Magnitude and time course of changes induced by continuous-flow left ventricular assist device unloading in chronic heart failure: insights into cardiac recovery

Deactivation of LVAD support for myocardial recovery-surgical perspectives

Left ventricular assist devices (LVADs) are excellent therapies for advanced heart failure patients either bridged to transplant or for lifetime use. LVADs also allow for reverse remodeling of the failing heart that is often associated with functional improvement. Indeed, growing enthusiasm exists to better understand this population of patients, whereby the LVAD is used as an adjunct to mediate myocardial recovery. When patients achieve benchmarks suggesting that they no longer need LVAD support, questions related to the discontinuation of LVAD therapy become front and center. The purpose of this review is to provide a surgical perspective on the practical and technical issues surrounding LVAD deactivation.

Impact of Diabetes and Glycemia on Cardiac Improvement and Adverse Events Following Mechanical Circulatory Support

BACKGROUND

Type 2 diabetes is prevalent in cardiovascular disease and contributes to excess morbidity and mortality. We sought to investigate the effect of glycemia on functional cardiac improvement, morbidity, and mortality in durable left ventricular assist device (LVAD) recipients.

METHODS AND RESULTS

Consecutive patients with an LVAD were prospectively evaluated (n=531). After excluding patients missing pre-LVAD glycated hemoglobin (HbA1c) measurements or having inadequate post-LVAD follow-up, 375 patients were studied. To assess functional cardiac improvement, we used absolute left ventricular ejection fraction change (ΔLVEF: LVEF post-LVAD-LVEF pre-LVAD). We quantified the association of pre-LVAD HbA1c with ΔLVEF as the primary outcome, and all-cause mortality and LVAD-related adverse event rates (ischemic stroke/transient ischemic attack, intracerebral hemorrhage, gastrointestinal bleeding, LVAD-related infection, device thrombosis) as secondary outcomes. Last, we assessed HbA1c differences pre- and post-LVAD. Patients with type 2 diabetes were older, more likely men suffering ischemic cardiomyopathy, and had longer heart failure duration. Pre-LVAD HbA1c was inversely associated with ΔLVEF in patients with nonischemic cardiomyopathy but not in those with ischemic cardiomyopathy, after adjusting for age, sex, heart failure duration, and left ventricular end-diastolic diameter. Pre-LVAD HbA1c was not associated with all-cause mortality, but higher pre-LVAD HbA1c was shown to increase the risk of intracerebral hemorrhage, LVAD-related infection, and device thrombosis by 3 years on LVAD support (P<0.05 for all). HbA1c decreased from 6.68±1.52% pre-LVAD to 6.11±1.33% post-LVAD (P<0.001).

CONCLUSIONS

Type 2 diabetes and pre-LVAD glycemia modify the potential for functional cardiac improvement and the risk for adverse events on LVAD support. The degree and duration of pre-LVAD glycemic control optimization to favorably affect these outcomes warrants further investigation.

Integrating molecular and clinical variables to predict myocardial recovery

Mechanical unloading and circulatory support with left ventricular assist devices (LVADs) mediate significant myocardial improvement in a subset of advanced heart failure (HF) patients. The clinical and biological phenomena associated with cardiac recovery are under intensive investigation. Left ventricular (LV) apical tissue, alongside clinical data, were collected from HF patients at the time of LVAD implantation (n=208). RNA was isolated and mRNA transcripts were identified through RNA sequencing and confirmed with RT-qPCR. To our knowledge this is the first study to combine transcriptomic and clinical data to derive predictors of myocardial recovery. We used a bioinformatic approach to integrate 59 clinical variables and 22,373 mRNA transcripts at the time of LVAD implantation for the prediction of post-LVAD myocardial recovery defined as LV ejection fraction (LVEF) ≥40% and LV end-diastolic diameter (LVEDD) ≤5.9cm, as well as functional and structural LV improvement independently by using LVEF and LVEDD as continuous variables, respectively. To substantiate the predicted variables, we used a multi-model approach with logistic and linear regressions. Combining RNA and clinical data resulted in a gradient boosted model with 80 features achieving an AUC of 0.731±0.15 for predicting myocardial recovery. Variables associated with myocardial recovery from a clinical standpoint included HF duration, pre-LVAD LVEF, LVEDD, and HF pharmacologic therapy, and LRRN4CL (ligand binding and programmed cell death) from a biological standpoint. Our findings could have diagnostic, prognostic, and therapeutic implications for advanced HF patients, and inform the care of the broader HF population.

Longitudinal analysis left ventricular chamber responses under durable LVAD support

BACKGROUND

Left ventricular assist device (LVAD) support offers remodeling potential in some patients. Our goal was to use noninvasively derived pressure-volume (PV) loops to understand the effect of demographic and device variables on serial changes in cardiac function under pump support.

METHODS

Thirty-two consecutive Medtronic HeartWare Ventricular Assist Device (HVAD) patients (mean 55.9 ± 12.3 years, 81.3% male) were prospectively recruited. Single-cycle ventricular pressure and volume were estimated using a validated algorithm. PV loops (n = 77) and corresponding cardiac chamber dynamics were derived at predefined postimplant timepoints (1, 3, 6 months). Changes in PV loop parameters sustained across the 6-month period were characterized using mixed-effects modeling. The influence of demographic and device variables on the observed changes was assessed.

RESULTS

Across a 6-month period, the mean ventricular function parameters remained stable. Significant predictors of monthly improvement of stroke work include: lower pump speeds (2400 rpm vs 2500-2800 rpm) [0.0.051 mm Hg/liter/month (p = 0.001)], high pulsatility index (>1.0 vs <1.0) [0.052 mm Hg/liter/month (p = 0.012)], and ischemic cardiomyopathy indication for LVAD implantation (vs nonischemic) [0.0387 mm Hg/liter/month (p = 0.007)]. Various other cardiac chamber function parameters including cardiac power, peak systolic pressure, and LV elastance also showed improvements in these cohorts.

CONCLUSIONS

Factors associated with improvement in ventricular energetics and hemodynamics under LVAD support can be determined with noninvasive PV loops. Understanding the basis of increasing ventricular load to optimize myocardial remodeling may prove valuable in selecting eligible recovery candidates.

