Clinical myocardial recovery during long-term mechanical support in advanced heart failure: Insights into moving the field forward

Mechanisms of myocardial reverse remodelling and its clinical significance: A scientific statement of the ESC Working Group on Myocardial Function

Cardiovascular disease (CVD) is the leading cause of morbimortality in Europe and worldwide. CVD imposes a heterogeneous spectrum of cardiac remodelling, depending on the insult nature, that is, pressure or volume overload, ischaemia, arrhythmias, infection, pathogenic gene variant, or cardiotoxicity. Moreover, the progression of CVD-induced remodelling is influenced by sex, age, genetic background and comorbidities, impacting patients' outcomes and prognosis. Cardiac reverse remodelling (RR) is defined as any normative improvement in cardiac geometry and function, driven by therapeutic interventions and rarely occurring spontaneously. While RR is the outcome desired for most CVD treatments, they often only slow/halt its progression or modify risk factors, calling for novel and more timely RR approaches. Interventions triggering RR depend on the myocardial insult and include drugs (renin-angiotensin-aldosterone system inhibitors, beta-blockers, diuretics and sodium-glucose cotransporter 2 inhibitors), devices (cardiac resynchronization therapy, ventricular assist devices), surgeries (valve replacement, coronary artery bypass graft), or physiological responses (deconditioning, postpartum). Subsequently, cardiac RR is inferred from the degree of normalization of left ventricular mass, ejection fraction and end-diastolic/end-systolic volumes, whose extent often correlates with patients' prognosis. However, strategies aimed at achieving sustained cardiac improvement, predictive models assessing the extent of RR, or even clinical endpoints that allow for distinguishing complete from incomplete RR or adverse remodelling objectively, remain limited and controversial. This scientific statement aims to define RR, clarify its underlying (patho)physiologic mechanisms and address (non)pharmacological options and promising strategies to promote RR, focusing on the left heart. We highlight the predictors of the extent of RR and review the prognostic significance/impact of incomplete RR/adverse remodelling. Lastly, we present an overview of RR animal models and potential future strategies under pre-clinical evaluation.

Cardiac Reverse Remodeling Mediated by HeartMate 3 Left Ventricular Assist Device: Comparison to Older Generation Devices

Currently, the fully magnetically levitated left ventricular assist device (LVAD) HeartMate 3 (HM3) is the only commercially available device for advanced heart failure (HF) patients. However, the left ventricular (LV) functional and structural changes following mechanical unloading and circulatory support (MCS) with the HM3 have not been investigated. We compared the reverse remodeling induced by the HM3 to older generation continuous-flow LVADs. Chronic HF patients (n = 405) undergoing MCS with HeartWare Ventricular Assist Device (HVAD, n = 115), HM3 (n = 186), and HeartMate II (HM2, n = 104) at four programs were included. Echocardiograms were obtained preimplant and at 1, 3, 6, and 12 months following LVAD implantation. There were no differences in the postimplant serial LV ejection fraction (LVEF) between the devices. The postimplant LV internal diastolic diameter (LVIDd) was significantly lower for HM2 at 3 and 6 months compared with HVAD and HM3. The proportion of patients achieving "cardiac reverse remodeling responder" status (defined as LVEF improvement to ≥40% and LVIDD ≤5.9 cm) was 11.9%, and was similar between devices. HeartMate 3 appears to result in similar cardiac reverse remodeling as older generation CF-LVADs, suggesting that the fully magnetically levitated device technology could provide an effective platform to further study and promote cardiac reverse remodeling.

Association of Renin-Angiotensin-Aldosterone System Inhibitors With Clinical Outcomes, Hemodynamics, and Myocardial Remodeling Among Patients With Advanced Heart Failure on Left Ventricular Assist Device Support

BACKGROUND

We evaluated the potential benefits of renin-angiotensin-aldosterone system inhibitors (RAASi) in patients with left ventricular assist device support.

METHODS AND RESULTS

A total of 165 consecutive patients undergoing left ventricular assist device implant and alive at 6-month on support were studied. RAASi status after 6-month visit along with clinical reasons for nonprescription/uptitration were retrospectively assessed. The primary outcome was a composite of heart failure hospitalization or cardiovascular death between 6 and 24 months after left ventricular assist device implant. Remodeling and hemodynamic outcomes were explored by studying the association of RAASi new prescription/uptitration versus unmodified therapy at 6-month visit with the change in echocardiographic parameters and hemodynamics between 6 and 18 months. After the 6-month visit, 76% of patients were on RAASi. Patients' characteristics among those receiving and not receiving RAASi were mostly similar. Of 85 (52%) patients without RAASi new prescription/uptitration at 6-month visit, 62% had no apparent clinical reason. RAASi were independently associated with the primary outcome (adjusted hazard ratio, 0.31 [95% CI, 0.16-0.69]). The baseline rates of optimal echocardiographic profile (neutral interventricular septum, mitral regurgitation less than mild, and aortic valve opening) and hemodynamic profile (cardiac index ≥2.2 L/min per m2, wedge pressure <18 mm Hg, and right atrial pressure <12 mm Hg) were similar between groups. At 18 months, patients receiving RAASi new prescription/uptitration at 6 months had higher rates of optimal hemodynamic profile (57.5% versus 37.0%; P=0.032) and trends for higher rates of optimal echocardiographic profile (39.6% versus 22.9%; P=0.055) compared with patients with 6-month unmodified therapy. Optimal 18-month hemodynamic and echocardiographic profiles were associated with the primary outcome (log-rank=0.022 and log-rank=0.035, respectively).

CONCLUSIONS

RAASi are associated with improved outcomes and improved hemodynamics among mechanically unloaded patients.

Results of non-elective withdrawal of continuous-flow left ventricular assist devices in selected patients

BACKGROUND

Protocols have been developed to identify patients for elective withdrawal of continuous-flow left ventricular device (cfLVAD) support. However, little is known about non-elective explantation or decommissioning of cfLVADs.

METHODS

A retrospective analysis of all patients who underwent left ventricular assist device (LVAD) explantation or decommissioning at a single center between 2002 and 2021 was performed.

RESULTS

Sixty-one patients underwent withdrawal of a cfLVAD (HeartMate II [Abbott] n = 17, HeartMate 3 [Abbott] n = 2, HeartWare HVAD [Medtronic] n = 36, INCOR [Berlin Heart] n = 6). The median follow-up after withdrawal was 1,039 days. The survival at 5 years was 76.1% (95% CI: 64.2%-95.2%). Predictors of worse outcomes in univariate regressive analysis were the duration of heart failure and the age at LVAD implantation. Of the 61 patients, 40 underwent elective withdrawal following a specific protocol. The other twenty-one patients underwent non-elective withdrawal of the cfLVAD because of device infection (n = 12), device thrombosis (n = 6), device malfunction (n = 2) or due to acute intracerebral bleeding (n = 1), also with an excellent survival at 5 years of 81.3%. (95% CI: 63.8-1). The withdrawal was performed in these patients even though they did not fulfill established criteria for successful explantation or decommissioning like clinical stability (n = 21), left ventricular end-diastolic diameter ≤ 55 mm (n = 3), performance of right heart catheterization (n = 6), or pulmonary artery wedge pressure ≤ 15 mm Hg (n = 3).

CONCLUSION

Non-elective withdrawal is possible in selected patients after discussion in a team of experienced cardiac surgeons, cardiologists, technicians, and VAD coordinators. The appropriate preoperative assessment before decommissioning or explantation of a cfLVAD warrants further investigation.

