Continuous flow left ventricular assist device implant significantly improves pulmonary hypertension, right ventricular contractility, and tricuspid valve competence

The Association Between Pulmonary Vascular Resistance and Posttransplant Outcomes Differs by Left Ventricular Assist Device Status

Elevated pulmonary vascular resistance (PVR) is a risk factor for mortality after heart transplantation (HT), but whether this association differs for patients with and without left ventricular assist device (LVAD) support before HT is unknown. We analyzed adult first-time HT recipients from the United Network for Organ Sharing (UNOS) registry transplanted between 2010 and 2021. We quantified the association between PVR and the outcomes of 30 day graft failure and 1 year mortality using multivariable logistic regression, stratified by LVAD support status at the time of HT. Pulmonary vascular resistance was modeled using restricted cubic splines to identify clinically relevant risk thresholds. We also examined the association with 10 year survival using multivariable Cox proportional hazards regression. For PVR values less than approximately 2 WU, higher PVR was independently associated with a higher risk of early graft failure (odds ratio [OR] = 1.58, 95% CI: 1.06-2.36) and a higher risk of 1 year mortality (OR = 1.32, 95% CI: 1.10-1.59) among LVAD patients only (interaction p = 0.023 and 0.03, respectively). However, for patients surviving at least 1 year, PVR was not associated with long-term mortality among either subgroup. Whether more aggressive reduction of PVR among HT candidates supported with LVADs can mitigate these risks requires further study.

Late follow-up for a randomized trial of surgical treatment of tricuspid valve regurgitation in patients undergoing left ventricular assist device implantation

BACKGROUND

We previously reported that concurrent tricuspid valve surgery (TVS) was not associated with a lower incidence of early right heart failure (RHF) in patients undergoing durable left ventricular assist device (LVAD) implantation. This follow-up analysis aimed to further define the clinical impact of concurrent TVS after 2 months of follow-up.

METHODS

Patients with moderate or severe tricuspid regurgitation (TR) on preoperative echocardiography (n = 71) were randomized to LVAD implantation either alone (no TVS group; n = 34) or with concurrent TVS (TVS group; n = 37). Randomization was stratified by preoperative right ventricular dysfunction. The patients were followed for at least 12 months after surgery. The incidence of RHF was determined by an adjudication committee using Interagency Registry for Mechanically Assisted Circulatory Support criteria. Functional studies and repeat echocardiography were performed at 12 months.

RESULTS

Demographics were similar in the 2 study arms. At 12 months, the rate of moderate or severe RHF was 50.0% in the no TVS arm versus 51.4% in the TVS arm. No patients developed RHF between 6 and 12 months following the procedure. Death from RHF was 5.4% in the TVS arm versus 8.8% in the no TVS arm. At 12 months, there was no significant difference in TR severity between the 2 arms, owing to improvement in TR severity in the no TVS arm. Cardiopulmonary exercise testing at 12+ months revealed no significant between-group difference in peak oxygen consumption.

CONCLUSIONS

In patients with significant preimplantation TR, the severity of TR improved over time in the no TVS arm with LVAD implantation alone. By 12 months, there was no significant difference in TR severity between the 2 arms. This may account for the lack of difference in late clinical or functional parameters.

Concomitant tricuspid valve surgery in patients undergoing left ventricular assist device: a systematic review and meta-analysis

INTRODUCTION

This study aims to investigate the effect of concomitant tricuspid valve surgery (TVS) during left ventricular assist device (LVAD) implantation due to the controversy over the clinical outcomes of concomitant TVS in patients undergoing LVAD.

METHODS

A systematic literature search was performed in PubMed and EMbase from the inception to 1 August 2023. Studies comparing outcomes in adult patients undergoing concomitant TVS during LVAD implantation (TVS group) and those who did not (no-TVS group) were included. The primary outcomes were right heart failure (RHF), right ventricular assist device (RVAD) implantation, and early mortality. All meta-analyses were performed using random-effects models, and a two-tailed P <0.05 was considered significant.

RESULTS

Twenty-one studies were included, and 16 of them were involved in the meta-analysis, with 660 patients in the TVS group and 1291 in the no-TVS group. Patients in the TVS group suffered from increased risks of RHF [risk ratios (RR)=1.31, 95% CI: 1.01-1.70, P =0.04; I2 =38%, pH =0.13), RVAD implantation (RR=1.56, 95% CI: 1.16-2.11, P =0.003; I2 =0%, pH =0.74), and early mortality (RR=1.61, 95% CI: 1.07-2.42, P =0.02; I2 =0%, pH =0.75). Besides, the increased risk of RHF holds true in patients with moderate to severe tricuspid regurgitation (RR=1.36, 95% CI: 1.04-1.78, P =0.02). TVS was associated with a prolonged cardiopulmonary bypass time. No significant differences in acute kidney injury, reoperation requirement, hospital length of stay, or ICU stay were observed.

CONCLUSIONS

Concomitant TVS failed to show benefits in patients undergoing LVAD, and it was associated with increased risks of RHF, RVAD implantation, and early mortality.

Outcomes of tricuspid valve prostheses after heart transplantation: a systematic review

Tricuspid regurgitation (TR) is the most common valvular pathology after heart transplantation (HTx) and endomyocardial biopsy (EMB) remains responsible for the majority of cases due to the high probability of structural valve damage. The aim of the present review was to describe the results of surgical management of severe tricuspid regurgitation through tricuspid valve replacement (TVR) after a previous HTx. A systematic review was conducted by searching Pubmed, ScienceDirect, SciELO, DOAJ, and Cochrane databases until June 2023 for publications reporting patients undergoing TVR surgery after a previous HTx. If no right heart valve surgery was undertaken, or a heterotopic heart transplant was performed, or if the concomitant procedure was performed during the transplant itself, the paper was excluded. Twenty articles met our inclusion criteria out of 1532 potentially eligible studies, with a total of 300 patients. Mean age was 55.1 ± 9.6 years, and 85.1% were male. The mean number of EMB per patient was 31.1 ± 5.5 with a mean time between HTx and TVR of 7.64 ± 3.31 years. Bioprostheses were used in 83.3% of cases and 75.0% of patients with a bioprosthesis were reported as alive at last follow-up. Tricuspid valve repair is a valuable option, but these patients will be susceptible to recurrent TR after EMB. TVR with a bioprosthesis may provide the optimal solution for this subset of patients, as EMB is not feasible with a mechanical valve.

