Risk Factors and Outcomes of Gastrointestinal Bleeding in Left Ventricular Assist Device Recipients

Development of in vitro microfluidic models to study endothelial responses to pulsatility with different mechanical circulatory support devices

Continuous-flow ventricular assist devices (CFVAD) and counterpulsation devices (CPD) are used to treat heart failure (HF). CFVAD can diminish pulsatility, but pulsatile modes have been implemented to increase vascular pulsatility. The effects of CFVAD in a pulsatile mode and CPD support on the function of endothelial cells (ECs) are yet to be investigated. In this study, two in vitro microfluidic models for culturing ECs are proposed to reproduce blood pressure (BP) and wall shear stress (WSS) on the arterial endothelium while using these medical devices. The layout and parameters of the two microfluidic systems were optimized based on the principle of hemodynamic similarity to efficiently simulate physiological conditions. Moreover, the unique design of the double-pump and double afterload systems could successfully reproduce the working mode of CPDs in an in vitro microfluidic system. The performance of the two systems was verified by numerical simulations and in vitro experiments. BP and WSS under HF, CFVAD in pulsatile modes, and CPD were reproduced accurately in the systems, and these induced signals improved the expression of Ca2+, NO, and reactive oxygen species in ECs, proving that CPD may be effective in normalizing endothelial function and replacing CFVAD to a certain extent to treat non-severe HF. This method offers an important tool for the study of cell mechanobiology and a key experimental basis for exploring the potential value of mechanical circulatory support devices in reducing adverse events and improving outcomes in the treatment of HF in the future.

Study on the hemodynamic effects of different pulsatile working modes of a rotary blood pump using a microfluidic platform that realizes in vitro cell culture effectively

Rotary blood pumps (RBPs) operating at a constant speed generate non-physiologic blood pressure and flow rate, which can cause endothelial dysfunction, leading to adverse clinical events in peripheral blood vessels and other organs. Notably, pulsatile working modes of the RBP can increase vascular pulsatility to improve arterial endothelial function. However, the laws and related mechanisms of differentially regulating arterial endothelial function under different pulsatile working modes are still unclear. This knowledge gap hinders the optimal selection of the RBP working modes. To address these issues, this study developed a multi-element in vitro endothelial cell culture system (ECCS), which could realize in vitro cell culture effectively and accurately reproduce blood pressure, shear stress, and circumferential strain in the arterial endothelial microenvironment. Performance of this proposed ECCS was validated with numerical simulation and flow experiments. Subsequently, this study investigated the effects of four different pulsation frequency modes that change once every 1-4-fold cardiac cycles (80, 40, 80/3, and 20 cycles per min, respectively) of the RBP on the expression of nitric oxide (NO) and reactive oxygen species (ROS) in endothelial cells. Results indicated that the 2-fold and 3-fold cardiac cycles significantly increased the production of NO and prevented the excessive generation of ROS, potentially minimizing the occurrence of endothelial dysfunction and related adverse events during the RBP support, and were consistent with animal study findings. In general, this study may provide a scientific basis for the optimal selection of the RBP working modes and potential treatment options for heart failure.

Associations Between Preimplant Cancer Type and Left Ventricular Assist Device Outcomes: An INTERMACS Registry Analysis

We used the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) database to examine whether history of a solid versus hematologic malignancy impacts outcomes after left ventricular assist device (LVAD) implantation. We included LVAD recipients (2007-2017) with cancer history reported (N = 14,799, 21% female, 24% Black). Multivariate models examined the association between cancer type and post-LVAD mortality and adverse events. Competing risk analyses compared death and heart transplantation between cancer types and those without cancer in bridge-to-transplant (BTT) patients. A total of 909 (6.1%) patients had a history of cancer (4.9% solid tumor, 1.3% hematologic malignancy). Solid tumors were associated with higher mortality (adjusted hazard ratio [aHR] = 1.31, 95% confidence interval [CI] = 1.09-1.57), major bleeding (aHR = 1.15, 95% CI = 1.00-1.32), and pump thrombosis (aHR = 1.52, 95% CI = 1.09-2.13), whereas hematologic malignancies were associated with increased major infection (aHR = 1.43, 95% CI = 1.14-1.80). Compared to BTT patients without a history of cancer, solid tumor patients were less likely to undergo transplantation (adjusted subdistribution HR [aSHR] = 0.63, 95% CI = 0.45-0.89) and hematologic malignancy patients were as likely to experience death (aSHR = 1.16, 95% CI = 0.63-2.14) and transplantation (aSHR = 0.69, 95% CI = 0.44-1.08). Cancer history and type impact post-LVAD outcomes. As LVAD utilization in cancer survivors increases, we need strategies to improve post-LVAD outcomes in these patients.

Gastrointestinal bleeding following Heartmate 3 left ventricular assist device implantation: The Michigan Bleeding Risk Model

BACKGROUND

Gastrointestinal bleeding (GIB) results in frequent hospitalizations and impairs quality of life in durable left ventricular assist device (LVAD) recipients. Anticipation of these events before implantation could have important implications for patient selection and management.

METHODS

The study population included all adult HeartMate 3 (HM3) primary LVAD recipients enrolled in the STS Intermacs registry from January 2017 to December 2020. Using multivariable modeling methodologies, we investigated the relationships between preimplantation characteristics and postimplant bleeding, bleeding and death, and additional bleeding episodes on subsequent bleeding episodes and created a risk score to predict the likelihood of post-LVAD GIB based solely on preimplantation factors.

RESULTS

Of 6,425 patients who received an HM3 LVAD, 1,010 (15.7%) patients experienced GIB. Thirteen preimplantation factors were independent predictors of post-LVAD GIB. A risk score was created from these factors and calculated for each patient. By 3 years postimplant, GIB occurred in 11%, 26%, and 43% of low-, medium- and high-risk patients, respectively. Experiencing 1 post-LVAD GIB event was associated with an increased risk for further GIB events, with 33.9% of patients experiencing at least 1 recurrence. While post-LVAD GIB was associated with mortality, there was no relationship between number of GIB events and death.

CONCLUSIONS

The Michigan Bleeding Risk Model is a simple tool, which facilitates the prediction of post-LVAD GIB in HM3 recipients using 13 preimplant variables. The implementation of this tool may help in the risk stratification process and may have therapeutic and clinical implications in HM3 LVAD recipients.

Numerical simulation analysis of multi-scale computational fluid dynamics on hemodynamic parameters modulated by pulsatile working modes for the centrifugal and axial left ventricular assist devices

Continuous flow (CF) left ventricular assist devices (LVAD) operate at a constant speed mode, which could result in increased risk of adverse events due to reduced vascular pulsatility. Consequently, pump speed modulation algorithms have been proposed to augment vascular pulsatility. However, the quantitative local hemodynamic effects on the aorta when the pump is operating with speed modulation using different types of CF-LVADs are still under investigation. The computational fluid dynamics (CFD) study was conducted to quantitatively elucidate the hemodynamic effects on a clinical patient-specific aortic model under different speed patterns of CF-LVADs. Pressure distribution, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and velocity were calculated to compare their differences at constant and pulsatile speeds under centrifugal and axial LVAD support. Results showed that pulse pressure on the aorta was significantly larger under pulsatile speed mode than that under constant speed mode for both CF-LVADs, indicating enhanced aorta pulsatility, as well as the higher peak blood flow velocity on some representative slices of aorta. Pulsatile speed modulation enhanced peak WSS compared to constant speed; high TAWSS region appeared near the branch of left common carotid artery and distal aorta regardless of speed modes and CF-LVADs but these regions also had low OSI; RRT was almost the same for all the cases. This study may provide a basis for the scientific and reasonable selection of the pulsatile speed patterns of CF-LVADs for treating heart failure patients.

