Determination of candidacy for mechanical circulatory support: importance of clinical indices

Heart transplantation is currently the most effective therapy for the treatment of advanced heart failure (CHF).1 However, its application is limited due to the lack of sufficient donor organs as well as the substantial incidence of post-transplant complications, such as rejection, infection, and cardiac allograft vasculopathy. Therefore, only a small minority of patients who suffer from advanced CHF are successfully treated with heart transplantation. Notwithstanding the strict criteria used in selection of heart transplant candidates, the number of patients listed for heart transplantation continues to increase because of the increasing incidence of chronic CHF2 resulting in ever increasing pre-transplant waiting time. Consequently, many ambulatory patients awaiting transplant experience progression of their disease, eventually become refractory to oral heart failure therapy.3 To address this issue, innovative surgical alternatives, such as left ventricular assist device (LVAD) implantation, have been explored, in an attempt to support patients who do not respond to traditional therapies until transplantation.4 Until recently, LVADs have generally been implanted in urgent or emergent situations, such as cardiogenic shock with related end-organ dysfunction or overt failure. Not surprisingly, the stress of surgery, when superimposed on the fragile underlying substrate, frequently contributes to poor outcomes, both in the short term as well as following transplantation in a candidate with ongoing medical complications. Recently there has been an increased tendency to insert mechanical circulatory support devices before the onset of frank end-organ dysfunction as an alternative to aggressive medical support, for example, maintenance inotropic therapy. Preliminary success with this approach has prompted some centers to consider “early” LVAD placement as a viable alternative to inotropic therapy as a bridge to heart transplant, particularly in patients thought to be at particularly high risk for progressive deterioration, or even as a potential alternative to transplantation itself. Although associated with shortterm risk and expense, LVADs can restore hemodynamic normalcy in patients with severe cardiac dysfunction and can maintain stability for months, thus preserving social autonomy, preventing costly hospitalizations, and allowing functional recovery of end-organ systems. Good post-transplant outcomes following prolonged LVAD support have been described.2,7 The advantages afforded by this pre-emptive approach must be weighed against the risks of the implantation surgery and devicerelated complications (hepatic and renal failure, thromboembolism, infections, bleeding, hemolysis, and mechanical device failure) as well as increased technical challenges at the time of the subsequent transplantation.2,6,7 This article will examine some of the current issues surrounding the role and implementation of LVAD support in managing patients with end-stage heart failure.