Managing valvular pathology during LVAD implantation

Since the time of their invention, implantable continuous flow left ventricular assist devices (LVADs) have improved the quality of life and extended survival for patients with advanced heart failure. The decision surgeons and their physician colleagues make with these patients to undergo implantation must come with full understanding of the immediate, short-term, and long-term implications of such a life-changing procedure. The presence of pathology regarding the aortic, mitral, and tricuspid valves introduces particularly complex problems for the surgical treatment strategy. Concomitant valve repair or replacement increases cardiopulmonary bypass and cross clamp times, and could potentially lead to worse outcomes in the perioperative setting. Following perioperative recovery, valvular pathology may worsen or arise de novo given the often drastic immediate physiologic changes in blood flow, septal function, and, over time, ventricular remodeling. Over the past two decades, there has been vast improvement in the device manufacturing, surgical techniques, and medical management surrounding LVAD implantation. Yet, addressing concomitant valvular pathology remains a complex question with no perfect solutions. This review aims to briefly describe the evolution of approach to valvular pathology in the LVAD patient and offer our opinion and treatment rationale.

Right heart failure after left ventricular assist device implantation: a persistent problem

Left ventricular assist device (LVAD) is an option for bridge-to-transplant or destination therapy for patients with end-stage heart failure. Right heart failure (RHF) remains a complication after LVAD implantation that portends high morbidity and mortality, despite advances in LVAD technology. Definitions of RHF vary, but generally include the need for inotropic or pulmonary vasodilator support, or potential right ventricular (RV) mechanical circulatory support. This review covers the complex pathophysiology of RHF related to underlying myocardial dysfunction, interventricular dependence, and RV afterload, as well as treatment strategies to curtail this challenging problem.

The clinical impact of tricuspid regurgitation in patients with a biatrial orthotopic heart transplant

In this study, we aim to elucidate the clinical impact and long-term course of tricuspid regurgitation (TR), taking into account its dynamic nature, after biatrial orthotopic heart transplant (OHT). All consecutive adult patients undergoing biatrial OHT (1984-2017) with an available follow-up echocardiogram were included. Mixed-models were used to model the evolution of TR. The mixed-model was inserted into a Cox model in order to address the association of the dynamic TR with mortality. In total, 572 patients were included (median age: 50 years, males: 74.9%). Approximately 32% of patients had moderate-to-severe TR immediately after surgery. However, this declined to 11% on 5 years and 9% on 10 years after surgery, adjusted for survival bias. Pre-implant mechanical support was associated with less TR during follow-up, whereas concurrent LV dysfunction was significantly associated with more TR during follow-up. Survival at 1, 5, 10, 20 years was 97% ± 1%, 88% ± 1%, 66% ± 2% and 23% ± 2%, respectively. The presence of moderate-to-severe TR during follow-up was associated with higher mortality (HR: 1.07, 95% CI (1.02-1.12), p = 0.006). The course of TR was positively correlated with the course of creatinine (R = 0.45). TR during follow-up is significantly associated with higher mortality and worse renal function. Nevertheless, probability of TR is the highest immediately after OHT and decreases thereafter. Therefore, it may be reasonable to refrain from surgical intervention for TR during earlier phase after OHT.

Tricuspid regurgitation in the setting of LVAD support

Tricuspid valve regurgitation (TR) is a common complication of end-stage heart failure. Increased pulmonary venous pressures caused by left ventricular (LV) dysfunction can result in a progressive dilation of the right ventricle and tricuspid valve annulus, resulting in functional TR. Here, we review what is known about TR in the setting of severe LV dysfunction necessitating long-term mechanical support with left ventricular assist devices (LVADs), including the occurrence of significant TR, its pathophysiology, and natural history. We examine the impact of uncorrected TR on LVAD outcomes and the impact of tricuspid valve interventions at the time of LVAD placement, revealing that TR frequently improves after LVAD placement with or without concomitant tricuspid valve intervention such that the benefit of concomitant intervention remains controversial. We summarize the current evidence on which to base medical decisions and provide recommendations for future directions of study to address outstanding questions in the field.

Role of the mitral valve in left ventricular assist device pathophysiology

Functional mitral regurgitation (MR) in the setting of heart failure results from progressive dilatation of the left ventricle (LV) and mitral annulus. This leads to leaflet tethering with posterior displacement. Contrary to common assumptions, MR often does not resolve with LVAD decompression of the LV alone. The negative impact of significant (moderate-severe) mitral regurgitation in the LVAD setting is becoming better recognized in terms of its harmful effect on right heart function, pulmonary vascular resistance and hospital readmissions. However, controversies remain regarding the threshold for intervention and management. At present, there are no consensus indications for the repair of significant mitral regurgitation at the time of LVAD implantation due to the conflicting data regarding potential adverse effects of MR on clinical outcomes. In this review, we summarize the current understanding of MR pathophysiology in patients supported with LVAD and potential future management strategies.

Management of Pulmonary Hypertension in Patients on Left Ventricular Assist Device Support

Left ventricular assist devices (LVADs) are increasingly utilized for patients with end-stage heart failure (HF). Pulmonary hypertension (PH) is highly prevalent in this patient population mainly due to prolonged left ventricular (LV) failure and chronically elevated filling pressures. The effect of LVADs on pulmonary circulation and right ventricular (RV) function has recently become an area of great attention in literature. PH can lead to post-LVAD right ventricular failure (RVF) that confers a high risk of morbidity and mortality. Multiple pulmonary vasodilators, that are primarily used for the treatment of pulmonary arterial hypertension (PAH), have been studied for the treatment of PH after LVAD implantation, and some of them have shown promising results. This review aims to investigate the treatment options for PH in patients on LVADs, as well as to give an overview about the pathophysiology of PH and RVF in these patients.

Cardiac remodeling in patients with centrifugal left ventricular assist devices assessed by serial echocardiography

AIM

The aim of the study was to characterize the remodeling process in a large cohort of patients supported with a centrifugal left ventricular assist device (cfLVAD) by standardized serial echocardiography.