Patient-specific severity of von Willebrand factor degradation identifies patients with a left ventricular assist device at high risk for bleeding

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) cause an acquired von Willebrand factor (VWF) deficiency and bleeding. Models to risk-stratify for bleeding are urgently needed. We developed a model of continuous-flow LVAD bleeding risk from patient-specific severity of VWF degradation.

METHODS

In a prospective, longitudinal cohort study, paired blood samples were obtained from patients (n = 67) with a continuous-flow LVAD before and during support. After 640 ± 395 days, patients were categorized as all-cause bleeders, gastrointestinal (GI) bleeders, or nonbleeders. VWF multimers and VWF clotting function were evaluated to determine bleeding risk.

RESULTS

Of 67 patients, 34 (51%) experienced bleeding, 26 (39%) experienced GI bleeding, and 33 (49%) did not bleed. In all patients, LVAD support significantly reduced high-molecular-weight VWF multimers (P < .001). Bleeders exhibited greater loss of high-molecular-weight VWF multimers (mean ± standard deviation, -10 ± 5% vs -7 ± 4%, P = .008) and reduced VWF clotting function versus nonbleeders (median [interquartile range], -12% [-31% to 4%] vs 0% [-9 to 26%], P = .01). A combined metric of VWF multimers and VWF function generated the All-Cause Bleeding Risk Score, which stratified bleeders versus nonbleeders (86 ± 56% vs 41 ± 48%, P < .001) with a positive predictive value of 86% (95% confidence interval, 66%-95%) and diagnostic odds ratio of 11 (95% confidence interval, 2.9-44). A separate GI Bleeding Risk Score stratified GI bleeders versus nonbleeders (202 ± 114 vs 120 ± 86, P = .003) with a positive predictive value of 88% (64%-97%) and diagnostic odds ratio of 18 (3.1-140).

CONCLUSIONS

The severity of loss of VWF multimers and VWF clotting function generated Bleeding Risk Scores with high predictive value for LVAD-associated bleeding. This model may guide personalized antithrombotic therapy and patient surveillance.

Gastrointestinal Bleeding in Patients Supported with Left Ventricular Assist Devices: The Journey from Bridging to Destination

End-stage heart failure is a prevalent and fatal cardiovascular disease. Almost 1 in 4 cases of mortality in the United States is attributed to heart failure. Left ventricular assist devices (LVADs) have emerged as a safe destination therapy or bridge to transplant. Despite remarkable results, LVAD is associated with significant adverse events, such as gastrointestinal bleeding (GIB). In this review, we aimed to understand the incidence and prevalence, pathophysiologic mechanisms, predictors, diagnostic mechanisms, management, and preventative measures of GIB in patients with an LVAD. GIB is a common adverse event in patients with an LVAD with an incidence of 15% to 25%. The exact pathogenesis of GIB is poorly understood. However, different mechanisms of bleeding have been described, such as arteriovenous malformations, acquired von Willebrand syndrome, coagulopathy, and treatment with antithrombotic therapy. Upper GIB is the most common site of GIB in patients with an LVAD. The management of GIB in patients with LVAD includes ensuring hemodynamic stability, holding or reversing antithrombotic therapy, and investigating and controlling the source of GIB through diagnostic and interventional endoscopic and radiologic means. Prophylactic medication use (e.g., danazol, octreotide, and bevacizumab) can decrease the risk of GIB in patients with an LVAD by decreasing arteriovenous malformations. Despite that the overall risk of GIB has decreased with new advancements in LVAD technology, further studies are needed regarding predictors, risk stratification, and optimal antithrombotic therapy to minimize the morbidity and mortality in patients with an LVAD. In conclusion, prompt diagnosis and management in a multidisciplinary team approach are crucial and lifesaving in such a life-threatening condition.

Gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices: A comprehensive review

BACKGROUND

Gastrointestinal bleeding is a major cause of morbidity that plagues the quality of life of patients supported on contemporary continuous-flow left ventricular assist devices (CF-LVADs). Despite benefits in survival and the nearly 50% reduction in complications provided by CF-LVADs, bleeding remains one of the most frequent adverse events with CF-LVAD implants. The CF-LVADs cause an increased risk of bleeding mainly due to the activation of the coagulation cascade.

METHODS

A literature search was done using PubMed and Google Scholar from Inception to February 2022. Qualitative analyses of the articles retrieved were used to construct this review. This review attempts to provide a comprehensive summary of the epidemiology, pathophysiology, risk stratification, and management of gastrointestinal bleeding as a complication of CF-LVAD as well as propose an algorithm for diagnosis and treatment.

RESULTS

Bleeding can occur at different sites in the gastrointestinal tract, the most common underlying pathology being arteriovenous malformations located in the upper gastrointestinal tract The increased prevalence of gastrointestinal (GI) bleeding in CF-LVAD patients has been attributed to the physiology of the LVAD itself, the use of anticoagulants, as well as patient comorbidities. Management involves pharmacologic and nonpharmacologic strategies.

CONCLUSIONS

CF-LVAD-supported patients have a significant risk of GI bleeding that is mainly caused by arteriovenous malformations located in the upper GI tract. The increased prevalence of GI bleeding in CF-LVAD patients is attributed to several etiologies that include factors attributed to the device itself and extrinsic factors such as the use of anticoagulation.

A Multicenter Study of Left Ventricular Assist Device-Related Gastrointestinal Bleeding

INTRODUCTION

Continuous left ventricular assist devices (LVADs) offer hemodynamic support in advanced and decompensated heart failure but are often complicated by gastrointestinal bleeding (GIB) in medically fragile patients.

METHODS

We performed a retrospective analysis of 475 consecutive patients who underwent LVAD implantation at the Massachusetts General Hospital and Tufts Medical Center from 2008 to 2019 and identified 128 patients with clinically significant GIB. Clinical characteristics of each bleeding event, including procedures and interventions, were recorded. We examined LVAD patients with overt and occult presentations to determine diagnostic endoscopic yield and analyzed predictors of recurrent GIB.

RESULTS

We identified 128 unique patients with LVAD implantation complicated by GIB. No significant difference was observed based on study center, underlying cardiomyopathy, race/ethnicity, serum indices, and medications used. Overt bleeders presented more commonly during LVAD implantation admission ( P = 0.001) than occult bleeders. Occult bleed presentations had only 1 lower and no middle GI bleed source identified, despite similar workups to overt bleeds. Destination therapy (e.g., among nontransplant candidates) LVAD implantation (odds ratio 2.38, 95% confidence interval 1.05-5.58) and a history of GIB (odds ratio 3.85, 95% confidence interval 1.29-12.7) were independently associated with an increased risk of recurrent GIB-related hospitalization.

DISCUSSION

Our findings confirm a high rate of GIB, especially in destination LVAD patients, and show a low diagnostic yield for colonoscopy and middle GI bleed assessments in LVAD patients with occult bleeds. Overt bleeding was more common and associated with vascular malformations. Although endoscopic interventions stopped active hemorrhage, GIB often recurred.

Prevalence, management, and outcomes of haemorrhagic events in left ventricular assist device recipients

AIMS

Left ventricular assist devices (LVADs) have reduced the mortality of patients with advanced heart failure both as bridge-to-transplant and as destination therapy. However, LVADs are associated with various complications, including bleedings, which affect the prognosis. The aim of the study was to explore the prevalence, management, and outcomes of haemorrhagic adverse events in LVAD recipients.

