The Structural Impact of Aortic Valve Replacement on Mitral Regurgitation

Background: Structural changes to the mitral annulus occur following aortic valve replacement (AVR) for severe aortic stenosis which may influence functional mitral regurgitation (MR). Methods: A retrospective review of 44 patients who underwent open AVR for aortic stenosis at a single center from 2010-2013 was performed. Patients undergoing concomitant aortic root surgery or with severe MR were excluded. MR was evaluated with preoperative and postoperative transthoracic echocardiograms. Univariate and multivariable analyses were performed to assess for factors associated with postoperative MR improvement and worsening. Results: Prior to AVR, none had severe MR, 5% (2 patients) had moderate, 9% (4 patients) mild-to-moderate, 46% (20 patients) mild, and 23% (9 patients) trace MR. Of patients with pre-operative MR, 44% (16 patients) experienced improvement of MR. Six patients had worsening of MR and the remaining 22 patients had no change. Cases of more severe MR were more likely to improve compared with mild or trace MR (P = 0.04). MR worsening was significantly more likely in patients with bicuspid aortic valves (83% vs. 24%; P = 0.004), and with larger aortic annulus diameters (P = 0.03). MR worsening was less frequent in cases of mitral annular calcification (0% vs 42%; P = 0.04) and left atrial enlargement (17% vs 65%; P = 0.03). Logistic regression analysis revealed negative predictors for MR improvement were mitral annular calcification (P = 0.04) and larger aortic annulus diastolic diameter (P = 0.05). Conclusion: Structural factors such as aortic annular size, mitral annular calcification and valve morphology may impact MR following AVR and should be investigated further as potential targets of surgical therapy.