Tethering Symmetry Reflects Advanced Left Ventricular Mechanical Dyssynchrony in Patients With Ischemic Mitral Regurgitation Undergoing Restrictive Mitral Valve Repair

Abstract

We evaluated the papillary muscle systolic dyssynchrony (DYS-PAP) using two-dimensional speckle tracking echocardiography (2D-STE) in patients with chronic ischemic mitral regurgitation (CIMR) showing different preoperative leaflet pattern and investigated the impact of baseline tethering pattern in the prediction of significant post-repair desynchronized papillary muscle contraction. We recruited 152 CIMR consecutive patients (64.4% male, mean age 65.9 ± 7.1 years) who survived coronary artery bypass grafting (CABG) and (undersized mitral ring annuloplasty, performed between 2001and 2010. The assessment of DYS-PAP was performed preoperatively and at follow-up (median 41.5 months [IQR 23-61]) by 2D-STE in the apical 4-chamber view for anterolateral papillary muscle and apical long-axis view for posteromedial papillary muscle). Based on the cutoff value (anterior-posterior tethering angle ratio α/β ≥ 0.76) patients were classified in 2 groups; symmetrical (group 1, n = 73, mean α/β = 0.81 ± 0.6) and asymmetrical preoperative tethering pattern (group 2, n = 79, mean α/β = 0.66 ± 0.4). Recurrent MR occurred in 67.1% (n = 49) in group 1 versus 3.8% (n = 3) in group 2 (p < 0.001). Comparing both groups at baseline, patients in group 1 had higher DYS-PAP (57.7 ± 5.3 vs 29.8 ± 2.4 ms in group 2, p < 0.001) that significantly worsened at follow-up (78.1 ± 8.8 ms, p < 0.001 versus baseline), whereas in group 2 it improved (26.6 ± 6.0 ms, p < 0.001 versus baseline). Tethering symmetry significantly correlated with DYS-PAP (r = 0.90, p < 0.001) and it was a strong multivariable predictor of significant postoperative DYS-PAP (odds ratio 4.2; 95% confidence level 3.4 to 5.2, p < 0.001). Tethering symmetry is an easy and immediate tool to identify CIMR patients with advanced DYS-PAP who are unlikely to benefit from mitral repair with undersized mitral ring annuloplasty.