Clinical myocardial recovery in advanced heart failure with long term left ventricular assist device support

Left ventricular assist-device (LVAD) implantation is a life-saving therapy for patients with advanced heart failure (HF). With chronic unloading and circulatory support, LVAD-supported hearts often show significant reverse remodeling at the structural, cellular and molecular level. However, translation of these changes into meaningful cardiac recovery allowing LVAD explant is lagging. Part of the reason for this discrepancy is lack of anticipation and hence promotion and evaluation for recovery post LVAD implant. There is additional uncertainty about the long-term course of HF following LVAD explant. In selected patients, however, guided by the etiology of HF, duration of disease and other clinical factors, significant functional improvement and LVAD explantation with long-term freedom from recurrent HF events has been demonstrated to be feasible in a reproducible manner. The identified predictors of myocardial recovery suggest that the elective therapeutic use of potentially less invasive VADs for reversal of HF earlier in the disease process is a future goal that warrants further investigation. Hence, it is prudent to develop and implement tools to predict HF reversibility prior to LVAD implant, optimize unloading-promoted recovery with guideline directed medical therapy and monitor for myocardial improvement. This review article summarizes the clinical aspects of myocardial recovery and together with its companion review article focused on the biological aspects of recovery, they aim to provide a useful framework for clinicians and investigators.

Biology of myocardial recovery in advanced heart failure with long-term mechanical support

Cardiac remodeling is an adaptive, compensatory biological process following an initial insult to the myocardium that gradually becomes maladaptive and causes clinical deterioration and chronic heart failure (HF). This biological process involves several pathophysiological adaptations at the genetic, molecular, cellular, and tissue levels. A growing body of clinical and translational investigations demonstrated that cardiac remodeling and chronic HF does not invariably result in a static, end-stage phenotype but can be at least partially reversed. One of the paradigms which shed some additional light on the breadth and limits of myocardial elasticity and plasticity is long term mechanical circulatory support (MCS) in advanced HF pediatric and adult patients. MCS by providing (a) ventricular mechanical unloading and (b) effective hemodynamic support to the periphery results in functional, structural, cellular and molecular changes, known as cardiac reverse remodeling. Herein, we analyze and synthesize the advances in our understanding of the biology of MCS-mediated reverse remodeling and myocardial recovery. The MCS investigational setting offers access to human tissue, providing an unparalleled opportunity in cardiovascular medicine to perform in-depth characterizations of myocardial biology and the associated molecular, cellular, and structural recovery signatures. These human tissue findings have triggered and effectively fueled a "bedside to bench and back" approach through a variety of knockout, inhibition or overexpression mechanistic investigations in vitro and in vivo using small animal models. These follow-up translational and basic science studies leveraging human tissue findings have unveiled mechanistic myocardial recovery pathways which are currently undergoing further testing for potential therapeutic drug development. Essentially, the field is advancing by extending the lessons learned from the MCS cardiac recovery investigational setting to develop therapies applicable to the greater, not end-stage, HF population. This review article focuses on the biological aspects of the MCS-mediated myocardial recovery and together with its companion review article, focused on the clinical aspects, they aim to provide a useful framework for clinicians and investigators.

Left Ventricular Assist Device Implantation in Cancer-Therapy-Related Heart Failure

Objectives: Cancer-therapy-related heart failure (CTrHF) due to cardiotoxic drugs or radiation is a growing cause of end-stage heart failure. Limited knowledge is available concerning the use of continuous-flow left-ventricular-assist devices (cfLVAD) in this setting. Methods: The files of all 1334 patients who underwent cfLVAD implantation between December 2008 and December 2020 were screened for the cause of heart failure. All patients with CTrHF were included in the analysis. Results: A total of 32 patients with a median age of 58 years (IQR: 46–65) were included in the study; 15 (47%) were male. The median time from the first diagnosis of heart failure (HF) to cfLVAD implantation was 6 months (IQR 2–24), and from cancer treatment to cfLVAD implantation 40 months (IQR 5–144). Malignancies comprised non-Hodgkin lymphoma (n = 12, 37%), breast cancer (n = 9, 28%), sarcoma (n = 5, 16%), leukemia (n = 5, 16%), and others (n = 1, 3%). In 24 patients, chemotherapy included anthracyclines (others n = 2, unknown n = 6). Chest radiation was performed in 13 patients (39%). Moreover, 71% were classified as INTERMACS profile 1 or 2. The 30-day survival rate after LVAD implantation was 88%. Rethoracotomy was necessary in nine (29%), and a temporary right ventricular assist device in seven (21%) patients. The median survival was 29 months. There was no significant difference in survival or right HF between patients with CTrHF and a matched control group. Conclusions: CfLVAD implantation is feasible in high-risk patients with CTrHF with or without prior chest radiation.

Ventricular fibrillation after endoscopic retrograde cholangiopancreatography in patient with left ventricular assist device – a case report

Congestive heart failure is a growing global health problem. Left ventricular assist device (LVAD) is a method used to extend the life of patients with congestive heart failure as a definitive treatment or to “bypass” the period until heart transplantation. Ventricular arrhythmias in patients with LVAD are not uncommon. The aim of this paper is to present the case of a patient with an already implanted LVAD and the need for appropriate interdisciplinary medical treatment. Case report: We present the case of a 54-year old patient, A. D., with implanted LVAD - HeartMate 3 due to severe congestive heart failure. The patient was admitted with jaundice at the PHIU Clinic for Gastroenterohepatology with performed endoscopic retrograde cholangiopancreatography (ERCP)) procedure and a stent was placed in the choledochus duct. Immeasurable blood pressure and pulse were recorded in this patient. The ECG was approaching VF (ventricular fibrillation) and it was all asymptomatic by the patient.  LVAD mechanical pump leads to continuous blood flow, which means that patients with LVAD not infrequently have no pulse or measurable blood pressure. Also, in patients with LVAD, ECG pulses are with electrical disturbances. VF and ventricular tachycardia (VT) are ventricular arrhythmias that are often seen on ECG in patients with implanted LVAD. Usually these arrhythmias occur with unknown duration and terminate spontaneously. Conclusion: Patients with LVAD are prone to cardiac arrhythmias. The continuous development of medical devices leads to a continuous educational and clinical approach to patients.                                                                        

LVAD as a Bridge to Remission from Advanced Heart Failure: Current Data and Opportunities for Improvement

Left ventricular assist devices (LVADs) are an established treatment modality for advanced heart failure (HF). It has been shown that through volume and pressure unloading they can lead to significant functional and structural cardiac improvement, allowing LVAD support withdrawal in a subset of patients. In the first part of this review, we discuss the historical background, current evidence on the incidence and assessment of LVAD-mediated cardiac recovery, and out-comes including quality of life after LVAD support withdrawal. In the second part, we discuss current and future opportunities to promote LVAD-mediated reverse remodeling and improve our pathophysiological understanding of HF and recovery for the benefit of the greater HF population.

Outcome of percutaneous HeartMate3 decommissioning: A single-centre experience

OBJECTIVES

To highlight the role of percutaneous left ventricular assist device (LVAD) decommissioning as a safe procedure after myocardial recovery in patients with advanced heart failure.

BACKGROUND

The HeartMate3 LVAD (Abbott, Chicago, IL, USA) is designed to provide circulatory support with enhanced hemocompatibility for patients with advanced heart failure. Most VADs are used as a bridge to heart transplantation; however, in certain cases, myocardial function recovers, and VADs can be explanted after the patient is weaned. Although surgical explantation remains the gold standard, minimally invasive percutaneous decommissioning has been described as a successful alternative. In this study, we present our experience, one-year outcomes, and adverse events associated with percutaneous LVAD decommissioning.

METHODS

We conducted a retrospective review of data from six consecutive patients who underwent percutaneous LVAD decommissioning.

RESULTS

Six patients were enrolled in the study. For all six patients, HM3 decommissioning was completed at least 6 months ago. No technical complications were documented. No strokes were observed within the study period, and the ejection fraction improved. The mean follow-up duration was 18 ± 8.5 months, and the survival rate was 100%.

CONCLUSION

Percutaneous HeartMate3 decommissioning appears to be safe. In particular, the survival after the procedure was 100%, and no events, especially thromboembolic ones, occurred.

