New prioritization of heart transplant candidates on mechanical circulatory support in an era of severe donor shortage

Pre-operative risk factors for driveline infection in left ventricular-assist device patients

AIMS

Implantation of left ventricular-assist devices (LVAD) to treat end-stage heart failure is of increasing relevance due to donor shortage. Infections of the driveline are common adverse events. LVAD infections can lead to high urgency listings for transplantation. However, transplantation in patients with infection leads to worse post-transplantation outcomes. This study aims to evaluate specific risk factors for driveline infections at the time of implantation.

METHODS AND RESULTS

Four hundred forty-one patients receiving either Heartmate II or Heartware system from August 2009 to October 2013 were assessed. An expert committee sorted patients into four different groups concerning the likeliness of infection. Twenty-eight (6%) of discussed infection cases were judged as secured, 33 (7%) as likely, 18 (4%) as possible, and 20 (4%) as unlikely. The remaining 342 (78%) subjects showed either no signs of infection at all times (329 [75%]) or developed signs of infection in a second observation period within 1 year after ending of the first observation period (13 [3%]). For a better discriminatory power, cases of secured and likely infections were tested against the group with no infection at all times in a Cox proportional hazard model. Among all variables tested by univariate analysis (significance level P < 0.15), only age (P = 0.07), LVAD-type (P = 0.12), need for another thoracic operation (P = 0.02), and serum creatinine value (P = 0.02) reached statistical significance. These were subsequently subjected to multivariate analysis to calculate the cumulative risk of developing a drive infection. The multivariate analysis showed that of all the potential risk factors tested, only the necessity of re-thoracotomy or secondary thoracic closure had a significant, protective effect (hazard ratio [95% CI] = 0.45 [0.21-0.95]; P = 0.04).

CONCLUSION

This single-centre cohort study shows that driveline infections are common adverse events. The duration of support represents the major risk factor for LVAD driveline infections.

Renal replacement therapy in congestive heart failure requiring left ventricular assist device augmentation

"Cardiorenal syndrome" is a term used to describe a dys-regulation of the heart affecting the kidneys, or vice versa, in an acute or chronic manner (1,2). Renal impairment can range from reversible ischemic damage to renal failure requiring short- or long-term renal replacement therapy (2). Patients who require mechanical circulatory support, such as a left ventricular assist device (LVAD), as definitive treatment for congestive heart failure or as a bridge to cardiac transplantation pose a unique challenge with respect to receiving dialysis, because they experience higher rates of morbidity and mortality from infection in the post-LVAD period (3-7). Acute dialysis access can pose an increased infection risk. In this article, we present a patient who required renal replacement therapy and a LVAD for management of acute-on-chronic cardiorenal syndrome while awaiting heart transplantation. A literature review to determine whether peritoneal dialysis or hemodialysis is superior for patients with profound hemodynamic dysfunction and the need to minimize risk of infection did not offer clear guidance about which modality is superior in patients with advanced congestive heart failure. However, there is clear evidence of the superiority of peritoneal dialysis in reducing the risk of systemic infection secondary to acute dialysis access. Given the high risk of LVAD infection, we therefore conclude that, to decrease mortality secondary to systemic infection, peritoneal dialysis should strongly be considered in patients who require renal replacement therapy before or after LVAD placement.

Lung and heart allocation in the United States

Lung and heart allocation in the United States has evolved over the past 20-30 years to better serve transplant candidates and improve organ utilization. The current lung allocation policy, based on the Lung Allocation Score, attempts to take into account risk of death on the waiting list and chance of survival posttransplant. This policy is flexible and can be adjusted to improve the predictive ability of the score. Similarly, in response to the changing clinical phenotype of heart transplant candidates, heart allocation policies have evolved to a multitiered algorithm that attempts to prioritize organs to the most infirm, a designation that fluctuates with trends in therapy. The Organ Procurement and Transplantation Network and its committees have been responsive, as demonstrated by recent modifications to pediatric heart allocation and mechanical circulatory support policies and by ongoing efforts to ensure that heart allocation policies are equitable and current. Here we examine the development of US lung and heart allocation policy, evaluate the application of the current policy on clinical practice and explore future directions for lung and heart allocation.

Current status of mechanical circulatory support: a systematic review

Heart failure is a major public health problem and its management requires a significant amount of health care resources. Even with administration of the best available medical treatment, the mortality associated with the disease remains high. As therapeutical strategies for heart failure have been refined, the number of patients suffering from the disease has expanded dramatically. Although heart transplantation still represents the gold standard therapeutical approach, the implantation of mechanical circulatory support devices (MCSDs) evolved to a well-established management for this disease. The limited applicability of heart transplantation caused by a shortage of donor organs and the concurrent expand of the patient population with end-stage heart failure led to a considerable utilization of MCSDs. This paper outlines the current status of mechanical circulatory support.

Mechanical circulatory assistance

Although heart transplantation is the gold standard for the treatment of advanced stage heart failure, the implantation of mechanical circulatory support devices (MCSDs) has become a well-established therapy for this disease. As the population of patients with severe heart failure has grown, the utilization of MCSDs has increased considerably. That trend is expected to continue, especially in light of dramatic advances in MCSD technology. This review outlines the current status and future directions of mechanical circulatory support therapy in the setting of a constantly evolving field of supportive devices and adjuvant therapies.