METHODS AND RESULTS

We conducted a retrospective, single-centre, cohort study including all patients who received an LVAD from January 2008 to December 2019 in our tertiary centre (Rangueil University Hospital, Toulouse, France). Bleeding events, death, and heart transplantation were collected from electronic medical files. Eighty-eight patients were included, and 43 (49%) presented at least one bleeding event. Gastrointestinal (GI) bleeding was the most frequent (n = 21, 24%), followed by epistaxis (n = 12, 14%) and intracranial haemorrhage (n = 9, 10%). Bleeding events were associated with increased mortality [hazard ratio (HR) 3.8, 95% confidence interval (CI) 1.5-9.3, P < 0.01], particularly in case of intracranial haemorrhage (HR 14.6, 95% CI 4.2-51.1, P < 0.0001). GI bleedings were associated with a trend towards increased mortality (HR 3.0, 95% CI 0.9-9.3, P = 0.05). Each bleeding episode multiplied the risk of death by 1.8 (95% CI 1.2-2.7, P < 0.01). Finally, only early bleedings (<9 months post-implantation) had an impact on mortality (HR 4.2, 95% CI 1.6-11.1, P < 0.01). Therapeutic management was mainly based on temporary interruption of anticoagulation and permanent interruption of antiplatelet therapy. Invasive management was rarely performed.

CONCLUSIONS

Haemorrhagic events in LVAD recipients are frequent and associated with increased mortality. GI bleedings are the most frequent, and intracranial haemorrhages the most associated with mortality. Management remains empirical requiring more research.

An external validation study of the Utah Bleeding Risk Score

OBJECTIVES

Gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices (CF-LVAD) impairs quality of life and increases hospitalization rate. The Utah Bleeding Risk Score (UBRS) has been created to predict gastrointestinal bleeding (GIB) in patients on left ventricular assist device. We here aimed to externally validate UBRS on our cohort of CF-LVAD patients.

METHODS

Utah Bleeding Risk Score was calculated, GIB events summarized on follow-up and patients stratified into 3 risk groups. Predictive ability of UBRS was examined at 3 years and during whole support time and person time incidence rates correlated to UBRS. In a sub-analysis, single effects of UBRS variables on freedom from GIB were assessed.

RESULTS

A total of 111 CF-LVAD patients were included. The median UBRS was 2 (3-1). Receiver operating characteristic curve analysis showed an area under the curve of 0.519 (P = 0.758, 95% confidence interval = 0.422-0.615) at 3 years and an area under the curve of 0.515 (P = 0.797, 95% confidence interval = 0.418-0.611) during whole support time. No significant difference was observed in UBRS between bleeders and non-bleeders (P = 0.80). No significant difference in freedom from GIB was observed (P3 years = 0.7; Psupport-time = 0.816) and no independent significance regarding the freedom from bleeding at 3 years for any variable was observed. Coronary artery disease was associated with higher risk of GIB beyond the 3rd year (P = 0.048).

CONCLUSIONS

UBRS was not able to predict GIB and therefore not applicable in our cohort of patients. Coronary artery disease could lead to a higher risk for GIB during support time. An additional validation in a larger cohort is advisable.

Impact of heart failure drug therapy on rates of gastrointestinal bleeding in LVAD recipients: An INTERMACS analysis

INTRODUCTION

Gastrointestinal bleeding (GIB) remains a common and vexing complication of left ventricular assist device (LVAD) support. Recent single-center analyses suggest that ACE inhibitors (ACEi)/angiotensin receptor blockers (ARB) and digoxin may prevent GIB in LVAD patients. Here we evaluate the effect of guideline-directed medical therapies (GDMT) for heart failure (HF) on rates of GIB through analysis of the INTERMACS registry database.

METHODS

Thirteen thousand seven hundred thirty-two patients who received a continuous-flow LVAD and were on antiplatelet therapy and anticoagulation with warfarin after 3 months of pump support were included in the analysis. GIB events following implant were assessed based on receipt of ACEi/ARB, beta-blockers (BB), mineralocorticoid receptor antagonist (MRA), amiodarone, digoxin, loop diuretics, and phosphiesterase-5 inhibitors (PDE5). Backwards stepwise cox regression was used to control for confounding of each drug class on each other, as well as for clinical variables like age, gender, renal function, HF etiology, and device strategy.

RESULTS

After 3 months of pump support medications used in LVAD patients were BB (65.0%), ACEi/ARB (51.7%), Amio (43.7%), MRA (37.9%), and loop diuretics (70.1%). In patients with available data, PDE and digoxin use were 18.2% and 16.9%, respectively. The overall incidence of GIB was 19.5% at 2 years of support. After adjustment for other clinical variables, loop diuretics (HR 1.274, p < 0.001) and PDE5 (HR 1.241, p < 0.001) use were associated with increased risk of GIB, while use of BB (HR 0.871, p = 0.006) was associated with lower risk of GIB. ACEi/ARB (HR 1.002, p = 0.971), Amio (HR 1.083, p = 0.106), AA (HR 0.967, p = 0.522) or digoxin (HR 1.087, p = 0.169) did not affect GIB rates on LVAD support (Figure).

CONCLUSION

Despite recent reports, ACEi/ARB, MRA, Amio, and digoxin use does not appear to be associated with GIB during LVAD support. The heightened risk seen in those on loop diuretics may reflect venous congestion in these patients, while antiplatelet effects of PDE5 could drive the higher risk of GIB.

Impact of Shared Care in Remote Areas for Patients With Left Ventricular Assist Devices

OBJECTIVES

The aim of this study was to evaluate the impact of a shared-care model on outcomes in patients with left ventricular assist devices (LVADs) living in remote locations.

BACKGROUND

Health care delivery through shared-care models has been shown to improve outcomes in patients with chronic diseases. However, the impact of shared-care models on outcomes in patients with LVAD is unknown.

METHODS

LVAD recipients in the authors' program (2007 to 2018) were classified based on the levels of care provided and training and resources used: level 1, was defined as outpatient primary care without LVAD-specific care; level 2 was level 1 services and outpatient LVAD-specific care; level 3 was level 2 services and inpatient LVAD-specific care and implantation center (IC). The Kaplan-Meier method was used to compare rates of survival, bleeding, pump thrombosis, infection, neurologic events, and readmissions among levels of care.

RESULTS

A total of 336 patients were included, with 255 patients (75.9%) cared for in shared-care facilities. Median follow-up was 810 (interquartile range: 321 to 1,096) days. In comparison to patients cared for by IC, patients at levels 2 and 3 shared-care centers had similar rates of death, bleeding, neurologic events, pump thromboses, and infections. However, the rates of death, pump thromboses, and infections were higher for level 1 patients than in IC patients.

CONCLUSIONS

Shared health care is an effective strategy to deliver care to patients with LVAD living in remote locations. However, patients in shared-care facilities unable to provide LVAD-specific care are at higher risk of unfavorable outcomes. Availability of LVAD-specific care should be strongly considered during patient selection and every effort made to ensure LVAD-specific training and resources are available at shared-care facilities.

Heart transplant waiting list implications of increased ventricular assist device use as a bridge strategy: A national analysis

The use of ventricular assist devices (VADs) as a bridge to heart transplant (HT) is increasing, while HT volume remains stagnant. This may portend longer waiting times and an otherwise more competitive environment for all patients on the HT waiting list. A retrospective analysis of patients who were listed for HT in the United Network for Organ Sharing (UNOS) database from 2000 to 2015 was conducted. Mean waiting time, proportion of HT reception (%HT), proportion of death (%death), and proportion of waiting list removal (%removal) were calculated across three eras: Era 1 (2000-2007), Era 2 (2008-2011), and Era 3 (2012-2015). During the study period, 29 728 patients successfully underwent HT. 19 127 (64.3%) were directly transplanted (direct HT); 4491 (15.1%) received VADs prior to listing as a bridge to decision (BTD); and 4593 (15.5%) received VADs after listing as a bridge to transplant (BTT). Across the three eras, the average number of registrants per year grew. Among all groups, waiting time increased across the eras. %HT generally decreased in the BTD and BTT groups but remained constant in the direct HT group. %removal increased, while %death decreased in all group across the eras. Waiting time for HT increased from 2000 to 2015. Patients with VADs as a bridge strategy experienced decreasing %HT and increasing %removal but stable survival. Improvements in VAD safety and durability will ensure their success as part of a bridge strategy to HT under the new UNOS allocation policy.

