ECMO and Valve surgeries
Outcomes for patients requiring EMCO for PCCS refractory to maximal-inotropic support and IABP support in patients who have undergone valve surgery have been analysed across few studies6, 22, 23. Rastan et al 6 carried out a study with a cohort of 517 patients who required ECMO for PCCS, of which 14.3% had undergone isolated valve surgery whilst 16.8% had undergone valve surgery in combination with CABG. This study found that post-operative ECMO requirement following mitral valve surgery was associated with a reduced survival rate when compared to other cardiac procedures (OR 2.08; 95% CI 1.20-3.63;P= 0.010). Similarly, Onorati et al 22found that in patients undergoing aortic valve replacement for aortic stenosis, post-operative ECMO was a predictor for early death as it was associated with a greater 30-day mortality rate (OR 9.8; 95% CI 1.1-63.4; P =0.029) when compared to that of other cardiac procedures. However, this study has not yet reached its 5-year endpoint, meaning the reported findings are only preliminary.
More recently, the institution of ECMO with a TandemHeart (TH) percutaneous Left VAD i.e. a TH-ECMO, was found to provide stabilisation of patient haemodynamics and hypoxaemia in two patients with acute severe mitral regurgitation (MR) associated with cardiogenic failure and hypoxaemia23. Acute severe MR associated with cardiogenic shock and hypoxaemia can only be definitively managed with mitral valve surgery, but usually this surgery is associated with high peri-operative mortality rates of 25-46%, a poor outcome due to patients being haemodynamically unstable and having refractory hypoxaemia. In this case series, the institution of TH-ECMO resulted in prompt stabilisation of the patients’ haemodynamics and hypoxaemia which in turn allowed them to have early surgical intervention to manage their acute severe MR. This case series shows the potential survival benefit of ECMO for acute severe MR associated with cardiogenic shock and hypoxaemia. However, it is important to note that the study only reported on two cases making the sample size far too small for results to be statistically significant and the patients would need to be followed up for a lengthier period of time to ascertain the longer-term outcomes associated with ECMO use. Outcomes in patients who had ECMO having undergone valve surgery are summarised in Table 4.
Whilst post-operative requirement following valve surgery may be associated with worse prognosis when compared to people who did not require ECMO post-valve surgery, it again does improve survival for refractory PCCS when compared to without the use of MCS. It is unclear when the best time to institute ECMO in patients undergoing valve-surgery would be but based on the studies analysed, ECMO institution was associated with increased mortality when inserted post-operatively6, 22. By contrast in the case series which showed improved outcomes for patients undergoing mitral valve surgery, ECMO was inserted pre-operatively allowing for haemodynamic stabilisation of patients before they underwent surgery which would suggest that ECMO may be most useful when inserted pre-operatively alongside inotropes in these patients23. However, more work on the potential survival benefit of ECMO use pre-operatively in patients undergoing valvular surgery is needed as only one paper has shown improved outcomes.