Cardiological Challenges Related to Long-Term Mechanical Circulatory Support for Advanced Heart Failure in Patients with Chronic Non-Ischemic Cardiomyopathy

Long-term mechanical circulatory support by a left ventricular assist device (LVAD), with or without an additional temporary or long-term right ventricular (RV) support, is a life-saving therapy for advanced heart failure (HF) refractory to pharmacological treatment, as well as for both device and surgical optimization therapies. In patients with chronic non-ischemic cardiomyopathy (NICM), timely prediction of HF's transition into its end stage, necessitating life-saving heart transplantation or long-term VAD support (as a bridge-to-transplantation or destination therapy), remains particularly challenging, given the wide range of possible etiologies, pathophysiological features, and clinical presentations of NICM. Decision-making between the necessity of an LVAD or a biventricular assist device (BVAD) is crucial because both unnecessary use of a BVAD and irreversible right ventricular (RV) failure after LVAD implantation can seriously impair patient outcomes. The pre-operative or, at the latest, intraoperative prediction of RV function after LVAD implantation is reliably possible, but necessitates integrative evaluations of many different echocardiographic, hemodynamic, clinical, and laboratory parameters. VADs create favorable conditions for the reversal of structural and functional cardiac alterations not only in acute forms of HF, but also in chronic HF. Although full cardiac recovery is rather unusual in VAD recipients with pre-implant chronic HF, the search for myocardial reverse remodelling and functional improvement is worthwhile because, for sufficiently recovered patients, weaning from VADs has proved to be feasible and capable of providing survival benefits and better quality of life even if recovery remains incomplete. This review article aimed to provide an updated theoretical and practical background for those engaged in this highly demanding and still current topic due to the continuous technical progress in the optimization of long-term VADs, as well as due to the new challenges which have emerged in conjunction with the proof of a possible myocardial recovery during long-term ventricular support up to levels which allow successful device explantation.

Durable Mechanical Circulatory Support: JACC Scientific Statement

Despite advances in medical therapy for patients with stage C heart failure (HF), survival for patients with advanced HF is <20% at 5 years. Durable left ventricular assist device (dLVAD) support is an important treatment option for patients with advanced HF. Innovations in dLVAD technology have reduced the risk of several adverse events, including pump thrombosis, stroke, and bleeding. Average patient survival is now similar to that of heart transplantation at 2 years, with 5-year dLVAD survival now approaching 60%. Unfortunately, greater adoption of dLVAD therapy has not been realized due to delayed referral of patients to advanced HF centers, insufficient clinician knowledge of contemporary dLVAD outcomes (including gains in quality of life), and deprioritization of patients with dLVAD support waiting for heart transplantation. Despite these challenges, novel devices are on the horizon of clinical investigation, offering smaller size, permitting less invasive surgical implantation, and eliminating the percutaneous lead for power supply.

LVAD therapy as a catalyst to heart failure remission and myocardial recovery

The management of chronic heart failure over the past decade has witnessed tremendous strides in medical optimization and device therapy including the use of left ventricular assist devices (LVAD). What we once thought of as irreversible damage to the myocardium is now demonstrating signs of reverse remodeling and recovery. Myocardial recovery on the structural, molecular, and hemodynamic level is necessary for sufficient recovery to withstand explant and achieve sustained recovery post-LVAD. Guideline-directed medical therapy and unloading have been shown to aid in recovery with the potential to successfully explant the LVAD. This review will summarize medical optimization, assessment for recovery, explant methodologies and outcomes post-recovery with explant of durable LVAD.

A latent cardiomyocyte regeneration potential in human heart disease

Cardiomyocytes in the adult human heart show a regenerative capacity, with an annual renewal rate around 0.5%. Whether this regenerative capacity of human cardiomyocytes is employed in heart failure has been controversial. Using retrospective 14C birth dating we analyzed cardiomyocyte renewal in patients with end-stage heart failure. We show that cardiomyocyte generation is minimal in end-stage heart failure patients at rates 18-50 times lower compared to the healthy heart. However, patients receiving left ventricle support device therapy, who showed significant functional and structural cardiac improvement, had a >6-fold increase in cardiomyocyte renewal relative to the healthy heart. Our findings reveal a substantial cardiomyocyte regeneration potential in human heart disease, which could be exploited therapeutically.

Left ventricular functional improvement appears to contribute to lower rates of device thrombosis in patients on durable mechanical circulatory support

By unloading the failing heart, left ventricular (LV) assist devices (LVADs) provide a favorable environment for reversing adverse structural and functional cardiac changes. Prior reports have suggested that an improved native LV function might contribute to the development of LVAD thrombosis. We used the Interagency Registry for Mechanically Assisted Circulatory Support and found that LV functional improvement is associated with a lower risk for device thrombosis. The risk for cerebrovascular accident and transient ischemic attack was comparable across post-LVAD LV function subgroups, while the risk of hemolysis was lower in subgroups of patients with better LV function on LVAD support.

The RNA editor ADAR2 promotes immune cell trafficking by enhancing endothelial responses to interleukin-6 during sterile inflammation

Immune cell trafficking constitutes a fundamental component of immunological response to tissue injury, but the contribution of intrinsic RNA nucleotide modifications to this response remains elusive. We report that RNA editor ADAR2 exerts a tissue- and stress-specific regulation of endothelial responses to interleukin-6 (IL-6), which tightly controls leukocyte trafficking in IL-6-inflamed and ischemic tissues. Genetic ablation of ADAR2 from vascular endothelial cells diminished myeloid cell rolling and adhesion on vascular walls and reduced immune cell infiltration within ischemic tissues. ADAR2 was required in the endothelium for the expression of the IL-6 receptor subunit, IL-6 signal transducer (IL6ST; gp130), and subsequently, for IL-6 trans-signaling responses. ADAR2-induced adenosine-to-inosine RNA editing suppressed the Drosha-dependent primary microRNA processing, thereby overwriting the default endothelial transcriptional program to safeguard gp130 expression. This work demonstrates a role for ADAR2 epitranscriptional activity as a checkpoint in IL-6 trans-signaling and immune cell trafficking to sites of tissue injury.