Cardiac Fibrosis in the Pressure Overloaded Left and Right Ventricle as a Therapeutic Target

Myocardial fibrosis is a remodeling process of the extracellular matrix (ECM) following cardiac stress. "Replacement fibrosis" is a term used to describe wound healing in the acute phase of an injury, such as myocardial infarction. In striking contrast, ECM remodeling following chronic pressure overload insidiously develops over time as "reactive fibrosis" leading to diffuse interstitial and perivascular collagen deposition that continuously perturbs the function of the left (L) or the right ventricle (RV). Examples for pressure-overload conditions resulting in reactive fibrosis in the LV are systemic hypertension or aortic stenosis, whereas pulmonary arterial hypertension (PAH) or congenital heart disease with right sided obstructive lesions such as pulmonary stenosis result in RV reactive fibrosis. In-depth phenotyping of cardiac fibrosis has made it increasingly clear that both forms, replacement and reactive fibrosis co-exist in various etiologies of heart failure. While the role of fibrosis in the pathogenesis of RV heart failure needs further assessment, reactive fibrosis in the LV is a pathological hallmark of adverse cardiac remodeling that is correlated with or potentially might even drive both development and progression of heart failure (HF). Further, LV reactive fibrosis predicts adverse outcome in various myocardial diseases and contributes to arrhythmias. The ability to effectively block pathological ECM remodeling of the LV is therefore an important medical need. At a cellular level, the cardiac fibroblast takes center stage in reactive fibrotic remodeling of the heart. Activation and proliferation of endogenous fibroblast populations are the major source of synthesis, secretion, and deposition of collagens in response to a variety of stimuli. Enzymes residing in the ECM are responsible for collagen maturation and cross-linking. Highly cross-linked type I collagen stiffens the ventricles and predominates over more elastic type III collagen in pressure-overloaded conditions. Research has attempted to identify pro-fibrotic drivers causing fibrotic remodeling. Single key factors such as Transforming Growth Factor β (TGFβ) have been described and subsequently targeted to test their usefulness in inhibiting fibrosis in cultured fibroblasts of the ventricles, and in animal models of cardiac fibrosis. More recently, modulation of phenotypic behaviors like inhibition of proliferating fibroblasts has emerged as a strategy to reduce pathogenic cardiac fibroblast numbers in the heart. Some studies targeting LV reactive fibrosis as outlined above have successfully led to improvements of cardiac structure and function in relevant animal models. For the RV, fibrosis research is needed to better understand the evolution and roles of fibrosis in RV failure. RV fibrosis is seen as an integral part of RV remodeling and presents at varying degrees in patients with PAH and animal models replicating the disease of RV afterload. The extent to which ECM remodeling impacts RV function and thus patient survival is less clear. In this review, we describe differences as well as common characteristics and key players in ECM remodeling of the LV vs. the RV in response to pressure overload. We review pre-clinical studies assessing the effect of anti-fibrotic drug candidates on LV and RV function and their premise for clinical testing. Finally, we discuss the mode of action, safety and efficacy of anti-fibrotic drugs currently tested for the treatment of left HF in clinical trials, which might guide development of new approaches to target right heart failure. We touch upon important considerations and knowledge gaps to be addressed for future clinical testing of anti-fibrotic cardiac therapies.

Recovery With Temporary Mechanical Circulatory Support While Waitlisted for Heart Transplantation

BACKGROUND

The 2018 U.S. heart allocation system offers an accelerated pathway for heart transplantation to the most urgent patients.

OBJECTIVES

This study sought to determine whether the new allocation system resulted in lower likelihood of candidate recovery.

METHODS

Adult patients waitlisted for heart transplantation with temporary mechanical circulatory support at the time of initial listing between 2010 and 2020 in the United Network for Organ Sharing registry were included. Competing events of heart transplantation, waitlist death or delisting for deteriorating condition, and delisting for improved condition (candidate recovery) were analyzed in the new vs old heart allocation system.

RESULTS

A total of 688 patients were waitlisted with venoarterial extracorporeal membrane oxygenation or a surgical nondischargeable biventricular assist device (status 1 or old 1A). Overall, 2,237 patients were waitlisted with an intra-aortic balloon pump, a percutaneous left ventricular assist device (LVAD), or a surgical nondischargeable LVAD (status 2 or old 1A). Patients waitlisted with venoarterial extracorporeal membrane oxygenation or a nondischargeable biventricular assist device had significantly shorter median waitlist times (5 vs 31 days), higher incidence for cardiac transplantation (81.5% vs 43.0%), and lower incidence of candidate recovery (1.5% vs 7.9%) in the new vs old heart allocation system (all P < 0.05). Patients waitlisted with an intra-aortic balloon pump or percutaneous or a nondischargeable LVAD also had significantly shorter median waitlist times (8 vs 35 days), higher incidence of transplantation (88.9% vs 64.9%), and lower incidence of candidate recovery (0.2% vs 1.6%) in the new vs old heart allocation system (all P < 0.05).

CONCLUSIONS

Current practice of the new allocation system may not offer select temporary mechanical circulatory support patients the opportunity and adequate time to recover to the point of waitlist removal. Further research will determine which patients would benefit from urgent transplantation vs recovery strategy.

Prognostic impact of functional mitral regurgitation prior to left ventricular assist device implantation

BACKGROUND

Functional mitral regurgitation (FMR) is a common finding of advanced heart failure with detrimental effects. The prognostic impact of uncorrected FMR prior to left ventricular assist device (LVAD) implantation remains controversial.

METHODS

Between 2016 and 2019 77 patients underwent continuous-flow LVAD implantation at our institution. 34 patients showed FMR ≥ 2 (MR-group), whereas 43 patients showed FMR < 2 (Control-group). Data was retrospectively analyzed. Primary composite endpoint comprised freedom from death, stroke, pump-thrombosis, major bleeding and right heart failure (RHF) after 1 year.

RESULTS

Baseline characteristics, including the severity of left and right ventricular dysfunction, and periprocedural results were comparable. The overall survival during a mean follow up of 24.9 months was 55.9% in the MR-group versus 58.1% in the Control-group (p = 0.963), whereas 1-year event-free survival was 35.3% in the MR-group compared to 44.2% in the Control-group (p = 0.404). RHF within the first postoperative year occurred more frequently in the MR-group (35.3% vs. 11.6%; p = 0.017). Furthermore, RV function was significantly reduced in comparison to baseline values in the MR-group. 12 months after surgery, 74% of patients in the MR-group were classified as NYHA III in comparison to 24% of patients in the Control-group (p < 0.001).

CONCLUSIONS

Preoperative uncorrected FMR prior to LVAD implantation did not affect overall survival, nevertheless it was associated with an impaired RV function and increased incidence of right heart failure during follow-up. Furthermore, preoperative FMR ≥ 2 was associated with persistent symptoms of heart failure.

MicroRNA-200c/429 mediated regulation of Zeb1 augments N-Cadherin in mouse cardiac mesenchymal cells

Cardiac mesenchymal cells (CMCs) are a promising cell type that showed therapeutic potential in heart failure models. The analysis of the underlying mechanisms by which the CMCs improve cardiac function is on track. This study aimed to investigate the expression of N-Cadherin, a transmembrane protein that enhances cell adhesion, and recently gained attention for differentiation and augmentation of stem cell function. The mouse CMCs were isolated and analyzed for the mesenchymal markers using flow cytometry. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis were used to assess the expression of N-Cadherin along with its counteracting molecule E-Cadherin and their regulator Zeb1 in CMCs and dermal fibroblast. The expression level of miR-200c and miR-429 was analyzed using miRNA assays. Transient transfection of miR-200c followed by qRT-PCR, western blot analysis, and immunostaining was done in CMCs to analyze the expression of Zeb1, N-Cadherin, and E-Cadherin. Flow cytometry analysis showed that CMCs possess mesenchymal markers and absence for hematopoietic and immune cell markers. Increased expression of N-Cadherin and Zeb1 in CMCs was observed in CMCs at both RNA and protein levels compared to fibroblast. We found significant downregulation of miR-200c and miR-429 in CMCs. The ectopic expression of miR-200c in CMCs significantly downregulated Zeb1 and N-Cadherin expression. Our findings suggest that the significant downregulation of miR-200c/429 in CMCs maintains the expression of N-Cadherin, which may be important for its functional integrity.

