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.

Integrated multi-omic characterization of congenital heart disease.

The heart, the first organ to develop in the embryo, undergoes complex morphogenesis that when defective results in congenital heart disease (CHD). With current therapies, more than 90% of patients with CHD survive into adulthood, but many suffer premature death from heart failure and non-cardiac causes1. Here, to gain insight into this disease progression, we performed single-nucleus RNA sequencing on 157,273 nuclei from control hearts and hearts from patients with CHD, including those with hypoplastic left heart syndrome (HLHS) and tetralogy of Fallot, two common forms of cyanotic CHD lesions, as well as dilated and hypertrophic cardiomyopathies. We observed CHD-specific cell states in cardiomyocytes, which showed evidence of insulin resistance and increased expression of genes associated with FOXO signalling and CRIM1. Cardiac fibroblasts in HLHS were enriched in a low-Hippo and high-YAP cell state characteristic of activated cardiac fibroblasts. Imaging mass cytometry uncovered a spatially resolved perivascular microenvironment consistent with an immunodeficient state in CHD. Peripheral immune cell profiling suggested deficient monocytic immunity in CHD, in agreement with the predilection in CHD to infection and cancer2. Our comprehensive phenotyping of CHD provides a roadmap towards future personalized treatments for CHD.

SUMOylation does not affect cardiac troponin I stability but alters indirectly the development of force in response to Ca2.

Post-translational modification of the myofilament protein troponin I by phosphorylation is known to trigger functional changes that support enhanced contraction and relaxation of the heart. We report for the first time that human troponin I can also be modified by SUMOylation at lysine 177. Functionally, TnI SUMOylation is not a factor in the development of passive and maximal force generation in response to calcium, however this modification seems to act indirectly by preventing SUMOylation of other myofilament proteins to alter calcium sensitivity and cooperativity of myofilaments. Utilising a novel, custom SUMO site-specific antibody that recognises only the SUMOylated form of troponin I, we verify that this modification occurs in human heart and that it is upregulated during disease.

Prior Freezing Has Minimal Impact on the Contractile Properties of Permeabilized Human Myocardium.

Background Experiments measuring the contractile properties of human myocardium are important for translational research but complicated by the logistical difficulties of acquiring specimens. Accordingly, many groups perform contractile assays using samples that are acquired from patients at one institution and shipped to another institution for experiments. This necessitates freezing the samples and performing subsequent assays using chemically permeabilized preparations. It is unknown how prior freezing affects the contractile function of these preparations. Methods and Results To examine the effects of freezing we measured the contractile function of never-frozen and previously frozen myocardial samples. Samples of left ventricular tissue were obtained from 7 patients who were having a ventricular assist device implanted. Half of each sample was chemically permeabilized and used immediately for contractile assays. The other half of the sample was snap frozen in liquid nitrogen and maintained at -180 °C for at least 6 months before being thawed and tested in a second series of experiments. Maximum isometric force measured in pCa 4.5 solution, passive force measured in pCa 9.0 solution, and Hill coefficients were not influenced by prior freezing (P=0.07, P=0.14, and P=0.27 respectively). pCa50 in never-frozen samples (6.11±0.04) was statistically greater (P<0.001) than that measured after prior freezing (5.99±0.04) but the magnitude of the effect was only ≈0.1 pCa units. Conclusions We conclude that prior freezing has minimal impact on the contractile properties that can be measured using chemically permeabilized human myocardium.

Retrospective review of secondary prevention strategies for gastrointestinal bleeding and associated clinical outcomes in left ventricular assist device patients.

BACKGROUND: Gastrointestinal bleeding (GIB) is one of the most common bleeding complications associated with left ventricular assist devices (LVAD). Currently, there is no strong evidence or clear guidance for which secondary GIB prophylaxis strategy should be implemented after the discontinuation of aspirin. METHODS: Our single-center study describes the outcomes of 26 LVAD patients who experienced a total of 49 GIB events: these individuals were either in Group-1 (lower INR target range) or Group-2 (lower INR target plus a hemostatic agent) as the secondary prophylaxis strategy. Each GIB event was considered an independent event. Outcomes assessed were bleeding reoccurrence rates, time to next GIB, acute GIB strategies, GIB-free days, thromboembolic events, survival, coagulation, and hematologic parameters. RESULTS: GIB reoccurrence rates were not statistically different: Group-1, 9 (40.9%), versus Group-2, 15 (55.6%); p = 0.308. Danazol was utilized 81.5% of the time as the designated hemostatic agent. Additionally, no significant differences were observed with all of our secondary outcome measures for bleeding, ischemic events, or survival. CONCLUSION: While our study was not powered to assess the clinical outcomes related to survival and thromboembolic events, no discernable increased risk for ischemic events including pump thrombosis were observed. Our data suggest that a lower INR target range plus danazol does not confer any additional benefit over a lower INR target range only approach. The results of this report are hypothesis-generating and additional studies are warranted to elucidate the optimal antithrombotic strategy and role of hemostatic agents in reducing the risk of recurrent GIB events.