Distinct Transcriptomic and Proteomic Profile Specifies Patients Who Have Heart Failure With Potential of Myocardial Recovery on Mechanical Unloading and Circulatory Support

BACKGROUND

Extensive evidence from single-center studies indicates that a subset of patients with chronic advanced heart failure (HF) undergoing left ventricular assist device (LVAD) support show significantly improved heart function and reverse structural remodeling (ie, termed "responders"). Furthermore, we recently published a multicenter prospective study, RESTAGE-HF (Remission from Stage D Heart Failure), demonstrating that LVAD support combined with standard HF medications induced remarkable cardiac structural and functional improvement, leading to high rates of LVAD weaning and excellent long-term outcomes. This intriguing phenomenon provides great translational and clinical promise, although the underlying molecular mechanisms driving this recovery are largely unknown.

METHODS

To identify changes in signaling pathways operative in the normal and failing human heart and to molecularly characterize patients who respond favorably to LVAD unloading, we performed global RNA sequencing and phosphopeptide profiling of left ventricular tissue from 93 patients with HF undergoing LVAD implantation (25 responders and 68 nonresponders) and 12 nonfailing donor hearts. Patients were prospectively monitored through echocardiography to characterize their myocardial structure and function and identify responders and nonresponders.

RESULTS

These analyses identified 1341 transcripts and 288 phosphopeptides that are differentially regulated in cardiac tissue from nonfailing control samples and patients with HF. In addition, these unbiased molecular profiles identified a unique signature of 29 transcripts and 93 phosphopeptides in patients with HF that distinguished responders after LVAD unloading. Further analyses of these macromolecules highlighted differential regulation in 2 key pathways: cell cycle regulation and extracellular matrix/focal adhesions.

CONCLUSIONS

This is the first study to characterize changes in the nonfailing and failing human heart by integrating multiple -omics platforms to identify molecular indices defining patients capable of myocardial recovery. These findings may guide patient selection for advanced HF therapies and identify new HF therapeutic targets.

Novel Plug Device for HeartMate 3 Explantation: First Multicenter Experience

Patients undergoing explantation of left ventricular assist devices (LVADs) after improvement of myocardial function remain a minority. Nevertheless, considering the growing population of LVAD patients, increasing demand for new explantation strategies is expected. Herein, we present a retrospective review of seven patients undergoing HeartMate3 explantation with the use of a custom-made apical ring plug in four medical centers. The primary outcome was status at intensive care unit discharge. Secondary outcomes included perioperative complications and transfusions. Six out of seven patients were males. The median age at explantation and time on LVAD support was 35 years (range:13-73) and 10 months (range:9-24), respectively. No technical difficulties were experienced during plug implantation via a conventional sternotomy or through a left lateral thoracotomy, either with or without cardiopulmonary bypass. Perioperative transfusions ranged from 0 to 3 units/patient. No re-operations for bleeding, hemorrhagic, embolic, or plug-related infective events were observed. Heparin was started 6 hours after surgery as a bridge to oral anticoagulation (international normalized ratio: 2-2.5). All patients were discharged alive from intensive care unit. This novel plug device for HeartMate3 explantation was successfully and safely implanted in this first patient series. Notwithstanding, its use should still be considered off-label and larger studies are required to investigate its long-term results.

Baseline QRS duration associates with cardiac recovery in patients with continuous-flow left ventricular assist device implantation

Objective

In chronic heart failure (HF) patients supported with continuous-flow left ventricular assist device (CF-LVAD), we aimed to assess the clinical association of pre-LVAD QRS duration (QRSd) with post-LVAD cardiac recovery, and its correlation with pre- to post-LVAD change in left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD).

Methods

Chronic HF patients (n = 402) undergoing CF-LVAD implantation were prospectively enrolled, at one of the centers comprising the U.T.A.H. (Utah Transplant Affiliated Hospitals) consortium. After excluding patients with acute HF etiologies, hypertrophic or infiltrative cardiomyopathy, and/or inadequate post-LVAD follow up (<3 months), 315 patients were included in the study. Cardiac recovery was defined as LVEF ≥ 40 % and LVEDD < 6 cm within 12 months post-LVAD implantation. Patients fulfilling this condition were termed as responders (R) and results were compared with non-responders (NR).

Results

Thirty-five patients (11 %) achieved 'R' criteria, and exhibited a 15 % shorter QRSd compared to 'NR' (123 ± 37 ms vs 145 ± 36 ms; p < 0.001). A univariate analysis identified association of baseline QRSd with post-LVAD cardiac recovery (OR: 0.986, 95 % CI: 0.976-0.996, p < 0.001). In a multivariate logistic regression model, after adjusting for duration of HF (OR: 0.990, 95 % CI: 0.983-0.997, p = 0.006) and gender (OR: 0.388, 95 % CI: 0.160-0.943, p = 0.037), pre-LVAD QRSd exhibited a significant association with post-LVAD cardiac structural and functional improvement (OR: 0.987, 95 % CI: 0.977-0.998, p = 0.027) and the predictive model showed a c-statistic of 0.73 with p < 0.001. The correlations for baseline QRSd with pre- to post-LVAD change in LVEF and LVEDD were also investigated in 'R' and 'NR' groups.

Conclusion

Chronic advanced HF patients with a shorter baseline QRSd exhibit an increased potential for cardiac recovery after LVAD support.

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.

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.

Left Ventricular Assist Device as a Bridge to Recovery: Single Center Experience of Successful Device Explantation

Continuous-flow left ventricular assist devices (CF-LVAD) have been shown to enhance reverse remodeling and myocardial recovery in certain patients allowing for device removal. We sought to analyze the characteristics and describe outcomes of patients who underwent CF-LVAD explantation at a large academic center. We retrospectively identified all patients who underwent CF-LVAD explants due to recovery from 2006 to 2019. Patient baseline characteristics and data on pre- and postexplant evaluation were collected and analyzed. Of 421 patients who underwent CF-LVAD implantation, 13 underwent explantation (3.1%). Twelve HeartMate II and one HeartWare LVAD were explanted. All patients had nonischemic cardiomyopathy. Median time from heart failure diagnosis to LVAD implant was 12 months (interquartile range [IQR], 2-44) and the median time supported on LVAD was 22 months (IQR, 11-28). Two patients died within 30 days of explant. Three additional patients died during the follow-up period and all were noted to be nonadherent to medical therapy. After a mean follow-up duration of 5 years, overall survival was 52%. Mean pre-explant ejection fraction was 49%, which decreased at most recent follow-up to 32%. Mean pre-explant left ventricular internal diameter in diastole (LVIDD) was 4.37 cm and increased to 5.52 cm at most recent follow-up. Continuous-flow left ventricular assist device explantation is feasible and safe in select 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.

