Single Versus Multidrug Regimen for Surgical Infection Prophylaxis in Left Ventricular Assist Device Implantation

Left Ventricular Assist Device: Review of Antimicrobial Prophylaxis Strategies and Incidence of Infections at a Tertiary Care Center 12-Year Experience

Background

Left ventricular assist devices (LVAD) have an associated infection rate of 13%-80% postimplant. An optimal strategy for surgical infection prophylaxis (SIP) at the time of implantation has not been well defined. We aimed to evaluate the different LVAD implantation antibiotic prophylaxis regimens as well as the incidence of LVAD infection at our institution.

Methods

We performed a single-center, retrospective study of patients who underwent LVAD implantation between February 2007 and June 2019. The primary outcome was the incidence of LVAD infection (LVADI), within 3 months and 1 year of placement, between patients who received expanded or narrow-spectrum regimens for SIP. We assessed outcomes using Kaplan-Meier, time-to-first event. We used a noninferiority analysis, which was established if the narrow-spectrum event rate was no more than 5% greater than the expanded-spectrum event rate.

Results

We included 399 patients, 305 (76.4%) patients received narrow-spectrum SIP, whereas the remaining 94 (23.6%) patients received the expanded-spectrum regimen. Statistical noninferiority of the narrow spectrum to the multiple drug regimen was demonstrated at both time points, and statistical superiority of the narrow-spectrum group across 12-month follow up was further evident (P = .037).

Conclusions

We report evidence supporting noninferiority, or even superiority, of the narrow-spectrum over expanded-spectrum antimicrobial prophylaxis strategy with respect to LVADI. These findings support data-driven antimicrobial prophylaxis strategies.

Infections in Patients With Left Ventricular Assist Devices: Current State and Future Perspectives

Mechanical circulatory support is increasingly being used as bridge-to-transplant and destination therapy in patients with advanced heart failure. Technologic improvements have led to increased patient survival and quality of life, but infection remains one of the leading adverse events following ventricular assist device (VAD) implantation. Infections can be classified as VAD-specific, VAD-related, and non-VAD infections. Risk of VAD-specific infections, such as driveline, pump pocket, and pump infections, remains for the duration of implantation. While adverse events are typically most common early (within 90 days of implantation), device-specific infection (primarily driveline) is a notable exception. No diminishment over time is seen, with event rates of 0.16 events per patient-year in both the early and late periods postimplantation. Management of VAD-specific infections requires aggressive treatment and chronic suppressive antimicrobial therapy is indicated when there is concern for seeding of the device. While surgical intervention/hardware removal is often necessary in prosthesis-related infections, this is not so easily accomplished with VADs. This review outlines the current state of infections in patients supported with VAD therapy and discusses future directions, including possibilities with fully implantable devices and novel approaches to treatment.

Non-patient factors associated with infections in LVAD recipients: A scoping review

BACKGROUND

Infections are the most common complication in recipients of durable left ventricular assist devices (LVAD) and are associated with increased morbidity, mortality, and expenditures. The existing literature examining factors associated with infection in LVAD recipients is limited and principally comprises single-center studies. This scoping review synthesizes all available evidence related to identifying modifiable, non-patient factors associated with infections among LVAD recipients.

METHODS

Published studies were identified through searching 5 bibliographic databases: PubMed, Scopus, EMBASE, CINAHL, and Web of Science Core Collection. Inclusion criteria required examination of factors associated with infections among recipients of contemporary, implantable, continuous flow LVADs. Key study characteristics were extracted by 4 independent reviewers and current literature described narratively. The Systems Engineering Initiative for Patient Safety (SEIPS) model was used to develop a taxonomy for non-patient related factors (e.g., tasks, tools, technologies, organization, and environment) associated with infections following LVAD implantation. All analyses took place between February 2019 and May 2021.

FINDINGS

A total of 43 studies met inclusion criteria. The majority of included studies were observational (n = 37), single-center (n = 29), from the U.S. (n = 38), and focused on driveline infections (n = 40). Among the 22 evaluated sub-domains of non-patient related factors, only two: increasing center experience and establishing a silicone-skin interface at the driveline exit site, were identified as consistently being associated with a lower risk of infection.

CONCLUSION

This review identified 43 studies that described non-patient related factors associated with infection in LVAD recipients. Only two factors were consistently associated with lower infection risk in LVAD recipients: increasing experience and establishing a silicone-skin interface at driveline exit site. The large variability in reporting across multiple studied interventions limited the ability to discern their effectiveness.

Impact of antimicrobial selection for prophylaxis of left ventricular assist device surgical infections

BACKGROUND

Surgical site infections (SSIs) after left ventricular assist device (LVAD) implantation are associated with high mortality, while surgical prophylaxis is variable.

