Aortic valve replacement for aortic stenosis in patients with concomitant mitral regurgitation: should the mitral valve be dealt with?

Co-existent mitral regurgitation may adversely influence both morbidity and mortality in patients undergoing aortic valve replacement for severe aortic stenosis. Whilst it is accepted that concomitant mitral intervention is required in severe, symptomatic mitral regurgitation, in cases of mild-moderate non-structural mitral regurgitation, improvement may be seen following aortic valve replacement alone, avoiding the increased risk of double-valve surgery. The exact benefit of such a conservative approach is, however, yet to be adequately quantified. We performed a systematic literature review identifying 17 studies incorporating 3053 patients undergoing aortic valve replacement for aortic stenosis with co-existing mitral regurgitation. These were meta-analysed using random effects modelling. Heterogeneity and subgroup analysis were assessed. Primary end points were change in mitral regurgitation severity and 30-day, 3-, 5- and 10-year mortality. Secondary end points were end-organ dysfunction (neurovascular, renal and respiratory), and the extent of ventricular remodelling following aortic valve replacement. Our results revealed improvement in the severity of mitral regurgitation following aortic valve replacement in 55.5% of patients, whereas 37.7% remained unchanged, and 6.8% worsened. No significant difference was seen between overall data and either the functional or moderate subgroups. The overall 30-day mortality following aortic valve replacement was 5%. This was significantly higher in moderate-severe mitral regurgitation than nil-mild mitral regurgitation both overall (p=0.002) and in the functional subgroup (p=0.004). Improved long-term survival was seen at 3, 5 and 10 years in nil-mild mitral regurgitation when compared with moderate-severe mitral regurgitation in all groups (overall p<0.0001, p<0.00001 and p=0.02, respectively). The relative risk of respiratory, renal and neurovascular complications were 7%, 6% and 4%, respectively. Reverse remodelling was demonstrated by a significant reduction in left-ventricular end-diastolic diameter and left-ventricular mass (p=0.0007 and 0.01, respectively), without significant heterogeneity. No significant change was seen in left-ventricular end-systolic diameter (p=0.10), septal thickness (p=0.17) or left atrial area (p=0.23). We conclude that despite reverse remodelling, concomitant moderate-severe mitral regurgitation adversely affects both early and late mortality following aortic valve replacement. Concomitant mitral intervention should therefore be considered in the presence of moderate mitral regurgitation, independent of the aetiology.