Does bridging to transplantation with a left ventricular assist device adversely affect posttransplantation survival? A comparative analysis of mechanical versus inotropic support

Impact of Bridge to Transplantation With Continuous-Flow Left Ventricular Assist Devices on Posttransplantation Mortality

BACKGROUND

Bridge to transplantation (BTT) with left ventricular assist devices (LVADs) is a mainstay of therapy for heart failure in patients awaiting heart transplantation (HT). Criteria for HT listing do not differ between patients medically managed and those mechanically bridged to HT. The objectives of the present study were to evaluate the impact of BTT with LVAD on posttransplantation survival, to describe differences in causes of 1-year mortality in medically and mechanically bridged patients, and to evaluate differences in risk factors for 1-year mortality between those with and those without LVAD at the time of HT.

METHODS

Using the United Network of Organ Sharing database, we identified 5486 adult, single-organ HT recipients transplanted between 2008 and 2015. Patients were propensity matched for likelihood of LVAD at the time of HT. Kaplan-Meier survival estimates were used to assess the impact of BTT on 1- and 5-year mortality. Logistic regression analysis was used to evaluate the odds ratio of 1-year mortality for patients BTT with LVAD compared with those with medical management across clinically significant variables at various thresholds.

RESULTS

Early mortality was higher in mechanically bridged patients: 9.5% versus 7.2% mortality at 1 year (P<0.001). BTT patients incurred an increased risk of 1-year mortality with an estimated glomerular filtration rate of 40 to 60 mL·min^-1·1.73 m^-2 (odds ratio, 1.69; P=0.003) and <40 mL·min^-1·1.73 m^-2 (odds ratio, 2.16; P=0.005). A similar trend was seen in patients with a body mass index of 25 to 30 kg/m² (odds ratio, 1.88; P=0.024) and >30 kg/m² (odds ratio, 2.11; P<0.001). When patients were stratified by BTT status and the presence of risk factors, including age >60 years, estimated glomerular filtration rate <40 mL·min^-1·1.73 m^-2, and body mass index >30 kg/m², there were significant differences in 1-year mortality between medium- and high-risk medically and mechanically bridged patients, with 1-year mortality in high-risk BTT patients at 17.6% compared with 10.4% in high-risk medically managed patients.

CONCLUSIONS

Bridge to HT with LVAD, although necessary because of organ scarcity and capable of improving wait list survival, confers a significantly higher risk of early posttransplantation mortality. Patients bridged with mechanical support may require more careful consideration for transplant eligibility after LVAD placement.

Current status of mechanical circulatory support for treatment of advanced end-stage heart failure: successes, shortcomings and needs

INTRODUCTION

Heart failure (HF) remains a major global burden in terms of morbidity and mortality. Despite advances in pharmacological and resynchronization device therapy, many patients worsen to end-stage HF. Although the gold-standard treatment for such patients is heart transplantation, there will always be a shortage of donor hearts. Areas covered: A left ventricular assist device (LVAD) is a valuable option for these patients as a bridge measure (to recovery, to candidacy for transplant, or to transplant itself) or as destination therapy. This review describes the current indications for and complications of the most commonly implanted LVADs. In addition, we review the potential and promising new LVADs, including the HeartMate 3, MVAD, and other LVADs. Studies investigating each were identified through a combination of online database and direct extraction of studies cited in previously identified articles. Expert commentary: The goal of LVADs has been to fill the gap between patients with end-stage HF who would likely not benefit from heart transplantation and those who could benefit from a donor heart. As of now, the use of LVADs has been limited to patients with end-stage HF, but next-generation LVAD therapy may improve both survival and quality of life in less sick patients.

Left ventricular assist device: a bridge to transplant or destination therapy?

