Pump thrombosis in the Thoratec HeartMate II device: An update analysis of the INTERMACS Registry

Multimodality imaging for the evaluation and management of patients with long-term (durable) left ventricular assist devices

Left ventricular assist devices (LVADs) are gaining increasing importance as therapeutic strategy in advanced heart failure (HF), not only as bridge to recovery or to transplant but also as destination therapy. Even though long-term LVADs are considered a precious resource to expand the treatment options and improve clinical outcome of these patients, these are limited by peri-operative and post-operative complications, such as device-related infections, haemocompatibility-related events, device mis-positioning, and right ventricular failure. For this reason, a precise pre-operative, peri-operative, and post-operative evaluation of these patients is crucial for the selection of LVAD candidates and the management LVAD recipients. The use of different imaging modalities offers important information to complete the study of patients with LVADs in each phase of their assessment, with peculiar advantages/disadvantages, ideal application, and reference parameters for each modality. This clinical consensus statement sought to guide the use of multimodality imaging for the evaluation of patients with advanced HF undergoing LVAD implantation.

Heart Transplantation and Left Ventricular Assist Devices: Long-Term Prognosis and Effects on Mental Health

Heart transplantation and left ventricular assist devices (LVADs) have emerged as crucial interventions for end-stage heart failure, dramatically improving patient outcomes. This narrative review examines their historical context, indications, procedures, and outcomes, as well as their impact on long-term survival, quality of life, functional status, and mental health. While heart transplantation remains the optimal treatment, donor scarcity limits its application. LVADs have become a viable alternative, either as a bridge to transplantation or as destination therapy. Both interventions demonstrate similar long-term survival rates and significant improvements in health-related quality of life and functional status. However, they present distinct long-term management challenges, including immunosuppression needs for transplant recipients and device-related issues for LVAD patients. Mental health effects are considerable, necessitating psychological support and adaptive coping strategies. Complications such as infection, bleeding, and thrombosis remain concerns for both interventions. Patient selection criteria, technological advancements, and long-term management strategies are critical factors in optimizing outcomes. Future research should focus on device miniaturization, enhanced biocompatibility, and less invasive insertion techniques to further advance these therapies and improve patient care in end-stage heart failure.

Association between psychosocial factors and left ventricular assist device implant outcomes: A systematic review

BACKGROUND

Psychosocial assessment is a core component of the multidisciplinary evaluation for left ventricular assist device (LVAD) implantation. The degree to which psychosocial conditions are considered a contraindication to LVAD implantation continues to be debated. This systematic review examines modifiable psychosocial factors as predictors of outcomes in patients undergoing LVAD implantation.

METHODS

We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The search resulted in 2509 articles. After deduplication, abstract and full-text review, 20 relevant articles were identified.

RESULTS

Included studies evaluated socioeconomic status (n = 6), caregiver characteristics (n = 6), non-adherence (n = 6), substance use (n = 13), and psychiatric disorder (n = 8). The most commonly measured outcomes were all-cause death, readmission rate, and adverse events. Studies varied widely in definition of each psychosocial factor and selected outcomes. No psychosocial factor was consistently associated with a specific outcome in all studies. Socioeconomic status was generally not associated with outcomes. Non-adherence, psychiatric disorder, and substance use were associated with higher risks of mortality, adverse events, and/or readmission. Findings on caregiver characteristics were mixed.

CONCLUSION

Of the psychosocial factors studied, non-adherence, psychiatric disorder, and substance use were the most consistently associated with an increased risk of mortality, readmission, and/or adverse events. Heterogeneity in research methodology and study quality across studies precludes firm conclusions regarding the impact of psychosocial factors on long-term patient outcomes. The results of this review reveal a need for adequately powered studies that use uniform definitions of psychosocial factors to clarify relationships between these factors and outcomes after LVAD implantation.

Clinical and cost-effectiveness of left ventricular assist devices as destination therapy for advanced heart failure: systematic review and economic evaluation

Background

Selected patients with advanced heart failure ineligible for heart transplantation could benefit from left ventricular assist device therapy as 'destination therapy'. There is evidence of the efficacy of destination therapy; however, it is not currently commissioned within the United Kingdom National Health Service due to the lack of economic evidence.

Objective

What is the clinical and cost-effectiveness of a left ventricular assist device compared to medical management for patients with advanced heart failure ineligible for heart transplantation (destination therapy)?

Methods

A systematic review of evidence on the clinical and cost-effectiveness of left ventricular assist devices as destination therapy was undertaken including, where feasible, a network meta-analysis to provide an indirect estimate of the relative effectiveness of currently available left ventricular assist devices compared to medical management. For the systematic reviews, data sources searched (up to 11 January 2022) were Cochrane CENTRAL, MEDLINE and EMBASE via Ovid for primary studies, and Epistemonikos and Cochrane Database of Systematic Reviews for relevant systematic reviews. Trial registers were also searched, along with data and reports from intervention-specific registries. Economic studies were identified in EconLit, CEA registry and the NHS Economic Evaluation Database (NHS EED). The searches were supplemented by checking reference lists of included studies. An economic model (Markov) was developed to estimate the cost-effectiveness of left ventricular assist devices compared to medical management from the United Kingdom National Health Service/personal social service perspective. Deterministic and probabilistic sensitivity analyses were conducted to explore uncertainties. Where possible, all analyses focused on the only currently available left ventricular assist device (HeartMate 3TM, Abbott, Chicago, IL, USA) in the United Kingdom.

Results

The clinical effectiveness review included 134 studies (240 articles). There were no studies directly comparing HeartMate 3 and medical management (a randomised trial is ongoing). The currently available left ventricular assist device improves patient survival and reduces stroke rates and complications compared to earlier devices and relative to medical management. For example, survival at 24 months is 77% with the HeartMate 3 device compared to 59% with the HeartMate II (MOMENTUM 3 trial). An indirect comparison demonstrated a reduction in mortality compared to medical management [relative risk of death 0.25 (95% confidence interval 0.13 to 0.47); 24 months; this study]. The cost-effectiveness review included 5 cost analyses and 14 economic evaluations covering different generations of devices and with different perspectives. The reported incremental costs per quality-adjusted life-year gained compared to medical management were lower for later generations of devices [as low as £46,207 (2019 prices; United Kingdom perspective; time horizon at least 5 years)]. The economic evaluation used different approaches to obtain the relative effects of current left ventricular assist devices compared to medical management from the United Kingdom National Health Service/personal social service perspective. All gave similar incremental cost-effectiveness ratios of £53,496-58,244 per quality-adjusted life-year gained - lifetime horizon. Model outputs were sensitive to parameter estimates relating to medical management. The findings did not materially differ on exploratory subgroup analyses based on the severity of heart failure.

Limitations

There was no direct evidence comparing the clinical effectiveness of HeartMate 3 to medical management. Indirect comparisons made were based on limited data from heterogeneous studies regarding the severity of heart failure (Interagency Registry for Mechanically Assisted Circulatory Support score distribution) and possible for survival only. Furthermore, the cost of medical management of advanced heart failure in the United Kingdom is not clear.

Conclusions

Using cost-effectiveness criteria applied in the United Kingdom, left ventricular assist devices compared to medical management for patients with advanced heart failure ineligible for heart transplant may not be cost-effective. When available, data from the ongoing evaluation of HeartMate 3 compared to medical management can be used to update cost-effectiveness estimates. An audit of the costs of medical management in the United Kingdom is required to further decrease uncertainty in the economic evaluation.

Study registration

This study is registered as PROSPERO CRD42020158987.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR128996) and is published in full in Health Technology Assessment; Vol. 28, No. 38. See the NIHR Funding and Awards website for further award information.