Framework to Classify Reverse Cardiac Remodeling With Mechanical Circulatory Support: The Utah-Inova Stages

BACKGROUND

Variable definitions and an incomplete understanding of the gradient of reverse cardiac remodeling following continuous flow left ventricular assist device (LVAD) implantation has limited the field of myocardial plasticity. We evaluated the continuum of LV remodeling by serial echocardiographic imaging to define 3 stages of reverse cardiac remodeling following LVAD.

METHODS

The study enrolled consecutive LVAD patients across 4 study sites. A blinded echocardiographer evaluated the degree of structural (LV internal dimension at end-diastole [LVIDd]) and functional (LV ejection fraction [LVEF]) change after LVAD. Patients experiencing an improvement in LVEF ≥40% and LVIDd ≤6.0 cm were termed responders, absolute change in LVEF of ≥5% and LVEF <40% were termed partial responders, and the remaining patients with no significant improvement in LVEF were termed nonresponders.

RESULTS

Among 358 LVAD patients, 34 (10%) were responders, 112 (31%) partial responders, and the remaining 212 (59%) were nonresponders. The use of guideline-directed medical therapy for heart failure was higher in partial responders and responders. Structural changes (LVIDd) followed a different pattern with significant improvements even in patients who had minimal LVEF improvement. With mechanical unloading, the median reduction in LVIDd was -0.6 cm (interquartile range [IQR], -1.1 to -0.1 cm; nonresponders), -1.1 cm (IQR, -1.8 to -0.4 cm; partial responders), and -1.9 cm (IQR, -2.9 to -1.1 cm; responders). Similarly, the median change in LVEF was -2% (IQR, -6% to 1%), 9% (IQR, 6%-14%), and 27% (IQR, 23%-33%), respectively.

CONCLUSIONS

Reverse cardiac remodeling associated with durable LVAD support is not an all-or-none phenomenon and manifests in a continuous spectrum. Defining 3 stages across this continuum can inform clinical management, facilitate the field of myocardial plasticity, and improve the design of future investigations.

Essential roles of the dystrophin-glycoprotein complex in different cardiac pathologies

The dystrophin-glycoprotein complex (DGC), situated at the sarcolemma dynamically remodels during cardiac disease. This review examines DGC remodeling as a common denominator in diseases affecting heart function and health. Dystrophin and the DGC serve as broad cytoskeletal integrators that are critical for maintaining stability of muscle membranes. The presence of pathogenic variants in genes encoding proteins of the DGC can cause absence of the protein and/or alterations in other complex members leading to muscular dystrophies. Targeted studies have allowed the individual functions of affected proteins to be defined. The DGC has demonstrated its dynamic function, remodeling under a number of conditions that stress the heart. Beyond genetic causes, pathogenic processes also impinge on the DGC, causing alterations in the abundance of dystrophin and associated proteins during cardiac insult such as ischemia-reperfusion injury, mechanical unloading, and myocarditis. When considering new therapeutic strategies, it is important to assess DGC remodeling as a common factor in various heart diseases. The DGC connects the internal F-actin-based cytoskeleton to laminin-211 of the extracellular space, playing an important role in the transmission of mechanical force to the extracellular matrix. The essential functions of dystrophin and the DGC have been long recognized. DGC based therapeutic approaches have been primarily focused on muscular dystrophies, however it may be a beneficial target in a number of disorders that affect the heart. This review provides an account of what we now know, and discusses how this knowledge can benefit persistent health conditions in the clinic.

Conventional cardiac surgery in patients with end-stage coronary artery disease: yesterday and today

Surgical therapy of combined coronary artery disease (CAD) and heart failure, also referred to as end-stage CAD, has evolved throughout the years and patients are currently being offered traditional coronary artery bypass grafting (CABG), with or without surgical ventricle restoration (SVR), interventions for ischemic mitral valve regurgitation, heart transplantation or implantation of mechanical cardiovascular support systems. Among surgical methods, operative myocardial revascularization (with or without ventricle restoration) is still playing an important role, aiming at restoration of proper myocardial perfusion, especially if heart muscle viability is present. Facing the donor shortage, CABG may constitute a valuable alternative to transplantation in selected patients. In individuals considered not suitable for surgical revascularization, implantation of mechanical circulatory support (MCS) not only appears as a salvage procedure, but also allows for reevaluation of future therapy directions. This article aims at providing an overview of evolving and current surgical practices in patients with end-stage CAD.

Neurohormonal Blockade and Clinical Outcomes in Patients With Heart Failure Supported by Left Ventricular Assist Devices

Importance

Left ventricular assist devices (LVADs) improve outcomes in patients with advanced heart failure, but little is known about the role of neurohormonal blockade (NHB) in treating these patients.

Objective

To analyze the association between NHB blockade and outcomes in patients with LVADs.

Design, Setting, and Participants

This retrospective cohort analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) included patients from more than 170 centers across the United States and Canada with continuous flow LVADs from 2008 to 2016 who were alive with the device in place at 6 months after implant. The data were analyzed between February and November 2019.

Exposures

Patients were stratified based on exposure to NHB and represented all permutations of the following drug classes: angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, β-blockers, and mineralocorticoid antagonists.

Main Outcomes and Measures

The outcomes of interest were survival at 4 years and quality of life at 2 years based on Kansas City Cardiomyopathy Questionnaire scores and a 6-minute walk test.

Results

A total of 12 144 patients in INTERMACS met inclusion criteria, of whom 2526 (20.8% ) were women, 8088 (66.6%) were white, 3024 (24.9%) were African American, and 753 (6.2%) were Hispanic; the mean (SD) age was 56.8 (12.9) years. Of these, 10 419 (85.8%) were receiving NHB. Those receiving any NHB medication at 6 months had a better survival rate at 4 years compared with patients not receiving NHB (56.0%; 95% CI, 54.5%-57.5% vs 43.9%; 95% CI, 40.5%-47.7%). After sensitivity analyses with an adjusted model, this trend persisted with patients receiving triple therapy with an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, β-blocker, and mineralocorticoid antagonist having the lowest hazard of death compared with patients in the other groups (hazard ratio, 0.34; 95% CI, 0.28-0.41). Compared with patients not receiving NHB, use of NHB was associated with a higher Kansas City Cardiomyopathy Questionnaire score (66.6; bootstrapped 95% CI, 65.8-67.3 vs 63.0; bootstrapped 95% CI, 60.1-65.8; P = .02) and a 6-minute walk test (1103 ft; bootstrapped 95% CI, 1084-1123 ft vs 987 ft; bootstrapped 95% CI, 913-1060 ft; P < .001).

Conclusions and Relevance

Among patients with LVADs who tolerated NHB therapy, continued treatment was associated with improved survival and quality of life. The optimal heart failure regimen for patients after LVAD implant may be the initiation and continuation of guideline-directed medical therapy.

Interleukin-1 Receptor Antagonism as Adjunct Therapy for Heart Failure Patients with Left Ventricular Assist Devices

While left ventricular assist devices (LVAD) successfully unload the failing ventricle, most hearts do not regain sufficient function to allow for device explantation. Herein, we report a pilot series of LVAD patients treated with interleukin-1 receptor antagonism as a biologic adjuvant that safely and effectively treated inflammation so as to create a milieu whereby the heart could functionally improve. This pilot study sets the stage for a more rigorous, controlled trial of interleukin-1 receptor antagonism in treating heart failure and promoting myocardial recovery in patients supported by LVADs.