METHODS AND RESULTS

From 3/2018 all cfLVAD patients underwent transthoracic echocardiography at 6 and 12 months after implantation using a standardized protocol. A total of 512 echocardiograms were reviewed (216 preoperative, 156 at 6 months, 140 at 12 months). While on cfLVAD support, left ventricular (LV) diameter decreased (p < .001). LV ejection fraction (LVEF) and LV fractional area change improved (p < .001). Potential for cfLVAD explantation (as defined by an LVEF ≥45% and opening of the aortic valve [AV]) was seen in nine patients at 6 and 21 patients at 12 months. The tricuspid annular excursion decreased significantly, while the right ventricular fractional area change did not change. Tricuspid regurgitation (TR) and mitral regurgitation (MR) improved significantly during LVAD support. Opening of the AV was seen in >64% of the patients at 6 months and in 66% at 12 months. Moderate aortic regurgitation (AR) was rare with 3.8% at 6 months but increased with the duration of cfLVAD support (8.5% at 12 months). We found no significant difference in echocardiographic parameters between patients supported with a HeartWare HVAD™ or a HeartMate 3™ device.

CONCLUSION

LVAD therapy can lead to reverse LV remodeling and improvement of MR and TR. However, right ventricular function does not improve and prevalence of AR progressively increases during mechanical support.

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Invasive Haemodynamic Assessment Before and After Left Ventricular Assist Device Implantation: A Guide to Current Practice

Mechanical circulatory support for the management of advanced heart failure is a rapidly evolving field. The number of durable long-term left ventricular assist device (LVAD) implantations increases each year, either as a bridge to heart transplantation or as a stand-alone ‘destination therapy’ to improve quantity and quality of life for people with end-stage heart failure. Advances in cardiac imaging and non-invasive assessment of cardiac function have resulted in a diminished role for right heart catheterisation (RHC) in general cardiology practice; however, it remains an essential tool in the evaluation of potential LVAD recipients, and in their long-term management. In this review, the authors discuss practical aspects of performing RHC and potential complications. They describe the haemodynamic markers associated with a poor prognosis in patients with left ventricular systolic dysfunction and evaluate the measures of right ventricular (RV) function that predict risk of RV failure following LVAD implantation. They also discuss the value of RHC in the perioperative period; when monitoring for longer term complications; and in the assessment of potential left ventricular recovery.

Left Ventricular Assist Device Implantation in Patients with Preoperative Severe Mitral Regurgitation

We examined cardiac features associated with residual mitral regurgitation (MR) following continuous-flow left ventricular assist device (cfLVAD) implant. From 2003 to 2017, 134 patients with severe MR underwent cfVLAD implant without mitral valve (MV) intervention. Echocardiographic (echo) assessment occurred pre-cfLVAD, early post-cfLVAD, and at last available echo. Ventricular and atrial volumes were calculated from established formulas and normalized to be predicted. Cluster analysis based on preoperative normalized left ventricular and atrial volumes, and MV height identified grades 1, 2, and 3 with progressively larger cardiac chamber sizes. Median early echo follow-up was 0.92 (0.55, 1.45) months and the last follow-up was 15.12 (5.28, 38.28) months. Mitral regurgitation improved early after cfLVAD by 2.10 ± 1.16 grades (p < 0.01). Mitral regurgitation severity at the last echocardiogram positively correlated with the preoperative left ventricular volume (p = 0.014, R = 0.212), left atrial volume (p = 0.007, R = 0.233), MV anteroposterior height (p = 0.032, R = 0.185), and MV mediolateral diameter (p = 0.043, R = 0.175). Morphologically, smaller grade 1 hearts were correlated with MR resolution at the late follow-up (p = 0.023). Late right ventricular failure (RVF) at the last clinical follow-up was less in grade 1 (4/48 [8.3%]) compared with grades 2 and 3 (26/86 [30.2%]), p = 0.004). Grade 1 cardiac dimensions correlates with improvement in severe MR and had less late RVF.

The role of renin-angiotensin system in patients with left ventricular assist devices

End-stage heart failure is a condition in which the up-regulation of the systemic and local renin-angiotensin-aldosterone system (RAAS) leads to end-organ damage and is largely irreversible despite optimal medication. Left ventricular assist devices (LVADs) can downregulate RAAS activation by unloading the left ventricle and increasing the cardiac output translating into a better end-organ perfusion improving survival. However, the absence of pulsatility brought about by continuous-flow devices may variably trigger RAAS activation depending on left ventricular (LV) intrinsic contractility, the design and speed of the pump device. Moreover, the concept of myocardial recovery is being tested in clinical trials and in this setting LVAD support combined with intense RAAS inhibition can promote recovery and ensure maintenance of LV function after explantation. Blood pressure control on LVAD recipients is key to avoiding complications as gastrointestinal bleeding, pump thrombosis and stroke. Furthermore, emerging data highlight the role of RAAS antagonists as prevention of arteriovenous malformations that lead to gastrointestinal bleeds. Future studies should focus on the role of angiotensin receptor inhibitors in preventing myocardial fibrosis in patients with LVADs and examine in greater details the target blood pressure for these patients.

Clinical impact and 'natural' course of uncorrected tricuspid regurgitation after implantation of a left ventricular assist device: an analysis of the European Registry for Patients with Mechanical Circulatory Support (EUROMACS)

OBJECTIVES

Data on the impact and course of uncorrected tricuspid regurgitation (TR) during left ventricular assist device (LVAD) implantation are scarce and inconsistent. This study explores the clinical impact and natural course of uncorrected TR in patients after LVAD implantation.

METHODS

The European Registry for Patients with Mechanical Circulatory Support was used to identify adult patients with LVAD implants without concomitant tricuspid valve surgery. A mediation model was developed to assess the association of TR with 30-day mortality via other risk factors. Generalized mixed models were used to model the course of post-LVAD TR. Joint models were used to perform sensitivity analyses.

