Multiple MitraClips: The balancing act between pressure gradient and regurgitation

Computational Methods for Fluid-Structure Interaction Simulation of Heart Valves in Patient-Specific Left Heart Anatomies

Given the complexity of human left heart anatomy and valvular structures, the fluid–structure interaction (FSI) simulation of native and prosthetic valves poses a significant challenge for numerical methods. In this review, recent numerical advancements for both fluid and structural solvers for heart valves in patient-specific left hearts are systematically considered, emphasizing the numerical treatments of blood flow and valve surfaces, which are the most critical aspects for accurate simulations. Numerical methods for hemodynamics are considered under both the continuum and discrete (particle) approaches. The numerical treatments for the structural dynamics of aortic/mitral valves and FSI coupling methods between the solid Ωs and fluid domain Ωf are also reviewed. Future work toward more advanced patient-specific simulations is also discussed, including the fusion of high-fidelity simulation within vivo measurements and physics-based digital twining based on data analytics and machine learning techniques.

Implantation of one, two or multiple MitraClips for transcatheter mitral valve repair: insights from a 1824-patient multicenter study

BACKGROUND

Transcatheter mitral valve repair (TMVR) with the MitraClip device is an established treatment for mitral regurgitation (MR). More than one MitraClip may be implanted if a single one does not reduce MR adequately. We aimed at appraising the outlook of patients undergoing implantation of one, two or multiple MitraClips for TMVR.

METHODS

Exploiting the ongoing prospective GIse registry Of Transcatheter treatment of mitral valve regurgitaTiOn (GIOTTO) Study dataset, we compared patients, procedural details and outcomes distinguishing those receiving one, two or multiple MitraClips. The primary endpoint was the composite of 1-year cardiac death or rehospitalization for heart failure. Additional endpoints included all cause death, surgical mitral repair, and functional class. Multivariable adjusted Cox proportional hazard analysis was used for confirmatory purposes.

RESULTS

As many as 1824 patients were included: 718 (39.4%) treated with a single MitraClip, and 940 (51.5%) receiving two MitraClips, and 166 (9.1%) receiving three or more. Significant differences were found for baseline features, including age, female gender, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, prior myocardial infarction, atrial fibrillation, permanent pacemaker, cardiac resynchronization therapy, implantable cardioverter defibrillator, and prior mitral valve repair (all p<0.05). Several imaging features were also different, including left ventricular dimensions, MR severity and proportionality, mitral valve area, flail leaflet, and pulmonary vein flow (all p<0.05). Among procedural features, significant differences were found for anesthesia type, MitraClip type, fluoroscopy, device, and operating room times, postprocedural mitral gradient, residual MR, smoke-like effect, device success partial detachment and surgical conversion (all p<0.05). In-hospital death occurred more frequently in patients receiving multiple MitraClips, and the same applied severe residual MR (all p<0.05). Mid-term follow-up (15±13 months) showed significant difference in the risk of death, cardiac death, rehospitalization for heart failure, and their composites, mainly, but not solely, associated with multiple MitraClips (all p<0.05). Adjusted analysis confirmed the significantly increased risk of composite adverse events when comparing the multiple vs single MitraClip groups (p=0.014 for death and rehospitalization, p=0.013 for cardiac death or rehospitalization).

CONCLUSIONS

Implantation of one or two MitraClips is associated with favorable clinical outcomes. Conversely, bail-out implantation of three or more MitraClips may portend a worse long-term prognosis.