Assessment of acute changes in ventricular volumes, function, and strain after interventional edge-to-edge repair of mitral regurgitation using cardiac magnetic resonance imaging

Abstract

Aims: Whereas haemodynamic and echocardiographic studies suggest benefits for left ventricular (LV) function and cardiac output following reduction in LV preload by interventional edge-to-edge repair for mitral regurgitation (MR), there is limited data on volumetric and functional LV and right ventricular (RV) changes using cardiac magnetic resonance (CMR) imaging.

Methods and results: Patients with moderate to severe MR and high surgical risk underwent MitraClip-implantation and CMR imaging before and within 7 days after the procedure. In addition to volumetric and flow studies, myocardial feature tracking (FT) technology for quantification of myocardial strain was applied. Twenty patients (age: 76 ± 8 years) with functional (n = 15) or degenerative MR (n = 5) with a mean logistic Euroscore I of 33 ± 16 underwent both successful MitraClip implantation and CMR imaging. MR fraction (36 ± 10 vs. 19 ± 12%; P < 0.001) and LV end-diastolic volume (115 ± 36 vs. 105 ± 41 mL/m2; P = 0.002) decreased significantly, whereas LV ejection fraction (42 ± 15 vs. 41 ± 16%, P = 0.8) and cardiac index (1.7 ± 0.5 vs. 1.8 ± 0.4 L/min/m2, P = 0.4) remained unchanged. MitraClip implantation resulted in a significant impairment of circumferential (-12.8 ± 4.8 vs. -8.2 ± 3.3; P = 0.002) and radial strain (15.4 ± 7.7 vs. 9.6 ± 5.3; P = 0.02) on basal short-axis view. On RV level, there were no significant changes in end-diastolic volume (83 ± 19 vs. 84 ± 18 mL/m2, P = 0.8), ejection fraction (42 ± 9 vs. 43 ± 11%, P = 0.8), or tricuspid regurgitation fraction (24 ± 17 vs. 25 ± 19%, P = 0.7). MitraClip implantation led to a significant improvement in New York Heart Association functional class (patients in functional class III-IV pre 100% vs. post 45%; P < 0.001).

Conclusion: In severely compromised patients, marked reduction in MR by MitraClip implantation might not result in immediate improved cardiac output and effective biventricular forward flow.

Keywords: Magnetic resonance imaging; MitraClip; Mitral insufficiency; Strain imaging.