Obesity Is Associated with Driveline Infection of Left Ventricular Assist Devices

Escalating Surgical Treatment for Left Ventricular Assist Device Infection and Expected Mortality: Clinical Risk Prediction Score

BACKGROUND

Left ventricular assist devices (LVAD) improve survival for patients with cardiac failure, but LVAD-specific infection (VSI) remains a challenge with poorly understood predictive risk factors. The indications and use of escalating medical treatment to surgical debridement and potential flap reconstruction are not well characterized.

STUDY DESIGN

A retrospective review of consecutive patients undergoing primary LVAD implantation at a tertiary academic center was performed. The primary outcome measures were 90-day and overall mortality after VSI. Cox proportional hazards regression was used to generate a risk prediction score for mortality.

RESULTS

Of the 760 patients undergoing primary LVAD implantation, 255 (34%) developed VSI; of these patients, 91 (36%) were managed medically, 134 (52%) with surgical debridement, and 30 (12%) with surgical debridement and flap reconstruction. One-year survival after infection was 85% with median survival of 2.40 years. Factors independently associated with increased mortality were diabetes (hazard ratio [HR] 1.44, p = 0.04), MRSA infection (HR 1.64, p = 0.03), deep space (pump pocket or outflow cannula) involvement (HR 2.26, p < 0.001), and extracorporeal membrane oxygenation after LVAD (HR 2.52, p < 0.01). Factors independently associated with decreased mortality were flap reconstruction (HR 0.49, p = 0.02) and methicillin-sensitive Staphylococcus aureus infection (HR 0.63, p = 0.03). A clinical risk prediction score was developed using these factors and showed significant differences in median survival, which was 5.67 years for low-risk (score 0 to 1), 3.62 years for intermediate-risk (score 2), and 1.48 years for high-risk (score ≥3; p < 0.001) patients.

CONCLUSIONS

We developed a clinical risk prediction score to stratify patients with VSI. In selected cases, escalating surgical treatment was associated with increased survival. Future work is needed to determine whether early surgical debridement and flap reconstruction can alter outcomes in select cases of VSI.

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.

Value of nutritional indices in predicting survival free from pump replacement and driveline infections in centrifugal left ventricular assist devices

Objective

There is a paucity of data assessing the impact of nutritional status on outcomes in patients supported with the HeartMate 3 (HM3) left ventricular assist device (LVAD).

Methods

Patients ≥18 years of age who underwent HM3 LVAD implantation between 2015 and 2020 were identified from a single tertiary care center. The primary outcome assessed was death or device replacement. A secondary outcome of driveline infection was also evaluated. Kaplan-Meier survival analysis and a multivariate Cox-proportional hazards model were used to identify predictors of outcome.

Results

Of the 289 patients identified, 94 (33%) experienced a primary outcome and 96 (33%) a secondary outcome during a median follow-up time of 2.3 years. Independent predictors of the primary outcome included peripheral vascular disease (hazard ratio [HR], 3.40; 95% confidence interval [CI], 1.66-6.97, P < .01), diabetes mellitus (HR, 0.46; 95% CI, 0.27-0.80, P < .01), body mass index ≥40 kg/m2 (HR, 2.63 per 1 kg/m2 increase; 95% CI, 1.22-5.70, P < .05), preoperative creatinine level (HR, 1.86 per 1 mg/dL increase; 95% CI, 1.31-2.65, P < .01), and preoperative prognostic nutritional index (PNI) score (HR, 0.88 per 1-point increase; 95% CI, 0.81-0.96, P < .01). Independent predictors of driveline infection included age at the time of implantation (HR, 0.97; 95% CI, 0.96-0.99, P < .01) and diabetes mellitus (HR, 1.79; 95% CI, 1.17-2.73, P < .01).

Conclusions

Preoperative PNI scores may independently predict mortality and the need for device replacement in patients with HM3 LVAD. Routine use of the PNI score during preoperative evaluation and, when possible, supplementation to PNI >33, may be of value in this population.

Artificial intelligence-based analysis of body composition predicts outcome in patients receiving long-term mechanical circulatory support

BACKGROUND

Obesity is a known cardiovascular risk factor and associated with higher postoperative complication rates in patients undergoing cardiac surgery. In heart failure (HF), conflicting evidence in terms of survival has been reported, whereas sarcopenia is associated with poor prognosis. An increasing number of HF patients require left ventricular assist device (LVAD) implantations. The postoperative mortality has improved in recent years but is still relatively high. The impact of body composition on outcome in this population remains unclear. The aim of this investigation was to examine the preoperative computed tomography (CT) body composition as a predictor of the postoperative outcome in advanced HF patients, who receive LVAD implantations.