An ISHLT consensus statement on strategies to prevent and manage hemocompatibility related adverse events in patients with a durable, continuous-flow ventricular assist device

Life expectancy of patients with a durable, continuous-flow left ventricular assist device (CF-LVAD) continues to increase. Despite significant improvements in the delivery of care for patients with these devices, hemocompatability-related adverse events (HRAEs) are still a concern and contribute to significant morbility and mortality when they occur. As such, dissemination of current best evidence and practices is of critical importance. This ISHLT Consensus Statement is a summative assessment of the current literature on prevention and management of HRAEs through optimal management of oral anticoagulant and antiplatelet medications, parenteral anticoagulant medications, management of patients at high risk for HRAEs and those experiencing thrombotic or bleeding events, and device management outside of antithrombotic medications. This document is intended to assist clinicians caring for patients with a CF-LVAD provide the best care possible with respect to prevention and management of these events.

Aspirin resistance in patients with ventricular assist devices: A follow-up study

BACKGROUND

Despite combined anticoagulation therapy consisting of a vitamin K antagonist and an antiplatelet agent, thromboembolic complications often occur in patients with a left ventricular assist device (LVAD). In addition, bleeding events are also common. Resistance to antiplatelet drugs is a well-known phenomenon; however, the utilization of laboratory chemistry testing for the presence of such resistance, and then switching therapy, is controversial.

METHODS

We tested 132 patients with LVAD (HeartWare n = 57, HeartMate II n = 22, HeartMate 3 n = 53) on acetylsalicylic acid (ASA) therapy for resistance and followed them for a maximum of 7 years regarding pump thrombosis. Light transmission aggregometry (LTA) and impedance aggregometry (IPA) were performed for testing platelet function.

RESULTS

We could show that patients with ASA resistance displayed an increased risk of pump thrombosis, regardless of the test used (LTA: OR = 6.20, CI [1.86-20.64], p = 0.003; IPA: OR = 12.14, CI [3.00-49.07], p < 0.001). In patients with a HeartMate 3, we could not detect any pump thrombosis associated with aspirin resistance. Furthermore, there was no significant difference in bleeding events between patients with ASA resistance and ASA responders.

CONCLUSION

Laboratory testing of ASA resistance seems to be a good tool to detect an increased risk of pump thrombosis, at least for patients with a HeartWare or HeartMate II. The extent to which these thromboses can be prevented with a change of medication has to be investigated in further studies. No pump thrombosis was detected in patients with a HeartMate 3, and the question should be asked as to what constellation of underlying and concomitant diseases must be present to justify ASA therapy for these patients.

Optimization design of semi-open impeller based on thrombogenicity in a blood pump

BACKGROUND

Blood clots are composed of aggregated fibrin and platelets, and thrombosis is the body's natural response to repairing injured blood vessels or stopping bleeding. However, when this process is activated abnormally, such as in a mechanical blood pump, it can lead to excessive thrombus formation. Therefore, how to avoid or reduce the probability of thrombus formation is an important indicator of the stable operation of a blood pump.

METHODS

In this paper, Lagrangian particle tracking trajectories are simulated to study platelet transport in a blood pump. The design of the thrombus blood pump was optimized using an orthogonal design method based on three factors: inlet angle, outlet angle, and blade number. The effect of blood pump pressure, rotational speed, impeller outlet angle, inlet angle, and number of blades on thrombus formation was analysed using Fluent software. The thrombogenic potential was derived by analyzing the trajectory and flow parameters of platelet particles in the blood pump, as well as the statistical parameters of residence time and stress accumulation thrombus in the platelet pump.

RESULTS

When the impeller inlet angle is 30°, the outlet angle is 20°, and the number of blades is 6, the probability of thrombus formation is minimized in the orthogonal design method, aligning with the requirements for blood pump performance.

CONCLUSIONS

These design parameters serve as a numerical guideline for optimizing the geometry of the semi-open impeller in blood pumps and provide a theoretical foundation for subsequent in vitro experiments.

Predictors of thrombosis during VV ECMO: an analysis of 9809 patients from the ELSO registry

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is a life-saving therapy for critically ill patients, but it carries an increased risk of thrombosis due to blood interacting with non-physiological surfaces. While the relationship between clinical variables and thrombosis remains unclear, our study aimed to identify which factors are most predictive of thrombosis. The Extracorporeal Life Support Organization Registry was queried to obtain a cohort of VV-ECMO patients aged 18 years and older from 2015 to 2019. Patients who were over 80-years-old, at the extremes of weight, who received less than 24 h of ECMO, multiple rounds of ECMO, or had missing data were excluded. Multivariate logistic regression modeling was used to assess predictors of thrombosis and mortality. A total of 9809 patients were included in the analysis, with a mean age of 47.1 ± 15.1 years and an average ECMO run time of 305 ± 353 h. Thrombosis occurred in 19.9% of the cohort, with circuit thrombosis (8.6%) and membrane lung failure (6.1%) being the most common. Multivariate analysis showed that ECMO runs over 14 days (OR: 2.62, P < 0.001) and pregnancy-related complications (OR: 1.79, P = 0.004) were associated with an increased risk of thrombosis. Risk factors for circuit thrombosis included incremental unit increases in the pump flow rate at 24 h (OR: 1.07 [1.00-1.14], P = 0.044) and specific cannulation sites. Increased body weight (OR: 1.02 [1.00-1.04], P = 0.026) and increased duration on ECMO (OR: 3.82 [3.12-4.71], P < 0.001) were predictive of membrane lung failure. Additionally, patients with thrombosis were at increased likelihood of in-hospital mortality (OR: 1.52, P < 0.001). This study identified multiple thrombotic risk factors in VV-ECMO, suggesting that future studies investigating the impact of pregnancy associated complications and ECMO flow rate on hemostasis would be illuminating.

The impact of obesity and LVAD-bridging on heart transplant candidate outcomes: a linked STS INTERMACS - OPTN/UNOS data analysis

BACKGROUND

Limited data integrating waitlist and postheart transplant (HT) mortality have evaluated outcomes of left ventricular assist device (LVAD)-bridged strategy vs no LVAD according to patient characteristics. We evaluated waitlist and post-HT mortality in LVAD-bridged vs nonbridged patients based on body mass index (BMI).

METHODS

We included linked adults listed for HT in Organ Procurement and Transplant Network/United Network for Organ Sharing and patients receiving durable LVAD as bridge to HT or candidacy in Society of Thoracic Surgeons/Interagency Mechanical Circulatory Support databases (2010-2019). Using BMI at listing or LVAD implant, we categorized patients as underweight (<18.5 kg/m2), normal weight (18.5-24.99 kg/m2), overweight (25-29.99 kg/m2), and obese (≥30 kg/m2). Kaplan-Meier analysis and multivariable Cox proportional hazards models informed the effect of LVAD-bridged and nonbridged strategy by BMI on waitlist, post-HT, and overall mortality (including waitlist and post-HT mortality).

RESULTS

Among 11,216 LVAD-bridged and 17,122 nonbridged candidates, bridged candidates were more frequently obese (37.3% vs 28.6%) (p < 0.001). Multivariable analysis indicated increased waitlist mortality in LVAD-bridged vs nonbridged with overweight (Hazard ratio (HR) 1.18, 95% confidence interval (CI) 1.02-1.36) or obesity (HR 1.35, 95%CI 1.17-1.56) in comparison to normal weight candidates (HR 1.02, 95%CI 0.88-1.19) (p-interaction < 0.001). Post-transplant mortality was not statistically different in LVAD-bridged vs nonbridged patients across BMI categories (p-interaction = 0.26). There was a nonsignificant graded increase in overall mortality in LVAD-bridged with overweight (HR 1.53, 95%CI 1.39-1.68) or obesity (HR 1.61, 95%CI 1.46-1.78) compared to nonbridged patients (p-interaction = 0.13).

CONCLUSIONS

LVAD-bridged candidates with obesity had higher waitlist mortality compared to nonbridged candidates with obesity. Post-transplant mortality was similar in LVAD-bridged and nonbridged patients, but obesity remained associated with increased mortality in both groups. This study may aid clinicians and advanced heart failure patients with obesity in decision-making.