Left Ventricular Hemodynamics and Relationship with Myocardial Recovery and Optimization in Patients Supported on CF-LVAD Therapy

BACKGROUND

Despite interest in left ventricular (LV) recovery, there is an absence of data on the relationship between intrinsic LV hemodynamics and both reverse remodeling on continuous flow left ventricular assist device (CF-LVAD) therapy. We hypothesized that markers of intrinsic LV function would be associated with remodeling, optimization, and outcomes.

METHODS

Patients with continuous flow LVADs between 2015 and 2019 who underwent combined left and right heart catheterization (LHC/RHC) ramp protocol at a single institution were enrolled. Patients were stratified by response to CF-LVAD therapy: full responders (FR), partial responders (PR), or non-responders (NR) per Utah-Inova criteria. Hemodynamic data, including LV hemodynamics of peak LV dP/dt and tau (τ) were obtained at each phase. One-year heart failure hospitalization-free survival was the primary endpoint.

RESULTS

Among 61 patients included in the current study 38 (62%) were classified as NR, 14 (23%) PR, and 9 (15%) FR. Baseline LV dP/dt and τ varied by response status (P≤.02) and generally correlated with reverse remodeling on linear regression. Biventricular filling pressures varied with τ and there was an interaction effect of speed on the relationship between τ and PCWP (P=.04). Lastly, τ was a prognostic marker and associated with one-year HF-hospital free survival (OR 1.04, 95%CI 1.00-1.07, P=.02 per ms increase).

CONCLUSIONS

Significant correlations between τ and LV dP/dt and reverse remodeling were noted with tau serving as a prognostic marker. Higher LVAD speed was associated with a greater reliance on LVAD for unloading. Future work should focus on defining the optimal level of LVAD support in relation to LV recovery.

Short- and long-term effects of a cardiac rehabilitation program in patients implanted with a left ventricular assist device

The efficacy of cardiac rehabilitation in heart-failure patients who received a left-ventricular assist device (LVAD) instead of heart transplantation (HTx) is still unclear. This study aims to evaluate whether cardiac rehabilitation is beneficial in LVAD as HTx patients in the short term and whether its effects in LVAD patients persist over time. Twenty-five LVAD patients were evaluated by functional and psychological tests at admission (T0) and discharge (T1) of a 4-week inpatient structured rehabilitation program, and follow-ups 3 (T2), 6 (T3), and 12 months (T4) after discharge. Twenty-five matched HTx patients were also studied from T0 to T1 to compare the improvements in the six-minute walk test (6MWT). The quality-of-life scores substantially improved in LVAD patients and the 6MWT showed the same functional recovery as in HTx patients from T0 to T1. After T1, numerous LVAD patients withdrew from the study. However, the 6MWT outcome increased further from T1 to T3, with a positive trend during the follow-ups. Hemoglobin and the ventilatory performance increased, and the psychological perception of heart-failure symptoms and pain further improved at T2. In conclusion, exercise-based rehabilitation programs provide similar beneficial effects in LVAD and HTx patients, without deterioration in LVAD patients up to 12 months after discharge.

LVAD decommissioning for myocardial recovery: Long-term ventricular remodeling and adverse events

BACKGROUND

Left ventricular assist devices (LVADs) mechanically unload the heart and coupled with neurohormonal therapy can promote reverse cardiac remodeling and myocardial recovery. Minimally invasive LVAD decommissioning with the device left in place has been reported to be safe over short-term follow-up. Whether device retention reduces long-term safety, or sustainability of recovery is unknown.

METHODS

This is a dual-center retrospective analysis of patients who had achieved responder status (left ventricular ejection fraction, LVEF ≥40% and left ventricular internal diastolic diameter, LVIDd ≤6.0 cm) and underwent elective LVAD decommissioning for myocardial recovery from May 2010 to January 2020. All patients had outflow graft closure and driveline resection with the LVAD left in place. Emergent LVAD decommissioning for an infection or device thrombosis was excluded. Patients were followed with serial echocardiography for up to 3-years. The primary clinical outcome was survival free of heart failure hospitalization, LVAD reimplantation, or transplant.

RESULTS

During the study period 515 patients received an LVAD and 29 (5.6%) achieved myocardial recovery, 12 patients underwent total device explantation or urgent device decommissioning, 17 patients underwent elective LVAD decommissioning, and were included in the analysis. Median age of patients at LVAD implantation was 42 years (interquartile range, IQR: 25-54 years), all had a nonischemic cardiomyopathy, and 5 (29%) were female. At LVAD implantation, median LVEF was 10% (IQR: 5%-15%), and LVIDd 6.6 cm (IQR: 5.8-7.1 cm). There were 11 hydrodynamically levitated centrifugal-flow (65%), and 6 axial-flow LVADs (35%). The median duration of LVAD support before decommissioning was 28.7 months (range 13.5-36.2 months). As compared to the turndown study parameters, 1-month post-decommissioning, median LVEF decreased from 55% to 48% (p = 0.03), and LVIDd increased from 4.8 cm to 5.2 cm (p = 0.10). There was gradual remodeling until 6 months, after which there was no statistical difference on follow-up through 3-years (LVEF 42%, LVIDd 5.6 cm). Recurrent infections affected 41% of patients leading to 3 deaths and 1 complete device explant. Recurrent HF occurred in 1 patient who required a transplant. Probability of survival free of HF, LVAD, or transplant was 94% at 1-year, and 78% at 3-years.

CONCLUSIONS

LVAD decommissioning for myocardial recovery was associated with excellent long-term survival free from recurrent heart failure and preservation of ventricular size and function up to 3-years. Reducing the risk of recurrent infections, remains an important therapeutic goal for this management strategy.

Impact of renin-angiotensin-aldosterone system inhibition on morbidity and mortality during long-term continuous-flow left ventricular assist device support: An IMACS report

BACKGROUND

Inhibition of the renin angiotensin aldosterone system (RAAS) improves survival and reduces adverse cardiac events in heart failure with reduced ejection fraction, but the benefit is not well-defined following left ventricular assist device (LVAD).