Heart failure is a major problem worldwide; it is the leading cause of hospitalisation and is posing a huge financial burden. Advances in healthcare have contributed to increased life expectancy, with a resultant increase in the number of patients with chronic heart failure. For many patients who are still severely symptomatic despite optimal medical therapy and cardiac resynchronisation therapy, cardiac transplantation would be the preferred treatment option. However, hopes are cut short with a limited donor pool of hearts for the increasing number of patients requiring cardiac transplantation. One uprising method to fill this treatment void for patients with advanced end-stage heart failure (ESHF) is the Left Ventricular Assist Device (LVAD). Although traditionally used as a bridge to transplantation, owing to limitation of suitable donors, evidence suggests increasing potential for the use of LVAD as destination therapy (DT), that is, lifelong permanent support. Exploration of DT is a promising avenue to many patients suffering with ESHF who may never be fortunate enough to receive a heart transplant, but not without reservations of its efficacy, safety, effects on quality-adjusted life years and cost-effectiveness, especially in comparison to heart transplantation.

Left ventricular assist devices as a bridge to cardiac transplantation

Heart failure remains a significant cause of morbidity and mortality, affecting over five million patients in the United States. Continuous-flow left ventricular assist devices (LVAD) have become the standard of care for patients with end stage heart failure. This review highlights the current state of LVAD as a bridge to transplant (BTT) in patients requiring mechanical circulatory support (MCS).

Ventricular assist devices or inotropic agents in status 1A patients? Survival analysis of the United Network of Organ Sharing database

BACKGROUND

Improved outcomes as well as lack of donor hearts have increased the use of ventricular assist devices (VADs), rather than inotropic support, for bridging to transplantation. Recognizing that organ allocation in the highest status patients remains controversial, we sought to compare outcomes of patients with VADs and those receiving advanced medical therapy.

METHODS

The United Network of Organ Sharing (UNOS) database was used to compare survival on the waiting list and posttransplantation survival in status 1A heart transplantation patients receiving VADs or high-dose/dual inotropic therapy or an intraaortic balloon pump( IABP), or both. Adjusted survival was calculated using Cox's proportional hazard model.

RESULTS

Adjusted 1-year posttransplantation mortality was higher among patients with VADs compared with patients receiving inotropic agents alone (hazard ratio [HR], 1.48; p<0.05). Survival remained better for patients receiving inotropic agents alone in the post-2008 era (HR, 1.36; p=0.03) and among those with isolated left-sided support (HR, 1.33; p=0.008). When patients who received IABPs were added and analyzed after 2008, the left ventricular assist device (LVAD) group had similar survival (HR, 1.2; p=0.3). Survival on the waiting list, however, was superior among patients with LVADs (HR, 0.56; p<0.05). In a therapy transition analysis, failure of inotropic agents and the need for LVAD support was a consistent marker for significantly worse mortality (HR, 1.7; p<0.05).

CONCLUSIONS

Although posttransplantation survival is better for patients who are bridged to transplantation with inotropic treatment only, the cost of failure of inotropic agents is significant, with a nearly doubled mortality for those who later require VAD support. Survival on the waiting list appears to be improved among patients receiving VAD support. Careful selection of the appropriate bridging strategy continues to be a significant clinical challenge.

Ventricular assistance devices as bridge to transplantation

The authors herein review the rationale and indications for the use of ventricular assistance devices as a bridge to heart transplantation and discuss the current evidence on the subject. The potential effects of device implantation on posttransplant outcomes and the therapeutic strategies in acute and elective cases are revised and illustrated.

Postcardiac transplant survival in the current era in patients receiving continuous-flow left ventricular assist devices

OBJECTIVES

Continuous-flow left ventricular assist devices have become the standard of care for patients with heart failure requiring mechanical circulatory support as a bridge to transplant. However, data on long-term post-transplant survival for these patients are limited. We evaluated the effect of continuous-flow left ventricular assist devices on postcardiac transplant survival in the current era.

METHODS

All patients who received a continuous-flow left ventricular assist device as a bridge to transplant at a single center from June 2005 to September 2011 were evaluated.

RESULTS

Of the 167 patients who received a continuous-flow left ventricular assist device as a bridge to transplant, 77 (46%) underwent cardiac transplantation, 27 died before transplantation (16%), and 63 (38%) remain listed for transplantation and continued with left ventricular assist device support. The mean age of the transplanted patients was 54.5 ± 11.9 years, 57% had an ischemic etiology, and 20% were women. The overall mean duration of left ventricular assist device support before transplantation was 310 ± 227 days (range, 67-1230 days). The mean duration of left ventricular assist device support did not change in patients who had received a left ventricular assist device in the early period of the study (2005-2008, n = 62) compared with those who had received a left ventricular assist device later (2009-2011, n = 78, 373 vs 392 days, P = NS). In addition, no difference was seen in survival between those patients supported with a left ventricular assist device for fewer than 180 days or longer than 180 days before transplantation (P = NS). The actuarial survival after transplantation at 30 days and 1, 3, and 5 years by Kaplan-Meier analysis was 98.7%, 93.0%, 91.1%, and 88.0%, respectively.