Clinical outcomes of ventricular assist device support by HIV infection status: An STS-INTERMACS analysis

BACKGROUND

Cardiovascular disease remains the leading cause of mortality in human immunodeficiency virus-infected (HIV-positive) patients. Ventricular assist device therapy is rarely offered to these patients and data on outcomes are sparse. We investigated outcomes following ventricular assist device implants for HIV-positive as compared to non-HIV-infected (HIV-negative) patients.

METHODS

We analyzed 22,065 patients from the Interagency Registry for Mechanically Assisted Circulatory Support registry for outcomes by HIV status. A propensity-matched analysis adjusting for 21 preimplant risk factors was also conducted.

RESULTS

Compared with 21,980 HIV-negative device recipients, the 85 HIV-positive recipients were younger (median age 58 years vs 59 years, p = 0.02), had lower body mass index (26 kg/m2 vs 29 kg/m2, p = 0.001), and had higher rates of prior stroke (8% vs 4%, p = 0.02). In the matched HIV-positive and HIV-negative cohorts, there was significantly higher mortality in HIV-positive patients in earlier implant years, however, this association was not seen in later implant years (2018-2020). In both unmatched and matched cohorts, no significant differences in postimplantation stroke, major bleeding, or major infection were noted.

CONCLUSIONS

With recent advancements in mechanical circulatory support and HIV treatment, ventricular assist device therapy is a viable therapeutic option for HIV-positive patients with end-stage heart failure.

Anticoagulation alone as an effective and safe antithrombotic therapy in LVAD: When less is more

To evaluate the safety and effectiveness of anticoagulation alone in HeartMate3 patients. According to antithrombotic regimen, patients were divided into 2 groups: Group-1(warfarin+aspirin) and Group-2(warfarin). A comparison of hemocompatibility-related adverse events (HRAEs), hemocompatibility score (HCS), and hemocoagulative laboratory markers, both qualitative and quantitative, between the 2 groups were performed. Fifty patients were enrolled, 28 (56%) in Group-1 and 22 in Group-2 (44%), without statistical differences at baseline. Median time of follow-up was 590 days (IQR: 410.25-1007.50). Eighteen HRAEs (36.0%) occurred: 17 in Group-1 (34%) and 1 in Group-2 (2%) (P < 0.001). The net HCS for Group-1 versus Group-2 was 24 points and 1 point (OR 12.116[2.034-233.226], P = 0.023), respectively. Hemocoagulative values turned into the normality and remained stable during follow-up, without differences between groups, except for ASPI-test (P = 0.003). HeartMate3 showed a high hemocompatibility independently from antithrombotic therapy. Aspirin avoidance resulted a safe and effective strategy since it reduced hemorrhagic events, without increasing thrombotic risk.

Biological Response to Sintered Titanium in Left Ventricular Assist Devices: Pseudoneointima, Neointima, and Pannus

Titanium alloys have traditionally been used in blood-contacting cardiovascular devices, including left ventricular assist devices (LVADs). However, titanium surfaces are susceptible to adverse coagulation, leading to thrombogenesis and stroke. To improve hemocompatibility, LVAD manufacturers introduced powder sintering on blood-wetted surfaces in the 1980s to induce endothelialization. This technique has been employed in multiple contemporary LVADs on the pump housing, as well as the interior and exterior of the inflow cannula. Despite the wide adoption of sintered titanium, reported biologic response over the past several decades has been highly variable and apparently unpredictable-including combinations of neointima, pseudoneoimtima, thrombus, and pannus. We present a history of sintered titanium used in LVAD, a review of accumulated clinical outcomes, and a synopsis of gross appearance and composition of various depositions found clinically and in animal studies, which is unfortunately confounded by the variability and inconsistency in terminology. Therefore, this review endeavors to introduce a unified taxonomy to harmonize published observations of biologic response to sintered titanium in LVADs. From these data, we are able to deduce the natural history of the biologic response to sintered titanium, toward development of a deterministic model of the genesis of a hemocompatible neointima.

Left Ventricular Assist Device in Patients With Alcohol Abuse or Illicit Drug Use

The impact of substance abuse, including alcohol abuse or illicit drug use, on outcomes after left ventricular assist device (LVAD) implantation, has not been fully elucidated. Accordingly, to test the hypothesis that such a history would be associated with worse outcomes, we analyzed the Interagency Registry for Mechanically Assisted Circulatory Support registry. All patients from the Interagency Registry for Mechanically Assisted Circulatory Support registry who received a continuous-flow LVAD from June 2006 to December 2017 were included. The median follow-up duration was 12.9 months (interquartile range, 5.3 to 17.5). The final study group consisted of 15,069 patients, of which 1,184 (7.9%) had a history of alcohol abuse and 1,139 (7.6%) had a history of illicit drug use. The overall mortality rates in the alcohol, illicit drug, and control groups were 25%, 21%, and 29%, respectively. Cox regression analysis showed that having a history of alcohol abuse (hazard ratio, 0.97, 95% confidence interval, 0.84 to 1.13, p = 0.72) or illicit drug use (hazard ratio, 1.02, 95% confidence interval, 0.86 to 1.21, p = 0.81) was not significantly associated with increased risk of all-cause mortality when compared with general LVAD population. On the contrary, after adjusting for other covariates, a history of alcohol abuse or illicit drug use was significantly associated with increased device malfunction/pump thrombosis, device-related infection, or all-cause hospitalization (all p <0.05). Furthermore, After LVAD implantation, these patients had a lower quality of life assessed by the Kansas City Cardiomyopathy Questionnaire compared with those who did not. In conclusion, our findings suggest that patients with a history of alcohol abuse or illicit drug use are at risk for adverse device-related events with a lower quality of life after continuous-flow LVAD implantation compared with the general LVAD population.

Warfarin Reversal With Four-Factor Prothrombin Complex Concentrate for Left Ventricular Assist Device Conversion Surgery Monitored by TEG6s: A Case Report

Left ventricular assist devices (LVADs) require careful therapeutic anticoagulation with warfarin to prevent pump thrombosis. However, the best method to reverse warfarin for elective LVAD conversion surgery with massive bleeding remains unclear. We report the case of a 39-year-old Japanese man who was administered a four-factor prothrombin complex concentrate (4F-PCC) as warfarin reversal when he underwent conversion surgery from paracorporeal LVAD to implantable LVAD. 4F-PCC with co-administration of vitamin K reduced the international normalized ratio and R time in TEG6s (Haemonetics Corporation, USA) immediately. The effect was prolonged, and good hemostasis was achieved. 4F-PCC with vitamin K provided good hemostasis in our patient; therefore, 4F-PCC could be a useful tool for elective LVAD conversion surgery with expected massive bleeding and requiring immediate warfarin reversal.

Left ventricular assist device and pump thrombosis: the importance of the inflow cannula position

Pump thrombosis is a devastating complication after left ventricular assist device implantation. This study aims to elucidate the relation between left ventricular assist device implantation angle and risk of pump thrombosis. Between November 2010 and March 2020, 53 left ventricular assist device-patients underwent a computed tomography scan. Using a 3-dimensional multiplanar reformation the left ventricular axis was reconstructed to measure the implantation angle of the inflow cannula. All patients were retrospectively analyzed for the occurrence of pump thrombosis. In 10 (91%) patients with a pump thrombosis, the implantation angle was towards the lateral wall of the left ventricle. In only 20 patients (49%) of the patients without a pump thrombosis the inflow cannula pointed towards the lateral wall of the left ventricle. The mean angle in patients with a pump thrombosis was 10.1 ± 11.9 degrees towards the lateral wall of the left ventricle compared to 4.1 ± 19.9 degrees towards the septum in non-pump thrombosis patients (P = 0.005). There was a trend towards a significant difference in time to first pump thrombosis between patients with a lateral or septal deviated left ventricular assist device (hazard ratio of 0.15, P = 0.07). This study demonstrates that left ventricular assist device implantation angle is associated with pump thrombosis. Almost all patients in whom a pump thrombosis occurred during follow-up had a left ventricular assist device implanted with the inflow-cannula pointing towards the lateral wall of the left ventricle.