High Prevalence of Cardiac Amyloidosis in Clinically Significant Aortic Stenosis: A Meta-Analysis.

Background: There is growing evidence of coexistence of aortic stenosis (AS) and transthyretin cardiac amyloidosis (CA). Not screening AS patients at the time of hospital/clinic visit for CA represents a lost opportunity. Methods: We surveyed studies that reported the prevalence of CA among AS patients. Studies that compared patients with aortic stenosis with cardiac amyloidosis (AS-CA) and AS alone were further analyzed, and meta-regression was performed. Results: We identified nine studies with 1,321 patients of AS, of which 131 patients had concomitant CA, with a prevalence of 11%. When compared to AS-alone, the patients with AS-CA were older, more likely to be males, had higher prevalence of carpal tunnel syndrome, right bundle branch block. On echocardiogram, patients with AS-CA had thicker interventricular septum, higher left ventricular mass index (LVMI), lower myocardial contraction fraction, and lower stroke volume index. Classical low-flow low-gradient (LFLG) physiology was more common among patients with AS-CA. Patients with AS-CA had higher all-cause mortality than patients with AS alone (33% vs. 22%, P = 0.02) in a follow-up period of at least 1 year. Conclusions: CA has a high prevalence in patients with AS and is associated with worse clinical, imaging, and biochemical parameters than patients with AS alone.

Mechanical circulatory support in pre and postheart transplant period.

PURPOSE OF REVIEW: Progression of heart failure (HF) and its unpredictable and volatile nature, often requires advanced therapies including heart transplant. Mechanical circulatory support plays an integral part in the advanced treatment options. This technology can be deployed in several ways, particularly in the preparation and patient optimization for heart transplants. This article discusses the use of temporary and durable devices and their deployment strategies in the pre and posttransplant period. RECENT FINDINGS: Recently temporary mechanical support devices have allowed us to improve survival to transplant as well as posttransplant. Early implementation of temporary devices both for stabilization of advanced HF patients being considered for transplant as well as those with posttransplant primary graft dysfunction (although utilization of extracorporeal membrane oxygenation has repeatedly shown to be associated with worse outcomes compared to the other devices discussed), is reflective of the degree of disease progression in these patients. The outcomes of patients supported with durable devices have significantly improved with advancing technology. HeartMate 3 device has not only been shown to improve survival as well as the quality of life but in comparison to its predecessor, has been shown to decrease the morbidity associated with this technology. SUMMARY: Both temporary and durable devices are now associated with improved survival and allow us to transplant patients in a more stable and safer manner with fewer adverse events. Based on the new United Network of Organ Sharing allocation system, it allows us to upgrade those who do not have the luxury of time to wait for a transplant. Primary graft dysfunction now also can be assisted with those devices, which is reflected in improved survival of posttransplant patients.

Prospective Multicenter Study of Myocardial Recovery Using Left Ventricular Assist Devices (RESTAGE-HF [Remission from Stage D Heart Failure]): Medium-Term and Primary End Point Results.

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.

Outcomes of Severely Obese Patients Supported by a Centrifugal-Flow Left Ventricular Assist Device.

BACKGROUND: Ventricular assist devices provide improved outcomes for patients with advanced heart failure, but their benefit in the severely obese is not well documented. METHODS: Patients enrolled in the HeartWare ADVANCE trial (n=382) were divided into 2 body mass index (BMI) groups. Patients with severe obesity (>35 kg/m2) were compared with a control group with BMI ≤35 kg/m2. The association of BMI with survival was tested using Kaplan-Meier analysis and major adverse events were compared. RESULTS: At implantation, 48 (13%) of patients were severely obese. There was no difference in survival through 2 years of support between severely obese patients and the control group. Severely obese patients were at higher risk of driveline infection (P = .01) and acute renal dysfunction (P = .002). Both groups experienced similar improvements in quality of life. Functional capacity improved in both severely obese and control patients, although severely obese patients had smaller improvements than controls in their 6-minute walk scores. CONCLUSIONS: Despite an increased risk of adverse events, severe obesity was not associated with reduced survival or quality of life. A better understanding of the risks and benefits of left ventricular assist device therapy in obese patients will help in the shared decision-making of the patient selection process.

Questionable utility of digoxin in left-ventricular assist device recipients: A multicenter, retrospective analysis.