Pharmacotherapy for durable left ventricular assist devices

Left ventricular assist devices (LVADs) have revolutionized the care of patients with advanced heart failure, yet still require concomitant medications in order to achieve the best possible clinical outcomes. Since the outset of routine placement of durable, continuous-flow LVADs, much of the medication management of these patients to date has been based on International Society of Heart and Lung Transplantation (ISHLT) guidance, most recently published in 2013. Since 2013, numerous multidisciplinary pharmacotherapy publications have increased the LVAD community's understanding of best practices with respect to medications. We identified the major domains of LVAD medication management and conducted a comprehensive search of US National Library of Medicine MEDLINE^® database using keywords chosen to identify medication-related publications of significance dated 2013 or later. Trials pertaining to the HeartMate II™ and the HeartMate™ 3 LVADs (Abbott, Chicago, IL) and the HeartWare™ HVAD™ System (Medtronic, Minneapolis, MN) were chosen for inclusion. Highest priority for inclusion was given to prospective, randomized, controlled studies. Absent these, controlled trials (retrospective or prospective observational) were given next-highest consideration, followed by retrospective uncontrolled studies, and finally case series. Reference lists of qualified publications were reviewed to find any other publications of interest that were not discovered on initial search. Case reports were generally excluded, except where the insight gained was deemed to be uniquely pertinent. This document serves to provide a comprehensive review of the current understanding of optimal medication management in patients with durable, continuous-flow LVADs.

A reappraisal of the pharmacologic management of gastrointestinal bleeding in patients with continuous flow left ventricular assist devices

Advancements in the design and functionality of continuous flow left ventricular assist devices (CF-LVADs), as well as a limited number of donor hearts, have resulted in an increased utilization of this therapy among advanced heart failure (HF) patients. Despite these advancements, gastrointestinal bleeding (GIB) remains a common complication after CF-LVAD implantation. The mechanism of GIB in these patients is complex and includes a combination of angiodysplasia, platelet dysfunction, acquired von Willebrand disease, and a variety of patient-specific factors including advanced age and history of GIB. Several pharmacotherapy options have been reported in the literature, though studies supporting the use of these agents are often small, retrospective reports. Within this review, we discuss the various pharmacologic agents, their proposed mechanisms of action, and the available literature pertaining to their effectiveness and tolerability. Additionally, we propose an evidence-based treatment algorithm, encompassing the updated literature, cost of therapy, medication side effects, and ease of administration.

Gastrointestinal Bleeding as a Complication in Continuous Flow Ventricular Assist Devices: A Systematic Review With Meta-Analysis

Background

The use of ventricular assist devices (VADs) has become predominant in this era of medicine. It is commonly used as a bridge to transplant, recovery and as a destination therapy for patients with severe heart failure, who are not responsive to maximum optimal management or ineligible for transplant. However, several complications are known to occur with the use of these devices. In this research, we will compare gastrointestinal bleeding in patients who used centrifugal flow versus axial flow VADs. We hope that the result of this meta-analysis and the review presented provide adequate information to future researchers, physicians and other healthcare professionals who are interested in this topic.

Methods

Published articles evaluated for inclusion were obtained from MEDLINE (PubMed), Cochrane, EBSCO, clinicaltrials.gov, and international clinical trials registry. This research was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Procured articles were reviewed by two independent reviewers. Only randomized control trials and observational studies were used. Quality assessment was done with Cochrane Collaboration’s tool (RoB.2 with visualization through robviz) and Newcastle-Ottawa Scale (NOS). Data analysis was carried out with the use of R data analysis tool (version 4.0.0; release date: April 24th, 2020).

Results

At the end of this meta-analysis, the occurrence of gastrointestinal bleeding was not significantly different between both groups; with odds ratio (OR): 0.81; 95% confidence interval (CI): 0.65 - 1.00; P value = 0.05. Between-study variance (Tau-squared) was zero (0), standard error (SE) = 0.06. The degree of heterogeneity measured with I-squared statistic was 0% (minimal). Egger’s regression test was not statistically significant, P = 0.93. Symmetry of distribution was observed on the funnel plot. Trim and fill analysis showed no missing studies on the left; SE = 1.68.

Conclusions

The result obtained from this research indicates that the occurrence of gastrointestinal bleeding is not significantly different in both groups of patients, irrespective of the type of continuous flow VAD used. Although, the study sample used in this meta-analysis was limited.

Decreased RPM reduces von Willebrand factor degradation with the EVAHEART LVAS: implications for device-specific LVAD management

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) produces supraphysiologic shear stress that causes von Willebrand factor (VWF) degradation and a bleeding diathesis. Reduction of revolutions per minute (RPM) with axial-flow LVADs does not decrease shear stress enough to reduce VWF degradation and bleeding. However, it is unknown if RPM reduction with centrifugal flow LVADs may minimize VWF degradation. We tested the hypothesis that RPM reduction preserves VWF multimers in the centrifugal-flow EVAHEART left ventricular assist system (LVAS), which is designed to minimize shear stress and blood trauma.

METHODS

Whole blood samples were collected from humans (n = 28). Blood was circulated in ex vivo mock circulatory loops for 6 hours with an EVAHEART LVAS at 2300 (n = 12), 2100 (n = 8), or 1800 RPM (n = 8). Immunoblotting was used to resolve and quantify VWF multimers and degradation fragments.

RESULTS

RPM reduction from 2300 to 2100 to 1800 RPM significantly decreased EVAHEART blood flow from 5.8 ± 0.4 to 4.3 ± 0.6 to 4.1 ± 0.5 L/min (analysis of variance [ANOVA], P = .03). RPM reduction protected VWF from pathologic degradation. At lower RPMs, significantly greater levels of VWF multimers were observed (ANOVA, P = .001). Similarly, at lower RPMs, significantly fewer VWF fragments, a product of VWF degradation, were observed (ANOVA, P = .007).

CONCLUSIONS

RPM reduction significantly reduced VWF degradation with the centrifugal-flow EVAHEART LVAS, an LVAD specifically designed with low shear stress. Different LVADs have unique hematologic footprints and should be managed with device-specific protocols. Adjustment of RPM to minimize blood trauma while still maintaining physiologic hemodynamics has the potential to decrease complications related to LVAD-associated von Willebrand's disease, such as gastrointestinal bleeding and hemorrhagic stroke.

The Effect of Age on Outcomes After Destination-Therapy Left Ventricular Assist Device Implantation: An Analysis of the IMACS Registry

BACKGROUND

As patients with advanced heart failure are living longer, defining the impact of left ventricular assist devices (LVADs) on outcomes in an aging population is of great importance. We describe overall survival, rates of adverse events (AEs), and post-AE survival in patients age ≥ 70 years vs age 50-69 years after destination-therapy (DT) LVAD implantation.

METHODS

A retrospective analysis was conducted with the use of the International Society for Heart and Lung Transplantation Mechanically Assisted Circulatory Support (IMACS) registry. All adults age ≥ 50 years with a continuous-flow DT LVAD from 2013 to 2017 were included. The primary outcome was all-cause mortality. The secondary outcomes were the incidence of and survival after gastrointestinal (GI) bleeding, infection, stroke, pump thrombosis, pump exchange, and right-side heart failure. Mortality and AEs were assessed with the use of competing risk models.