METHODS

Preoperative CT scans of 137 patients who received LVADs between 2015 and 2020 were retrospectively analysed using an artificial intelligence (AI)-powered automated software tool based on a convolutional neural network, U-net, developed for image segmentation (Visage Version 7.1, Visage Imaging GmbH, Berlin, Germany). Assessment of body composition included visceral and subcutaneous adipose tissue areas (VAT and SAT), psoas and total abdominal muscle areas and sarcopenia (defined by lumbar skeletal muscle indexes). The body composition parameters were correlated with postoperative major complication rates, survival and postoperative 6-min walk distance (6MWD) and quality of life (QoL).

RESULTS

The mean age of patients was 58.21 ± 11.9 years; 122 (89.1%) were male. Most patients had severe HF requiring inotropes (Interagency Registry for Mechanically Assisted Circulatory Support [INTERMACS] profile I-III, 71.9%) secondary to coronary artery diseases or dilated cardiomyopathy (96.4%). Forty-four (32.1%) patients were obese (body mass index ≥ 30 kg/m2 ), 96 (70.1%) were sarcopene and 19 (13.9%) were sarcopene obese. Adipose tissue was associated with a significantly higher risk of postoperative infections (VAT 172.23 cm2 [54.96, 288.32 cm2 ] vs. 124.04 cm2 [56.57, 186.25 cm2 ], P = 0.022) and in-hospital mortality (VAT 168.11 cm2 [134.19, 285.27 cm2 ] vs. 135.42 cm2 [49.44, 227.91 cm2 ], P = 0.033; SAT 227.28 cm2 [139.38, 304.35 cm2 ] vs. 173.81 cm2 [97.65, 254.16 cm2 ], P = 0.009). Obese patients showed no improvement of 6MWD and QoL within 6 months postoperatively (obese: +0.94 ± 161.44 months, P = 0.982; non-obese: +166.90 ± 139.00 months, P < 0.000; obese: +0.088 ± 0.421, P = 0.376; non-obese: +0.199 ± 0.324, P = 0.002, respectively). Sarcopenia did not influence the postoperative outcome and survival within 1 year after LVAD implantation.

CONCLUSIONS

Preoperative AI-based CT body composition identifies patients with poor outcome after LVAD implantation. Greater adipose tissue areas are associated with an increased risk for postoperative infections, in-hospital mortality and impaired 6MWD and QoL within 6 months postoperatively.

Driveline infections in left ventricular assist devices-Incidence, epidemiology, and staging proposal

BACKGROUND

Driveline infections (DLI) are a serious complication in patients with left ventricular assist devices (LVAD). Apart from the differentiation between superficial and deep DLI, there is no consensus on the classification of the severity of DLI. Little is known about risk factors and typical bacteria causing DLI in centrifugal-flow LVADs.

METHODS

In this single-center study with 245 patients, DLI were classified by their local appearance using a modification of a score suggested by the Sharp Memorial group. The driveline exit site was inspected routinely every 6 months.

RESULTS

Severe DLI were detected in 34 patients (15%) after 6 months and in 24 patients (22%) after 24 months. The proportion of patients with DLI increased significantly during the follow-up (p = 0.0096). The most common bacteria in local smears were Corynebacterium, coagulase-negative Staphylococcus, and Staphylococcus aureus. Fifty-nine patients were hospitalized more than once for DLI. In these patients, S. aureus was the most common bacterium. It was also the most common bacterium in blood cultures. Higher BMI, no partnership, and a HeartMate 3 device were identified as risk factors for DLI in a multivariable cause-specific Cox regression.

CONCLUSION

This study is a standardized analysis of DLI in a large cohort with centrifugal-flow LVADs.

Body mass index-dependent immunological profile changes after left ventricular assist device implantation

Purpose

Infection is a common complication following left ventricular assist device (LVAD) implantation. Patients with obesity are particularly at risk due to their high percentage of adipose tissue and the resulting chronic inflammatory state and resulting immunological changes. This study investigated changes of immunological parameters in relation to body mass index (BMI) during the first year after LVAD implantation.

Methods

Blood samples were obtained prior to LVAD implantation and at 3 (1st FU), 6 (2nd FU) and 12 mo (3rd FU) after LVAD implantation. Patients were divided into three groups (normal weight: BMI of 18.5-24.9 kg/m2; n=12; pre-obesity: 25.0-29.9 kg/m2; n=15; obesity: ≥ 30.0 kg/m2; n=17) based on their BMI at the time of LVAD implantation. Flow cytometric analyses for CD4+ and CD8+ T cells, regulatory T cells (Tregs), B cells as well as dendritic cells (DCs) were performed.