METHODS

We analyzed the ISHLT IMACS registry for adults with a primary, continuous-flow LVAD from January 2013 to September 2017 who were alive at postoperative month 3 without a major adverse event, and categorized patients according to treatment an angiotensin converting enzyme inhibitor (ACEI/ARB) or mineralocorticoid receptor antagonist (MRA). Propensity score matching was performed separately for ACEI/ARB vs none (n = 4,118 each) and MRA vs none (n = 3,892 each).

RESULTS

Of 11,494 patients included, 50% were treated with ACEI/ARB and 38% with MRA. Kaplan-Meier survival was significantly better for patients receiving ACEI/ARB (p < 0.001) but not MRA (p = 0.31). In Cox proportional hazards analyses adjusted for known predictors of mortality following LVAD, ACEI/ARB use (hazard ratio 0.81 [95% confidence interval 0.71-0.93], p < 0.0001) but not MRA use (hazard ratio 1.03 [95% confidence interval 0.88-1.21], p = 0.69) was independently associated with lower mortality. Among patients treated with an ACEI/ARB, there was a significantly lower unadjusted risk of cardiovascular death (p < 0.001), risk of gastrointestinal bleeding (p = 0.01), and creatinine level (p < 0.001). MRA therapy was associated with lower risk of gastrointestinal bleeding (p = 0.01) but higher risk of hemolysis (p < 0.01). Potential limitations include residual confounding and therapy crossover.

CONCLUSION

These findings suggest a benefit for ACEI/ARB therapy in patients with heart failure after LVAD implantation.

Circulating and Myocardial Cytokines Predict Cardiac Structural and Functional Improvement in Patients With Heart Failure Undergoing Mechanical Circulatory Support

Background Recent prospective multicenter data from patients with advanced heart failure demonstrated that left ventricular assist device (LVAD) support combined with standard heart failure medications, induced significant cardiac structural and functional improvement, leading to high rates of LVAD weaning in selected patients. We investigated whether preintervention myocardial and systemic inflammatory burden could help identify the subset of patients with advanced heart failure prone to LVAD-mediated cardiac improvement to guide patient selection, treatment, and monitoring. Methods and Results Ninety-three patients requiring durable LVAD were prospectively enrolled. Myocardial tissue and blood were acquired during LVAD implantation, for measurement of inflammatory markers. Cardiac structural and functional improvement was prospectively assessed via serial echocardiography. Eleven percent of the patients showed significant reverse remodeling following LVAD support (ie, responders). Circulating tumor necrosis factor alpha, interleukin (IL)-4, IL-5, IL-6, IL-7, IL-13, and interferon gamma were lower in responders, compared with nonresponders (P<0.05, all comparisons). The myocardial tissue signal transducer and activator of transcription-3, an inflammatory response regulator, was less activated in responders (P=0.037). Guided by our tissue studies and a multivariable dichotomous regression analysis, we identified that low levels of circulating interferon gamma (odds ratio [OR], 0.06; 95% CI, 0.01-0.35) and tumor necrosis factor alpha (OR, 0.05; 95% CI, 0.00-0.43), independently predict cardiac improvement, creating a 2-cytokine model effectively predicting responders (area under the curve, 0.903; P<0.0001). Conclusions Baseline myocardial and systemic inflammatory burden inversely correlates with cardiac improvement following LVAD support. A circulating 2-cytokine model predicting significant reverse remodeling was identified, warranting further investigation as a practical preintervention tool in identifying patients prone to LVAD-mediated cardiac improvement and device weaning.

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.

Prognostic Value of Natriuretic Peptides for All-Cause Mortality, Right Ventricular Failure, Major Adverse Events, and Myocardial Recovery in Advanced Heart Failure Patients Receiving a Left Ventricular Assist Device: A Systematic Review

Aims: Major adverse event (MAE) rates during left ventricular assist device (LVAD) therapy in advanced heart failure (HF) patients are high, and impair quality of life and survival. Prediction and risk stratification of MAEs in order to improve patient selection and thereby outcome during LVAD therapy is therefore warranted. Circulating natriuretic peptides (NPs) are strong predictors of MAEs and mortality in chronic HF patients. However, whether NPs can identify patients who are at risk of MAEs and mortality or tend toward myocardial recovery after LVAD implantation is unclear. The aim of this systematic review is to analyze the prognostic value of circulating NP levels before LVAD implantation for all-cause mortality, MAEs and myocardial recovery after LVAD implantation.

Methods and Results: Electronic databases were searched for studies analyzing circulating NP in adults with advanced HF before LVAD implantation in relation to mortality, MAEs, or myocardial recovery after LVAD implantation. Twenty-four studies published between 2008 and 2021 were included. Follow-up duration ranged from 48 hours to 5 years. Study sample size ranged from 14 to 15,138 patients. Natriuretic peptide levels were not predictive of all-cause mortality. However, NPs were predictive of right ventricular failure (RVF) and MAEs such as ventricular arrhythmias, moderate or severe aortic regurgitation, and all-cause rehospitalization. No relation between NPs and myocardial recovery was found.

Conclusion: This systematic review found that NP levels before LVAD implantation are not predictive of all-cause mortality after LVAD implantation. Thus, NP levels may be of limited value in patient selection for LVAD therapy. However, NPs help in risk stratification of MAEs and may be used to identify patients who are at risk for RVF, ventricular arrhythmias, moderate or severe aortic regurgitation, and all-cause rehospitalization after LVAD implantation.

The evolution of long-term pediatric ventricular assistance devices: a critical review

Introduction: The gap between the number of heart failure patients and the number of potential heart donors has never been larger than today, especially among the pediatric population. The use of mechanical circulatory support is seen as a potential alternative for clinicians to treat more patients. This treatment has proven its efficiency on short-term use. However, in order to replace heart transplant, the techniques should be used over longer periods of time.Areas covered: This review aims at furnishing an engineering vision of the evolution of ventricular assistance devices used in pediatrics. A critical analysis of the clinical complications related to devices generation is made to give an overview of the design improvements made since their inception.Expert opinion: The long-term use of a foreign device in the body is not without consequences, especially among fragile pediatric patients. Moreover, the size of their body parts increases the technical difficulties of such procedure. The balance between the living cells of the body is disturbed by the devices, mostly by the shear stress generated. To provide a safe mechanical circulatory support for long-term use, the devices should be more hemocompatible, preserving blood cells, adapted to the patient's systemic grid and miniaturized for pediatric use.

