Medical and device therapy has provided great benefit for many millions of patients with heart failure: 15% of patients with stable heart failure with reduced ejection fraction (HeFREF) recover their left ventricular function within three years, the same proportion as those who deteriorate or die suddenly and surgical intervention is sometimes necessary.
Surgical treatment for heart failure includes:
- mechanical circulatory support
- – left ventricular assist devices (LVAD)
- cardiac transplantation
- coronary revascularisation
- surgical ventricular restoration.
Left ventricular assist devices (LVAD)
Mechanical circulatory support (MCS) was developed as a rescue therapy for patients in intractable cardiogenic shock. The first devices were conceived as a continuum for patients who were unable to wean from cardiopulmonary bypass (CPB) and have progressed to separate, implantable left ventricular assist devices (LVADs) (figure 1).
Until recently, LVADs were only indicated as a holding measure until an organ became available or until a decision was made regarding cardiac transplantation; so-called ‘bridge to transplantation’ (BTT) or ‘bridge to decision’ (BTD). However, in 2015 the National Institute for Health and Clinical Excellence (NICE) published guidelines also recommending LVADs as long-term therapy for patients ineligible for transplantation; so-called ‘destination therapy’ (DT).1 LVADs are used as DT more commonly than other indications worldwide (figure 2).2 In a minority of patients, the haemodynamic relief provided by the LVAD can facilitate recovery of myocardial function and explant of the device, though the majority will require continued support.
The standard LVAD circuit pumps blood from the left ventricular (LV) cavity through the device into the ascending aorta, creating a mechanical bypass of the LV outflow. The left ventricle is thus off-loaded (and the aortic valve may remain closed). Cardiac output is thus increased.
Beneficial effects of LVAD include:
- increased systemic blood pressure
- improved organ perfusion and subsequent beneficial neuro-hormonal changes
- reduced cardiac chamber size
- reduced left atrial and pulmonary pressures.
Despite developments in design, the morbidity associated with LVAD therapy continues to obstruct further progress in the field: 70% of patients with either continuous or pulsatile LVAD suffer a first episode of infection, bleeding, device malfunction, stroke or death within one year4 (figure 4).
The most frequent problems encountered during LVAD therapy are:
High adverse event rates are inevitable in severely unwell and unstable patients such as those suitable for LVAD therapy. Trials of LVADs in patients with less severe disease have had mixed results. REVIVE-IT (Randomised Evaluation of VAD Interventillation before Inotropic therapy), a randomised controlled trial of LVADs in patients who were less ill than patients currently eligible for destination therapy (New York Heart Association [NYHA] class II-IV with ‘advanced heart failure’ defined by markers such as hyponatraemia or high natriuretic peptide), was discontinued because of the high adverse event rate.5
The ROADMAP (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients) study (n=200, average age 64 years and median brain natriuretic peptide [BNP] 547 pg/mL in the LVAD arm), is a non-randomised trial of second-generation LVADs versus optimal medical therapy (OMT). The primary end point was survival on original therapy with >75 m improvement in six-minute walk distance at one year. More patients in the LVAD group met the primary endpoint, with the difference increasing at two years’ follow up (30% vs. 12%; P=0.012).6,7 In an as-treated analysis, LVAD implantation was associated with a better one year survival (80% vs. 63%, p=0.02), but because 30% of patients in the OMT group had LVAD implantation over two years, there was no significant difference in intention-to-treat analysis.6
The future of LVADs lies not only in developing technology to reduce the morbidity and cost of long-term therapy, but also in the appropriate deployment of these devices, avoiding their use very late in the natural history of heart failure when there is serious co-morbidity. Thus the timing of LVAD insertion remains critical. Only with this will the balance of risk be shifted in their favour and the health economic argument won.