The Role of Nonglycolytic Glucose Metabolism in Myocardial Recovery Upon Mechanical Unloading and Circulatory Support in Chronic Heart Failure

BACKGROUND

Significant improvements in myocardial structure and function have been reported in some patients with advanced heart failure (termed responders [R]) following left ventricular assist device (LVAD)-induced mechanical unloading. This therapeutic strategy may alter myocardial energy metabolism in a manner that reverses the deleterious metabolic adaptations of the failing heart. Specifically, our previous work demonstrated a post-LVAD dissociation of glycolysis and oxidative-phosphorylation characterized by induction of glycolysis without subsequent increase in pyruvate oxidation through the tricarboxylic acid cycle. The underlying mechanisms responsible for this dissociation are not well understood. We hypothesized that the accumulated glycolytic intermediates are channeled into cardioprotective and repair pathways, such as the pentose-phosphate pathway and 1-carbon metabolism, which may mediate myocardial recovery in R.

METHODS

We prospectively obtained paired left ventricular apical myocardial tissue from nonfailing donor hearts as well as R and nonresponders at LVAD implantation (pre-LVAD) and transplantation (post-LVAD). We conducted protein expression and metabolite profiling and evaluated mitochondrial structure using electron microscopy.

RESULTS

Western blot analysis shows significant increase in rate-limiting enzymes of pentose-phosphate pathway and 1-carbon metabolism in post-LVAD R (post-R) as compared with post-LVAD nonresponders (post-NR). The metabolite levels of these enzyme substrates, such as sedoheptulose-6-phosphate (pentose phosphate pathway) and serine and glycine (1-carbon metabolism) were also decreased in Post-R. Furthermore, post-R had significantly higher reduced nicotinamide adenine dinucleotide phosphate levels, reduced reactive oxygen species levels, improved mitochondrial density, and enhanced glycosylation of the extracellular matrix protein, α-dystroglycan, all consistent with enhanced pentose-phosphate pathway and 1-carbon metabolism that correlated with the observed myocardial recovery.

CONCLUSIONS

The recovering heart appears to direct glycolytic metabolites into pentose-phosphate pathway and 1-carbon metabolism, which could contribute to cardioprotection by generating reduced nicotinamide adenine dinucleotide phosphate to enhance biosynthesis and by reducing oxidative stress. These findings provide further insights into mechanisms responsible for the beneficial effect of glycolysis induction during the recovery of failing human hearts after mechanical unloading.

Outcomes of patients after successful left ventricular assist device explantation: a EUROMACS study

AIMS

Sufficient myocardial recovery with the subsequent explantation of a left ventricular assist device (LVAD) occurs in approximately 1-2% of the cases. However, follow-up data about this condition are scarcely available in the literature. This study aimed to report the long-term outcomes and clinical management following LVAD explantation.

METHODS AND RESULTS

An analysis of the European Registry for Patients with Mechanical Circulatory Support was performed to identify all adult patients with myocardial recovery and successful explantation. Pre-implant characteristics were retrieved and compared with the non-recovery patients. The follow-up data after explantation were collected via a questionnaire. A Kaplan-Meier analysis for freedom of the composite endpoint of death, heart transplantation, LVAD reimplantion, or heart failure (HF) relapse was conducted. A total of 45 (1.4%) cases with myocardial recovery resulting in successful LVAD explantation were identified. Compared with those who did not experience myocardial recovery, the explanted patients were younger (44 vs. 56 years, P < 0.001), had a shorter duration of cardiac disease (P < 0.001), and were less likely to have ischaemic cardiomyopathy (9% vs. 41.8%, P < 0.001). Follow-up after explantation could be acquired in 28 (62%) cases. The median age at LVAD implantation was 43 years (inter-quartile range: 29-52), and 23 (82%) were male. Baseline left ventricular ejection fraction was 18% (inter-quartile range: 10-20%), and 60.7% of the patients had Interagency Registry for Mechanically Assisted Circulatory Support Profile 1 or 2. Aetiologies of HF were dilated cardiomyopathy in 36%, myocarditis in 32%, and ischaemic in 14% of the patients, and 18% had miscellaneous aetiologies. The devices implanted were HeartMate II in 14 (50%), HVAD in 11 (39%), HeartMate 3 in 2 (7%), and 1 unknown with a median duration of support of 410 days (range: 59-1286). The median follow-up after explantation was 26 months (range 0.3-73 months), and 82% of the patients were in New York Heart Association Class I or II. Beta-blockers were prescribed to 85%, angiotensin-converting enzyme inhibitors to 71%, and loop diuretics to 50% of the patients, respectively. Freedom from the composite endpoint was 100% after 30 days and 88% after 2 years.

CONCLUSIONS

The survival after LVAD explantation is excellent without the need for heart transplantation or LVAD reimplantation. Only a minority of the patients suffer from a relapse of significant HF.

Use of Ventricular Assist Devices and Heart Transplantation for Advanced Heart Failure

There are only 2 treatments for the thousands of patients who progress to the most advanced form of heart failure despite the application of guideline-based medical therapy, use of ventricular assist devices and heart transplantation. There has been a great deal of progress in both of these therapies that have led to improved outcomes including significant improvement in survival and functional capacity. Heart transplantation offers the best short- and long-term survival for patients with end-stage heart failure, and the majority of these recipients achieve relatively limitless functional capacity for their age. However, the chronic shortage of available donors limits the number of recipients in the United States to an only 2500 patients/y or only a fraction of potential candidates. The significant improvement in outcomes now possible with durable ventricular assist devices has led to a significant increase in their use, which now exceeds the volume of heart transplants in the United States, with the greatest growth in use for those not considered to be candidates for heart transplantation, previously referred to as destination therapy. This article will review the substantial progress that has taken place for both of these life-saving treatment options, as well as the future directions.

Comparative analysis of cardiac mechano-energetics in isolated hearts supported by pulsatile or rotary blood pumps

The previously more frequently implanted pulsatile blood pumps (PBPs) showed higher recovery rates than the currently preferred rotary blood pumps (RBPs), with unclear causality. The aim of this study was to comparatively assess the capability of PBPs and RPBs to unload the left ventricle and maintain cardiac energetics as a possible implication for recovery. An RBP and a heartbeat synchronized PBP were alternately connected to isolated porcine hearts. Rotational speed of RBPs was set to different support levels. For PBP support, the start of ejection was phased to different points during the cardiac cycle, prescribed as percentage delays from 0% to 90%. Cardiac efficiency, quantified by the ratio of external work over myocardial oxygen consumption, was determined. For RBP support, higher degrees of RBP support correlated with lower left atrial pressures (LAP) and lower cardiac efficiency (r = 0.91 ± 0.12). In contrast, depending on the phase delay of a PBP, LAP and cardiac efficiency exhibited a sinusoidal relationship with the LAP minimum at 90% and efficiency maximum at 60%. Phasing of a PBP offers the possibility to maintain a high cardiac efficiency and simultaneously unload the ventricle. These results warrant future studies investigating whether optimized cardiac energetics promotes functional recovery with LVAD therapy.

An in silico twin for epicardial augmentation of the failing heart

Advances in ventricular assist device (VAD) technology for the treatment of end-stage congestive heart failure (CHF) are needed to cope with the increasing numbers of patients that cannot be provided with donor hearts for transplantation. We develop and investigate a novel extravascular VAD technology that provides biventricular, epicardial pressure support for the failing heart. This novel VAD concept avoids blood contact that is accompanied with typical complications such as coagulation and infections. To date, in vivo porcine model results with a prototype of the implant exist, further studies to improve the implant's performance and promote its applicability in humans are needed. In this contribution, we present a personalised functional digital twin of the heart, the vascular system, and the novel VAD technology in terms of a calibrated, customized computational model. The calibration procedure is based on patient-specific measurements and is performed by solving an inverse problem. This in silico model is able to (a) confirm in vivo experimental data, (b) predict healthy and pathologic ventricular function, and (c) assess the beneficial impact of the novel VAD concept to a high level of fidelity. The model shows very good agreement with in vivo data and reliably predicts increases in stroke volume and left ventricular pressure with increasing ventricular support. Furthermore, the digital twin allows insight into quantities that are poorly or not at all amenable in any experimental setup. Conclusively, the model's ability to link integral hemodynamic variables to local tissue mechanical deformation makes it a highly valuable tool for the dimensioning of novel VAD technologies and future treatment strategies in heart failure. The presented in silico twin enhances in vivo studies by facilitating the accessibility and increasing the range of quantities of interest. Because of its flexibility in the assessment of design variants and optimization loops, it may substantially contribute to a reduction of the amount of animal experiments in this and similar settings.

