Discordant Imaging Results in Patients Referred for Mitral Valve Surgery: What Can the Left Ventricle Tell Us?

Introduction: The assessment of mitral regurgitation (MR) severity is often based on echocardiographic (Echo) criteria and clinical assessment. Recently MRI has been used to quantify MR. In clinical practice these imaging modalities can be discordant. In an ongoing multicenter prospective study, we evaluated the degree of discordance between Echo and MRI in patients with isolated MR. We also correlated the pre-surgical MR volume (MRVol) to the decrease in left ventricular end-diastolic volume (LV EDV) after successful mitral valve surgery (MVS). Hypothesis: Does the post-surgical change in LV EDV correlate with MRVol? Methods: The study included 96 pts (60 ± 14yrs, male 57%) with isolated MR (19 fxnl, 43 degen, 34 other). 31 pts had isolated MVS. Each pt had MRVol quantified using Echo (PISA method) and MRI (LV stroke volume - forward flow). MR severity was categorized as mild <30ml, moderate 30-59ml, or severe ≥60ml. Patients who had MVS (10 MVR, 21 MV repair) also had MRI 4 months following surgery. The pre-surgical MRVol was correlated with the postoperative decrease in LV EDV. Results: MRI and Echo estimates of mitral RVol. were correlated (y=0.6x + 26) (r=0.6, p <0.001). There was agreement in 51/96 (53%) when using the categories of mild, moderate and severe, and 67/96 (70%) when comparing severe vs. not severe. The modalities agreed in only 11/31 (33%) pts referred for MVS. Post-surgery MRI was performed in 21 pts. While there was good correlation between MRI MRVol and post surgical negative remodeling (r=0.8, p<0.001), there was no correlation between Echo MRVol and post surgical negative remodeling (r =0.1, p =0.5) (figure). Conclusions: There is often discordance between Echo PISA and MRI when quantifying MRVol even in patients referred for surgery. To the degree that post-surgical LV remodeling reflects the reduction in LV volume overload achieved with successful MVS, these data suggest that MRVol quantified by MRI may be more accurate than MRVol quantified by Echo PISA.