Prof. Bernard Iung,
The session dedicated to ischaemic mitral regurgitation (MR) was a joint session between the ESC Working Groups on Cardiovascular Surgery and the WG on Valvular Heart Disease.
Luc Piérard (Liège, Belgium) detailed the echocardiographic assessment of ischaemic MR. The first application of echocardiography is to confirm the diagnosis of functional MR and to distinguish it from organic MR. The quantification of MR severity should integrate all echo parameters and use specific thresholds: ischaemic MR is considered as severe if the effective regurgitant area is 0.20 cm² or the regurgitant volume ≥ 30 ml. Exercise echocardiography is useful to assess the dynamic component of MR. An increase in MR severity and/or systolic pulmonary artery pressure during exercise is of prognostic value. It also has a diagnostic value in intermittent ischemic MR, which may be overlooked when using only rest echocardiography. The evaluation of left ventricular systolic volumes and function is paramount since left ventricular remodeling is the cause of ischaemic MR. Stress echocardiography is useful to search for myocardial viability and ischaemia. Left ventricular dyssynchrony also contributes to ischaemic MR and may be decreased after cardiac resynchronization therapy. Finally, when there is an indication for surgery, echocardiography may contribute to the choice of the technique. The presence of predictive factors of failure of mitral valve repair, which are related to the severity of tenting and valve tethering.
Miguel Sousa Uva (Lisbon, Portugal) reviewed the causes of failure of mitral valve repair in ischaemic MR. Recurrence rates of at least moderate MR have been reported in almost 30% 6 months to 3 years after mitral valve repair for ischemic MR. The analysis of the causes of failure are difficult given the heterogeneity of patients, in particular regarding tethering patterns on the valve and the degrees of left ventricular remodeling, dysfunction and viability. The reference technique of valve repair in ischaemic MR is undersized annuloplasty. There are different techniques according to the type of ring, the degree of undersizing and the combination with other procedures such as edge-to-edge repair or procedures on the left ventricle. Recurrence of MR is explained in particular by continuous left ventricular remodeling. Failure of repair concerns recurrence rates of MR but also the failure of left ventricular reverse remodeling, which has been reported to depend on the degree of left ventricular dilatation. Meta-analyses suggest that valve repair is associated with a better outcome than valve replacement, but the difference is less marked than for organic regurgitation. Mitral valve repair using an undersized semi-rigid ring remains the preferred treatment in ischaemic MR. However, mitral valve replacement can be considered in patients who have echocardiographic predictors of failure of valve repair or severe left ventricular enlargement (end-diastolic diameter > 65 mm and/or end-systolic diameter > 55 mm). Mitral subvalvular apparatus should be preserved. The usefulness of other procedures of left ventricular reduction, such as papillary muscle sling, or chordal cutting needs to be documented by more data.
Alain Berrebi (Paris, France) was asked to answer the question: when is it too late for surgery? According to the new ESC/EACTS guidelines, indications for the surgical correction of ischaemic MR are mainly considered in patients in whom there is an indication for myocardial revascularization. Indications are more restrictive, only class IIb, in patients with no indication for revascularization, provided left ventricular ejection fraction is > 30%. In patients without indication for revascularization and/or severe left ventricular dysfunction, the evaluation of the individual risk profile according to comorbidity is important in decision-making. Surgery should be considered only after optimization of medical therapy for left ventricular systolic dysfunction, including cardiac resynchronization therapy if indicated according to guidelines. In high-risk patients for surgery, the alternative of percutaneous techniques is the subject of growing interest. This concerns mainly the edge-to-edge repair using the Mitraclip, which has been shown to be feasible at low risk in patients with severe ischaemic MR. However, patients with ischaemic MR represented a small subgroup in the only randomized trial to date (the Everest trial) and potential clinical benefit should be evaluated by specific randomized trial in ischaemic MR. Finally, heart transplantation is an alternative in patients with severe left ventricular dysfunction that is unlikely to improve after surgery.
Manuel Antunes (Coimbra, Portugal) reviewed the indications for the correction of ischaemic MR in patients with moderate MR. The degree of MR may decrease after myocardial isolated revascularization, but it is now recognized that this is not always the case. On the other hand, the severity of ischaemic MR can increase during follow-up, with ongoing left ventricular remodeling. The presence of residual MR after coronary revascularization has a negative prognostic impact on late clinical outcome. The degree of ischaemic MR cannot be reliably assessed during surgical intervention because of the particular loading conditions under cardiopulmonary bypass. Therefore, the decision to combine surgical correction of ischaemic MR should be taken before intervention in a patient undergoing coronary artery bypass grafting. There is a current trend to favour combined mitral valve repair with coronary artery bypass grafting in patients with moderate ischaemic MR, as attested by the IIa recommendation in recent guidelines.
This joint session highlighted the need for close interaction between cardiologists, in particular imaging specialists, and surgeons in the management of patients with ischaemic MR. A number of factors may impact the results of surgery and appropriate trials are lacking to assess the effect of surgical correction of ischaemic MR. Such trials are also needed to evaluate the benefit of percutaneous techniques to avoid their uncontrolled use.
Ischaemic mitral regurgitation: burning questions
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