RESULTS

A total of 2496 procedures were included (median age: 56 years; men: 83%). TR was not directly associated with higher 30-day mortality, but mediation analyses suggested an indirect association via preoperative elevated right atrial pressure and creatinine (P = 0.035) and bilirubin (P = 0.027) levels. Post-LVAD TR was also associated with increased late mortality [hazard ratio 1.16 (1.06–1.3); P = 0.001]. On average, uncorrected TR diminished after LVAD implantation. The probability of having moderate-to-severe TR immediately after an implant in patients with none-to-mild TR pre-LVAD was 10%; in patients with moderate-to-severe TR pre-LVAD, it was 35% and continued to decrease in patients with moderate-to-severe TR pre-LVAD, regardless of pre-LVAD right ventricular failure or pulmonary hypertension.

CONCLUSIONS

Uncorrected TR pre-LVAD and post-LVAD is associated with increased early and late mortality. Nevertheless, on average, TR diminishes progressively without intervention after an LVAD implant. Therefore, these data suggest that patient selection for concomitant tricuspid valve surgery should not be based solely on TR grade.

Development of tricuspid regurgitation and right ventricular performance after implantation of centrifugal left ventricular assist devices

Background

Tricuspid regurgitation (TR) after left ventricular assist device (LVAD) implantation is associated with a poor prognosis. This study evaluates the development of TR and right ventricular (RV) performance after LVAD implantation.

Methods

Retrospective analysis of patients who underwent LVAD implantation between March 2018 and June 2019. Patients who underwent concomitant tricuspid valve surgery and patients with congenital heart disease were excluded.

Results

A total of 155 patients underwent LVAD implantation. Fourteen patients were excluded. Of the remaining patients, thirty-one died during the first six months, six were lost to follow-up and two underwent transplantation. 102 patients presented at 6.3 months (5.8 to 7.0). Patients were supported with HeartWare HVAD (74%) or HeartMate 3 (26%). 50.4% were rated as INTERMACS profile 1 or 2. At six months, systolic pulmonary artery pressure dropped from 36 to 21 mmHg (P<0.001). Tricuspid annular plane systolic excursion decreased from 17.3 to 14.3 mm (P<0.001), RV fractional area change did not change (P=0.839). Twenty-two patients (22%) presented with moderate-to-severe or severe (ms-s) TR pre-operatively. Of these, eighteen (81%) showed improvement to ≤ moderate TR. At follow-up twelve patients presented with ms-s TR. Of these, only four patients (33%) had been diagnosed with ms-s TR pre-operatively. There were no differences in pre-operative echocardiographic or clinical parameters between the twelve patients with ms-s late TR and the other ninety patients in the cohort.

Conclusions

TR can show an impressive improvement with LVAD support. Longitudinal RV function decreases; this appears to be compensated by transverse shortening. Late TR can develop independently from pre-operative parameters including TR.

Right Ventricular Failure Post-Implantation of Left Ventricular Assist Device: Prevalence, Pathophysiology, and Predictors

Despite advances in left ventricular assist device (LVAD) technology, right ventricular failure (RVF) continues to be a complication after implantation. Most patients undergoing LVAD implantation have underlying right ventricular (RV) dysfunction (either as a result of prolonged LV failure or systemic disorders) that becomes decompensated post-implantation. Additional insults include intra-operative factors or a sudden increase in preload in the setting of increased cardiac output. The current literature estimates post-LVAD RVF from 3.9% to 53% using a diverse set of definitions. A few of the risk factors that have been identified include markers of cardiogenic shock (e.g., dependence on inotropes and Interagency Registry for Mechanically Assisted Circulatory Support profiles) as well as evidence of cardiorenal or cardiohepatic syndromes. Several studies have devised multivariable risk scores; however, their performance has been limited. A new functional assessment of RVF and a novel hepatic marker that describe cholestatic properties of congestive hepatopathy may provide additional predictive value. Furthermore, future studies can help better understand the relationship between pulmonary hypertension and post-LVAD RVF. To achieve our ultimate goal-to prevent and effectively manage RVF post-LVAD-we must start with a better understanding of the risk factors and pathophysiology. Future research on the different etiologies of RVF-ranging from acute post-surgical complication to late-onset RV cardiomyopathy-will help standardize definitions and tailor therapies appropriately.

Impact of tricuspid valve insufficiency on the performance of left ventricular assist devices

Objective

To evaluate the impact of severe tricuspid valve insufficiency (TVI) at the time of left ventricular assist device (LVAD) implantation on the hemodynamic and LVAD parameters in an acute ovine model.

Methods

Stable heart failure (HF) was induced in 10 ovines through the application of 3 ± 1 coronary ligations. Once stable HF was obtained (after 15 ± 5 days), the animals were supported with an LVAD. Hemodynamic data and pump parameters were obtained and compared in 2 settings; first with LVAD in place after weaning from the cardiopulmonary bypass machine (no TVI condition) and second following the induction of severe TVI through resection of the tricuspid valve (TVI condition).

Results

There were no statistically significant differences in the hemodynamic and pump parameters between TVI condition and no TVI conditions except for lower cardiac output in the TVI condition (2 [1.38-2.8] L/min vs 3.2 [1.55-3.7] L/min, P = .027) and the expected greater central venous pressure in the TVI condition (26 [24-31] mm Hg vs 15 [13-25] mm Hg, P = .020). A median pump flow of 2.8 (2.45-3.75) L/min versus 2.9 (2.75-3.8) L/min in the TVI condition and no TVI condition was documented (P = .160).

Conclusions

Results from this acute animal study suggest that severe TVI in HF with preserved right ventricular function does not have significant impact on the LVAD pump parameters. The observed reduction in cardiac output may warrant further investigations, especially under loading conditions.

Off-label use of pulmonary vasodilators after left ventricular assist device implantation: Calling in the evidence

Left ventricular assist devices (LVAD) are increasingly implanted in advanced heart failure patients to improve survival and quality of life either as a bridge to transplant, bridge to recovery or as destination therapy. LVAD therapy is often accompanied by a profound lowering of pulmonary artery pressure due to mechanical unloading of the left ventricle. Persistent pulmonary hypertension (PH) after LVAD implantation increases the risk of right ventricular failure (RVF). In this context pulmonary vasodilators have been implemented: a) as a strategy to reduce afterload and wean patients with RVF from inotropes in the early postoperative period, b) as long-term therapy aiming to optimize right heart hemodynamics and prevent late RVF and c) in order to lower persistently elevated pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) after LVAD and enable candidacy for heart transplantation. However, considerable uncertainty exists regarding the risks and benefits of these strategies and practices vary widely among institutions. This article provides an overview of the available evidence and existing recommendations regarding the use of pulmonary vasodilators in LVAD recipients.