CONCLUSIONS

The short- and long-term post-transplant survival for patients bridged with a continuous-flow left ventricular assist device in the current era has been excellent. Furthermore, the duration of left ventricular assist device support did not affect post-transplant survival. The hemodynamic benefits of ventricular unloading with continuous-flow left ventricular assist devices, in addition to their durability and reduced patient morbidity, have contributed to improved post-transplant survival.

Septuagenarians bridged to heart transplantation with a ventricular assist device have outcomes similar to younger patients

BACKGROUND

Although orthotopic heart transplantation (OHT) is increasingly being offered to older patients, few studies have evaluated outcomes in patients older than 70 years of age. We undertook this study to characterize the outcomes of septuagenarians bridged to transplantation (BTT) in the modern era.

METHODS

We conducted a retrospective cohort study of all adult OHT in the United Network for Organ Sharing database from 2005 to 2011. Primary stratification was by age 70 years or older. Subgroup analysis evaluated patients who received BTT. The primary outcome was survival as determined by the Kaplan-Meier method.

RESULTS

From January 2005 to December 2011, 12,274 adults underwent OHT, including 3,243 (26.4%) who received BTT. In the entire cohort, 11,996 (97.7%) recipients were aged 18 to 70 years, and 277 (2.3%) were 70 years of age or older. Overall, patients 70 years or older who underwent OHT had decreased 90-day survival (93.6% versus 88.8%; p<0.01), 1-year survival (89.0% versus 81.6%; p<0.01), and 2-year survival (85.4% versus 79.9%; p<0.01) compared with recipients of other ages. However in the BTT subgroup, recipients 70 years and older (n=43) had similar 90-day (91.2% versus 84.7%; p=0.2), 1-year (86.1% versus 81.7%; p=0.4), and 2-year (82.8% versus 81.7%; p=0.6) survival compared with recipients of other ages (n=3,200). After adjusting for multiple recipient and donor factors, age greater than or equal to 70 years was still not associated with an increased hazard of mortality at 90 days, 1 year, or 2 years. These results were verified by analysis of a propensity-matched cohort.

CONCLUSIONS

Although patients older than the age of 70 years undergoing OHT have decreased survival, among patients who received BTT, septuagenarians have outcomes similar to those of younger recipients. In carefully selected patients dependent on left ventricular assist devices (LVADs), recipient age greater than or equal to 70 years should not be viewed as a contraindication to OHT.

How does successful bridging with ventricular assist device affect cardiac transplantation outcome?

A best evidence topic in cardiac surgery was written according to a structured protocol. The issue was to determine the impact of bridge-to-transplant ventricular assist device support on survival after cardiac transplantation. Altogether 428 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The treatment options for patients with advanced heart failure or those with deteriorating end-organ function on maximal medical therapy are limited to intravenous inotropes and mechanical assistance with intra-aortic balloon pump (IABP) or ventricular assist device (VAD). Studies exploring the effect of VADs on post-transplant mortality have yielded conflicting results. The Registry of the International Society for Heart and Lung Transplantation continues to identify mechanical support as a risk factor for decreased survival after transplantation. A limitation of this report is that the multivariable adjustment uses variables recorded not at the time of device implant but at the time of transplant. Some of the recipient characteristics thus may be altered by the device implant. Compared with the previous reports the latest data show improvement in post-transplant survival in the recent era. In addition, the excess risk appears to be limited to the early post-transplant period. Experienced centers consistently report outstanding post-transplant results with left ventricular assist device (LVAD) bridging. Of the 12 papers seven showed no difference in survival, and five showed a reduced survival. In the papers showing no difference, one year survival averaged from 85% in supported patients to 87% in non-supported patients. In papers reporting a difference in outcome, one year averaged survival was 74% in LVAD recipients compared to 90% in non-bridged patients. Decreased survival is associated with patients suffering from dilated cardiomyopathy, transplanted within two weeks of LVAD implantation and bridged to transplantation before 2003 as opposed to patients transplanted more recently. Based on the available evidence we conclude that in selected patients survival after heart transplantation in patients bridged with VAD is comparable to those who did not receive the device.

