, inotrope-dependent and routine transplant candidates. VAD and non-VAD patients had similar post-transplant adverse event rates.

CONCLUSIONS

There was a role for VAD bridge to transplant for selected patients in the UK, despite the availability of an effective urgent transplant list. VAD patients who underwent transplantation had survival rates similar to other transplant candidates.