Diagnostic and surgical management of HeartMate 3 outflow graft obstruction due to two different mechanisms

Outflow graft obstruction is a potentially catastrophic complication of left ventricular assist devices that may occur secondary to different mechanisms. Two cases of Heartmate 3 outflow graft obstruction associated with two different pathophysiological mechanisms are presented. The first one was a 70-year-old man who developed outflow graft obstruction secondary to kinking. The second case was a 72-year-old man who presented with signs and symptoms of heart failure due to outflow graft extrinsic obstruction. Both cases were diagnosed with 3D-CT scan and successfully surgically treated.

A Case of Successful Use of the "Anchoring Technique" for Percutaneous Treatment of Left Ventricular Assist Device Graft Occlusion

Left ventricular assist device (LVAD) obstruction can be a dramatic and life-threatening complication in patients with advanced heart failure (HF). Despite surgical redo is often required in these patients, it is associated with a high risk of periprocedural negative outcome. We report the case of a 68-year-old male with a thrombotic stenosis of the LVAD proximal outflow-graft. Following Heart Team debate, a percutaneous intervention was planned during veno-arterial Extra Corporeal Membrane Oxygenation (ECMO) assistance. To achieve the needed catheter support, we used the "distal balloon anchoring technique" through the outflow-graft and managed to implant a covered stent, rapidly restoring the flow through the LVAD. The patient was discharged without further complications. Our case shows that, in selected cases, percutaneous treatment of LVAD obstructions can be feasible, especially using advanced techniques derived from the experiences in coronary interventions and under ECMO assistance. More cases and prospective studies are mostly needed to explore long-term patency of the LVADs and clinical outcomes in these high-risk patients.

Phenomapping a Novel Classification System for Patients With Destination Therapy Left Ventricular Assist Devices

Patients with continuous flow destination therapy (DT) left ventricular assist devices (LVAD) comprise a heterogeneous population. We hypothesized that phenotypic clustering of individuals with DT LVADs by their implantation characteristics will be associated with different long-term risk profiles. We analyzed 5,999 patients with continuous flow DT LVADs in Interagency Registry for Mechanically Assisted Circulatory Support using 18 continuous variable baseline characteristics. We Z-transformed the variables and applied a Gaussian finite mixture model to perform unsupervised clustering resulting in identification of 4 phenogroups. Survival analyses considered the competing risk for cumulative incidence of transplant or the composite end point of death or heart transplant where appropriate. Phenogroup 1 (n = 1,163, 19%) was older (71 years) and primarily white (81%). Phenogroups 2 (n = 648, 11%) and 3 (n = 3,671, 61%) were of intermediate age (70 and 62 years), weight (85 and 87 kg), and ventricular size. Phenogroup 4 (n = 517, 9%) was younger (40 years), heavier (108 kg), and more racially diverse. The cumulative incidence of death, heart transplant, bleeding, LVAD malfunction, and LVAD thrombosis differed among phenogroups. The highest incidence of death and the lowest rate of heart transplant was seen in phenogroup 1 (p <0.001). For adverse outcomes, phenogroup 4 had the lowest incidence of bleeding, whereas LVAD device thrombosis and malfunction were lowest in phenogroup 1 (p <0.001 for all). Finally, the incidence of stroke, infection, and renal dysfunction were not statistically different. In conclusion, the present unsupervised machine learning analysis identified 4 phenogroups with different rates of adverse outcomes and these findings underscore the influence of phenotypic heterogeneity on post-LVAD implantation outcomes.

Long-term survival on LVAD support: Device complications and end-organ dysfunction limit long-term success

BACKGROUND

Preoperative variables can predict short term left ventricular assist device (LVAD) survival, but predictors of extended survival remain insufficiently characterized.

METHOD

Patients undergoing LVAD implant (2012-2018) in the Intermacs registry were grouped according to time on support: short-term (<1 year, n = 7,483), mid-term (MT, 1-3 years, n = 5,976) and long-term (LT, ≥3 years, n = 3,015). Landmarked hazard analyses (adjusted hazard ratio, HR) were performed to identify correlates of survival after 1 and 3 years of support.

RESULTS

After surviving 1 year of support, additional LVAD survival was less likely in older (HR 1.15 per decade), Caucasian (HR 1.22) and unmarried (HR 1.16) patients (p < 0.05). After 3 years of support, only 3 preoperative characteristics (age, race, and history of bypass surgery, p < 0.05) correlated with extended survival. Postoperative events most negatively influenced achieving LT survival. In those alive at 1 year or 3 years, the occurrence of postoperative renal (creatinine HR MT = 1.09; LT HR = 1.10 per mg/dl) and hepatic dysfunction (AST HR MT = 1.29; LT HR = 1.34 per 100 IU), stroke (MT HR = 1.24; LT HR = 1.42), infection (MT HR = 1.13; LT HR = 1.10), and/or device malfunction (MT HR = 1.22; LT HR = 1.46) reduced extended survival (all p ≤ 0.03).

CONCLUSIONS

Success with LVAD therapy hinges on achieving long term survival in more recipients. After 1 year, extended survival is heavily constrained by the occurrence of adverse events and postoperative end-organ dysfunction. The growth of destination therapy intent mandates that future LVAD studies be designed with follow up sufficient for capturing outcomes beyond 24 months.

Bleeding and thrombotic events in adults supported with venovenous extracorporeal membrane oxygenation: an ELSO registry analysis

PURPOSE

This study aimed at analyzing the prevalence, mortality association, and risk factors for bleeding and thrombosis events (BTEs) among adults supported with venovenous extracorporeal membrane oxygenation (VV-ECMO).

METHODS

We queried the Extracorporeal Life Support Organization registry for adults supported with VV-ECMO from 2010 to 2017. Multivariable logistic regression modeling was used to assess the association between BTEs and in-hospital mortality and the predictors of BTEs.

RESULTS

Among 7579 VV-ECMO patients meeting criteria, 40.2% experienced ≥ 1 BTE. Thrombotic events comprised 54.9% of all BTEs and were predominantly ECMO circuit thrombosis. BTE rates decreased significantly over the study period (p < 0.001). The inpatient mortality rate was 34.9%. Bleeding events (1.69 [1.49-1.93]) were more strongly associated with in-hospital mortality than thrombotic events (1.23 [1.08-1.41]) p < 0.01 for both. The BTEs most strongly associated with mortality were ischemic stroke (4.50 [2.55-7.97]) and medical bleeding, including intracranial (5.71 [4.02-8.09]), pulmonary (2.02 [1.54-2.67]), and gastrointestinal (1.54 [1.2-1.98]) hemorrhage, all p < 0.01. Risk factors for bleeding included acute kidney injury and pre-ECMO vasopressor support and for thrombosis were higher weight, multisite cannulation, pre-ECMO arrest, and higher PaCO₂ at ECMO initiation. Longer time on ECMO, younger age, higher pH, and earlier year of support were associated with bleeding and thrombosis.

CONCLUSIONS

Although decreasing over time, BTEs remain common during VV-ECMO and have a strong, cumulative association with in-hospital mortality. Thrombotic events are more frequent, but bleeding carries a higher risk of inpatient mortality. Differential risk factors for bleeding and thrombotic complications exist, raising the possibility of a tailored approach to VV-ECMO management.

Impact of COVID-19 on Patients Supported with a Left Ventricular Assist Device

Patients on left ventricular assist device (LVAD) support may be susceptible to severe disease and complications from coronavirus disease-19 (COVID-19). The purpose of this study was to describe the clinical course of COVID-19 in LVAD patients. A retrospective review was performed at our center; 28 LVAD patients who developed COVID-19 between March 2020 and March 2021, and six patients with a prior COVID-19 infection who underwent LVAD implantation, were identified and examined. Of the 28 patients, nine (32%) died during the study period, five (18%) during their index hospitalization for COVID-19. Two patients (7%) presented with suspected pump thrombosis. In a nonadjusted binary regression logistic analysis, admission to the intensive care unit (unadjusted odds ratio, 7.6 [CI, 1.2-48], P = 0.03), and the need for mechanical ventilation (unadjusted odds ratio 14 [CI, 1.3-159], P = 0.03) were associated with mortality. The six patients who previously had COVID-19 and subsequently received a LVAD were on intra-aortic balloon pump and inotropic support at time of surgery. All six experienced a complicated and prolonged postoperative course. Three patients (50%) suffered from ischemic stroke, and there was one (17%) 30 day mortality. We observed an increased risk of morbidity and mortality in LVAD patients with COVID-19.