Changing outcomes in patients bridged to heart transplantation with continuous- versus pulsatile-flow ventricular assist devices: an analysis of the registry of the International Society for Heart and Lung Transplantation

BACKGROUND

Patients bridged to heart transplantation with left ventricular assist devices (LVADs) have been reported to have higher post-transplant mortality compared with those without LVADs. Our aim was to determine the impact of the type of LVAD and implant era on post-transplant survival.

METHODS

In this study we included 8,557 patients from the registry of the International Society for Heart and Lung Transplantation. We examined post-transplant outcomes in 1,100 patients bridged to transplant with pulsatile-flow LVADs between January 2000 and June 2004 (first era), 880 patients bridged with pulsatile-flow LVADs between July 2004 and May 2008 (second era), and 417 patients bridged with continuous-flow LVADs in the second era. Patients who required intravenous inotropes but not LVAD support (n = 2,728) and patients who did not require either LVAD or inotropes (n = 3,432) served as controls.

RESULTS

Post-transplant survival of patients bridged with pulsatile LVADs improved significantly between the first and the second era (p = 0.03). In the second era, there was no significant difference in post-transplant survival of patients bridged with pulsatile- vs continuous-flow LVADs (p = 0.26), and survival rates in the 2 groups were not statistically different from that of the non-LVAD group. Graft rejection was similar in patients bridged with LVADs compared to those without LVADs.

CONCLUSIONS

In the most recent era, the use of either pulsatile- or continuous-flow LVADs did not result in increased post-transplant mortality. This finding is important as the proportion of patients with LVADs at the time of transplant has been rising.

Post-cardiac transplant survival after support with a continuous-flow left ventricular assist device: impact of duration of left ventricular assist device support and other variables

OBJECTIVE

Although left ventricular assist devices (LVADs) are associated with excellent outcomes in patients with end-stage heart failure, there are conflicting reports on posttransplant survival in these patients. Furthermore, prior studies with pulsatile LVADs have shown that transplantation, either early (<6 weeks) or late (>6 months) after LVAD implantation, adversely affected post-cardiac transplant survival. We sought to determine factors related to posttransplant survival in patients supported with continuous-flow LVADs.

METHODS

The HeartMate II LVAD (Thoratec Corporation, Pleasanton, Calif) was implanted in 468 patients as a bridge to transplant at 36 centers in a multicenter trial. Patients who underwent transplantation after support were stratified by demographics: gender, age, etiology, body mass index, duration of device support, and by adverse events during support. The median age was 54 years (range 18-73 years); 43% had ischemic etiology, and 18% were women. Survival was determined at the specific intervals of 30 days and 1 year after transplantation.

RESULTS

Of 468 patients, 250 (53%) underwent cardiac transplant after a median duration of LVAD support of 151 days (longest: 3.2 years), 106 (23%) died, 12 (2.6%) recovered ventricular function and the device was removed, and 100 (21%) were still receiving LVAD support. The overall 30-day and 1-year posttransplant survivals were 97% and 87%. There were no significant differences in survival based on demographic factors or LVAD duration of less than 30 days, 30 to 90 days, 90 to 180 days, and more than 180 days. Patients requiring more than 2 units of packed red blood cells in 24 hours during LVAD support had a statistically significant decreased 1-year survival (82% vs 94%) when compared with patients who did not require more than 2 units of packed red blood cells in 24 hours during LVAD support (P = .03). There was a trend for slightly lower survival at 1 year in patients with percutaneous lead infections during LVAD support versus no infection (75% vs 89%; P = .07).

CONCLUSIONS

Post-cardiac transplant survival in patients supported with continuous-flow devices such as the HeartMate II LVAD is equivalent to that with conventional transplantation. Furthermore, posttransplant survival is not influenced by the duration of LVAD support. The improved durability and reduced short- and long-term morbidity associated with the HeartMate II LVAD has reduced the need for urgent cardiac transplantation, which may have adversely influenced survival in the pulsatile LVAD era. This information may have significant implications for changing the current United Network for Organ Sharing criteria regarding listing of heart transplant candidates.