RESULTS

At total of 5,572 patients were included: 3,700 aged 50-69 and 1,872 aged ≥ 70. All-cause mortality by 42 months was 55.8% in patients aged ≥ 70 and 44.8% in patients aged 50-69 (P = 0.001). Patients aged ≥ 70 had a 37.8% higher risk of death after DT LVAD implantation (hazard ratio 1.378, 95% CI 1.251-1.517). Patients aged ≥ 70 had higher risk of GI bleeding but lower risk of right-side heart failure. There was no difference between age groups for risk of infection or stroke. Experiencing any AE was associated with an increased risk of death that did not vary with age.

CONCLUSIONS

Patients aged ≥ 70 years have reduced survival after DT LVAD, in part because of increased GI bleeding, while the incidence of other AEs is similar to that of patients aged 50-69 years. Careful patient selection beyond age alone may allow for optimal outcomes after DT LVAD implantation.

Anticoagulant treatment and bleeding complications in patients with left ventricular assist devices

INTRODUCTION

The treatment options for advanced heart failure patients drastically changed with the introduction of left ventricular assist devices (LVADs), either as bridge to transplant or as destination therapy for patients ineligible for transplant. Despite major benefits in terms of survival, functional status and quality of life, managing patients with LVADs comes with several challenges. The most significant challenge is balancing between the risks of thrombotic and bleeding complications.

AREAS COVERED

The present review describes the pathophysiological mechanisms explaining the alterations in the hemostatic profile of LVAD patients, and summarizes current evidence to guide clinical decision making with regard to anticoagulant treatment and management of bleeding complications.

EXPERT OPINION

LVAD patients require life-long anticoagulant therapy to reduce the risk of pump thrombosis. However, exposing LVAD patients to anticoagulant therapy, in combination with common acquired coagulopathies after LVAD implantation such as acquired von Willebrand syndrome, comes with high risks of bleeding. There is a need for randomized controlled trials in LVAD patients to determine the optimal antithrombotic regimen and find the most effective balance between thrombotic and bleeding complications. In addition, strategies to specifically target the acquired von Willebrand syndrome and its associated angiodysplasias need to be evaluated in the LVAD population.

Identifying Temporal Relationships Between In-Hospital Adverse Events After Implantation of Durable Left Ventricular Assist Devices

Background

This study evaluated the impact of adverse events (AEs) on the development of subsequent AEs after left ventricular assist device (LVAD) surgery.

Methods and Results

The INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) was used to identify primary durable LVADs implanted between 2006 and 2016. The temporal relationships between AEs occurring during the index hospitalization were evaluated using separate risk‐adjusted Cox proportional hazard models. LVADs were implanted in 18 763 patients. The strongest positive relationships were renal failure leading to hepatic dysfunction (hazard ratio [HR], 6.62; 95% CI, 5.12–8.54; P<0.001), respiratory failure leading to renal failure (HR, 5.51; 95% CI, 4.79–6.34; P<0.001), respiratory failure leading to hepatic dysfunction (HR, 4.36; 95% CI, 3.25–5.83; P<0.001), renal failure leading to respiratory failure (HR, 4.18; 95% CI, 3.76–4.64; P<0.001), and renal failure leading to right ventricular assist device implant (HR, 3.70; 95% CI, 2.31–5.90; P<0.001). Although bleeding, infection, and right ventricular assist device implant were each associated with several subsequent AEs, the magnitude of association was less substantial. The lowest 1‐year post‐LVAD survival was associated with the primary AEs of renal failure (68.1%) and respiratory failure (70.7%) (log‐rank P<0.001).

Conclusions

Most in‐hospital AEs after LVAD implantation have a significant association with the development of subsequent AEs, with the most profound impact associated with primary renal or respiratory failure, which are also associated with the lowest 1‐year survival. Targeting the reduction of renal or respiratory failure as the primary AE after LVAD surgery would likely yield the greatest reductions in overall AE burden and subsequent mortality.

Effect of Angiotensin II Inhibitors on Gastrointestinal Bleeding in Patients With Left Ventricular Assist Devices

BACKGROUND

Angiotensin II receptor activation may result in angiogenesis, and ultimately arteriovenous malformations (AVM), through transforming growth factor (TGF)-β and angiopoietin-2 pathway activation.

OBJECTIVES

The goal of this study was to determine whether angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) were associated with lower risk of major gastrointestinal bleeds (GIB) and AVM-related GIBs in continuous-flow left ventricular assist device (CF-LVAD) patients.

METHODS

The authors reviewed HeartMate II CF-LVAD recipients between January 2009 and July 2016. Major GIBs were endoscopically confirmed requiring ≥2 U of packed red blood cells or resulting in death. ACE inhibitor/ARB dose was abstracted from medical records. ACE inhibitor/ARB exposure status was landmarked at 30 days post-operatively to avoid immortal time bias. Fine and Gray hazard models assessed the impact of ACE inhibitor/ARB therapy on major GIB and AVM-related GIB, whereas standard Cox regression assessed the impact on mortality, adjusting for baseline variables.

RESULTS

One-hundred and eleven patients were included with a mean 2.1 ± 1.4 years follow-up. Patients who received an ACE inhibitor/ARB within 30 days post-operatively had a 57% reduction in the risk of major GIB (adjusted hazard ratio [aHR]: 0.43; 95% confidence interval [CI]: 0.19 to 0.97; p = 0.042) and a 63% reduction in the risk of AVM-related GIB (aHR: 0.37; 95% CI: 0.16 to 0.84; p = 0.017). When the mean daily post-operative lisinopril-equivalent ACE inhibitor/ARB dose was >5 mg, the risk of major GIB decreased in a dose-threshold manner (aHR: 0.28; 95% CI: 0.09 to 0.85; p = 0.025).

CONCLUSIONS

ACE inhibitor/ARB therapy is associated with a protective effect of developing GIBs in CF-LVAD patients, with a dose threshold of >5 mg of daily lisinopril equivalence, possibly due to prevention of AVM formation.

The Predicament of Gastrointestinal Bleeding in Patients With a Continuous-Flow Left Ventricular Assist Device: Pathophysiology, Evaluation, and Management

Heart failure affects over 5 million Americans, with numbers expected to rise. While heart transplantation is the most effective long-term strategy for end-stage heart failure, there is a limited cardiac donor pool, and these organs are often unavailable at the time of need. Left ventricular assist devices, therefore, continue to be used to bridge this gap. Originally implanted as a bridge to transplant, these devices are now additionally utilized as destination therapy for patients ineligible for transplant. With the widespread applicability of these devices for not just temporary measures, but also for prolonged use, the short- and long-term impact on other organ systems has become more evident. For example, gastrointestinal (GI) bleeding, with an incidence approaching 30%, is one such complication post-continuous-flow left ventricular assist device implantation. This high incidence of GI bleeding is thought to stem from a combination of factors, including the need for concomitant anticoagulant and antiplatelet therapy, and intrinsic device-related properties resulting in acquired Von Willebrand disease and arteriovenous malformations. Due to the significant morbidity associated with these GI bleeding events, a standardized protocol optimizing medical and endoscopic management, alongside close coordination between the gastroenterology and cardiology services, should be advocated for and ultimately employed.

Clinical Approach to Manage Gastrointestinal Bleeding with a Left Ventricular Assist Device (LVAD)

Left ventricular assist devices (LVADs) are an exceedingly important form of mechanical support for patients with end-stage heart failure. LVADs can be utilized both as a bridge to cardiac transplant and also as a definitive treatment. However, a few complications are associated with LVAD placement, the most common and cumbersome of which is gastrointestinal (GI) bleeding with an incidence of about 30%. These bleeding events often require transfusion therapy, but they are rarely fatal.