Clinical impact of concomitant tricuspid valve procedures during left ventricular assist device implantation

BACKGROUND

Tricuspid regurgitation (TR) is common in patients with end-stage heart failure receiving left ventricular assist devices (LVADs), but the benefit of concomitant tricuspid valve procedures (TVPs) remains uncertain. This study examined the impact of TVP at the time of LVAD implantation on clinical outcomes and quality of life (QOL) metrics.

METHODS

We included adult patients in the Interagency Registry for Mechanical Circulatory Support database with various degrees of TR who received continuous-flow LVADs from 2008 to 2017. Patients undergoing concomitant TVP were compared with those without the intervention in a stratified analysis. Descriptive analyses, survival analyses, and Andersen‒Gill hazard models were used as appropriate to examine associations with clinical and patient-centered QOL outcomes.

RESULTS

Our analysis included 8,263 (53.1%) mild, 4,252 (33.3%) moderate, and 2,100 (13.5%) severe TR cases. TVP rate increased with severity: 8.6% of mild, 18.0% of moderate, and 43.9% of severe cases. TVP was not associated with survival benefit in cases of mild (adjusted hazard ratio [aHR]: 0.97, 95% CI: 0.79-1.19, p = 0.75), moderate (aHR: 1.03, 95% CI: 0.88-1.20, p = 0.72), or severe (aHR: 1.20, 95% CI: 0.98-1.48, p = 0.08) TR. For patients with combined moderate or severe TR, TVP was associated with increased mortality (log-rank p < 0.01, aHR: 1.13, 95% CI: 1.00-1.27, p = 0.04). After adjusting for TR severity, TVP was associated with increased risk of bleeding, arrhythmia, and stroke (p < 0.01 each) and no improvements in QOL (p > 0.05).

CONCLUSIONS

TVP at the time of LVAD implantation was not associated with either improved survival or QOL, and there were associations with increased risk of adverse events among patients with moderate and severe TR.

Continuous-Flow Left Ventricular Assist Devices and Valvular Heart Disease: A Comprehensive Review

Mechanical circulatory support with implantable durable continuous-flow left ventricular assist devices (CF-LVADs) represents an established surgical treatment option for patients with advanced heart failure refractory to guideline-directed medical therapy. CF-LVAD therapy has been demonstrated to offer significant survival, functional, and quality-of-life benefits. However, nearly one-half of patients with advanced heart failure undergoing implantation of a CF-LVAD have important valvular heart disease (VHD) present at the time of device implantation or develop VHD during support that can lead to worsening right or left ventricular dysfunction and result in development of recurrent heart failure, more frequent adverse events, and higher mortality. In this review, we summarize the recent evidence related to the pathophysiology and treatment of VHD in the setting of CF-LAVD support and include a review of the specific valve pathologies of aortic insufficiency (AI), mitral regurgitation (MR), and tricuspid regurgitation (TR). Recent data demonstrate an increasing appreciation and understanding of how VHD may adversely affect the hemodynamic benefits of CF-LVAD support. This is particularly relevant for MR, where increasing evidence now demonstrates that persistent MR after CF-LVAD implantation can contribute to worsening right heart failure and recurrent heart failure symptoms. Standard surgical interventions and novel percutaneous approaches for treatment of VHD in the setting of CF-LVAD support, such as transcatheter aortic valve replacement or transcatheter mitral valve repair, are available, and indications to intervene for VHD in the setting of CF-LVAD support continue to evolve.

Association of Cardiac Rehabilitation With Decreased Hospitalizations and Mortality After Ventricular Assist Device Implantation

OBJECTIVES

This study characterized cardiac rehabilitation (CR) use in ventricular assist device (VAD) recipients in the United States and the association of CR with 1-year hospitalization and mortality by using the 2013 to 2015 Medicare files.

BACKGROUND

Exercise-based CR is indicated in patients with heart failure with reduced ejection fraction, but no data exist regarding CR participation after VAD implantation.

METHODS

The study included Medicare beneficiaries enrolled for disability or age >65 years. The investigators identified VAD recipients by diagnosis codes and cumulated CR sessions occurring within 1 year after VAD implantation. Multivariable-adjusted Andersen-Gill models were used to evaluate the association of CR with 1-year hospitalization risk, and Cox regression was used to evaluate the association of CR with 1-year mortality.

RESULTS

There were 1,164 VADs implanted in Medicare beneficiaries in the United States in 2014. CR use was low, with 348 patients (30%) participating in CR programs. The Midwest had the highest proportion of VAD recipients who began CR (38%), whereas the Northeast had the lowest proportion of CR participants (25%). Each 5-year increase in age was associated with attending an additional 1.6 CR sessions (95% confidence interval [CI]: 0.7 to 2.5; p < 0.001). CR participation was associated with a 23% lower 1-year hospitalization risk (95% CI: 11% to 33%; p < 0.001) and a 47% lower 1-year mortality risk (95% CI: 18% to 66%; p < 0.01) after multivariable adjustment.

CONCLUSIONS

Approximately one-third of VAD recipients attend CR. Although it is not possible to account fully for unmeasured confounding, VAD recipients who participate in CR appear to have lower risks for hospitalization and mortality.

A modified implantation technique for temporary right ventricular assist device: Enabling ambulation and less invasive decannulation

This report describes our unique temporary right ventricular assist device (RVAD) implantation technique, which enables early mobilization even during biventricular support and subsequent less invasive RVAD removal without needing resternotomy upon recovery.

Pulmonary Hypertension Due to Left Heart Disease: an Update

PURPOSE OF REVIEW

Pulmonary hypertension (PH) frequently complicates heart failure and portends a worse prognosis. This review will summarize and discuss recent updates in the classification and management of patients with PH due to left heart disease.