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.

Experimental investigation of the influence of the hydraulic performance of an axial blood pump on intraventricular blood flow

Blood flow inside the left ventricle (LV) is a concern for blood pump use and contributes to ventricle suction and thromboembolic events. However, few studies have examined blood flow inside the LV after a blood pump was implanted. In this study, in vitro experiments were conducted to emulate the intraventricular blood flow, such as blood flow velocity, the distribution of streamlines, vorticity and the standard deviation of velocity inside the LV during axial blood pump support. A silicone LV reconstructed from computerized tomography (CT) data of a heart failure patient was incorporated into a mock circulatory loop (MCL) to simulate human systemic circulation. Then, the blood flow inside the ventricle was examined by particle image velocimetry (PIV) equipment. The results showed that the operating conditions of the axial blood pump influenced flow patterns within the LV and areas of potential blood stasis, and the intraventricular swirling flow was altered with blood pump support. The presence of vorticity in the LV from the thoracic aorta to the heart apex can provide thorough washing of the LV cavity. The gradually extending stasis region in the central LV with increasing blood pump support is necessary to reduce the thrombosis potential in the LV.

OptiVol for Volume Assessment in Patients With Continuous Flow Left Ventricular Assist Device

OptiVol (Medtronic PLC, Minneapolis, MN) is a diagnostic feature of some cardiac implantable electronic devices (CIEDs) based on changes in thoracic impedance (TI) over time. Changes in TI can predict heart failure (HF) hospitalizations and mortality in HF populations. However, the utility of this feature is unknown in patients with a left ventricular assist device (LVAD). To determine if OptiVol and TI correlate with clinical HF events in a population of LVAD patients, hospitalization outcomes were collected retrospectively from the electronic health records at a single academic medical center in 80 LVAD patients with an OptiVol-capable CIED. Demographics, medical history, and available clinical data were reviewed and reported. The primary outcomes of interest were TI and OptiVol trends before and after hospitalization, and association of trends before and after these events was evaluated. Most patients had a HeartMate II LVAD and most CIEDs were defibrillators, and 23 (29%) had at least one HF hospitalization during the study period. HF hospitalizations were preceded by signs of volume overload in Optivol (60%) and TI (78%) with recovery of these measures post hospitalization in 33% and 25% of patients, respectively. Monitoring of TI and OptiVol may be one effective component of HF management in LVAD patients as part of a comprehensive program.

Racial and socioeconomic disparity associates with differences in cardiac DNA methylation among men with end-stage heart failure

Heart failure (HF) is a multifactorial syndrome that remains a leading cause of worldwide morbidity. Despite its high prevalence, only half of patients with HF respond to guideline-directed medical management, prompting therapeutic efforts to confront the molecular underpinnings of its heterogeneity. In the current study, we examined epigenetics as a yet unexplored source of heterogeneity among patients with end-stage HF. Specifically, a multicohort-based study was designed to quantify cardiac genome-wide cytosine-p-guanine (CpG) methylation of cardiac biopsies from male patients undergoing left ventricular assist device (LVAD) implantation. In both pilot (n = 11) and testing (n = 31) cohorts, unsupervised multidimensional scaling of genome-wide myocardial DNA methylation exhibited a bimodal distribution of CpG methylation found largely to occur in the promoter regions of metabolic genes. Among the available patient attributes, only categorical self-identified patient race could delineate this methylation signature, with African American (AA) and Caucasian American (CA) samples clustering separately. Because race is a social construct, and thus a poor proxy of human physiology, extensive review of medical records was conducted, but ultimately failed to identify covariates of race at the time of LVAD surgery. By contrast, retrospective analysis exposed a higher all-cause mortality among AA (56.3%) relative to CA (16.7%) patients at 2 yr following LVAD placement (P = 0.03). Geocoding-based approximation of patient demographics uncovered disparities in income levels among AA relative to CA patients. Although additional studies are needed, the current analysis implicates cardiac DNA methylation as a previously unrecognized indicator of socioeconomic disparity in human heart failure outcomes.

NEW & NOTEWORTHY A bimodal signature of cardiac DNA methylation in heart failure corresponds with racial differences in all-cause mortality following mechanical circulatory support. Racial differences in promoter methylation disproportionately affect metabolic signaling pathways. Socioeconomic factors are associated with racial differences in the cardiac methylome among men with end-stage heart failure.

Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/racial-socioeconomic-determinants-of-the-cardiac-epigenome/.

The pyruvate-lactate axis modulates cardiac hypertrophy and heart failure

The metabolic rewiring of cardiomyocytes is a widely accepted hallmark of heart failure (HF). These metabolic changes include a decrease in mitochondrial pyruvate oxidation and an increased export of lactate. We identify the mitochondrial pyruvate carrier (MPC) and the cellular lactate exporter monocarboxylate transporter 4 (MCT4) as pivotal nodes in this metabolic axis. We observed that cardiac assist device-induced myocardial recovery in chronic HF patients was coincident with increased myocardial expression of the MPC. Moreover, the genetic ablation of the MPC in cultured cardiomyocytes and in adult murine hearts was sufficient to induce hypertrophy and HF. Conversely, MPC overexpression attenuated drug-induced hypertrophy in a cell-autonomous manner. We also introduced a novel, highly potent MCT4 inhibitor that mitigated hypertrophy in cultured cardiomyocytes and in mice. Together, we find that alteration of the pyruvate-lactate axis is a fundamental and early feature of cardiac hypertrophy and failure.