The etiologies of GI bleeding following LVAD are multifactorial and include unstable hemodynamics, an acquired von Willebrand factor (vWf) deficiency, impaired platelet aggregation, and activation of fibrinolytic systems. The treatment of choice in LVAD implantation-associated GI bleeding is endoscopy, which plays a vital role in both its diagnosis and management. Even so, its effectiveness in controlling post-LVAD implantation GI bleeding is still poorly ascertained. In this article, we will review the use of medication and alterations in the LVAD setting to prevent the occurrence of GI bleeding, as well as the findings of previously reported literature on LVAD implantation-associated GI bleeding.

Sequential Pattern Mining of Longitudinal Adverse Events After Left Ventricular Assist Device Implant

Left ventricular assist devices (LVADs) are an increasingly common therapy for patients with advanced heart failure. However, implantation of the LVAD increases the risk of stroke, infection, bleeding, and other serious adverse events (AEs). Most post-LVAD AEs studies have focused on individual AEs in isolation, neglecting the possible interrelation, or causality between AEs. This study is the first to conduct an exploratory analysis to discover common sequential chains of AEs following LVAD implantation that are correlated with important clinical outcomes. This analysis was derived from 58,575 recorded AEs for 13,192 patients in International Registry for Mechanical Circulatory Support (INTERMACS) who received a continuous-flow LVAD between 2006 and 2015. The pattern mining procedure involved three main steps: (1) creating a bank of AE sequences by converting the AEs for each patient into a single, chronologically sequenced record, (2) grouping patients with similar AE sequences using hierarchical clustering, and (3) extracting temporal chains of AEs for each group of patients using Markov modeling. The mined results indicate the existence of seven groups of sequential chains of AEs, characterized by common types of AEs that occurred in a unique order. The groups were identified as: GRP1: Recurrent bleeding, GRP2: Trajectory of device malfunction & explant, GRP3: Infection, GRP4: Trajectories to transplant, GRP5: Cardiac arrhythmia, GRP6: Trajectory of neurological dysfunction & death, and GRP7: Trajectory of respiratory failure, renal dysfunction & death. These patterns of sequential post-LVAD AEs disclose potential interdependence between AEs and may aid prediction, and prevention, of subsequent AEs in future studies.

Clinical and In Vitro Evidence That Left Ventricular Assist Device-Induced von Willebrand Factor Degradation Alters Angiogenesis

Background Gastrointestinal bleeding from angiodysplasia is a major problem in continuous-flow left ventricular assist device (LVAD) patients. LVAD shear stress causes pathologic degradation of VWF (von Willebrand factor). A mechanistic relationship between VWF degradation and angiodysplasia has not been explored. We tested 2 novel hypotheses: (1) clinical hypothesis: VWF fragments are elevated in LVAD patients that develop angiodysplasia and (2) in vitro hypothesis: VWF fragments generated during LVAD support alter angiogenesis, which may contribute to angiodysplasia. Methods and Results Clinical study: Paired blood samples were collected from continuous-flow LVAD patients (n=35). VWF was quantified with immunoblotting. In vitro experiments: (1) To investigate whether LVAD support alters angiogenesis, human endothelial cells were cultured with LVAD patient plasma (n=11). To investigate mechanism, endothelial cells were cultured with VWF fragments produced by exposing human VWF and ADAMTS-13 (VWF protease) to LVAD-like shear stress (175 dyne/cm², n=8). Clinical study results: in all patients (n=35, mean support 666±430 days), LVAD support degraded high-molecular-weight VWF multimers ( P<0.0001) into low-molecular-weight VWF multimers ( P<0.0001) and VWF fragments ( P<0.0001). In patients with gastrointestinal bleeding from angiodysplasia (n=7), VWF fragments were elevated ( P=0.02) versus nonbleeders. In contrast, in patients with gastrointestinal bleeding without angiodysplasia, VWF fragments were not elevated versus nonbleeders ( P=0.96). In vitro experiments results: LVAD patient plasma caused abnormal angiogenesis with reduced tubule length ( P=0.04) and migration ( P=0.05). Similarly, endothelial cells grown with VWF degradation fragments exhibited reduced tubule length ( P<0.001) and migration ( P=0.01). Conclusions LVAD patients who bled from angiodysplasia had higher levels of VWF fragments than nonbleeders and gastrointestinal bleeders without angiodysplasia. VWF fragments caused abnormal angiogenesis in vitro. These findings suggest that VWF fragments may be a mechanistic link between LVAD support, abnormal angiogenesis, angiodysplasia, and gastrointestinal bleeding.

Novel Model to Predict Gastrointestinal Bleeding During Left Ventricular Assist Device Support

BACKGROUND

Gastrointestinal bleeding (GIB) is a leading cause of morbidity during continuous-flow left ventricular assist device (CF-LVAD) support. GIB risk assessment could have important implications for candidate selection, informed consent, and postimplant therapeutic strategies. The aim of the study is to derive and validate a predictive model of GIB in CF-LVAD patients.

METHODS AND RESULTS

CF-LVAD recipients at the Utah Transplantation Affiliated Hospitals program between 2004 and 2017 were included. GIB associated with a decrease in hemoglobin ≥2 g/dL was the primary end point. A weighted score comprising preimplant variables independently associated with GIB was derived and internally validated. A total of 351 patients (median age, 59 years; 82% male) were included. After a median of 196 days, GIB occurred in 120 (34%) patients. Independent predictors of GIB included age >54 years, history of previous bleeding, coronary artery disease, chronic kidney disease, severe right ventricular dysfunction, mean pulmonary artery pressure <18 mm Hg, and fasting glucose >107 mg/dL. A weighted score termed Utah bleeding risk score, effectively stratified patients based on their probability of GIB: low (0-1 points) 4.8%, intermediate (2-4) 39.8%, and high risk (5-9) 83.8%. Discrimination was good in the development sample (c-index: 0.83) and after internal bootstrap validation (c-index: 0.74).

CONCLUSIONS

The novel Utah bleeding risk score is a simple tool that can provide personalized GIB risk estimates in CF-LVAD patients. This scoring system may assist clinicians and investigators in designing tailored risk-based strategies aimed at reducing the burden posed by GIB in the individual CF-LVAD patient and healthcare systems.

Special considerations in the management of lower GI bleed by interventional radiology

Despite the rapid development of diagnostic and therapeutic modalities and techniques to manage LGIB patients from interventional radiology's standpoint, a successful localization of the bleeding site that leads to an effective embolotherapy remains a significant technical challenge. The interventional radiologist's decisions when managing patients with LGIB may significantly impact the clinical outcomes; therefore, management should be made based on careful and thorough considerations of factors such as etiology, locations, patient's comorbidities, and potential post-procedure complications, among others. The purpose of this paper is to review the management of LGIB by interventional radiology, focusing on a few challenging and common clinical situations that require special consideration by interventional radiologists.

Clinical outcomes of inpatient cardiac rehabilitation for patients with treated left ventricular assist device in Korea: 1-year follow-up

In Korea, the first patient with a left ventricular assist device (LVAD) for destination therapy had successful implantation of a continuous-flow model in 2012. We investigated the safety and efficacy of exercise therapy with LVAD implantation 15 Korean patients. We retrospectively reviewed 15 patients (mean age, 67.4±11.6 years; 10 males, 5 female, left ventricular ejection fraction 23.6%±7.1%), including 4 with implanted continuous-flow and 11 an axial-flow LVAD. The New York Heart Association functional classification, ejection fraction, and quality of life were obtained. Survival rate, adverse events, admission rates, and enrollment rates in cardiac rehabilitation were investigated. Survival at 6 and 12 months was 100% and 89%, respectively. The New York Heart Association functional classification improved from 3.4±0.5 to 2.3±0.05 at 12 months postoperatively (P<0.0001). The ejection fraction significantly increased from 23.6%±7.2% on the preoperative day to 35.4%±14.2% at 1 year (P<0.0018). The quality of life was also improved at 1 year (P<0.0001). The most common adverse events were bleeding (56%) and dyspnea (44%). The number of admissions was 3.2 per patient-year. LVAD therapy is a safe and effective treatment option with exercise intervention for Korean patients waiting for heart transplantation or those who were ineligible for heart transplantation. A larger study with longer follow-up is needed to determine details clinical outcomes after LVAD.

