Centrifugal continuous-flow left ventricular assist device in patients with hypertrophic cardiomyopathy: a case series.

The study by Muthiah et al.1 is an important contribution to the progress of left ventricular assist device (LVAD) therapy as a surgical option in patients with hypertrophic cardiomyopathy (HCM). Continuous-flow LVAD therapy is now an established surgical option for patients with end-stage congestive heart failure. The Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) registry reports data on more than 4,000 pumps implanted in the USA alone.2 The year 2009–2010 alone demonstrated an increase of 70% in LVAD use. Left ventricular assist device therapy in patients with dilated and ischemic cardiomyopathy has demonstrated a significant improvement in survival compared to medical therapy.3 Patients on LVAD with the newer generation continuous-flow devices benefit from an increased functional capacity and improved quality of life after surgery.4 Patients with HCM and congestive heart failure are a subset of a broad entity called congestive heart failure with preserved ejection fraction (HFEF). Cardiac amyloidosis, restrictive cardiomyopathy, and radiation-induced heart disease are other etiologies of this condition. Colleagues at our institute retrospectively analyzed admissions for congestive heart failure over a 15 year period, which demonstrated a significant increase in the prevalence of HFEF; more importantly, prognosis for this condition remained unchanged over the entire study period.5 It is now very clear that survival in this cohort is very poor even with optimal medical therapy.5,6 These patients suffer from diastolic dysfunction and often have a bi-ventricular pathology. They have a predominant diastolic dysfunction with a much smaller ventricular cavity, as demonstrated by Muthiah et al.1 Additionally, we have found these patients to have higher serum bilirubin levels (1.6 [0.62, 2.4] vs. 1.0 [0.7, 1.52]), which may be an indirect indicator of poorer right ventricular function.7 As demonstrated by our colleagues in Australia, LVAD implant in these patients is possible. At our institute, we incorporate minor modifications to the routine surgical technique.7,8 Our colleagues have demonstrated no difference in mortality and other adverse events during the LVAD support period. While early mortality in both series may be comparable, we have found that these patients may need a longer inotropic therapy.1,7 A significant reduction in the right atrial (from 18 + 7.8 to 11.3 + 5.1 mm Hg) and mean pulmonary artery pressures (43.3 + 4.9 to 22.2 + 2.8 mm Hg) was present at the end of 3 months. Along with a decrease in the ventricular dimensions, this demonstrates definitive clinical improvement in these HCM patients. We have demonstrated a similar trend in both clinical and laboratory parameters at our institution.7 Patients with HCM and end-stage heart failure may fail medical management and need mechanical support while waiting for a transplant. Muthiah et al. successfully implemented extracorporeal membrane oxygenation and then transitioned to an LVAD in one patient. Organ availability is a major issue with cardiac transplantation, and wait-times are uncertain. However, some heart failure specialists are still hesitant to recommend LVAD implant as a temporary option for transplant-eligible patients with end-stage heart failure. The main concerns regarding LVAD bridging are allo-sensitization and a difficult surgical procedure at the time of cardiac transplantation. Recent studies demonstrate comparable outcome in patients undergoing transplant, either direct or bridged with an LVAD.9,10 We have demonstrated that the 1 year of survival of these patients on inotropic therapy is 12.1% [95% confidence interval, 0–55.2]. In contrast, patients with LVAD implant demonstrated a survival of 87.5% [95% confidence interval, 52.9– 97.8] at the end of 1 year.7 At present, therapeutic options for these patients are very limited, and Muthiah et al.1 are to be applauded for attempting to implement LVAD therapy in this complex subset of patients. While both the surgery and postoperative care of these patients are challenging, they have demonstrated that it can be done, with results comparable to that in patients with dilated and ischemic cardiomyopathy. We hope that this study will encourage other colleagues to implement LVAD therapy for patients with HCM. This option is like a beacon of hope and while this journey may present unforeseen obstacles, we are confident that this therapy will ultimately help the lives of millions of patients with restrictive and HCM. Invited Commentary