Hybrid Positron Emission Tomography/Magnetic Resonance Imaging in Arrhythmic Mitral Valve Prolapse

Importance Myocardial replacement fibrosis has been reported to occur in one-third of patients with mitral valve prolapse (MVP) and significant mitral regurgitation (MR). However, it remains unknown whether there are detectable changes in myocardial metabolism suggestive of inflammation or ischemia that accompany the development of fibrosis. Objectives To characterize the burden and distribution of fluorine 18-labeled (F-18) fluorodeoxyglucose (FDG) uptake and late gadolinium enhancement (LGE) in patients with degenerative MVP and ventricular ectopy. Design, Setting, and Participants Prospective observational study of 20 patients with MVP and significant primary degenerative MR who were referred for mitral valve repair and underwent hybrid positron emission tomography/magnetic resonance imaging (PET/MRI). Ventricular arrhythmias were categorized as either complex (n = 12) or minor (n = 8). Coregistered hybrid(18)F FDG-PET and MRI LGE images were assessed and categorized. Recruitment occurred in the new patient clinic of a mitral valve repair reference center. This study was conducted from January 11, 2018, to June 26, 2019. Exposures Simultaneous cardiac(18)F FDG-PET and MRI with LGE imaging on a hybrid PET/MRI system and ambulatory rhythm monitoring. Main Outcomes and Measures Patients were categorized by the presence and pattern of FDG uptake and LGE, the severity of ventricular arrhythmias, and the indication for mitral valve surgery. Results In the cohort of 20 patients, the median age was 59.5 years (interquartile range, 52.5-63.2 years). Focal, or focal-on-diffuse uptake, of(18)F-FDG (PET positive) was detected in 17 of 20 patients (85%). The FDG uptake coexisted with areas of LGE (PET/MRI positive) in 14 patients (70%). Of the 5 asymptomatic patients with normal ventricular indices and absence of any surgical indications, all were PET/MRI positive. Conclusions and Relevance In this pilot study, we demonstrate a novel association between degenerative MVP and FDG uptake, a surrogate for myocardial inflammation and/or ischemia. Such evidence of myocardial injury, even in asymptomatic patients, suggests an ongoing subclinical disease process. These findings warrant further investigation into whether imaging for myocardial inflammation, ischemia, and scar has a role in arrhythmic risk stratification and whether it provides incremental prognostic value in patients with chronic severe mitral regurgitation undergoing active surveillance. Question Do patients with primary degenerative mitral valve prolapse, severe mitral regurgitation, and ventricular ectopy have evidence of occult myocardial inflammation or ischemia in addition to characteristic myocardial fibrosis? Findings In this study of 20 patients, most patients with severe degenerative mitral regurgitation and ventricular ectopy exhibited myocardial fluorine 18-labeled fluorodeoxyglucose uptake, a surrogate marker of myocardial inflammation. Additionally, the segments of fluorine 18-labeled fluorodeoxyglucose uptake frequently coexisted with areas of myocardial fibrosis, even in asymptomatic patients with normal left ventricular function and dimensions. Meaning These findings suggest that patients with degenerative mitral valve prolapse and ventricular ectopy have evidence of subclinical myocardial inflammation or ischemia. This study characterizes the burden and distribution of fluorine 18-labeled fluorodeoxyglucose uptake and late gadolinium enhancement in patients with degenerative mitral valve prolapse and ventricular ectopy.