Recommendations for Psychosocial Evaluation of VAD candidates: Adoption, completion, and barriers to implementation

BACKGROUND

Recommendations exist to guide clinicians on a comprehensive psychosocial (PS) evaluation prior to Mechanical Circulatory Support (MCS) implantation.

OBJECTIVES

Assess adoption, beliefs, methodologies, and barriers to completion of the 2018 ISHLT/APM/AST/ICCAC/STSW Recommendations for Psychosocial evaluation of adult cardiothoracic transplant and long term mechanical circulatory support.

METHODS

Cross-sectional survey distributed to all 183 implanting LVAD centers in North America via mail and email.

RESULTS

Total of 58 Programs (35.6% response rate) representing 29 states and all regions of the United States responded. Respondents reported implanting 1,183 adults (range 0 - 85; mean = 21.5, SD = 18) in 2018. A majority (n = 55, 94.8%) reported that the 2018 Recommendations were consistent with their clinical practice and most (n = 51, 87.9%) had adopted the recommendations. The Stanford Integrated Psychosocial Assessment for Transplant (SIPAT) (n = 25, 47.1%) was the most commonly cited assessment tool in the use, although 15 centers reported utilizing more than one tool during the assessment process. Most common barriers influencing completion of the PS evaluation include patient too ill (total responses = 104), lack of time (total responses = 89), patient poor candidate (total responses = 44), and lack of Insurance coverage/reimbursement (total responses = 41).

CONCLUSION

The 2018 ISHLT Recommendations for PS evaluation of LVAD Candidates are widely adopted by respondents in clinical practice, although barriers are still reported to their implementation. Additional research is needed to understand strategies to reduce barriers to implementation and maintenance of the recommendations in clinical practice.

Cerebral Microvascular Injury in Patients with Left Ventricular Assist Device: a Neuropathological Study

Strokes are common among patients with left ventricular devices (LVAD). We hypothesize that there is ongoing cerebral microvascular injury with LVAD support and aim to describe this among LVAD-implanted patients through post-mortem neuropathologic evaluation. We identified and reviewed medical records of LVAD patients who underwent brain autopsy between January 2006 and December 2019 at a tertiary center. Cerebral injury was defined as both gross and microscopic injuries within the intracranial space including cerebral infarct (CI), hypoxic-ischemic brain injury (HIBI), intracranial hemorrhage (ICH), and cerebral microvascular injury. Cerebral microvascular injury was defined as microscopic brain intraparenchymal or perivascular hemorrhage, perivascular hemosiderin deposition, and perivascular inflammation. Twenty-one patients (median age = 57 years, 67% male) had autopsy after LVAD support (median LVAD support = 51 days). The median time from death to autopsy was 19 h. All 21 patients had cerebral injuries and 19 (90%) patients had cerebral microvascular injuries. Fourteen patients (78%) harbored more than one type of cerebral injury. On gross examination, 8 patients (38%) had CI, and 6 patients (29%) had ICH. On microscopic exam, 12 patients (57%) had microscopic intraparenchymal hemorrhage, 3 patients (14%) had perivascular hemorrhage, 11 patients (43%) had perivascular hemosiderin deposition, 5 patients (24%) had meningeal hemorrhage, 13 patients had chronic perivascular inflammation (62%), and 2 patients had diffuse HIBI (10%). Among patients with LVAD, there is a high prevalence of subclinical microvascular injuries and cerebral microbleeds (CMBs), which may provide some insights to the cause of frequent cerebral injury in LVAD population.

Incidence of Heparin-Induced Thrombocytopenia in Patients With Newly Implanted Mechanical Circulatory Support Devices

BACKGROUND

Heparin exposure and device-related thrombocytopenia complicate the diagnosis of heparin-induced thrombocytopenia (HIT) in patients receiving mechanical circulatory support (MCS). To improve anticoagulation management for patients with newly implanted MCS devices, incidence of confirmed HIT needs to be further characterized.

OBJECTIVES

The purpose of this study is to describe the incidence of HIT and clinical utility of the 4Ts score in patients with newly implanted MCS devices.

METHODS

This is a retrospective analysis of MCS patients receiving unfractionated heparin from 2014 to 2017. The primary end point was incidence of laboratory-confirmed HIT. Strong positive, likely positive, low probability, and negative HIT categories were established based on heparin-induced platelet antibody (HIPA) and serotonin release assay (SRA). Secondary end points include characterization of platelet trends, argatroban use, incidence of HIT among each of the MCS devices, and utility of 4Ts score.

RESULTS

A total of 342 patient encounters met inclusion criteria, of which 68 HIPA tests and 25 SRAs were ordered. The incidence of HIT was 0.88% (3/342) and 4.4% (3/68) in patients with suspected HIT. Of the 68 HIPA tests, 3 (4.4%) were considered strong positive and 3 of the 25 SRAs were positive. Median 4Ts score was 4 [2.5-4] and optical density 0.19 [0.11-0.54]. The positive predictive value for the 4Ts score was 0.15 (CI = 0.03-0.46) and negative predictive value, 0.93 (CI = 0.82-0.98).

CONCLUSION AND RELEVANCE

HIT occurs infrequently with newly implanted MCS devices. The 4Ts score appears to have a high negative predictive value for ruling out HIT.

Alternatives for Vitamin K Antagonists as Thromboprophylaxis for Mechanical Heart Valves and Mechanical Circulatory Support Devices: A Systematic Review

The holy grail of anticoagulation in patients with intracardiac devices, such as mechanical heart valves (MHVs) and left ventricular assist devices (LVADs), comprises safe prevention of thrombosis without interrupting normal hemostasis. Device-induced thrombosis and anticoagulant-related bleeding problems are dreaded complications that may cause a significantly reduced quality of life and increased morbidity and mortality. Vitamin K antagonists are the current standard for oral anticoagulation therapy in patients with MHVs and LVADs. Even within the therapeutic range, hemorrhage is the primary complication of these drugs, which emphasizes the need for safer anticoagulants for the prevention of device-induced thrombosis. Device-induced thrombosis is a complex multifactorial phenomenon that likely requires anticoagulant therapy targeting multiple pathways. Here, we review the preclinical and clinical data describing the efficacy of a variety of anticoagulants as thromboprophylaxis after implantation of intracardiac devices.

Acoustic Properties of Axial and Centrifugal Flow Left Ventricular Assist Devices and Prediction of Pump Thrombosis

OBJECTIVE

To characterize the properties of the audible tones produced by current left ventricular assist device (LVAD) pumps approved for use, and to ascertain if changes in those may be present in the setting of pump thrombosis.

PATIENTS AND METHODS

From August 31, 2016, to January 16, 2020, LVAD recipients consented to have surface recordings obtained using a high-fidelity digital stethoscope. Audio data were analyzed using digital recording and editing software to produce an acoustic spectrogram by Fast Fourier transformation.

RESULTS

Recordings were obtained in 53 patient encounters (27 HeartMate II, 19 HeartWare and 7 HeartMate 3). In 12 patients (9 HeartMate II, 3 HeartWare) there was a clinical concern for pump thrombosis. In all patients and pump models, a fundamental frequency was noted, and the second and third harmonics were also clearly detectable. Where thrombosis occurred in the HeartMate II pump, the absolute (normal -46.9 [-57.5,-42.9] dB vs thrombosis -41.4 [-49.8,-26.8] dB; P=.08) and relative (normal 0.72 [0.62, 0.92] vs thrombosis 0.95 [0.86, 1.24]; P=.01) third harmonic frequencies were increased in amplitude. Where paired data were available, an increase in the absolute and relative third harmonic frequencies was observed in all patients. In the case of the HeartWare device, a consistent difference in harmonic amplitudes in the setting of thrombosis could not be identified.