The Impact of Erythrocytes Injury on Blood Flow in Bionic Arteriole with Stenosis Segment

Ventricular assist device (VAD) implantation is an effective treatment for patients with end-stage heart failure. However, patients who undergo long-term application of VADs experience a series of VAD-related adverse effects including pump thrombosis, which is induced by rotate impeller-caused blood cell injury and hemolysis. Blood cell trauma-related flow patterns are the key mechanism for understanding thrombus formation. In this study, we established a new method to evaluate the blood cell damage and investigate the real-time characteristics of blood flow patterns in vitro using rheometer and bionic microfluidic devices. The variation of plasma free hemoglobin (PFH) and lactic dehydrogenase (LDH) in the rheometer test showed that high shear stress was the main factor causing erythrocyte membrane injury, while the long-term exposure of high shear stress further aggravated this trauma. Following this rheometer test, the damaged erythrocytes were collected and injected into a bionic microfluidic device. The captured images of bionic microfluidic device tests showed that with the increase of shear stress suffered by the erythrocyte, the migration rate of damaged erythrocyte in bionic microchannel significantly decreased and, meanwhile, aggregation of erythrocyte was clearly observed. Our results indicate that mechanical shear stress caused by erythrocyte injury leads to thrombus formulation and adhesion in arterioles.

Gastrointestinal Bleeding With Left Ventricular Assist Devices (LVAD): Locating the Leak and Identifying Outcomes

BACKGROUND AND GOALS

Gastrointestinal bleeding (GIB) is a significant complication following left ventricular assist device (LVAD) implantation. We evaluated the incidence, predictors, endoscopic findings, and outcomes of GIB in LVAD recipients.

STUDY

Retrospective review of 205 adult patients undergoing HeartMate II LVAD implantation from January 2012 to June 2016. Patients were reviewed and separated into GIB (n=57; 28%) and non-GIB (n=148; 72%) groups.

RESULTS

Median time to GIB was 55 (range, 3 to 730) days. The GIB group patients were older (61±12 vs. 56±13, P=0.0042), more often underwent concomitant tricuspid valve (TV) repair (16% vs. 4%, P=0.007), and a higher percentage were assigned for destination therapy (75% vs. 55%, P=0.01). Angioectasia (33%) was the most common identified cause of GIB. Median time to endoscopic intervention was 1 day. The total number of hospital readmissions after LVAD was higher in the GIB group (median of 5 vs. 3, P=0.001), as was the total number of blood products transfused after LVAD (29 vs. 13, P≤0.0001). GIB was associated with an increased risk of death (hazard ratio, 1.94; 95% confidence interval, 1.16-3.25; P=0.01) and the mortality rate during hospitalization for GIB was 11% (P=0.0004). Receiving a heart transplant was associated with a decreased hazard of death (hazard ratio, 0.40; 95% confidence interval, 0.19-0.85; P=0.016).

CONCLUSIONS

Older age and destination therapy as implant strategy were found to be associated with an increased risk of GIB, consistent with previous studies. A unique finding in our study is the association of TV repair with a higher incidence of GIB. Further studies are needed to investigate possible mechanisms by which TV repair increases the incidence of GIB.

Role of imaging in diagnosis and management of left ventricular assist device complications

Heart failure is a clinical condition that is associated with significant morbidity and mortality. With the advent of left ventricular assist device (LVAD), an increasing number of patients have received an artificial heart both as a bridge-to-therapy and as a destination therapy. Clinical trials have shown clear survival benefits of LVAD implantation. However, the increased survival benefits and improved quality of life come at the expense of an increased complication rate. Common complications include perioperative bleeding, infection, device thrombosis, gastrointestinal bleeding, right heart failure, and aortic hemodynamic changes. The LVAD-associated complications have unique pathophysiology. Multiple imaging modalities can be employed to investigate the complications, including computed tomography (CT), positron emission tomography-computed tomography (PET-CT), catheter angiography and echocardiography. Imaging studies not only help ascertain diagnosis and evaluate the severity of disease, but also help direct relevant clinical management and predict prognosis. In this article, we aim to review the common LVAD complications, present the associated imaging features and discuss the role of imaging in their management.

Timing of Gastrointestinal Bleeding After Implantation of Left Ventricular Assist Devices Associates With Anatomic Location, Presentation, and Management

BACKGROUND & AIMS

Continuous-flow left ventricular assist devices (LVADs) for advanced heart failure have been associated with gastrointestinal bleeding (GIB). We examined the association between time of GIB after LVAD implantation and bleeding location (determined by endoscopy), etiology, and patient outcomes.

METHODS

We performed a retrospective study of consecutive patients who underwent implantation of continuous-flow LVADs from 2008 through 2015. We analyzed data on anatomic location of GIB, etiology, length of hospital stay, transfusion requirement, time to endoscopy, and readmission to the hospital within 30 days (30-day readmission).

RESULTS

GIB developed in 59 of the 271 patients (22%). Higher proportions of patients with GIB during their index hospitalization for LVAD implantation had upper or lower GIB (86.7%) than patients with GIB during a subsequent hospitalization (50.0%; P = .013). Patients with GIB during their index hospitalization also had lower rates of middle GIB (0 vs 20.5%; P = .052), higher rates of overt GIB (100% vs 63.6%; P = .006), longer hospital stays (24 days vs 11 days; P < .001), and more transfusions before endoscopy (7 units vs 4 units; P = .021) than patients with GIB during a subsequent hospitalization. There were no significant differences between groups in time to endoscopy (2 days vs 2.5 days) or 30-day readmission (6.7% vs 9.3%). Angiodysplasias were identified in 100% of patients with middle GIB compared to 48.5% of patients with upper or lower GIB (P < .001) in whom a bleeding lesion was identified.

CONCLUSION

In a retrospective study of patients who underwent implantation of continuous-flow LVADs, we found that timing of GIB associates with the location and severity of bleeding. Although patients with LVADs have an overall increase in risk of middle GIB, patients with GIB during their index LVAD hospitalization should undergo initial evaluation by upper endoscopy and colonoscopy, due to insufficient time for development of small bowel angiodysplasias. Patients who later develop GIB should be evaluated early for middle GI bleeding.

To Scope or Not to Scope? The Safety of Upper Endoscopy in the Setting of Pulmonary Embolism

OBJECTIVES

We aimed to describe the frequency of upper endoscopy and associated outcomes in subjects hospitalized with upper GI bleeding (UGIB) and pulmonary embolism (PE).

METHODS

We performed a cross-sectional study using the Nationwide Inpatient Sample from 2007 to 2014. The association between upper endoscopy and in-hospital mortality was evaluated using propensity score matching.

RESULTS

A total of 44,412 subjects had a coexistent PE and UGIB. 63.5% had an inpatient upper endoscopy with a lower likelihood of in-hospital death and a shorter length of stay.

CONCLUSIONS

A substantial proportion of inpatients with PE and UGIB undergo endoscopy with a relatively lowmortality rate.