Insights Into Myocardial Oxygen Consumption, Energetics, and Efficiency Under Left Ventricular Assist Device Support Using Noninvasive Pressure-Volume Loops

Background:

Assessment of left ventricular (LV) recovery under continuous-flow LV assist device therapy is hampered by concomitant pump support. We describe derivation of noninvasive pressure-volume loops in continuous-flow LV assist device patients and demonstrate an application in the assessment of recovery.

Methods and Results:

Using pump controller parameters and noninvasive arterial pressure waveforms, central aortic pressure, outflow conduit pressure gradient, and instantaneous LV pressure were calculated. Instantaneous LV volumes were calculated from echocardiographic LV end-diastolic volume accounting for the integral of pump flow with respect to time and aortic ejection volume derived from the pump speed waveform. Pressure-volume loops were derived during pump speed adjustment and following bolus intravenous milrinone to assess changes in loading conditions and contractility, respectively. Fourteen patients were studied. Baseline noninvasive LV end-diastolic pressure correlated with invasive pulmonary arterial wedge pressure ( r 2 =0.57, root mean square error 5.0 mm Hg, P =0.003). Measured noninvasively, milrinone significantly increased LV ejection fraction (40.3±13.6% versus 36.8±14.2%, P <0.0001), maximum dP/dt (623±126 versus 555±122 mm Hg/s, P =0.006), and end-systolic elastance (1.03±0.57 versus 0.89±0.38 mm Hg/mL, P =0.008), consistent with its expected inotropic effect. Milrinone reduced myocardial oxygen consumption (0.15±0.06 versus 0.16±0.07 mL/beat, P =0.003) and improved myocardial efficiency (43.7±14.0% versus 41.2±15.5%, P =0.001). Reduced pump speed caused increased LV end-diastolic volume (190±80 versus 165±71 mL, P <0.0001) and LV end-diastolic pressure (14.3±10.2 versus 9.9±9.3 mm Hg, P =0.024), consistent with a predictable increase in preload. There was increased myocardial oxygen consumption (0.16±0.07 versus 0.14±0.06 mL O 2 /beat, P <0.0001) despite unchanged stroke work ( P =0.24), reflecting decreased myocardial efficiency (39.2±12.7% versus 45.2±17.0%, P =0.003).

Conclusions:

Pressure-volume loops are able to be derived noninvasively in patients with the HeartWare HVAD and can detect induced changes in load and contractility.

Intraventricular placement of a spring expander does not attenuate cardiac atrophy of the healthy heart induced by unloading via heterotopic heart transplantation

An important complication of the prolonged left ventricle assist device support in patients with heart failure is unloading-induced cardiac atrophy which proved resistant to various treatments. Heterotopic heart transplantation (HTx) is the usual experimental model to study this process. We showed previously that implantation of the newly designed intraventricular spring expander can attenuate the atrophy when examined after HTx in the failing heart (derived from animals with established heart failure). The present study aimed to examine if enhanced isovolumic loading achieved by implantation of the expander would attenuate cardiac post-HTx atrophy also in the healthy heart. Cardiac atrophy was assessed as the ratio of the transplanted-to-native heart weight (HW) and its degree was determined on days 7, 14, 21 and 28 after HTx. The transplantation resulted in 32±3, 46±2, 48±3 and 46±3 % HW loss when measured at the four time points; implantation of the expander had no significant effect on these decreases. We conclude that enhanced isovolumic loading achieved by intraventricular implantation of the expander does not attenuate the development of cardiac atrophy after HTx in the healthy heart. This indicates that such an approach does not represent a useful therapeutic measure to attenuate the development of unloading-induced cardiac atrophy.

Left Ventricular Assist Devices (LVADS): History, Clinical Application and Complications

Congestive heart failure is a major cause of morbidity and mortality as well as a major health care cost in the developed world. Despite the introduction of highly effective heart failure medical therapies and simple devices such as cardiac resynchronization therapy that reduce mortality, improve cardiac function and quality of life, there remains a large number of patients who do not respond to these therapies or whose heart failure progresses despite optimal therapy. For these patients, cardiac transplantation is an option but is limited by donor availability as well as co-morbidities which may limit survival post-transplant. For these patients, left ventricular assist devices (LVADs) offer an alternative that can improve survival as well as exercise tolerance and quality of life. These devices have continued to improve as technology has improved with substantially improved durability of the devices and fewer post-implant complications. Pump thrombosis, stroke, gastrointestinal bleeding and arrhythmias post-implant have become less common with the newest devices, making destination therapy where ventricular assist device are implanted permanently in patients with advanced heart failure, a reality and an appropriate option for many patients. This may offer an opportunity for long term survival in many patients. As the first of the totally implantable devices are introduced and go to clinical trials, LVADs may be introduced that may truly be alternatives to cardiac transplantation in selected patients. Post-implant right ventricular failure remains a significant complication and better ways to identify patients at risk as well as to manage this complication must be developed.

Reverse Ramp Testing in Left Ventricular Assist Device Support and Myocardial Recovery

Mechanical unloading with left ventricular assist device (LVAD) support can lead to clinically meaningful reversal of stress-related compensatory mechanisms. However, true assessment of left ventricular ejection fraction (LVEF) is not possible, whereas the left ventricle is unloaded by LVAD therapy making identification of patients with myocardial recovery even more challenging. We introduce our new protocol, the "reverse ramp test" for HeartWare HVAD, HeartMate II, and HeartMate 3. The reverse ramp is transthoracic echo (TTE) and right heart catheterization (RHC)-based protocol with LVAD turn down steps to minimal support allowing for a more accurate assessment of myocardial function.

The heterotopic heart transplantation in mice as a small animal model to study mechanical unloading - Establishment of the procedure, perioperative management and postoperative scoring

BACKGROUND

Unloading of failing hearts by left ventricular assist devices induces an extensive cardiac remodeling which may lead to a reversal of the initial phenotype-or to its deterioration. The mechanisms underlying these processes are unclear.

HYPOTHESIS

Heterotopic heart transplantion (hHTX) is an accepted model for the study of mechanical unloading in rodents. The wide variety of genetically modified strains in mice provides an unique opportunity to examine remodeling pathways. However, the procedure is technically demanding and has not been extensively used in this area. To support investigators adopting this method, we present our experience establishing the abdominal hHTX in mice and describe refinements to the technique.

METHODS

In this model, the transplanted heart is vascularised but implanted in series, and therefore does not contribute to systemic circulation and results in a complete mechanical unloading of the donor heart. Training followed a systematic program using a combination of literature, video tutorials, cadaveric training, direct observation and training in live animals.

RESULTS

Successful transplantation was defined as a recipient surviving > 24 hours with a palpable, beating apex in the transplanted heart and was achieved after 20 transplants in live animals. A success rate of 90% was reached after 60 transplants. Operative time was shown to decrease in correlation with increasing number of procedures from 200 minutes to 45 minutes after 60 operations. Cold/warm ischemia time improved from 45/100 to 10/20 minutes. Key factors for success and trouble shootings were identified.

