Minimally invasive transcather-based procedures have emerged over the past decade as a therapy for selected patients with valvular disease as an alternative to riskier open-heart surgery, particularly in patients with high surgical risk due to multiple comorbidities. As the technology improves and successful clinical outcomes increase, lower-risk patients are likely to be eligible for these procedures as demonstrated by recent clinical trials for transcather aortic valve replacement. Noninvasive imaging, which has supported the growth of transcather interventions by providing excellent preprocedural planning, could also become useful for stratifying patients based on quantifiable prognostic parameters. For example, transcatheter mitral valve replacement (TMVR) is a relatively new minimally invasive procedure to treat mitral regurgitation (MR); however, its effect on left ventricular (LV) function has not yet been characterized. In addition, patients with secondary MR as a result of left ventricular remodeling due to ischemic or idiopathic cardiomyopathy can have a large portion of their myocardium which is already dysfunctional which requires regional characterization of LV function. The proposed project aims to evaluate the net effect of MR and implantation of the bioprosthetic valve on LV function by identifying akinetic, dyskinetic, hypokinetic and normal regions of myocardium before and 1-month post minimally invasive valve replacement using noninvasive single heartbeat 4DCT-derived metrics. It is hypothesized that the fraction and spatial distribution of normal vs. abnormal tissue will correlate with the ability of the LV to recover post intervention. Regional maps of endocardial longitudinal strain, circumferential strain, and rotation will be compared to traditional global metrics such as stroke volume and ejection fraction. In addition, we will investigate the effect of the position of the bioprosthetic mitral valve device and anchoring system upon the remodeling process of the LV by performing statistical shape modeling pre and post procedure. In order to characterize regional myocardial function as normal or abnormal with estimated confidence intervals, the precision of the 4DCT-derived measurement tools will be quantified. This project aims to evaluate the effect of spatial resolution, temporal resolution, the signal-to-noise ratio, and the patient?s heart rate on the precision of myocardial function metrics. In addition, the proposed 4DCT-derived metrics will be validated in subjects who undergo both MRI tagging and 4DCT exams within the same day.
Transcather mitral valve replacement (TMVR) is a relatively new procedure to treat mitral regurgitation (MR) yet little is known about its effects on left ventricular (LV) function. This proposal will investigate the precision of 4DCT-derived metrics of regional cardiac function and their ability to quantify the extent of myocardial dysfunction before and 1-month post TMVR. Results will lead to a better understanding of the effect mitral regurgitation and TMVR on LV function and LV remodeling, and identify prognostic parameters which can be used to stratify patients for the procedure.
