**1. Introduction**

Heart failure (HF) is among the commonest chronic diseases, with a prevalence of 6.2 million adults in the United States (U.S.) and 64.3 million worldwide [1, 2]. Patients with the most advanced form of HF are classified as stage D and have high mortality. Population studies estimate the prevalence of stage D HF to be between 0.2–3.0% [3], with up to 4.5% of patients with chronic (stage C) HF progressing to stage D per year [4]. In the U.S., this is ~150,000–250,000 with stage D disease [3, 5]. Orthotopic heart transplantation (OHT) remains the gold standard therapy for this population. However, there remains a tremendous shortfall of available organs; despite recent increases, only 3817 OHT surgeries were performed in the U.S. in 2021 (~1.5–2.5% of the estimated stage D population) [6].

Left ventricular assist device (LVAD) surgery has revolutionized the treatment of end-stage HF, providing increased longevity and a superior quality of life (QOL) for patients with stage D disease. LVAD technology has progressed dramatically over the last 3 decades, with each successive generation of pump providing robust improvements in outcomes [7]. However, LVAD-associated morbidity remains substantial (**Figure 1**) [8, 9]. Among the commonest complications is recurrent HF. This is almost uniformly associated with increased mortality and worse QOL.

#### **Figure 1.**

*Contemporary adverse event rates after LVAD. Events per patient-year (EEPY) occurring >90 days after implant in the STS-INTERMACS registry [8], or from the MOMENTUM 3 continued access protocol (CAP) trial [9]. \*No event rate data exist for right HF from STS-INTERMACS.*

Recurrent HF after LVAD has many causes and critically, management depends on the underlying etiology. Recurrent HF is either related to problems extrinsic to the LVAD or to a problem with the device itself (**Figure 2**) [10]. By far the commonest cause is failure of the right ventricle (RV). This chapter will review the causes of recurrent HF and provide strategies to diagnose and manage these distinct problems.
