**2. Epidemiology of ventricular arrhythmia and cardiac sudden death**

The highest rates of VD occur in the first 30 days after LVAD placement; however, late ventricular dysrhythmias have also been described. VD incidence ranges from 22% to 59% after LVAD implant [10–12] and 35% of post-LVAD recipients within 30 days [13, 14].

Several factors can predict VD events after LVAD implantation, i.e., previous ventricular dysrhythmias before LVAD implant (hazard ratio 3.28) [15], previous history of atrial fibrillation [14–16], the type of LVAD implanted, or the presence concomitant chronic ischemic heart disease [17]. In total, 42.4% of patients with a history of VD pre-LVAD experienced VD events post-LVAD in comparison with 16.7% without previous VD [12]. Ischemic heart disease was the major cause of cardiomyopathy in 71% of patients in the VD group and 45% of patients in the group without VD where dilated cardiomyopathy was more frequent (no difference was made between inheriting cardiomyopathy, enolic, cardiotoxicity, or idiopathic cause). Chronic ischemic heart disease could trigger VD due to persistent subendocardial ischemia, arrhythmogenic substrate associated with myocyte remodeling, and fibrosis [17].

VD often leads to sudden cardiac death in the non-LVAD population. However, long-term survival has been reported in those patients with LVADs despite VD [11]. Interestingly, neither the presence of VD nor ICD therapies (appropriate in 19.1% or inappropriate in 3.1%) were associated with higher mortality rates after 10 months of follow-up [15].

Controversially, other studies have described higher mortality in patients with VD events. Bedi et al. showed an absolute 15% or higher risk of death in the first week after LVAD implantation [17]. Brenyo et al. describe an increase in mortality of up to 10 times higher in patients with LVADs if there is concomitant VD, although 1 year of mean follow-up makes it difficult to correlate VD as a cause of death or as a progression marker of disease [18].