Short-Term Ventricular Structural Changes Following Left Ventricular Assist Device Implantation

Reverse remodeling of the left ventricle has been reported following left ventricular assist device (LVAD) implantation. However, left ventricular (LV) and right ventricular (RV) volumetric and shape changes have not been described. Consecutive candidates for LVAD were prospectively enrolled. Comprehensive 2- and 3-dimensional echocardiographic (2DE, 3DE) images were acquired before and 1 to 2 months following LVAD implantation. 3D endocardial surfaces were analyzed to derive shape indices, including LV sphericity and conicity and RV septal and free-wall curvatures. Sixty patients were enrolled with a mean age 56 ± 13 years, 77% male, and 83% destination therapy. 3DE showed that LV end-diastolic volume (EDV) improved from 461 ± 182 to 287 ± 144 ml (p < 0.001) and RV EDV showed no change (p = 0.08). RV longitudinal strain (LS) worsened from -9.1 ± 3.1 to -5.9 ± 2.6% (p < 0.01). LV sphericity and conicity improved (p < 0.001 for both), whereas the curvature of the interventricular septum and RV free wall did not change (p = 0.79 and 0.26, respectively). At 1 month following LVAD implantation, LV volumes decrease dramatically, and there is a favorable LV shape improvement, indicating reverse remodeling. RV shape did not change, whereas RV LS worsened, indicating an absence of RV reverse remodeling.

Weaning from ventricular assist device support after recovery from left ventricular failure with or without secondary right ventricular failure

Although complete myocardial recovery after ventricular assist device (VAD) implantation is rather seldom, systematic search for recovery is worthwhile because for recovered patients weaning from VADs is feasible and can provide survival benefits with long-term freedom from heart failure (HF) recurrence, even if a chronic cardiomyopathy was the primary cause for the drug-refractory HF necessitating left ventricular (LVAD) or biventricular support (as bridge-to-transplantation or definitive therapy) and even if recovery remains incomplete. LVAD patients explanted for myoacardial recovery compared to those transplanted from LVAD support showed similar survival rates and a significant proportion of explanted patients can achieve cardiac and physical functional capacities that are within the normal range of healthy controls. In apparently sufficiently recovered patients, a major challenge remains still the pre-explant prediction of the weaning success which is meanwhile reliably possible for experienced clinicians. In weaning candidates, the combined use of certain echocardiography and right heart catheterization parameters recorded before VAD explantation can predict post-weaning cardiac stability with good accuracy. However, in the absence of standardization or binding recommendations, the protocols for assessment of native cardiac improvement and also the weaning criteria differ widely among centers. Currently there are still only few larger studies on myocardial recovery assessment after VAD implantation. Therefore, the weaning practice relies mostly on small case series, local practice patterns, and case reports, and the existing knowledge, as well as the partially differing recommendations which are based mainly on expert opinions, need to be periodically systematised. Addressing these shortcomings, our review aims to summarize the evidence and expert opinion on the evaluation of cardiac recovery during mechanical ventricular support by paying special attention to the reliability of the methods and parameters used for assessment of myocardial recovery and the challenges met in both evaluation of recovery and weaning decision making.

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.

Prospective Multicenter Study of Myocardial Recovery Using Left Ventricular Assist Devices (RESTAGE-HF [Remission from Stage D Heart Failure])

Background:

Left ventricular assist device (LVAD) unloading and hemodynamic support in patients with advanced chronic heart failure can result in significant improvement in cardiac function allowing LVAD removal; however, the rate of this is generally considered to be low. This prospective multicenter nonrandomized study (RESTAGE-HF [Remission from Stage D Heart Failure]) investigated whether a protocol of optimized LVAD mechanical unloading, combined with standardized specific pharmacological therapy to induce reverse remodeling and regular testing of underlying myocardial function, could produce a higher incidence of LVAD explantation.

Methods:

Forty patients with chronic advanced heart failure from nonischemic cardiomyopathy receiving the Heartmate II LVAD were enrolled from 6 centers. LVAD speed was optimized with an aggressive pharmacological regimen, and regular echocardiograms were performed at reduced LVAD speed (6000 rpm, no net flow) to test underlying myocardial function. The primary end point was the proportion of patients with sufficient improvement of myocardial function to reach criteria for explantation within 18 months with sustained remission from heart failure (freedom from transplant/ventricular assist device/death) at 12 months.

Results:

Before LVAD, age was 35.1±10.8 years, 67.5% were men, heart failure mean duration was 20.8±20.6 months, 95% required inotropic and 20% temporary mechanical support, left ventricular ejection fraction was 14.5±5.3%, end-diastolic diameter was 7.33±0.89 cm, end-systolic diameter was 6.74±0.88 cm, pulmonary artery saturations were 46.7±9.2%, and pulmonary capillary wedge pressure was 26.2±7.6 mm Hg. Four enrolled patients did not undergo the protocol because of medical complications unrelated to the study procedures. Overall, 40% of all enrolled (16/40) patients achieved the primary end point, P <0.0001, with 50% (18/36) of patients receiving the protocol being explanted within 18 months (pre-explant left ventricular ejection fraction, 57±8%; end-diastolic diameter, 4.81±0.58 cm; end-systolic diameter, 3.53±0.51 cm; pulmonary capillary wedge pressure, 8.1±3.1 mm Hg; pulmonary artery saturations 63.6±6.8% at 6000 rpm). Overall, 19 patients were explanted (19/36, 52.3% of those receiving the protocol). The 15 ongoing explanted patients are now 2.26±0.97 years after explant. After explantation survival free from LVAD or transplantation was 90% at 1-year and 77% at 2 and 3 years.

Conclusions:

In this multicenter prospective study, this strategy of LVAD support combined with a standardized pharmacological and cardiac function monitoring protocol resulted in a high rate of LVAD explantation and was feasible and reproducible with explants occurring in all 6 participating sites.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01774656.

Feasibility of high-intensity interval training in patients with left ventricular assist devices: a pilot study

Aims

Patients with left ventricular assist device (LVAD) suffer from persistent exercise limitation despite improvement of their heart failure syndrome. Exercise training (ET) programmes to improve aerobic capacity have shown modest efficacy. High‐intensity interval training (HIIT), as an alternative to moderate continuous training, has not been systematically tested in this population. We examine the feasibility of a short, personalized HIIT programme in patients with LVAD and describe its effects on aerobic capacity and left ventricular remodelling.