RECENT FINDINGS

Careful hemodynamic assessment is critical to the classification of patients with PH and heart failure. Two hemodynamic subgroups of PH in heart failure patients have been described: isolated post-capillary pulmonary hypertension and combined post- and precapillary pulmonary hypertension. The cornerstone in management of PH due to left heart disease is the treatment of the underlying left heart pathology; however, ongoing trials have been designed to test pulmonary vasodilators in this cohort. PH-specific therapies have not demonstrated a benefit in patients with pulmonary hypertension due to left heart disease. Understanding the distinct pathobiology of each hemodynamic subgroup may lead to the development of useful biomarkers and effective targeted therapies.

Intersection of Pulmonary Hypertension and Right Ventricular Dysfunction in Patients on Left Ventricular Assist Device Support: Is There a Role for Pulmonary Vasodilators?

Left ventricular assist devices (LVADs) improve survival and quality of life in patients with advanced heart failure. Despite these benefits, combined post- and precapillary pulmonary hypertension can be particularly problematic in patients on LVAD support, often exacerbating right ventricular (RV) dysfunction. Both persistently elevated pulmonary vascular resistance and RV dysfunction are associated with adverse outcomes, including death after LVAD. These observations have led to significant interest in the use of pulmonary vasodilators to treat pulmonary hypertension and preserve RV function among LVAD-supported patients. Although pulmonary vasodilators are commonly used for the treatment of pulmonary hypertension and RV dysfunction in LVADs, the benefits of this practice remain unclear. The purpose of this review is to highlight the current challenges in managing pulmonary vascular disease and RV dysfunction in patients with heart failure on LVAD support.

Atrial Fibrillation Should Guide Prophylactic Tricuspid Procedures During Left Ventricular Assist Device Implantation

Atrial fibrillation (AF) and tricuspid regurgitation (TR) are common in patients undergoing left ventricular assist device (LVAD) implantation. TR progression is associated with the presence of AF, and questions remain as to who benefits from tricuspid valve procedures (TVPs). We examined the impact of preoperative AF on TR progression after LVAD implantation. From February 2007 to May 2014, 250 patients underwent LVAD implantation at our institution. Patients with concomitant TVP were excluded from this analysis (113 patients). The indication for LVAD was destination therapy in 80 patients (58%) and the etiology of heart failure was ischemic in 73 (53%). Follow-up was available in all early survivors for a total of 393 patient-years of support. Of the 137 non-TVP patients, 52 (38%) had AF preoperatively. Observed overall survival at 1, 3, and 5 years was 82%, 67%, and 55%, respectively. Median grade of TR increased from 2 preoperatively to 3 (p = 0.04) in the AF group and 2.2 (p = 0.75) in the non-AF group at 5 years of follow-up. We also observed a significant difference in the degree of TR between groups at 3 months (p = 0.03) and 12 months (p = 0.01) postimplantation, and a trend toward significance at 18 (p = 0.06) and 24 (p = 0.07) months. The presence of AF is associated with early progression of TR after LVAD implantation. Addition of concomitant TVP in patients with preoperative AF may be considered in patients with less than severe TR. The impact of these findings on right ventricular failure/remodeling remains to be evaluated.

Temporary assist device support for the right ventricle: pre-implant and post-implant challenges

Severe right ventricular (RV) failure is more likely reversible than similar magnitudes of left ventricular (LV) failure and, because reversal of both adaptive remodeling and impaired contractility require most often only short periods of support, the use of temporary RV assist devices (t-RVADs) can be a life-saving therapy option for many patients. Although increased experience with t-RVADs and progresses made in the development of safer devices with lower risk for complications has improved both recovery rate of RV function and patient survival, the mortality of t-RVAD recipients can still be high but it depends mainly on the primary cause of RV failure (RVF), the severity of end-organ dysfunction, and the timing of RVAD implantation, and much less on adverse events and complications related to RVAD implantation, support, or removal. Reduced survival of RVAD recipients should therefore not discourage appropriate application of RVADs because their underuse further reduces the chances for RV recovery and patient survival. The article reviews and discusses the challenges related to the pre-implant and post-implant decision-making processes aiming to get best possible therapeutic results. Special attention is focused on pre-implant RV assessment and prediction of RV improvement during mechanical unloading, patient selection for t-RVAD therapy, assessment of unloading-promoted RV recovery, and prediction of its stability after RVAD removal. Particular consideration is also given to prediction of RVF after LVAD implantation which is usually hampered by the complex interactions between the different risk factors related indirectly or directly to the RV potential for reverse remodeling and functional recovery.

Effect of concomitant mitral valve procedures for severe mitral regurgitation during left ventricular assist device implantation

The effect of performing a concomitant mitral valve procedure (MVP) during continuous-flow left ventricular assist device (CF-LVAD) implantation has been reported for patients with moderate-to-severe mitral regurgitation (MR), but moderate MR is less of a clinical concern for CF-LVAD patients. There is a paucity of reports focusing on patients with severe MR. Thus, the purpose of this study was to analyze the effect of performing a concomitant MVP during CF-LVAD implantation in patients with severe preoperative MR. Between November 2003 and March 2016, 526 patients underwent primary implantation of a CF-LVAD at our center. Patients with severe MR who underwent a concomitant MVP were compared to those who did not in regard to overall survival, perioperative complications, postoperative echocardiography data, bridge-to-transplantation success, and CF-LVAD explantation. Of the 108 patients with severe MR, 26 underwent a concomitant MVP and 82 did not. These groups showed no difference in survival (p = 0.61). Additionally, the two groups had similar rates of postoperative right heart failure (p = 0.69) and readmissions (p = 0.42). The 24-month follow-up echocardiography results were also similar. Furthermore, the groups showed no difference in bridge-to-cardiac transplantation success (30.0% vs 25.0%, p = 0.80) or CF-LVAD explantation rates (0.0% vs 0.0%. p = 1.0). Our findings suggest that patients with severe MR who undergo a MVP during CF-LVAD implantation do not have superior outcomes to those who do not. However, assessments of other outcomes may show some benefits to performing concomitant MVPs.

Changes in pulmonary artery pressure before and after left ventricular assist device implantation in patients utilizing remote haemodynamic monitoring

Aims

The time course of changes in pulmonary artery (PA) pressure due to left ventricular assist devices (LVADs) is not well understood. Here, we describe longitudinal haemodynamic trends during the peri‐LVAD implantation period in patients previously implanted with a remote monitoring PA pressure sensor.