CONCLUSION

A consistent pattern of fundamental and harmonic frequencies is common to all LVADs currently approved for use. Alterations in the amplitude of higher order harmonics may signal the onset of pump thrombosis in axial flow LVADs.

Antiplatelet and anticoagulation strategies for left ventricular assist devices

Left ventricular assist devices (LVAD) have revolutionized the management of advanced heart failure. However, complications rates remain high, among which hemorrhagic and thrombotic complications are the most important. Antiplatelet and anticoagulation strategies form a cornerstone of LVAD management and may directly affect LVAD complications. Concurrently, LVAD complications influence anticoagulation and anticoagulation management. A thorough understanding of device, patient, and management, including anticoagulation and antiplatelet therapies, are important in optimizing LVAD outcomes. This article provides a comprehensive state of the art review of issues related to antiplatelet and anticoagulation management in LVADs. We start with a historical overview, the epidemiology and pathophysiology of bleeding and thrombotic complications in LVADs. We then discuss platelet and anticoagulation biology followed by considerations prior to, during, and after LVAD implantation. This is followed by discussion of anticoagulation and the management of thrombotic and hemorrhagic complications. Specific problems, including management of heparin-induced thrombocytopenia, anticoagulant reversal, novel oral anticoagulants, artificial heart valves, and noncardiac surgeries are covered in detail.

The Preimplantation Psychosocial Evaluation and Prediction of Clinical Outcomes During Mechanical Circulatory Support: What Information Is Most Prognostic?

BACKGROUND

Psychosocial evaluations are required for long-term mechanical circulatory support (MCS) candidates, no matter whether MCS will be destination therapy (DT) or a bridge to heart transplantation. Although guidelines specify psychosocial contraindications to MCS, there is no comprehensive examination of which psychosocial evaluation domains are most prognostic for clinical outcomes. We evaluated whether overall psychosocial risk, determined across all psychosocial domains, predicted outcomes, and which specific domains appeared responsible for any effects.

METHODS

A single-site retrospective analysis was performed for adults receiving MCS between April 2004 and December 2017. Using an established rating system, we coded psychosocial evaluations to identify patients at low, moderate, or high overall risk. We similarly determined risk within each of 10 individual psychosocial domains. Multivariable analyses evaluated whether psychosocial risk predicted clinical decisions about MCS use (DT versus bridge), and postimplantation mortality, transplantation, rehospitalization, MCS pump exchange, and standardly defined adverse medical events (AEs).

RESULTS

In 241 MCS recipients, greater overall psychosocial risk increased the likelihood of a DT decision (odds ratio, 1.76; P = 0.017); and postimplantation pump exchange and occurrence of AEs (hazard ratios [HRs] ≥ 1.25; P ≤ 0.042). The individual AEs most strongly predicted were cardiac arrhythmias and device malfunctions (HRs ≥ 1.39; P ≤ 0.032). The specific psychosocial domains predicting at least 1 study outcome were mental health problem severity, poorer medical adherence, and substance use (odds ratios and HRs ≥ 1.32; P ≤ 0.010).

CONCLUSIONS

The psychosocial evaluation predicts not only clinical decisions about MCS use (DT versus bridge) but important postimplantation outcomes. Strategies to address psychosocial risk factors before or soon after implantation may help to reduce postimplantation clinical risks.

Clinical outcomes and healthcare expenditures in the real world with left ventricular assist devices - The CLEAR-LVAD study

BACKGROUND

Several distinctly engineered left ventricular assist devices (LVADs) are in clinical use. However, contemporaneous real world comparisons have not been conducted, and clinical trials were not powered to evaluate differential survival outcomes across devices.

OBJECTIVES

Determine real world survival outcomes and healthcare expenditures for commercially available durable LVADs.

METHODS

Using a retrospective observational cohort design, Medicare claims files were linked to manufacturer device registration data to identify de-novo, durable LVAD implants performed between January 2014 and December 2018, with follow-up through December 2019. Survival outcomes were compared using a Cox proportional hazards model stratified by LVAD type and validated using propensity score matching. Healthcare resource utilization was analyzed across device types by using nonparametric bootstrap analysis methodology. Primary outcome was survival at 1-year and total Part A Medicare payments.

RESULTS

A total of 4,195 de-novo LVAD implants were identified in fee-for-service Medicare beneficiaries (821 HeartMate 3; 1,840 HeartMate II; and 1,534 Other-VADs). The adjusted hazard ratio for mortality at 1-year (confirmed in a propensity score matched analysis) for the HeartMate 3 vs HeartMate II was 0.64 (95% CI; 0.52-0.79, p< 0.001) and for the HeartMate 3 vs Other-VADs was 0.51 (95% CI; 0.42-0.63, p < 0.001). The HeartMate 3 cohort experienced fewer hospitalizations per patient-year vs Other-VADs (respectively, 2.8 vs 3.2 EPPY hospitalizations, p < 0.01) and 6.1 fewer hospital days on average (respectively, 25.2 vs 31.3 days, p < 0.01). The difference in Medicare expenditures, conditional on survival, for HeartMate 3 vs HeartMate II was -$10,722, p < 0.001 (17.4% reduction) and for HeartMate 3 vs Other-VADs was -$17,947, p < 0.001 (26.1% reduction).

CONCLUSIONS

In this analysis of a large, real world, United States. administrative dataset of durable LVADs, we observed that the HeartMate 3 had superior survival, reduced healthcare resource use, and lower healthcare expenditure compared to other contemporary commercially available LVADs.

Mechanical Blood-Immersed Bearings in Continuous-Flow Rotary Blood Pumps

Mechanical blood-immersed bearings have been used in many continuous-flow rotary blood pumps to reduce friction between relatively moving parts, but their use has been associated with a significant incidence of pump thrombosis. As newer cardiac assist devices with more advanced bearings become available, the rate of pump thrombosis will likely decrease. Nevertheless, it is important to understand the design limitations of mechanical bearings as pumps utilizing them are still in use as chronic support devices and especially in the acute setting for temporary support devices. A properly designed journal bearing should support the spinning rotor with no surface-to-surface contact between the bearing and journal surfaces. The journal continuously undergoes orbital motion within the bearing, which can be "stable" or "unstable." Unstable orbital motion causes the journal to move progressively off-center until it collides with the bearing, and even minor variations in manufacturing can create off-design operation and dynamic instability of the journal. Since blood is the lubricant in most clinically-used rotary blood pumps, lubricant viscosity can vary abruptly in response to changes in hematocrit or plasma protein concentration. Additionally, shear stress from the high-speed rotor can cause hemolysis and plasma protein denaturation. We reviewed theoretical design and operating principles of mechanical bearings and discuss why the phenomenon of mechanical bearing thrombosis may be an inherent design issue dependent on variables that are beyond the control of clinicians.

Early Detection of Pump Thrombosis in Patients With Left Ventricular Assist Device

Pump thrombosis (PT) is a serious adverse event in patients receiving left ventricular assist devices (LVAD). The study aims to determine whether pump parameters and clinical data may enable early detection of PT. This retrospective study included 88 patients who received an LVAD between 2012 and 2015 among which those with intra-PT were identified. In a propensity score-matched control group observation, time periods were matched with time before thrombosis. International normalized ratio (INR) time in therapeutic range (TTR) and lactate dehydrogenase (LDH) were analyzed for 60 days preceding PT. Furthermore, pump data (power, flow, and speed) in HeartWare ventricular assist devices (HVAD) patients were analyzed 7 days before PT using a mixed-design analysis of variance to investigate temporal changes in pump data. Pump thrombosis occurred in 15 patients (13 males, age 58 ± 10 years, 7 HeartMate II and 8 HVAD). International normalized ratio therapeutic range (2.0-3.0) and acetylsalicylic acid daily doses (100-200 mg) were similar for both groups, but patients with PT had lower TTR (36% vs. 65%; p = 0.025). No significant difference in LVAD power between groups was seen at baseline (p = 0.31), and power did not change in the control group over time (p > 0.99). Lactate dehydrogenase increased already 1 week prior PT and power from 4.4 ± 0.8 W at baseline to 4.9 ± 0.8 W (p = 0.007) 2 days before readmission and to 6.5 ± 1.8 W (p = 0.015) at readmission. Pump thrombosis is associated with a lower percentage of INR TTR and elevated LDH before the event. A better monitoring of pump parameters would enable PT detection already up to 2 days in advance.