Results

After LVAD implantation, obese patients (0.51 ± 0.20%) showed a higher proportion of overall DCs than normal-weight (0.28 ± 0.10%) and pre-obese patients (0.32 ± 0.11%, p<0.01) at 3rd FU. The proportion of BDCA3+ myeloid DCs was lower in obese patients (64.3 ± 26.5%) compared to normal-weight patients (82.7 ± 10.0%, pnormal-weight vs. obesity=0.05) at 2nd FU after LVAD implantation. The analysis of BDCA4+ plasmacytoid DCs revealed a reduced proportion in pre-obese (21.1 ± 9.8%, pnormal-weight vs. pre-obesity=0.01) and obese patients (23.7 ± 10.6%, pnormal-weight vs. obesity=0.05) compared to normal-weight patients (33.1 ± 8.2%) in the 1st FU. T cell analysis showed that CD4+ T cells of obese patients (62.4 ± 9.0%) significantly increased in comparison to pre-obese patients (52.7 ± 10.0%, ppre-obesity vs. obesity=0.05) and CD8+ T cells were lower in obese patients (31.8 ± 8.5%) than in normal-weight patients (42.4 ± 14.2%; pnormal-weight vs. obesity=0.04) at the 3rd FU. Furthermore, we observed significantly reduced proportions of Tregs in pre-obese patients compared to normal-weight and obese patients at 2nd FU (p=0.02) and 3rd FU (p=0.01) after LVAD implantation.

Conclusion

This study reported changes of the innate and adaptive immune system of pre-obese and obese compared to normal-weight patients one year after LVAD implantation. DCs and their subsets, CD8+ T cells and Tregs were affected immune cell populations that indicate immunological changes which might increase the incidence of postoperative infection.

Cardiac Regenerative Therapy Using Human Pluripotent Stem Cells for Heart Failure: A State-of-the-Art Review

Heart transplantation (HT) is the only definitive treatment available for patients with end-stage heart failure who are refractory to medical and device therapies. However, HT as a therapeutic option, is limited by a significant shortage of donors. To overcome this shortage, regenerative medicine using human pluripotent stem cells (hPSCs), such as human embryonic stem cells and human-induced pluripotent stem cells (hiPSCs), has been considered an alternative to HT. Several issues, including the methods of large-scale culture and production of hPSCs and cardiomyocytes, the prevention of tumorigenesis secondary to contamination of undifferentiated stem cells and non-cardiomyocytes, and the establishment of an effective transplantation strategy in large-animal models, need to be addressed to fulfill this unmet need. Although post-transplantation arrhythmia and immune rejection remain problems, the ongoing rapid technological advances in hPSC research have been directed toward the clinical application of this technology. Cell therapy using hPSC-derived cardiomyocytes is expected to serve as an integral component of realistic medicine in the near future and is being potentially viewed as a treatment that would revolutionize the management of patients with severe heart failure.

Patient factors associated with left ventricular assist device infections: A scoping review

Infections are widely prevalent in left ventricular assist device (LVAD) recipients and associated with adverse events including mortality and rehospitalizations. Current evidence examining factors associated with infections in this setting predominantly comprises single-center observational data. We performed a scoping review to systematically summarize all existing studies examining patient-related factors associated with infections after LVAD implantation. Studies published between 01/06 and 02/19 were identified through searching 5 bibliographic databases: PubMed, Scopus, EMBASE, CINAHL, and Web of Science Core Collection. Inclusion criteria required examination of patient-related factors associated with infections among recipients of contemporary implantable, continuous flow LVADs. Key study characteristics were extracted by four independent reviewers and current literature described narratively. All analyses took place between February 2019 and May 2021. A total of 31 studies met inclusion criteria. All included studies were observational, and most commonly focused on driveline infections (n = 17). Factors studied most commonly included body composition (n = 8), diabetes and other comorbidities (n = 8), and psychosocial/socio-economic factors (n = 6). Studies were frequently single-center with heterogeneity in definition of infectious outcomes as well as exposure variables. Patient race and sex did not correlate with infection risk. There was no consistent association noted between obesity, diabetes, or psychosocial/socio-economic factors and infections in LVAD recipients. Two studies reported a significant association between malnutrition and hypoalbuminemia and post implant infections. This review summarizes 31 studies that described patient-related factors associated with infection after LVAD implantation. Patient related comorbidities, especially body composition and diabetes, were most commonly evaluated, but were not consistently associated with infections after LVAD implantation.