Methods and results

We retrospectively studied PA pressure trends in patients implanted with CardioMEMS™ PA pressure sensor between October 2007 and March 2017 who subsequently had an LVAD procedure. Data are presented as mean ± standard deviation, and P‐values are calculated using standard t‐test with equal variance. Among 436 patients in cohort, 108 (age 58 ± 11 years, 82% male) received an LVAD and 328 (age 60 ± 13 years, 70% male) did not. The mean PA pressure at sensor implant was higher by 29% (P < 0.001) among patients who later received LVAD. Mean PA pressure 6 months prior to LVAD implant was 35.5 ± 8.5 mmHg, increasing to 39.4 ± 9.9 mmHg (P = 0.04) at 4 weeks before LVAD, and then decreasing 27% to 28.8 ± 8.4 mmHg (P < 0.001) at 3 months post‐implant and stabilizing at 31.0 ± 9.4 mmHg at 1 year.

Conclusions

Patients who later receive LVADs have higher PA pressures at sensor implant and show a further increase leading up to LVAD implantation. There is a significant reduction of PA pressures post‐LVAD implantation that persists long term. PA pressure monitoring may aid in the clinical decision making of timing for LVAD implantation and in management of LVAD patients.

Impact of Residual Valve Disease on Survival After Implantation of Left Ventricular Assist Devices

BACKGROUND

This retrospective single-institutional study investigated the effect of significant valvular regurgitation after left ventricular assist device (LVAD) implantation and the role of concomitant valve surgery during LVAD surgery.

METHODS

All patients receiving an LVAD (HeartMate II; Abbott, Abbott Park, IL) during 2008 and 2015 were enrolled. The cohort was divided into two groups based on the valve status at the end of the operation: patients without significant valvular regurgitation (no-VR) and those with significant valvular regurgitation (residual-VR).

RESULTS

An LVAD was implanted in 270 patients. Of these, 233 had significant preoperative valve disease(s), and 180 (66.6%) received concomitant valve interventions (35 aortic, 90 mitral, 138 tricuspid). At the completion of the LVAD operation, 204 had no-VR and 66 had residual-VR. Short-term outcomes were similar in two groups, except for longer cardiopulmonary bypass time in the no-VR group (149 minutes) than in the residual-VR group (132 minutes, p = 0.038). During follow-up, mean pulmonary artery pressure (24 mm Hg in no-VR vs 27 mm Hg in residual-VR; p = 0.018) and pulmonary vascular resistance (1.8 Wood units in no-VR vs 2.7 Wood units in residual-VR, p = 0.008) significantly improved in no-VR group compared with the residual-VR group. Survival and heart failure admission-free rates at 1 year were significantly superior in the no-VR group compared with the residual-VR group (1-year survival: 72% ± 3% No-VR vs 55% ± 6% residual-VR; log-rank p = 0.026; admission-free survival: 91% ± 2% no-VR vs 74% ± 7% residual-VR; log-rank p = 0.026). Concomitant valve intervention was not an independent predictor of in-hospital death and morbidity.

CONCLUSIONS

Absence of valvular lesion after LVAD implantation was associated with improved midterm hemodynamics and survival in the current study. Aggressive surgical intervention for significant valve disease(s) at the time of LVAD implant may be beneficial to selected patients.

Mitral Intervention with LVAD: Preparing for Recovery

Left ventricular assist device (LVAD) insertion is an increasingly common treatment of advanced heart failure. Insertion guidelines suggest regurgitant lesions of the mitral valve should not be addressed. However, recent evidence suggests that mitral regurgitation may not necessarily improve with LVAD insertion, and such patients may have worse outcomes. Thus, practice variability is high given the discrepancy between traditional thinking and new evidence that unrepaired mitral regurgitation may increase perioperative mortality. Additionally, the challenges of LVADs can make transesophageal echocardiography evaluation and assessment of mitral valve pathology difficult.

Prevention and Treatment of Right Ventricular Failure During Left Ventricular Assist Device Therapy

Left ventricular assist devices (LVAD) are increasingly used for the treatment of end-stage heart failure. Right ventricular (RV) failure after LVAD implantation is an increasingly common clinical problem, occurring in patients early after continuous flow LVAD implant. RV failure is associated with a substantial increase in post-LVAD morbidity and mortality. RV failure can be predicted using preoperative hemodynamic, clinical, and echocardiographic variables and a variety of risk prediction algorithms. However, RV failure may also develop due to unanticipated intraoperative or perioperative factors. Early recognition and treatment are critical in terms of mitigating the impact of RV failure on post-LVAD outcomes.

Mechanical circulatory support is effective to treat pulmonary hypertension in heart transplant candidates disqualified due to unacceptable pulmonary vascular resistance

Introduction

High pulmonary vascular resistance (PVR) in orthotopic heart transplantation (OHT) candidates is a risk factor of right ventricle failure after the procedure. However, the increase of PVR may be a consequence of the life-threatening deterioration of the left ventricle function. The use of mechanical circulatory support (MCS) seems to be the best solution, but it is reimbursed only in active OHT candidates.

Aim

We performed a retrospective analysis of MCS effectiveness in maintaining PVR at values accepted for OHT.

Material and methods

Starting from the year 2008 we identified 6 patients (all males, 42.8 ±17 years old) with dilated (n = 3), ischemic (n = 2), and restrictive cardiomyopathy (n = 1) in whom MCS – pulsatile left ventricle assist device (LVAD, n = 4), continuous flow LVAD (n = 1), and pulsatile biventricular assist device (BIVAD, n = 1) – was used at a time when PVR was unacceptable for OHT, and the reversibility test with nitroprusside was negative. After an average time of support of 261 ±129 days they were all transplanted.