CONCLUSION

Abdominal hHTX in the mouse may enable future examination of specific pathways in unloading induced myocardial remodeling. Establishment of the technique, however, is challenging. Structured training programs utilising a variety of training methods can help to expedite the process. Postoperative management, including daily scoring increases animal wellbeing and helps to predict survival.

Analysis of fibrosis in control or pressure overloaded rat hearts after mechanical unloading by heterotopic heart transplantation

Mechanical unloading (MU) by implantation of left ventricular assist devices (LVAD) has become clinical routine. This procedure has been shown to reverse cardiac pathological remodeling, with the underlying molecular mechanisms incompletely understood. Most studies thus far were performed in non-standardized human specimens or MU of healthy animal hearts. Our study investigates cardiac remodeling processes in sham-operated healthy rat hearts and in hearts subjected to standardized pathological pressure overload by transverse aortic constriction (TAC) prior to MU by heterotopic heart transplantation (hHTx/MU). Rats underwent sham or TAC surgery. Disease progression was monitored by echocardiography prior to MU by hHTx/MU. Hearts after TAC or TAC combined with hHTx/MU were removed and analyzed by histology, western immunoblot and gene expression analysis. TAC surgery resulted in cardiac hypertrophy and impaired cardiac function. TAC hearts revealed significantly increased cardiac myocyte diameter and mild fibrosis. Expression of hypertrophy associated genes after TAC was higher compared to hearts after hHTx/MU. While cardiac myocyte cell diameter regressed to the level of sham-operated controls in all hearts subjected to hHTx/MU, fibrotic remodeling was significantly exacerbated. Transcription of pro-fibrotic and apoptosis-related genes was markedly augmented in all hearts after hHTx/MU. Sarcomeric proteins involved in excitation-contraction coupling displayed significantly lower phosphorylation levels after TAC and significantly reduced total protein levels after hHTx/MU. Development of myocardial fibrosis, cardiac myocyte atrophy and loss of sarcomeric proteins was observed in all hearts that underwent hHTX/MU regardless of the disease state. These results may help to explain the clinical experience with low rates of LVAD removal due to lack of myocardial recovery.

Outflow Cannula Systolic Slope in Patients With Left Ventricular Assist Devices: A Novel Marker of Myocardial Contractility

Left ventricular (LV) unloading with a LV assist device (LVAD) reverse remodels the heart and may lead to favorable changes in cellular architecture and LV geometry promoting myocardial recovery. Currently, there are no standardized methods for evaluating myocardial recovery. This study assesses the systolic slope of the LVAD outflow cannula as a marker for myocardial contractility. Doppler echocardiography (transthoracic echocardiogram [TTE]) of the LVAD outflow cannula and TTE of the LV cavity were prospectively collected in 57 patients with LVADs. Systolic acceleration of the LVAD outflow cannula was measured in each patient as the peak change of velocity over time (dv/dt) during systole from continuous-wave Doppler signal acquired from the LVAD outflow cannula. Ventricular volumes were concurrently measured by TTE. In a subset of 10 patients, the systolic slope was measured during each stage of a ramp study to study the properties of this parameter across a variety of loading conditions. The systolic slope of the LVAD outflow cannula was successfully measured in 53 of 57 patients (93%). Systolic slope strongly correlated with ejection fraction (EF) (R = 0.92). Analysis of systolic slope stratified by EF (EF >30%, EF 20-30%, EF 10-20%, and EF <10%) revealed systolic slopes that were significantly different between the groups (1,371 cm/s ± 324; 983 cm/s ± 122; 578 cm/s ± 139; and 495 cm/s ± 107, respectively; p < 0.001). Systolic slope did not change significantly across variable preload and afterload conditions during a ramp study. Systolic slope of the LVAD outflow cannula strongly correlates with EF and can be used to assess underlying myocardial contractility across a variety of LVAD loading conditions.

Sir Magdi H. Yacoub, the Leonardo da Vinci of cardiac surgery

The second half of the 20th century witnessed the emergence and the triumph of cardiac surgery. One of the legends of the period is Sir Magdi H. Yacoub (1935-), pioneer surgeon, scientist, master craftsman, and philanthropist. Yacoub established heart transplantation in the United Kingdom and introduced a variety of new concepts and new operations. His recent work focuses on molecular cardiology. This personal reminiscence highlights his personality, his surgical dexterity, and his many accomplishments and honors.

Recovery of failing hearts by mechanical unloading: Pathophysiologic insights and clinical relevance

By reduction of ventricular wall-tension and improving the blood supply to vital organs, ventricular assist devices (VADs) can eliminate the major pathophysiological stimuli for cardiac remodeling and even induce reverse remodeling occasionally accompanied by clinically relevant reversal of cardiac structural and functional alterations allowing VAD explantation, even if the underlying cause for the heart failure (HF) was dilated cardiomyopathy. Accordingly, a tempting potential indication for VADs in the future might be their elective implantation as a therapeutic strategy to promote cardiac recovery in earlier stages of HF, when the reversibility of morphological and functional alterations is higher. However, the low probability of clinically relevant cardiac improvement after VAD implantation and the lack of criteria which can predict recovery already before VAD implantation do not allow so far VAD implantations primarily designed as a bridge to cardiac recovery. The few investigations regarding myocardial reverse remodeling at cellular and sub-cellular level in recovered patients who underwent VAD explantation, the differences in HF etiology and pre-implant duration of HF in recovered patients and also the differences in medical therapy used by different institutions during VAD support make it currently impossible to understand sufficiently all the biological processes and mechanisms involved in cardiac improvement which allows even VAD explantation in some patients. This article aims to provide an overview of the existing knowledge about VAD-promoted cardiac improvement focusing on the importance of bench-to-bedside research which is mandatory for attaining the future goal to use long-term VADs also as therapy-devices for reversal of chronic HF.

Outcomes from a recovery protocol for patients with continuous-flow left ventricular assist devices

BACKGROUND

In this retrospective analysis we evaluated a standardized echocardiographic assessment and an invasive technique for patient selection for successful continuous-flow left ventricular assist device (CF-LVAD) explantation.

METHODS

Inclusion criteria for LVAD recovery assessment were: clinically stable condition; LVAD support for >6 months; physical activity; normal echocardiography findings; and no more than mild valvular disease and aortic valve opening. In a second step, echocardiography was performed under CF-LVAD reduction and stop conditions (PStopE). In the third step, patients who presented with stable parameters underwent right heart catheterization under CF-LVAD stoppage and occlusion of the outflow graft with a balloon catheter. Criteria for explantation were normal pulmonary artery pressure and pulmonary capillary wedge pressure <16 mmHg.

RESULTS

Thirty-three of 424 patients entered the second step of evaluation and 20 entered the third step. Fourteen presented positive results and the pump was successfully explanted. The PCWP at baseline was 8.5 (2.8) mmHg in the explantation group and 10.6 (2.8) mmHg in the non-explantation group (p = 0.105). It increased to 10.9 (3.0) mmHg vs 20.8 (4.9) mmHg under outflow graft occlusion. The wedge pressure was significantly higher in the non-explantation group (p < 0.001). Median duration of follow-up after explantation was 9.74 (interquartile range 4.3 to 20.60) months, with survival of 93%.

CONCLUSIONS

The protocol presented is feasible and safe. The criteria applied provide good patient selection for sustained mid-term myocardial recovery after LVAD explantation.

Mechanical Unloading in Heart Failure

Myocardial injury induces significant changes in ventricular structure and function at both the cellular and anatomic level, leading to ventricular remodeling and subsequent heart failure. Unloading left ventricular pressure has been studied in both the short-term and long-term settings, as a means of preventing or reversing cardiac remodeling. In acute myocardial infarction, cardiac unloading is used to reduce oxygen demand and limit infarct size. Research has demonstrated the benefits of short-term unloading with mechanical circulatory support devices before reperfusion in the context of acute myocardial infarction with cardiogenic shock, and a confirmatory trial is ongoing. In chronic heart failure, ventricular unloading using mechanical circulatory support can reverse many of the cellular and anatomic changes that accompany ventricular remodeling. Ongoing research is evaluating the ability of left ventricular assist devices to promote myocardial recovery and remission from clinical heart failure.