Methods and results

Patients on durable LVAD support were prospectively enrolled in a 15‐session, 5 week HIIT programme. Turndown echocardiogram, Kansas City Cardiomyopathy Questionnaire, and cardiopulmonary exercise test were performed before and after HIIT. Training workloads for each subject were based on pretraining peak cardiopulmonary exercise test work rate (W). Percentage of prescribed training workload completed and adverse events were recorded for each subject. Fifteen subjects were enrolled [10 men, age = 51 (29–71) years, HeartMate II = 12, HeartMate 3 = 3, and time on LVAD = 18 (3–64) months]. Twelve completed post‐training testing. HIIT was well tolerated, and 90% (inter‐quartile range: 78, 99%) of the prescribed workload (W) was completed with no major adverse events. Improvements were seen in aV̇O₂ at ventilatory threshold [7.1 (6.5, 9.1) to 8.5 (7.7, 9.3) mL/kg/min, P = 0.04], work rate at ventilatory threshold [44 (14, 54) to 55 (21, 66) W, P = 0.05], and left ventricular end‐diastolic volume [168 (144, 216) to 159 (124, 212) mL, n = 7, P = 0.02]. HIIT had no effect on maximal oxygen consumption (V̇O_2peak) or Kansas City Cardiomyopathy Questionnaire score.

Conclusions

Cardiopulmonary exercise test‐guided HIIT is feasible and can improve submaximal aerobic capacity in stable patients with chronic LVAD support. Further studies are needed on its effects on the myocardium and its potential role in cardiac rehabilitation programmes.

A 3-dimensional-printed left ventricle model incorporated into a mock circulatory loop to investigate hemodynamics inside a severely failing ventricle supported by a blood pump

Intraventricular blood stasis is a design consideration for continuous flow blood pumps and might contribute to adverse events such as thrombosis and ventricular suction. However, the blood flow inside left ventricles (LVs) supported by blood pumps is still unclear. In vitro experiments were conducted to imitate how the hydraulic performance of an axial blood pump affects the intraventricular blood flow of a severe heart failure patient, such as velocity distribution, vorticity, and standard deviation of velocity. In this study, a silicone model of the LV was constructed from the computed tomography data of one patient with heart failure and was 3D printed. Then, intraventricular flow was visualized by particle image velocimetry equipment within a mock circulation loop. The results showed that the axial blood pump suctions most of the blood in a severely failing LV, there was an altered flow status within the LV, and blood stasis appeared in the central region of the LV. Some blood may be suctioned from the aortic valve to the blood pump because the patient's native heart was severely failing. Blood stasis at the LV center may cause thrombosis in the LV. The vortex flow near the inner wall of the LV can thoroughly wash the left ventricular cavity.

Improvement of ejection fraction and mortality in ischaemic heart failure

OBJECTIVE

The frequency and predictors of improvement in left ventricular ejection fraction (LVEF) in ischaemic cardiomyopathy and its association with mortality is poorly understood. We sought to assess the predictors of LVEF improvement ≥10% and its effect on mortality.

METHODS

We compared characteristics of patients enrolled in The Surgical Treatment for Ischaemic Heart Failure (STICH) trial with and without improvement of LVEF ≥10% at 24 months. A logistic regression model was constructed to determine the independent predictors of LVEF improvement. A Cox proportional hazards model was created to assess the independent association of improvement in LVEF ≥10% with mortality.

RESULTS

Of the 1212 patients enrolled in STICH, 618 underwent echocardiographic assessment of LVEF at baseline and 24 months. Of the patients randomised to medical therapy plus coronary artery bypass graft surgery (CABG), 58 (19%) had an improvement in LVEF >10% compared with 51 (16%) patients assigned to medical therapy alone (p=0.30). Independent predictors of LVEF improvement >10% included prior myocardial infarction (OR 0.44, 95% CI: 0.28 to 0.71, p=0.001) and lower baseline LVEF (OR 0.94, 95% CI: 0.91 to 0.97, p<0.001). Improvement in LVEF >10% (HR 0.61, 95% CI: 0.44 to 0.84, p=0.004) and randomisation to CABG (HR 0.72, 95% CI: 0.57 to 0.90, p=0.004) were independently associated with a reduced hazard of mortality.

CONCLUSIONS

Improvement of LVEF ≥10% at 24 months was uncommon in patients with ischaemic cardiomyopathy, did not differ between patients assigned to CABG and medical therapy or medical therapy alone and was independently associated with reduced mortality.

TRIAL REGISTRATION NUMBER

NCT00023595.

Stem Cell Therapy for Chronic and Advanced Heart Failure

PURPOSE OF REVIEW

The purpose of this review is to discuss recent advances in the field of cell therapy in patients with heart failure with reduced ejection fraction (HFrEF) of ischemic (iCMP) and nonischemic (dCMP) etiology, heart failure with preserved ejection fraction (HFpEF), and in advanced heart failure patients undergoing mechanical circulatory support (LVAD).

RECENT FINDINGS

In HFrEF patients (iCMP and dCMP cohorts), autologous and/or allogeneic cell therapy was shown to improve myocardial performance, patients' functional capacity, and neurohumoral activation. In HFpEF patient population, the concept of cell therapy in novel and remains largely unexplored. However, initial data are very encouraging and suggest at least a similar benefit in improvements of myocardial performance (also diastolic function of the left ventricle), exercise capacity, and neurohumoral activation. Recently, cell therapy was explored in the sickest population of advanced heart failure patients undergoing LVAD support also showing a potential benefit in promoting myocardial reverse remodeling and recovery. In the past decade, several cell therapy-based clinical trials showed promising results in various chronic and advanced heart failure patient cohorts. Future cell treatment strategies should aim for more personalized therapeutic approaches by defining optimal stem cell type or their combination, dose, and delivery method for an individual patient adjusted for patient's age and stage/duration of heart failure.

Targeted anti-inflammatory therapy is a new insight for reducing cardiovascular events: A review from physiology to the clinic

Despite considerable progressions, cardiovascular disease (CVD) is still one of the major causes of mortality around the world, indicates an important and unmet clinical need. Recently, extensive studies have been performed on the role of inflammatory factors as either a major or surrogate factor in the pathophysiology of CVD. Epidemiological observations suggest the theory of the role of inflammatory mediators in the development of cardiovascular events. This may support the idea that targeted anti-inflammatory therapies, on the background of traditional validated medical therapies, can play a significant role in prevention and even reduction of cardiovascular disorders. Many randomized controlled trials have shown that drugs commonly useful for primary and secondary prevention of CVD have an anti-inflammatory mechanism. Further, many anti-inflammatory drugs are being examined because of their potential to reduce the risk of cardiovascular problems. In this study, we review the process of inflammation in the development of cardiovascular events, both in vivo and clinical evidence in immunotherapy for CVD.