METHODS

This retrospective study included adult patients who underwent LVAD implantation at a single center. We compared outcomes in patients who received narrow antimicrobial prophylaxis (cefazolin, vancomycin, or both) to those who received broad antimicrobial prophylaxis (any antimicrobial combination targeting gram-positive and gram-negative organisms not included in the narrow group) at 30-day and 1-year postimplantation. Cox-proportional hazards models and log-rank tests were used for survival analysis.

RESULTS

Among the 39 and 65 patients comprising narrow and broad groups respectively, there was no difference in rate of SSI at 30 days (6.2% vs. 12.8%, p = .290) and 1 year (16.9% vs. 25.6%, p = .435). Comparing narrow to broad prophylaxis, the risk of mortality (hazard ratio [HR] = 0.44, 95% confidence interval [CI] = 0.15-1.35, logrank p = .14), and composite of mortality and infection was reduced (HR = 0.92, 95% CI = 0.45-1.88, logrank p = .83), but did not reach statistical significance. Most culture positive infections were due to gram-positive bacteria (70%) and the most common organisms were the Staphylococcus spp (47%). There were no significant differences in the rate of SSI at 1-year (p = 1.00) and mortality (p = .33) by device type.

CONCLUSIONS

The rates of infection and all-cause mortality were not different between patients who received narrow or broad prophylaxis. This highlights an opportunity for institutions to narrow their surgical infection prophylaxis protocols to primarily cover gram-positive organisms.

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.

Surgical infection prophylaxis prior to left ventricular assist device implantation: A survey of clinical practice

BACKGROUND

Short duration, antimicrobial prophylaxis that includes antistaphylococcal activity is recommended at the time of left ventricular assist device (LVAD) implantation to reduce infection-related complications. There continues to be wide variability in surgical infection prophylaxis (SIP) regimens among implantation centers. The aim of this study is to characterize current SIP regimens at different LVAD centers.

METHODS

A survey study was conducted from 26 September 2017 to 25 October 2017. Surveys were distributed electronically to LVAD coordinators and infectious diseases specialists at 75 US medical centers identified as having an LVAD program. Data collection included information about antimicrobial selection, duration, Staphylococcus aureus screening, and decolonization procedures.

RESULTS

We received 29 survey responses. The majority of surveys were completed by infectious diseases physicians (72.4% [21 out of 29]). Most responding centers reported LVAD programs established for greater than 10 years (20 out of 29 [69%]). Cardiac transplantation was performed in 28 out of 29 (96%) centers. Of centers reporting a defined SIP regimen for non-penicillin allergic patients (96% [28 out of 29]), 17.9% (5 out of 28) reported a four-drug regimen, 35.7% (10 out of 28) reported a three-drug regimen, and 46.4% (13 out of 28) reported a two-drug regimen, while no centers reported a single-drug regimen. Empiric fluconazole was common (50% [14 out of 28]) and 96.4% (27 out of 28) of regimens included vancomycin. Duration of antimicrobial prophylaxis (24 hours to 5 days), S. aureus screening, decolonization procedures, and alterations due to drug allergies varied across participating centers.

CONCLUSIONS

Our survey results indicate wide variation in SIP regimens among participating LVAD centers. These results highlight the need for studies evaluating the implications of SIP regimens, and whether clinical factors that prolong antimicrobial duration impact postoperative infection rates.

In Full Flow: Left Ventricular Assist Device Infections in the Modern Era

With the rising prevalence of heart disease in the United States, there is increasing reliance on durable mechanical circulatory support (MCS) to treat patients with end-stage heart failure. Left ventricular assist devices (LVADs), the most common form of durable MCS, are implanted mechanical pumps that connect to an external power source through a transcutaneous driveline. First-generation LVADs were bulky, pulsatile pumps that were frequently complicated by infection. Second-generation LVADs have an improved design, though infection remains a common and serious complication due to the inherent nature of implanted MCS. Infections can affect any component of the LVAD, with driveline infections being the most common. LVAD infections carry significant morbidity and mortality for LVAD patients. Therefore, it is paramount for the multidisciplinary team of clinicians caring for these patients to be familiar with this complication. We review the epidemiology, prevention, diagnosis, treatment, and outcomes of LVAD infections.

Ventricular assist device-related infections and solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

The Infectious Diseases Community of Practice of the American Society of Transplantation has published evidenced-based guidelines on the prevention and management of infectious complications in SOT recipients since 2004. This updated guideline reviews the epidemiology of ventricular assist device (VAD) infections and provides recommendations for the management and prevention of these infections. Almost one half of those awaiting heart transplantation are supported with VADs. Despite advances in device technologies, VAD infections commonly complicate mechanical circulatory support and remain typified by common components and anatomic locations. These infections have important implications for transplant candidates, most notably increased wait-list mortality. Strategic management of these infections is crucial for successful transplantation. Coincidentally, explantation of all VAD components at the time of transplantation is often the definitive cure for the device-associated infection. Highlighted in this updated guideline is the reported success of transplantation in patients with a variety of pre-existing VAD infections and guidance on post-transplant management strategies.