Results

Right heart catheterization (RHC) results before MCS implantation were as follows: pulmonary artery systolic, diastolic, and mean pressure (PAPs/d/m) 60 ±20/28 ±7/40 ±11 mm Hg, pulmonary capillary wedge pressure (PCWP) 21 ±7 mm Hg, transpulmonary gradient (TPG) 19 ±7 mm Hg, cardiac output (CO) 3.6 ±0.8 l/min, PVR 5.7 ±2.1 Wood units (WU). Right heart catheterization results during MCS therapy were as follows: PAPs/d/s 27 ±11/12 ±4/17 ±6 mm Hg, PCWP 10 ±4 mm Hg, TPG 7 ±4 mm Hg, CO 5.1 ±0.7 l/min, PVR 1.4 ±0.6 WU. None of the patients experienced right ventricle failure after OHT with only one early loss due to multiorgan failure.

Conclusions

Mechanical circulatory support is an effective method of pulmonary hypertension treatment for patients disqualified for OHT due to high PVR.

Outcomes and Trends of Ventricular Assist Device Selection in Children with End-Stage Heart Failure

We aimed to examine trends in ventricular assist device (VAD) selection, continuous flow devices (CFD) versus pulsatile flow devices (PFD), and their associated outcomes in children eligible for both device types. To accomplish this, the United Network for Organ Sharing database was reviewed for pediatric patients listed for heart transplant (HT) from January 2007 to June 2014. Patients were included if a durable VAD was present at wait listing or when removed from the waiting list and who met size eligibility for a CFD (BSA > 1.0 m). In total, 253 patients met inclusion criteria, 144 (57%) CFD and 109 (43%) PFD. Device type varied significantly based on year with CFD increasing from 11% in 2007 to 88% in 2014 (p < 0.01). PFD patients were younger, had a lower BSA, and an increased rate of extracorporeal membrane oxygenation and biventricular assist device support at listing. Survival to transplant or recovery was similar for CFDs and PFDs (96 vs. 94%; p = 0.57), as was the post-HT survival, 95% for both device types. Despite PFD patients having more risk factors for a poor outcome, survival was similar between device types. Even so, there is a dramatic trend toward CFD utilization in patients who are large enough to support one.

Clinical implications of hemodynamic assessment during left ventricular assist device therapy

Left ventricular assist devices (LVADs) significantly improve outcomes of advanced heart failure patients. However, patients continue to have high readmission rates due to complications ranging from bleeding, thrombosis, heart failure, and infection. Considering that the hallmark benefit of LVAD therapy is improvement in hemodynamics (cardiac unloading and increased cardiac output), hemodynamic assessment on LVAD support is key to better understand these difficult complications and may serve as a tool to resolving them. In this review, we will discuss the hemodynamic changes following LVAD implantation, and the implications and prognostic impact of hemodynamic optimization on outcomes and complications.

Treatment and Prognosis of Pulmonary Hypertension in the Left Ventricular Assist Device Patient

This review will discuss the medical management of pulmonary hypertension in patients with left ventricular assist devices. Although much has been written on the management of primary pulmonary hypertension, also called pulmonary arterial hypertension, this review will instead focus on the treatment of pulmonary hypertension secondary to left heart disease. The relevant pharmacotherapy can be divided into medications for treating heart failure, such as diuretics and β-blockers, and medications for treating pulmonary hypertension. We also discuss important preoperative considerations in patients with pulmonary hypertension; the relationships between left ventricular assist devices, pulmonary hemodynamics, and right heart failure; as well as optimal perioperative and long-term postoperative medical management of pulmonary hypertension.

Tricuspid valve regurgitation after heart transplantation

Tricuspid valve regurgitation (TVR) in the orthotopic heart transplant (OHT) recipient is quite common and has varied clinical sequelae. In its severest forms, it can lead to right-sided failure symptoms indistinguishable from that seen in native heart TVR disease. While certain implantation techniques are widely recognized to reduce the risk of TVR in the cardiac allograft, concomitant tricuspid annuloplasty, while having advocates, is not currently accepted as a routinely established adjunct. Decisions to surgically correct TVR in the OHT recipient must be made carefully, as certain clinical scenarios have high risk of failure. Like in the native heart, anatomic etiologies typically have the greatest chances for success compared to functional etiologies. While repair options have been utilized, there is emerging data to support replacement as the more durable option. While mechanical prostheses are impractical in the heart transplant recipient, biologic valves offer the advantage of continued access to the right ventricle for biopsies in addition to acceptable durability in the low pressure system of the right side.

The inodilator levosimendan in repetitive doses in the treatment of advanced heart failure

Inotropes may be an appropriate response for some patients with advanced heart failure who remain highly symptomatic despite optimization of evidence-based therapy. These patients need to be supported waiting for a heart transplant or ventricular assist device, or may be candidates for inotropy as an intervention in its own right to maintain a patient in the best achievable circumstances. Objectives in such a situation include relieving symptoms, improving quality of life and reducing unplanned hospitalizations and the costs associated with such admissions. Levosimendan, a calcium sensitizer and potassium channel opener with inotrope and vasodilator actions, has emerged as a potentially valuable addition to the armamentarium in this context, used in repeated or intermittent cycles of therapy. Detailed proposals and guidance are offered for the identification of candidate patients with good prospects of a beneficial response to levosimendan, and for the safe and effective implementation of a course of therapy.

Early Biventricular Assist Device Use in Children: A Single-Center Review of 31 Patients

Biventricular assist device (BiVAD) support is considered a risk factor for worse outcomes compared with left ventricular assist device (LVAD) alone for children with end-stage heart failure. It remains unclear whether this is because of the morbidity associated with a second device or the underlying disease severity. We aimed to show that early BiVAD support can result in good survival by analyzing our prospectively collected database for all pediatric patients who underwent BiVAD implantation. From 2005 to 2009, BiVADs were used exclusively. From 2010 to 2014, LVAD alone was considered, maintaining a low threshold for BiVAD support. All BiVADs were pulsatile devices. Thirty-one patients with median age of 3.5 years received BiVAD support. Diagnoses included dilated cardiomyopathy in 17 (55%), myocarditis in 6 (19%), and congenital heart disease in 3 (10%). Survival to transplant was achieved in 27 (87%) with a median duration of 41 days (interquartile range, 15-69). Adverse event rates (per 100 days of support) were bleeding at 0.52, infection at 1.17, and central nervous system dysfunction at 0.78. Of those who survived to transplant, 26 (96%) remain alive with a median follow-up of 55 months. These results show that BiVAD support can bridge patients to transplant with excellent long-term survival.