BACKGROUND: While clinical experience with left ventricular assist devices (LVAD) continues to grow and evolve, little is known regarding the ongoing use of certain medications in this population. We sought to evaluate the utility of digoxin in LVAD recipients and its association with outcomes. METHODS: A total of 505 patients who underwent continuous-flow LVAD implantation at 5 centers from 2007-2015 were included. Patients were divided into 4 groups: not on digoxin at any time (ND; n = 257), received digoxin pre implant (PreD; n = 144), received digoxin pre and post implant (ContD; n = 55), and received digoxin only post implant (PostD; n = 49). Survival and all-cause readmission were compared between the 4 groups. RESULTS: There was no difference in survival at 1 year nor at 3 years between groups (ND = 88%, 66%, respectively; PreD = 85%, 66%; ContD = 86%, 57%; PostD = 90%, 51%; p = 0.7). Readmission per 100 days also was not different between groups (ND = 0.5, PreD = 0.6, ContD = 0.5, PostD = 0.7; p = 0.1). CONCLUSIONS: In this large, multicenter cohort, use of digoxin was not associated with any significant benefit in regard to mortality or hospitalization in patients supported with a continuous-flow LVAD. Importantly, its discontinuation post implant did not worsen all-cause hospitalization or survival.

Impact of QRS Duration and Ventricular Pacing on Clinical and Arrhythmic Outcomes in Continuous Flow Left Ventricular Assist Device Recipients: A Multicenter Study.

OBJECTIVES: Wide QRS duration and ventricular pacing are common in recipients of continuous-flow left ventricular assist devices (CF-LVADs) but their impact on outcomes remains unclear. We assessed the clinical and arrhythmic outcomes of CF-LVAD patients with wide QRS or right ventricular (RV) pacing at baseline, compared with those with narrow QRS and those with continued cardiac resynchronization therapy (CRT). METHODS AND RESULTS: A total of 520 patients (57 ± 13 years) with an implantable cardioverter-defibrillator (ICD) (n = 240) or CRT-defibrillator (n = 280) who underwent CF-LVAD implantation at 5 centers in 2007-2015 were studied. Patients were divided into 3 groups: ICD-N (QRS ≤120 ms; n = 134), ICD-W (QRS >120 ms; n = 106), and CRT (n = 280). Mortality, hospitalization, and ventricular arrhythmia (VA) incidence were compared among the groups. Baseline QRS duration was different among the groups (100 ± 13 [ICD-N] vs 155 ± 26 [ICD-W] vs 159 ± 29 ms [CRT]; P < .0001). In the ICD-W group, 37 (35%) had >80% RV pacing at baseline. Median biventricular pacing in the CRT group was 96%. Over 523 days of CF-LVAD support, Kaplan-Meier analysis showed no difference in survival among groups (log rank P = .9). According to multivariate Cox regression, wide QRS duration and RV pacing were not associated with survival. QRS narrowed during CF-LVAD support in the ICD-W and CRT groups but was not associated with improved survival (P = .9). No differences were noted among the groups in hospitalizations (P = .9), VA (P = .2), or ICD shocks (P = .06). CONCLUSIONS: In this large CF-LVAD cohort, a wide QRS duration, high percentage of RV pacing at baseline, and changes in QRS duration after LVAD implantation were not associated with survival. Continued CRT after CF-LVAD implantation also was not associated with improved survival or HF hospitalizations.

Management of Antiplatelet Therapy During Continuous-Flow Left Ventricular Assist Device Support After Thrombotic Hemorrhagic Events.

Hemorrhagic or thrombotic events are common complications in heart failure patients with continuous-flow left ventricular assist device (CF-LVAD) support. Aim of this study is to investigate the effect of change in antiplatelet therapy after thrombotic or hemorrhagic events in patients with CF-LVAD support. A total of 231 CF-LVAD patients were included in this study. Patients with CF-LVAD were categorized into three groups: (1) high antiplatelet regimen as control group (aspirin [ASA] 325 mg; n = 115), (2) low antiplatelet regimen (ASA 81 mg; n = 82), started after hemorrhagic complications, and (3) double antiplatelet therapy (ASA/clopidogrel; n = 34) started after thrombotic complications. In our analysis, indications for low antiplatelet therapy were gastrointestinal (GI) bleeding (36%), hemorrhagic stroke (8%), and epistaxis (9%). Freedom from major bleeding events after changing therapy was comparable at 1 year for all three groups respectively 96%, 97%, and 91% (log rank = 0.421). Major indications for double antiplatelet therapy were pump thrombosis (15%) and coronary artery stent placement (2.5%). Freedom from thrombotic events after changing therapy was comparable at 1 year for groups 1, 2, and 3, respectively, 97%, 98%, and 91% (log rank = 0.317). Logistic regression shows that Heartmate II patients required more antiplatelet therapy changes compared with HeartWare (odds ratio [OR]: 3.611, 95% confidence interval [CI]: 1.8-6.9; p = 0.0001). HeartMate II required more adjustment of antiplatelet therapy during follow-up. Reducing or increasing antithrombotic therapies in response to major thrombotic hemorrhagic events in CF-LVAD patients is a safe strategy to avoid recurrences.