Consensus Report on Destination Therapy in Japan - From the DT Committee of the Council for Clinical Use of Ventricular Assist Device Related Academic Societies

Destination therapy (DT) is the indication to implant a left ventricular assist device (LVAD) in a patient with stage D heart failure who is not a candidate for heart transplantation. The implantable LVAD has been utilized in Japan since 2011 under the indication of bridge to transplant (BTT). After almost 10 year lag, DT has finally been approved and reimbursed in May 2021 in Japan. To initiate the DT program in Japan, revision of the LVAD indication from BTT is necessary. Also, in-depth discussion of caregiver issues as well as end-of-life care is indispensable. For that purpose, we assembled a DT committee of multidisciplinary members in August 2020, and started monthly discussions via web-based communication during the COVID-19 pandemic. This is a summary of the consensus reached after 6 months' discussion, and we have included as many relevant topics as possible. Clinical application of DT has just started, and we are willing to revise this consensus to meet the forthcoming issues raised during real-world clinical experience.

Ventricular Assist Device Driveline Infections: A Systematic Review

Infection is the most common complication in patients undergoing ventricular assist device (VAD) implantation. Driveline exit site (DLES) infection is the most frequent VAD infection and is a significant cause of adverse events in VAD patients, contributing to morbidity, even mortality, and repetitive hospital readmissions. There are many risk factors for driveline infection (DLI) including younger age, smaller constitution of patients, obesity, exposed velour at the DLES, longer duration of device support, lower cardiac index, higher heart failure score, DLES trauma, and comorbidities such as diabetes mellitus, chronic kidney disease, and depression. The incidence of DLI depends also on the device type. Numerous measures to prevent DLI currently exist. Some of them are proven, whereas the others remain controversial. Current recommendations on DLES care and DLI management are predominantly based on expert consensus and clinical experience of the certain centers. However, careful and uniform DLES care including obligatory driveline immobilization, previously prepared sterile dressing change kits, and continuous patient education are probably crucial for prevention of DLI. Diagnosis and treatment of DLI are often challenging because of certain immunological alterations in VAD patients and microbial biofilm formation on the driveline surface areas. Although there are many conservative and surgical methods described in the DLI treatment, the only possible permanent solution for DLI resolution in VAD patients is heart transplantation. This systematic review brings a comprehensive synthesis of recent data on the prevention, diagnostic workup, and conservative and surgical management of DLI in VAD patients.

The Predictive Value of Changes in Body Mass Index for the Incidence of Device-Specific Infections in Patients With Implantable Left Ventricular Assist Devices

BACKGROUND

Implantable left ventricular assist devices (LVAD) have improved quality of life and survival in patients with advanced heart failure. However, LVAD-specific infections and predicting which patients will develop infections remain challenging. This study investigated whether changes in body mass index (BMI) during hospitalization following LVAD implantation are associated with LVAD-specific infections within 1 year of implantation.Methods and Results:Patients (n=135) undergoing LVAD implantation were retrospectively divided into 2 groups based on changes in BMI from LVAD implantation to discharge: those with and without decreases in BMI. Each group was further subdivided according to baseline albumin concentrations (high [>3.7 g/dL] and low [≤3.7 g/dL]). Twenty patients developed LVAD-specific infections within 1 year. Receiver operating characteristic curve analysis resulted in a ∆BMI cut-off of less than -0.128 kg/m². In multivariate analysis, younger patients and those with decreases in BMI had significantly higher rates of LVAD-specific infection (P=0.010 and P=0.035, respectively). LVAD-specific infection rates were significantly higher for patients with low albumin and decreases in BMI than for patients with low albumin but no decrease in BMI.

CONCLUSIONS

Decreases in BMI during hospitalization after LVAD implantation and younger age were independently associated with LVAD-specific infection within 1 year. Strict patient management may be needed to avoid decreases in BMI during hospitalization after LVAD implantation, particularly in patients with low baseline albumin concentrations.

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.

Obesity, transplantation, and bariatric surgery: An evolving solution for a growing epidemic

The increasing obesity epidemic has major implications in the realm of transplantation. Patients with obesity face barriers in access to transplant and unique challenges in perioperative and postoperative outcomes. Because of comorbidities associated with obesity, along with the underlying end-stage organ disease leading to transplant candidacy, these patients may not even be referred for transplant evaluation, much less be waitlisted or actually undergo transplant. However, the use of bariatric surgery in this population can help optimize the transplant candidacy of patients with obesity and end-stage organ disease and improve perioperative and postoperative outcomes. We review the impact of obesity on kidney, liver, and cardiothoracic transplant candidates and recipients and explore potential interventions to address obesity in these populations.