Favorable Effects of Atrial Fixation Transcatheter Mitral Valve Replacement on Left Atrium Volume and Strain

The AltaValve System transcatheter mitral valve replacement (TMVR) has a spherical nitinol frame designed to fit the left atrium (LA) in a compliant fashion.

The objective of the study was to evaluate the anatomical and functional changes of the LA with the AltaValve System.

A total of 16 patients with severe, symptomatic mitral regurgitation who underwent AltaValve System transcatheter mitral valve replacement implantation via either a transseptal (n = 8) or transapical (n = 8) approach were examined. Transthoracic echocardiography was performed at baseline and 6-month follow-up. LA volumes and strain were evaluated using dedicated software (TomTec) with paired statistical testing.

All patients (median age, 77 years; 75% women [12/16]) had successful implantation. Most had atrial fibrillation (87%) and normal/reduced left ventricular ejection fraction. There was significant reduction in LA volume at 6 months (117.4 ± 39 mL vs 93.0 ± 37.0 mL; P = 0.002). For LA strain, there was significant reduction in both reservoir (10.8% ± 5.8% vs 1.6% ± 2.1%; P < 0.001) and conduit phase (-9.7% ± 3.2% vs -4.2% ± 4.4%; P = 0.013) of LA cycle. There were no significant change in the contraction phase (-1.1% vs -2.7%; P = 0.079). There was significant improvement in exercise capacity among 13 patients (average 6-minute walk test distance from 253 m at baseline to 296 m) and in functional status 55.1 ± 20.5 at baseline to 67.0 ± 22.5 (P = 0.04) at 6-month follow-up. For the responders, there were statistically significant differences at 6-month follow-up for majority of the LA parameters including strain.

There was a presence of LA remodeling following AltaValve System implantation and this was accompanied by a reduction in LA strain for both the reservoir and conduit phases, without changes in contractility.