Geometric Changes in Mitral Valve Apparatus During Long-term Cardiac Resynchronization Therapy As Assessed with Cardiac CT.

Purpose: To assess long-term geometric changes of the mitral valve apparatus using cardiac CT in individuals who underwent cardiac resynchronization therapy (CRT). Materials and Methods: Participants from a randomized controlled trial with cardiac CT examinations before CRT implantation and at 6 months follow-up (Clinicaltrials.gov identifier NCT01323686) were invited to undergo an additional long-term follow-up cardiac CT examination. The geometry of the mitral valve apparatus, including mitral valve annulus area, A2 leaflet angle, tenting height, and interpapillary muscle distances, were assessed. Geometric changes at the long-term follow-up examination were reported as mean differences (95% CI), and the Pearson correlation test was used to assess correlation between statistically significant geometric changes and left ventricular (LV) volumes and function. Results: Thirty participants (mean age, 68 years +/- 9 [SD]; 25 male participants) underwent cardiac CT imaging after a median long-term follow-up of 9.0 years (IQR, 8.4-9.4). There were reductions in end-systolic A2 leaflet angle (-4 degrees [95% CI: -7, -2]), end-systolic tenting height (-1 mm [95% CI: -2, -1]), and end-systolic and end-diastolic interpapillary muscle distances (-4 mm [95% CI: -6, -2]) compared with pre-CRT implantation values. The mitral valve annulus area remained unchanged. LV end-diastolic and end-systolic volumes decreased (-68 mL [95% CI: -99, -37] and -67 mL [95% CI: -96, -39], respectively), and LV ejection fraction increased (13% [95% CI: 7, 19]) at the long-term follow-up examination. Changes in interpapillary muscle distances showed moderate to strong correlations with LV volumes (r r = 0.42-0.72; P < .05), while A2 leaflet angle and tenting height were not correlated to LV volumes or function. Conclusion: Among the various geometric changes in the mitral valve apparatus after long-term CRT, the reduction in interpapillary muscle distances correlated with LV volumes while the reduced A2 leaflet angle and tenting height did not correlate with LV volumes. Supplemental material is available for this article.