Resource utilization and hospital readmission associated with gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices

Gastrointestinal bleeding (GIB) occurs in up to 40% of patients with continuous-flow (CF) left ventricular assist devices (LVADs). We sought to identify targets to improve hospital resource utilization and decrease readmissions after GIB. We performed a single-center, retrospective analysis of LVAD-associated GIB resulting in hospital admission between July 2011 and April 2014. Follow-up data were collected through March 2015. We analyzed 57 admissions for GIB in 23 patients. One or more diagnostic imaging study was performed in 47% of admissions, with a definite or probable source of GIB identified in 23%. A total of 76 endoscopies were performed (≥ 1 endoscopy in 79% of admissions, ≥ 2 in 42%). Definite or probable bleeding sources were identified in 25% and 12% of endoscopies, respectively. Patients who underwent multiple endoscopies were no more likely to have a bleeding source identified (OR 1.48; 95% CI 0.50-4.32; p = 0.59) and had longer hospital stays (11.1 vs. 7.8 days, p < 0.02). Readmission rates for GIB at 30 and 90 days were 33% and 53%, respectively. A decrease in antiplatelet regimen at discharge was associated with lower rate of readmission for GIB (OR 0.16; 95% CI 0.03-0.82; p = 0.03) or any cause (OR 0.21; 95% CI 0.05-0.85; p = 0.04) at 30 and 90 days. GIB in patients with CF-LVADs is associated with significant in-hospital resource utilization and high rates of readmission. Imaging and endoscopy are common, but have low diagnostic yield and infrequently result in successful intervention. Strategies to reduce resource utilization and prevent readmission are warranted.

Implantable Ventricular Assist Device Use and Outcomes in People With End-Stage Renal Disease

Background

People with end‐stage renal disease (ESRD) are at risk for advanced heart failure, but little is known about use and outcomes of durable mechanical circulatory support in this setting. We examined use and outcomes of implantable ventricular assist devices (VADs) in a national ESRD cohort.

Methods and Results

We performed a retrospective cohort study of Medicare beneficiaries with ESRD who underwent implantable VAD placement from 2006 to 2014. We examined in‐hospital and 1‐year mortality, all‐cause and cause‐specific hospitalizations, and heart/kidney transplantation outcomes. We investigated as predictors demographic factors, time‐period of VAD implantation, primary or post‐cardiotomy implantation, and duration of ESRD before VAD implantation. We identified 96 people with ESRD who underwent implantable VAD placement. At time of VAD implantation, 74 (77.1%) were receiving hemodialysis, 10 (10.4%) were receiving peritoneal dialysis and 12 (12.5%) had renal transplant. Time from incident ESRD to VAD implantation was median 4.0 (interquartile range 1.1, 8.2) years. Mortality during the implantation hospitalization was 40.6%. Within 1 year of implantation 61.5% of people had died. On multivariable analysis, males had half the mortality risk of females. Lower mortality risk was also seen with VAD implantation in a primary setting, and with more recent year of implantation, but these results did not reach statistical significance.

Conclusions

Medicare beneficiaries with ESRD are undergoing durable VAD implantation, often several years after incident ESRD, although in low numbers. Mortality is high among these patients, highlighting the need for investigations to improve treatment selection and management.

Controversies and Challenges of Ventricular Assist Device Therapy

Left ventricular assist device (LVAD) therapy has emerged as an increasingly vital facet of the treatment algorithm for advanced heart failure. Growing experience with LVAD support has led to substantial improvements in outcomes, with 1-year survival rates approaching that of cardiac transplantation. These therapeutic refinements have engendered growing interests in the potential for expanding the clinical indications for LVAD therapy to patients with less advanced heart failure. The primary obstacles to this evolution of care center largely on the prevention and/or management of the adverse events associated with LVAD therapy along with patient preference. Many programs also face the mounting difficulty of balancing quality outcomes with the increased volume of implants. During the recently assembled Users Meeting organized by St. Jude Medical, heart failure clinicians from nearly 50 LVAD implanting centers discussed these and other challenges and controversies impacting the field. The present review summarizes the key insights gleaned from this meeting.

Long-Acting Octreotide Reduces the Recurrence of Gastrointestinal Bleeding in Patients With a Continuous-Flow Left Ventricular Assist Device

BACKGROUND

Recurrent gastrointestinal bleeding is one of the most significant adverse events in patients with left ventricular assist devices (LVADs).

METHODS

We enrolled LVAD patients who had received an intramuscular injection of 20 mg octreotide every 4 weeks as secondary prevention for recurrent gastrointestinal bleeding despite conventional medical therapies and repeated transfusions. The frequency of gastrointestinal bleeding and other associated clinical outcomes before and during octreotide therapy were compared.

RESULTS

Thirty LVAD patients (66.4 ± 8.8 years old, 16 men [53%]) received octreotide therapy for 498.8 ± 356.0 days without any octreotide-associated adverse events. The frequency of gastrointestinal bleeding was decreased significantly during octreotide therapy (from 3.4 ± 3.1 to 0.7 ± 1.3 events/year; P < .001), accompanied by significant reductions in red blood cell and flesh frozen plasma transfusions, days in hospital, and need for endoscopic procedures (P < .05 for all).

CONCLUSIONS

Octreotide therapy reduced the frequency of recurrent gastrointestinal bleeding and may be considered for secondary prevention.

Prevention and Treatment of Thrombotic and Hemorrhagic Complications in Patients Supported by Continuous-Flow Left Ventricular Assist Devices

PURPOSE OF REVIEW

The purpose of this review is to describe the current knowledge in prevention and treatment of thrombotic (pump thrombosis and ischemic stroke) and bleeding (gastrointestinal and hemorrhagic stroke) complications in patients supported by continuous-flow left ventricular assist devices (CF-LVAD).

RECENT FINDINGS

Left ventricular assist devices (LVADs) are now widely used for the management of end-stage heart failure. Unfortunately, in spite of the indisputable positive impact LVADs have on patients, the frequency and severity of complications are limitations of this therapy. Stroke, pump thrombosis, and gastrointestinal bleeding are among the most serious and frequent complications in these patients. The balance between hemorrhagic and thrombotic complications in patients supported with CF-LVAD is difficult as most patients do not necessarily fit a "bleeder" or a "clotter" profile but rather move from one side to the other of the thrombotic/bleeding spectrum. Further research is necessary to better understand the risk factors and mechanisms involved in the development of these complications.

Tolerability and Biological Effects of Long-Acting Octreotide in Patients With Continuous Flow Left Ventricular Assist Devices

Patients with implanted continuous, nonpulsatile, left ventricular assist devices (LVADs) have increased the occurrence of gastrointestinal bleeding (GIB). Although the pathophysiology is multifactorial, there are few treatments beyond supportive care. Octreotide acetate is a somatostatin analog that reduces GIB in various patient populations. However, there are sparse case series that suggest octreotide acetate may reduce GIB in LVAD patients. This 10 patient, 28 week phase I study evaluated the safety and tolerability of octreotide acetate long-acting release (LAR) 20 mg depot injection every 4 weeks until week 16 after LVAD placement. Secondary aims were occurrence of GIB and measurement of vascular endothelial growth factor, fibrinogen, von Willebrand factor, and platelet aggregation across the study period. Ten patients were enrolled, and eight completed the study. The two study dropouts were not related to octreotide. None of the patients experienced side effects or safety concerns related to octreotide nor did GIB occur in the study population. Vascular endothelial growth factor levels were maintained in the reference range throughout the duration of the study. There did appear to be laboratory evidence of acquired von Willebrand syndrome, with mildly low platelet aggregation studies. In conclusion, octreotide acetate LAR 20 mg depot injection was safe and effective in this population.

Mechanical Circulatory Support in the Treatment of Advanced Heart Failure

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