HVAD: The ENDURANCE Supplemental Trial.

OBJECTIVES: The aim of this study was to prospectively evaluate the impact of blood pressure management on stroke rates in patients receiving the HeartWare HVAD System. BACKGROUND: The ENDURANCE trial demonstrated noninferiority of the HeartWare HVAD System versus control (HeartMate II) in patients with advanced heart failure ineligible for heart transplantation. However, stroke was more common in HVAD subjects. Post hoc analyses demonstrated increased mean arterial blood pressure as a significant independent risk factor for stroke. METHODS: The ENDURANCE Supplemental Trial was a prospective, multicenter evaluation of 465 patients with advanced heart failure ineligible for transplantation, randomized 2:1 to HVAD (n = 308) or control (n = 157). The primary endpoint was the 12-month incidence of transient ischemic attack or stroke with residual deficit 24 weeks post-event. Secondary endpoints included the composite of freedom from death, disabling stroke, and need for device replacement or urgent transplantation, as well as comparisons of stroke or transient ischemic attack rates in HVAD cohorts in ENDURANCE Supplemental and ENDURANCE. RESULTS: The enhanced blood pressure protocol significantly reduced mean arterial blood pressure. The primary endpoint was not achieved (14.7% with HVAD vs. 12.1% with control, noninferiority [margin 6%] p = 0.14). However, the secondary composite endpoint demonstrated superiority of HVAD (76.1%) versus control (66.9%) (p = 0.04). The incidence of stroke in HVAD subjects was reduced 24.2% in ENDURANCE Supplemental compared with ENDURANCE (p = 0.10), and hemorrhagic cerebrovascular accident was reduced by 50.5% (p = 0.02). CONCLUSIONS: The ENDURANCE Supplemental Trial failed to demonstrate noninferiority of HVAD versus control regarding the pre-specified primary endpoint. However, the trial confirmed that BP management is associated with reduced stroke rates in HVAD subjects. HVAD subjects, relative to control subjects, more commonly achieved the composite endpoint (freedom from death, disabling stroke, and device replacement or urgent transplantation). (A Clinical Trial to Evaluate the HeartWare™ Ventricular Assist System [ENDURANCE SUPPLEMENTAL TRIAL] [DT2]; NCT01966458).

Cardiac Resynchronization Therapy and Clinical Outcomes in Continuous Flow Left Ventricular Assist Device Recipients.

BACKGROUND: Many patients with heart failure continue cardiac resynchronization therapy (CRT) after continuous flow left ventricular assist device (CF-LVAD) implant. We report the first multicenter study to assess the impact of CRT on clinical outcomes in CF-LVAD patients. METHODS AND RESULTS: Analysis was performed on 488 patients (58±13 years, 81% male) with an implantable cardioverter defibrillator (ICD) (n=223) or CRT-D (n=265) who underwent CF-LVAD implantation at 5 centers from 2007 to 2015. Effects of CRT on mortality, hospitalizations, and ventricular arrhythmia incidence were compared against CF-LVAD patients with an ICD alone. Baseline differences were noted between the 2 groups in age (60±12 versus 55±14, P<0.001) and QRS duration (159±29 versus 126±34, P=0.001). Median biventricular pacing in the CRT group was 96%. During a median follow-up of 478 days, Kaplan-Meier analysis showed no difference in survival between groups (log rank P=0.28). Multivariate Cox regression demonstrated no survival benefit with type of device (ICD versus CRT-D; P=0.16), whereas use of amiodarone was associated with increased mortality (hazard ratio 1.77, 95% confidence interval 1.1-2.8, P=0.01). No differences were noted between CRT and ICD groups in all-cause (P=0.06) and heart failure (P=0.9) hospitalizations, ventricular arrhythmia incidence (43% versus 39%, P=0.3), or ICD shocks (35% versus 29%, P=0.2). During follow-up, 69 (26%) patients underwent pulse generator replacement in the CRT-D group compared with 36 (15.5%) in the ICD group (P=0.003). CONCLUSIONS: In this large, multicenter CF-LVAD cohort, continued CRT was not associated with improved survival, hospitalizations, incidence of ventricular arrhythmia and ICD therapies, and was related to a significantly higher number of pulse generator changes.