Isovolumic loading of the failing heart by intraventricular placement of a spring expander attenuates cardiac atrophy after heterotopic heart transplantation

Cardiac atrophy is the most common complication of prolonged application of the left ventricle (LV) assist device (LVAD) in patients with advanced heart failure (HF). Our aim was to evaluate the course of unloading-induced cardiac atrophy in rats with failing hearts, and to examine if increased isovolumic loading obtained by intraventricular implantation of an especially designed spring expander would attenuate this process. Heterotopic abdominal heart transplantation (HT_x) was used as a rat model of heart unloading. HF was induced by volume overload achieved by creation of the aorto-caval fistula (ACF). The degree of cardiac atrophy was assessed as the weight ratio of the heterotopically transplanted heart (HW) to the control heart. Isovolumic loading was increased by intraventricular implantation of a stainless steel three-branch spring expander. The course of cardiac atrophy was evaluated on days 7, 14, 21, and 28 after HT_x Seven days unloading by HT_x in failing hearts sufficed to substantially decrease the HW (-59 ± 3%), the decrease progressed when measured on days 14, 21, and 28 after HT_x Implantation of the spring expander significantly reduced the decreases in whole HW at all the time points (-39 ± 3 compared with -59 ± 3, -52 ± 2 compared with -69 ± 3, -51 ± 2 compared with -71 ± 2, and -44 ± 2 compared with -71 ± 3%, respectively; P<0.05 in each case). We conclude that the enhanced isovolumic heart loading obtained by implantation of the spring expander attenuates the development of unloading-induced cardiac atrophy in the failing rat heart.

Effects of increased myocardial tissue concentration of myristic, palmitic and palmitoleic acids on the course of cardiac atrophy of the failing heart unloaded by heterotopic transplantation

The present experiments were performed to evaluate if increased heart tissue concentration of fatty acids, specifically myristic, palmitic and palmitoleic acids that are believed to promote physiological heart growth, can attenuate the progression of unloading-induced cardiac atrophy in rats with healthy and failing hearts. Heterotopic abdominal heart transplantation (HT(x)) was used as a model for heart unloading. Cardiac atrophy was assessed from the ratio of the native- to-transplanted heart weight (HW). The degree of cardiac atrophy after HT(x) was determined on days 7, 14, 21 and 28 after HT(x) in recipients of either healthy or failing hearts. HT(x) of healthy hearts resulted in 23+/-3, 46+/-3, 48+/-4 and 46+/-4 % HW loss at the four time-points. HT(x) of the failing heart resulted in even greater HW losses, of 46+/-4, 58+/-3, 66+/-2 and 68+/-4 %, respectively (P<0.05). Activation of "fetal gene cardiac program" (e.g. beta myosin heavy chain gene expression) and "genes reflecting cardiac remodeling" (e.g. atrial natriuretic peptide gene expression) after HT(x) was greater in failing than in healthy hearts (P<0.05 each time). Exposure to isocaloric high sugar diet caused significant increases in fatty acid concentrations in healthy and in failing hearts. However, these increases were not associated with any change in the course of cardiac atrophy, similarly in healthy and post-HT(x) failing hearts. We conclude that increasing heart tissue concentrations of the fatty acids allegedly involved in heart growth does not attenuate the unloading-induced cardiac atrophy.

Mechanical Circulatory Support in the Treatment of Advanced Heart Failure

According to the Centers for Disease Control, heart failure (HF) remains a pervasive condition with high morbidity and mortality, affecting 5.8 million people in the United States and 23 million worldwide. For patients with refractory end-stage HF, heart transplantation is the "gold standard" for definitive treatment. However, the demand for heart transplantation has consistently exceeded the availability of donor hearts, with approximately 2331 orthotopic heart transplantations performed in the United States in 2015 despite an estimated 100 000 to 250 000 patients with New York Heart Association class IIIB or IV symptoms that are refractory to medical treatment, making such patients potential transplant candidates. As such, the need for mechanical circulatory support (MCS) to treat patients with end-stage HF has become paramount. In this review, we focus on the history, advancements, and current use of durable MCS device therapy in the treatment of advanced heart failure.

Clinical and histopathological effects of heart failure drug therapy in advanced heart failure patients on chronic mechanical circulatory support

AIMS

Adjuvant heart failure (HF) drug therapy in patients undergoing chronic mechanical circulatory support (MCS) is often used in conjunction with a continuous-flow left ventricular assist device (LVAD), but its potential impact is not well defined. The objective of the present study was to examine the effects of conventional HF drug therapy on myocardial structure and function, peripheral organ function and the incidence of adverse events in the setting of MCS.

METHODS AND RESULTS

Patients with chronic HF requiring LVAD support were prospectively enrolled. Paired myocardial tissue samples were obtained prior to LVAD implantation and at transplantation for histopathology. The Meds group comprised patients treated with neurohormonal blocking therapy (concurrent beta-blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, and aldosterone antagonist), and the No Meds group comprised patients on none of these. Both the Meds (n = 37) and No Meds (n = 44) groups experienced significant improvements in cardiac structure and function over the 6 months following LVAD implantation. The degree of improvement was greater in the Meds group, including after adjustment for baseline differences. There were no differences between the two groups in arrhythmias, end-organ injury, or neurological events. In patients with high baseline pre-LVAD myocardial fibrosis, treatment with HF drug therapy was associated with a reduction in fibrosis.

CONCLUSIONS

Clinical and histopathological evidence showed that adjuvant HF drug therapy was associated with additional favourable effects on the structure and function of the unloaded myocardium that extended beyond the beneficial effects attributed to LVAD-induced unloading alone. Adjuvant HF drug therapy did not influence the incidence of major post-LVAD adverse events during the follow-up period.

Reverse remodelling and myocardial recovery in heart failure

Advances in medical and device therapies have demonstrated the capacity of the heart to reverse the failing phenotype. The development of normative changes to ventricular size and function led to the concept of reverse remodelling. Among heart failure therapies, durable mechanical circulatory support is most consistently associated with the largest degree of reverse remodelling. Accordingly, research to analyse human tissue after a period of mechanical circulatory support continues to yield a wealth of information. In this Review, we summarize the latest findings on reverse remodelling and myocardial recovery. Accumulating evidence shows that the molecular changes associated with heart failure, in particular in the transcriptome, metabalome, and extracellular matrix, persist in the reverse-remodelled myocardium despite apparent normalization of macrolevel properties. Therefore, reverse remodelling should be distinguished from true myocardial recovery, in which a failing heart regains both normal function and molecular makeup. These findings have implications for future research to develop therapies to repair fully the failing myocardium. Meanwhile, recognition by society guidelines of this new clinical phenotype, which is coming to be known as a state of heart failure remission, underscores the need to accurately define and identify reverse modelled myocardium for the establishment of appropriate therapies.

Left Ventricular Assist Devices for Lifelong Support

Continuous-flow left ventricular assist devices (LVADs) have revolutionized advanced heart failure care. These compact, fully implantable heart pumps are capable of providing meaningful increases in survival, functional capacity, and quality of life. Implantation volumes continue to grow, but several challenges remain to be overcome before LVADs will be considered as the therapy of choice for all patients with advanced heart failure. They must be able to consistently extend survival for the long term (7 to 10 years), rather than the midterm (3 to 5 years) more typical of contemporary devices; they must incorporate design elements that reduce shear stress and avoid stasis to reduce the frequent adverse events of bleeding, stroke, and pump thrombosis; and they must become more cost-effective. The advancements in engineering, implantation technique, and medical management detailed in this review will highlight the progress made toward achieving lifelong LVAD support and the challenges that remain.