The influence of preoperative use of ventricular assist devices on survival after heart transplantation: propensity score matched analysis

OBJECTIVE

To determine the influence of the preoperative placement of a left ventricular assist device on survival after heart transplantation.

DESIGN

Prospective cohort study.

SETTING

Organ sharing database with patient level data on heart transplants in the United States.

PARTICIPANTS

2786 adults aged 18 or older in status 1A or 1B (highest priority for heart transplantation with either some form of ventricular assist device, intravenous inotrope, or life expectancy of less than seven days), based on the United Network for Organ Sharing Registry, 1996-2004.

MAIN OUTCOME MEASURE

Survival after heart transplantation in patients who did and did not receive a left ventricular assist device.

RESULTS

The left ventricular assist device was not associated with decreased survival, even after the data were stratified by propensity score (the odds of being a treated patient). Inspection of the strata showed no difference in survival between patients who received the device and those who did not. The hazard ratios in strata 1 to 5 were 0.69, 1.37, 1.55, 0.75, and 1.19, respectively, and none was statistically significant.

CONCLUSION

Overall, survival after heart transplantation in patients who received a left ventricular assist device before transplantation was comparable to those who did not receive the device.

Heart failure

Despite advances in management of heart failure, the condition remains a major public-health issue, with high prevalence, poor clinical outcomes, and large health-care costs. Risk factors are well known and, thus, preventive strategies should have a positive effect on disease burden. Treatment of established systolic chronic heart failure includes use of agents that block the renin-angiotensin-aldosterone and sympathetic nervous systems to prevent adverse remodelling, to reduce symptoms and prolong survival. Diuretics are used to achieve and maintain euvolaemia. Devices have a key role in management of advanced heart failure and include cardiac resynchronisation in patients with evidence of cardiac dyssynchrony and implantation of a cardioverter defibrillator in individuals with low ejection fraction. Approaches for treatment of acute heart failure and heart failure with preserved ejection fraction are supported by little clinical evidence. Emerging strategies for heart failure management include individualisation of treatment, novel approaches to diagnosis and tracking of therapeutic response, pharmacological agents aimed at new targets, and cell-based and gene-based methods for cardiac regeneration.

Surgical aspects of congestive heart failure

Despite tremendous advances in the medical management of congestive heart failure the gold standard for the treatment of end stage congestive heart failure remains cardiac transplantation. The acknowledged critical limitation of sufficient suitable organ donors has resulted in the refinement and development of novel surgical alternatives for the treatment of congestive heart failure. These approaches include the extension of current conventional cardiac operations such as mitral valve repair to the failing ventricle, surgically reconstructing the size and shape of the failing left ventricle in order to optimize geometry and render it a more efficient pump, and partial or complete replacement of the ventricle with a mechanical device. The continued evolution of such therapies is likely to one day have a significant epidemiologic impact on patients suffering from end stage heart failure.

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

AIMS

To evaluate the clinical and cost-effectiveness of left ventricular (LV) assist devices (LVADs) as a bridge to transplant (BTT) for people with end-stage heart failure (ESHF) through a systematic review and economic evaluation.

METHODS AND RESULTS

The systematic review and economic evaluation was conducted according to internationally recognized methods. The search strategy identified systematic reviews, randomized controlled trials, quasi-experimental studies, and observational studies evaluating the effects of LVADs on survival, functional capacity, and quality of life. Cost-effectiveness was assessed through a 5-year decision analytic model to estimate the incremental cost-effectiveness ratio of LVADs compared with usual care. Despite the poor methodological quality of the 18 studies included, LVADs appear beneficial improving survival, functional status, and quality of life. Adverse events are a serious concern. The economic evaluation showed that LVADs had a cost per quality adjusted life year of pound 65,242 (95% confidence interval pound 34,194-364,564). Sensitivity analysis showed that post-heart transplant survival gains, pre-heart transplant patient utility, and one-off costs associated with implantation determine cost-effectiveness.

