Undersizing mitral annuloplasty alters left ventricular mechanics in a swine model of ischemic mitral regurgitation

• Type of Material: Article
• Authors: Dongyang Xu, Emory University Hospital Midtown; Erin McBride, Emory University Hospital Midtown; Kanika Kalra, Emory University; Keawepono Wong, Emory University Hospital Midtown; Robert Guyton, Emory University; Eric L Sarin, Emory University Hospital Midtown; Muralidhar Padala, Emory University
• Language: English
• Date: 2022-08-10
• Publisher: MOSBY-ELSEVIER
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 by The American Association for Thoracic Surgery
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.jtcvs.2020.09.141
• Title of Journal or Parent Work: JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY
• Volume: 164
• Issue: 3
• Start Page: 850
• End Page: +
• Grant/Funding Information: This work was partially supported by grants 1R01HL135145, 1R01HL133667, and 1R01HL140325 from the National Institutes of Health, grant 14SDG20380081 from the American Heart Association, and infrastructure funding from the Carlyle Fraser Heart Center at Emory University Hospital Midtown to M.Padala
• Keywords: REPAIR; Surgery; Life Sciences & Biomedicine; Science & Technology; SYSTOLIC FUNCTION; EJECTION FRACTION; functional mitral regurgitation; Cardiac & Cardiovascular Systems; ischemic mitral regurgitation; mitral valve repair; secondary mitral regurgitation; Cardiovascular System & Cardiology; Respiratory System; heart failure; mitral valve replacement; MORTALITY; annuloplasty; MYOCARDIAL-INFARCTION

Abstract

Objective: Undersizing mitral annuloplasty (UMA) is a frequently used surgical repair technique to correct ischemic mitral regurgitation in patients with heart failure. In this study, we sought to test the hypothesis that downsizing the mitral annulus can adversely affect the shape and mechanics of the left ventricle inhibiting its functional recovery. Methods: Eighteen farm swine that underwent an inferolateral myocardial infarction and developed ischemic mitral regurgitation of >2+ severity after 2 months were assigned as follows: 9 swine received an undersized mitral annuloplasty, 6 received papillary muscle approximation (PMA), and 3 animals did not receive any other intervention. Animals lived another 3 months and cardiac magnetic resonance imaging was performed before termination to assess ventricle mechanics and function. Results: Ejection fraction was comparable between the 2 repair groups before surgery, but was significantly lower in UMA at 38.89% ± 7.91% versus 50.83% ± 9.04% in the PMA group (P =.0397). Animals receiving UMA had lower regional peak fractional shortening and reduced systolic and diastolic radial velocities compared with PMA and in some regions were lower than sham. Animals that underwent UMA had higher circumferential strain than sham, but lower than PMA. UMA animals have lower longitudinal strain compared to sham group and lower LV torsion than PMA. Conclusions: Undersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricle mechanics. Mitral valve repair strategies should focus not only on restoring valve competence, but preserving ventricle mechanics.