Thrombolysis as first-line therapy for Medtronic/HeartWare HVAD left ventricular assist device thrombosis

OBJECTIVES

METHODS

From March 2006 to November 2018, 30 Medtronic/HeartWare HVAD left ventricular assist device patients had 48 PT events. We analysed outcomes with intravenous Alteplase as a first-line therapy for PT. Pump exchange or urgent heart transplantation was only considered after the failure of TL or existing contraindications to TL.

RESULTS

TL was used as the first-line therapy in 44 PT events in 28 patients without a contraindication to TL. TL was successful in 61.4% of PT events. More than 1 cycle of TL was necessary in 55.6% of events. The combined success of TL and heart transplantation or device exchange was 81.8%. In 15.9% of events, PT was fatal. Causes of death were severe complications (9.1%) related to TL or discontinuation of therapy for multi-organ failure (6.8%). Intracranial bleeding and arterial thromboembolism were observed in 4.5% and 11.5% of the PT events after TL.

CONCLUSIONS

Intravenous TL as a first-line therapy for PT in Medtronic/HeartWare HVAD patients can be a reasonable treatment option and does not preclude subsequent heart transplantation or device exchange. However, thromboembolic and bleeding complications are common. The decision to perform TL or device exchange should, therefore, be made on an individual basis after balancing the risks and benefits of different treatment approaches.

Left Ventricular Assist Device Exchange Increases Heart Transplant Wait-List Mortality

BACKGROUND

The new heart transplant allocation criteria prioritize inpatients who require temporary mechanical circulatory support and give lower urgency to candidates on a durable left ventricular assist device (LVAD) who require a device exchange. This study explores whether the latter group should warrant higher priority to reduce wait-list mortality.

METHODS

This is a retrospective observational study of 13,113 adult heart transplant candidates in the Organ Procurement and Transplantation Network database who underwent LVAD implantation between 2007 and 2017. It evaluates the impact of LVAD exchange on the composite endpoint of death or removal from the wait list owing to worsening medical condition 1 y after device implantation.

RESULTS

There were 1085 pump exchanges in 954 patients (7% of candidates), of which 22% were women. The pump exchange rate was 5.92 events per 100 patient-years. One-year survival was lower for those who required a pump exchange (76.3% versus 88.5%, logrank P < 0.001). This was congruent with the risk-adjusted mortality 1-y after implantation (hazards ratio: 2.56, 95% confidence interval: 2.18-3.00, P < 0.001).

CONCLUSIONS

These findings indicate that among candidates awaiting heart transplantation with a durable LVAD, undergoing pump exchange doubles the risk of 1-y mortality. Giving priority to these candidates may reduce wait-list mortality.

Limited Efficacy of Thrombolytics for Pump Thrombosis in Durable Left Ventricular Assist Devices

BACKGROUND

This study reports a single-center experience with thrombolytics for left ventricular assist device (LVAD) pump thrombosis.

METHODS

Adults undergoing continuous-flow LVAD implantation between 2004 and 2018 at a single center were reviewed and those with pump thrombosis were identified. Primary outcomes included 1-year survival and success rates of thrombolytic therapy. Secondary outcomes included posttreatment adverse events, freedom from major bleeding at 1 year, and freedom from stroke at 1-year follow-up.

RESULTS

A total of 341 patients underwent LVAD implantation and 10.8% (n = 37) developed pump thrombosis. Of those 37, 26 received initial thrombolytic therapy (70.2%), 5 underwent direct pump exchange (13.5%), and 6 received only intravenous heparin owing to presentation with acute stroke or severe multiorgan failure (16.2%). Successful treatment was achieved in 11.5% of patients receiving thrombolytics (n = 3). Early adverse events after thrombolytic therapy included major bleeding in 11.5% (n = 3) and new stroke in 7.7% (n = 2). Most patients undergoing thrombolytic therapy underwent subsequent device exchange (69.2%; n = 18). Overall survival in patients with pump thrombosis after treatment was 96.8% at 30 days, 78.9% at 90 days, and 63.1% at 1 year. Freedom from major bleeding and stroke at 1 year was 74.2% and 87.2%, respectively.

CONCLUSIONS

In this single-center experience of thrombolytics for pump thrombosis in LVAD patients, there was limited efficacy; most patients required subsequent pump exchange. Combined with the risk for major bleeding or stroke with thrombolysis, this underscores the importance of further refining patient selection for direct pump exchange in those presenting with pump thrombosis.

Decoupling Between Diastolic Pulmonary Artery and Pulmonary Capillary Wedge Pressures Is Associated With Right Ventricular Dysfunction and Hemocompatibility-Related Adverse Events in Patients With Left Ventricular Assist Devices

Background

Decoupling between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure is an index of pulmonary vascular damage. This study assessed the impact of decoupling on right heart function and hemocompatibility‐related adverse events.

Methods and Results

In this prospective study, patients underwent invasive hemodynamic tests following left ventricular assist device implantation. Decoupling was defined as a difference of >5 mm Hg between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure. Among 92 patients with left ventricular assist devices (median age, 61 years; 57% male), 44 patients (48%) had decoupling. Right heart function and size by echocardiographic assessment worsened during a 1‐year observational period in the decoupling group as compared with the control group (P<0.05). The decoupling group had significantly lower 1‐year freedom from any hemocompatibility‐related adverse events (49% versus 79%; P=0.005), as well as a higher hemocompatibility score (2.14 versus 0.67; P=0.004). The scoring system depicts the severity of hemocompatibility‐related adverse events using 4 escalating tiers. Increased tier I scores (1–2 gastrointestinal bleedings or medically managed pump thrombosis; P=0.027) and tier IIIB scores (disabling stroke or hemocompatibility‐related adverse event–related death; P=0.041) occurred more frequently in the decoupling group.

Conclusions

The presence of decoupling between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure was associated with worsening of right heart function and hemocompatibility‐related adverse events in patients with left ventricular assist devices.

Outcomes following left ventricular assist device exchange

INTRODUCTION

Left ventricular assist device (LVAD) exchange has been historically associated with a significant risk of morbidity and mortality. It is unknown, however, whether these outcomes have improved. We aimed to compare clinical outcomes following LVAD exchange to those following initial LVAD implant in a contemporary patient cohort.

METHODS

A total of 115 LVAD patients were enrolled between 2014 and 2017 and followed for 1 year. Of these, 15 patients (54.5 ± 13.3 years old, 87% male) underwent LVAD exchange at 277 (IQR 191-597) days following LVAD implantation and 100 patients (57.5 ± 12.3 years old, 76% male) did not undergo an LVAD exchange (non-exchange group).

RESULTS

One-year survival rate following LVAD exchange tended to be higher than the non-exchange patients (93% vs 76%, P = .15). Readmission rates for each comorbidity did not significantly differ between the two groups (P > .05 for all) except for the higher rate of pump thrombosis in the LVAD exchange group (P < .05).

DISCUSSION

LVAD exchange cohorts seem to have comparable clinical outcome with the non-exchange cohorts.

CONCLUSION

LVAD exchange might be an increasingly appropriate therapeutic option for the management of pump thrombosis, although careful monitoring for recurrent pump thrombosis is required.

Deep Y-Descent in Right Atrial Waveforms Following Left Ventricular Assist Device Implantation

BACKGROUND

Characterization of right heart catheterization (RHC) waveforms provides diagnostic and clinical information in heart failure patients. We aimed to investigate the implication of RHC waveforms, specifically the y-descent, in patients with left ventricular assist device (LVAD).