CONCLUSION

Although LVADs appear clinically effective as a BTT for people with ESHF, it is unlikely that they will be cost-effective unless costs decrease or the benefits of their use increase.

Clinical outcomes in patients with chronic congestive heart failure who undergo left ventricular assist device implantation

OBJECTIVE

The use of left ventricular assist devices as a bridge to transplantation for patients with chronic congestive heart failure is well accepted. However, few studies have examined outcomes solely for these patients. This study details one center's left ventricular assist device experience with this population.

METHODS

Two hundred one patients received HeartMate left ventricular assist devices (Thoratec Corp, Pleasanton, Calif) from January 1, 1996, to April 30, 2004. Of these, 119 (59.2%) had chronic congestive heart failure (diagnosis >6 months) as the primary indication. Outcome parameters included early mortality after left ventricular assist device placement (<30 days), bridge-to-transplantation rate, and posttransplantation survival. Variables examined included patient demographic data; preoperative pacemaker, internal defibrillator, and balloon pump use; and preoperative laboratory values.

RESULTS

Advanced age, female sex, and diabetes were independent predictors of early death (P = .048, odds ratio 1.879 per 10 years of age, 95% confidence interval 1.005-3.515; P = .002, odds ratio 10.029, 95% confidence interval 2.256-44.583; P = .040, odds ratio 3.974, 95% confidence interval 1.063-14.861). Advanced age, female sex, and low preoperative albumin were independent predictors of poor bridge-to-transplantation rate (P = .029, odds ratio 0.135 per 10 years of age, 95% confidence interval 0.022-0.819; P = .002, odds ratio 0.013, 95% confidence interval 0.001-0.197; P = .023, odds ratio 19.178 per 1 g/dL albumin, 95% confidence interval 1.504-244.598). There were no independent predictors of poor posttransplantation survival and prolonged intensive care unit stay. Overall bridge-to-transplantation rate was 81.5%. The 1-, 3-, 5-, and 7-year posttransplantation survivals were 88.4%, 84.5%, 78.4%, and 76.0%.

CONCLUSION

Among patients with chronic congestive heart failure, advanced age, female sex, diabetes, and low preoperative albumin predict poor clinical course. Careful risk stratification and comprehensive evaluation by care providers should be performed for candidates who are female, are elderly, and have diabetes, and preoperative nutritional optimization should be encouraged to enhance patient outcomes.

Is severe right ventricular failure in left ventricular assist device recipients a risk factor for unsuccessful bridging to transplant and post-transplant mortality

BACKGROUND

Bridging to transplant with a left ventricular assist device (LVAD) can be limited by severe right ventricular failure (RVF). The focus of this study was to ascertain whether early implantation (< 24 hours) of a right ventricular assist device (RVAD) in patients with severe RVF improved survival and whether severe RVF adversely affected post-transplant survival.

METHODS

We conducted a 10-year review of our bridge to transplant experience using the Heartmate device (Thoratec, Pleasanton, CA, USA), studying patients who required an Abiomed RVAD (Abiomed, Danvers, MA, USA).

RESULTS

There were 243 patients who underwent LVAD implantation, of which 17 (7.0%) required an RVAD. Ten patients underwent early RVAD insertion (< 24 hours) while 7 underwent delayed insertion (> 24 hours). Bridging to transplant was successful in 11 (64.7%) RVAD patients versus 163 (72.1%) non-RVAD patients (p = 0.046). Of the 10 patients who underwent early RVAD insertion, 7 (70.0%) were successfully bridged. Of the 7 patients who underwent delayed RVAD insertion, 4 (57.1%) were successfully bridged (p < 0.001). There was no significant difference in post-transplant 1, 5, and 10-year survival between RVAD and non-RVAD patients (71.4%, 71.4%, and 71.4% for RVAD patients, vs 90.5%, 80.4%, and 78.5%, respectively, for non-RVAD patients; p = 0.366). Pretransplant RVAD support was not a risk factor for post-transplant mortality (p = 0.864).

CONCLUSIONS

Severe RVF adversely impacted bridging to transplant, although survival was improved with early RVAD insertion. The trend toward worse post-transplant survival in the RVAD cohort raises the possibility that if additional patients were evaluated, a difference in survival might be observed, suggesting the need for a multicenter analysis.