METHODS AND RESULTS

Patients underwent RHC and waveforms were quantified prior to and 6 months after LVAD implantation. The impact of a deep y-descent (>3 mmHg) on echocardiographic measures of right heart function and 1-year hemocompatibility-related adverse event rates were investigated. Eighty-nine patients (median 59 years old, 65 male) underwent RHC. RHC waveform showed unique changes following LVAD implantation, particularly an increase in the steepness of the y-descent. A post-LVAD deep y-descent was associated with reduced right ventricular function and enlarged right heart. Patients with post-LVAD deep y-descent had higher rates of gastrointestinal bleeding (0.866 vs 0.191 events/year) and stroke (0.199 vs 0 events/year) compared with those without (P< .05 for both).

CONCLUSION

RHC waveforms characterized by deep y-descent on RHC waveform during LVAD support was associated with impaired right ventricular function and worse clinical outcomes.

Initial conservative management strategy of HeartWare left ventricular assist device thrombosis with intravenous heparin or bivalirudin

Introduction and objectives:

Pump thrombosis is a serious left ventricular assist device complication, though there are no guidelines regarding its treatment. The main aim of this study was to describe a strategy of intravenous anticoagulation as the initial treatment in these patients and then to compare intravenous heparin with bivalirudin.

Methods:

All consecutive patients who received a HeartWare left ventricular assist device from July 2009 to March 2019 were retrospectively analysed. Patients developing a pump thrombosis were selected, and treatment, outcomes and complications were recorded.

Results:

During this period of time (116 months), 220 patients underwent HeartWare left ventricular assist device implantation and 57 developed pump thrombosis, with an incidence rate of first pump thrombosis of 0.17 events per patient-year of support (incidence rate of all episodes of pump thrombosis: 0.30 events per patient-year of support). All the patients were initially treated medically, predominantly with either intravenous heparin (n = 26) or bivalirudin (n = 16). Patients treated with bivalirudin during the first pump thrombosis episode had less subsequent re-thrombosis episodes (18.7% vs 57.7%, p < 0.05). In addition, percentage time in therapeutic range was greater for bivalirudin compared with heparin (68.5% ± 16.9% vs 37.4% ± 31.0%, p < 0.01). During the first pump thrombosis episode, 26.3% of the patients needed surgery (left ventricular assist device exchange (n = 8), transplant (n = 6) or decommissioning (n = 1)). The overall survival at 1 year was 61.4%, and there was no significant difference in survival.

Conclusion:

Left ventricular assist device thrombosis is a serious life-threatening complication; hence, we propose an initial conservative management of pump thrombosis with enhanced intravenous anticoagulation with either intravenous heparin or bivalirudin, with surgery reserved for refractory cases.

Circulatory loop design and components introduce artifacts impacting in vitro evaluation of ventricular assist device thrombogenicity: A call for caution

Mechanical circulatory support (MCS) devices continue to be hampered by thrombotic adverse events (AEs), a consequence of device-imparted supraphysiologic shear stresses, leading to shear-mediated platelet activation (SMPA). In advancing MCS devices from design to clinical use, in vitro circulatory loops containing the device under development and testing are utilized as a means of assessing device thrombogenicity. Physical characteristics of these test circulatory loops may also contribute to inadvertent platelet activation through imparted shear stress, adding inadvertent error in evaluating MCS device thrombogenicity. While investigators normally control for the effect of a loop, inadvertent addition of what are considered innocuous connectors may impact test results. Here, we tested the effect of common, additive components of in vitro circulatory test loops, that is, connectors and loop geometry, as to their additive contribution to shear stress via both in silico and in vitro models. A series of test circulatory loops containing a ventricular assist device (VAD) with differing constituent components, were established in silico including: loops with 0~5 Luer connectors, a loop with a T-connector creating 90° angulation, and a loop with 90° angulation. Computational fluid dynamics (CFD) simulations were performed using a k - ω shear stress transport turbulence model to platelet activation index (PAI) based on a power law model. VAD-operated loops replicating in silico designs were assembled in vitro and gel-filtered human platelets were recirculated within (1 hour) and SMPA was determined. CFD simulations demonstrated high shear being introduced at non-smooth regions such as edge-connector boundaries, tubing, and at Luer holes. Noticeable peaks' shifts of scalar shear stress (sss) distributions toward high shear-region existed with increasing loop complexity. Platelet activation also increased with increasing shear exposure time, being statistically higher when platelets were exposed to connector-employed loop designs. The extent of platelet activation in vitro could be successfully predicted by CFD simulations. Loops employing additional components (non-physiological flow pattern connectors) resulted in higher PAI. Loops with more components (5-connector loop and 90° T-connector) showed 63% and 128% higher platelet activation levels, respectively, versus those with fewer (0-connector (P = .023) and a 90° heat-bend loop (P = .0041). Our results underscore the importance of careful consideration of all component elements, and suggest the need for standardization in designing in vitro circulatory loops for MCS device evaluation to avoid inadvertent additive SMPA during device evaluation, confounding overall results. Specifically, we caution on the use and inadvertent introduction of additional connectors, ports, and other shear-generating elements which introduce artifact, clouding primary device evaluation via introduction of additive SMPA.

Hemodynamics of concomitant tricuspid valve procedures at LVAD implantation

BACKGROUND

Tricuspid regurgitation (TR) is common in patients receiving left ventricular assist device (LVAD) implantation. The current literature is conflicting regarding the effects of concomitant tricuspid valve repair (TVR) at LVAD implantation. We investigated the hemodynamic effects of concomitant TVR at LVAD implantation.

METHODS

Consecutive clinically stable LVAD outpatients who underwent hemodynamic ramp testings were enrolled in this study, and they were stratified by concomitant TVR. Results of hemodynamic ramp tests were compared between the TVR group and the non-TVR group.

RESULTS

Among 65 LVAD patients undergoing ramp tests, 34 patients had received TVR, and 31 had not. There were no significant differences in baseline characteristics between two groups except for higher degree of TR and lower pulmonary artery pulsatility index in the TVR group (P < .05 for both). Following LVAD implantation, the degree of TR improved significantly in the TVR group down to the comparable level with the non-TVR group. During ramp tests, the TVR group had steeper cardiac index slope (0.14 ± 0.12 vs 0.07 ± 0.07 L/min/m² /step, P = .002) and higher cardiac index at set LVAD speed (2.99 ± 0.84 vs 2.52 ± 0.42 L/min/m² , P = .007).

CONCLUSIONS

Concomitant TVR improves cardiac output and its response to LVAD speed change following LVAD implantation. Longitudinal clinical implications of such hemodynamic changes are unknown.

Recurrent pump thrombosis is common after axial continuous-flow left ventricular assist device exchange

In selected patients with left ventricular assist device-associated infection or malfunction, pump exchange may become necessary after conservative treatment options fail and heart transplantation is not readily available. We examined the survival and complication rate in patients (⩾19 years of age) who underwent HeartMate II to HeartMate II exchange at our institution from 1 January 2010 to 28 February 2018. Clinical outcomes were analyzed and compared for patients who underwent exchange for pump thrombosis (14 patients), breach of driveline integrity (5 patients), and device-associated infection (2 patients). There were no differences in 30-day mortality (p = 0.58), need for temporary renal replacement therapy (p = 0.58), right ventricular mechanical support (p = 0.11), and postoperative stroke (p = 0.80) among groups. Survival at 1 year was 90% ± 7% for the whole cohort and 85% ± 10% for those who underwent exchange for pump thrombosis. In patients exchanged for device thrombosis, freedom from re-thrombosis and survival free from pump re-thrombosis at 1 year were 49% ± 16% and 42% ± 15%, respectively. No association of demographic and clinical variables with the risk of recurrent pump thrombosis after the first exchange was identified. Survival after left ventricular assist device exchange compares well with published results after primary left ventricular assist device implantation. However, recurrence of thrombosis was common among patients who required a left ventricular assist device exchange due to pump thrombosis. In this sub-group, consideration should be given to alternative strategies to improve the outcomes.