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Arrhythmic Mitral Valve Prolapse With Mild or Moderate MR
Quick Takes
- This small prospective pilot study of patients with mitral valve prolapse (MVP) and mild or moderate mitral regurgitation set out to characterize their ventricular arrhythmia complexity and myocardial inflammation and fibrosis, as imaged by hybrid PET/MRI.
- Focal uptake of FDG was seen in 83% of all patients, while myocardial inflammation, concordant with myocardial fibrosis/scar was detected in 75% of all patients.
- This suggests that chronic myocardial inflammation may contribute to myocardial injury in patients with classic MVP before they develop severe MR.
Study Questions:
In patients with mitral valve prolapse (MVP) and only mild or moderate mitral regurgitation (MR), what are the characteristics of their ventricular arrhythmia (VA) complexity and myocardial inflammation and fibrosis, as imaged by hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI)?
Methods:
This was a prospective observational pilot study of 12 patients with degenerative MVP with only mild or moderate MR and a history of premature ventricular contractions (PVCs). They were recruited from a cardiac electrophysiology (EP) clinic at an academic hospital. Exclusion criteria included presence of pacemaker/implantable cardioverter-defibrillator, history of VA ablation, or known sustained VA. MR was confirmed by echocardiography according to standard guidelines, and length of mitral annular disjunction was also measured. “Pickelhaube” sign was present when pulse-wave tissue Doppler of the lateral mitral annulus revealed a spiked systolic velocity signal ≥16 cm/s. Patients wore ambulatory event monitors. VAs were either minor (isolated unifocal PVCs) or complex (pleomorphic PVCs, couplets, triplets, nonsustained ventricular tachycardia [VT]). All patients underwent 18F-fluorodeoxyglucose (18F-FDG)–PET to assess for inflammation, followed by MRI to assess for late-gadolinium enhancement (LGE) as a marker for fibrosis/scar. Co-registered, short-axis, hybrid 18F-FDG PET and LGE MRI images were categorized.
Results:
In this study, 8 of 12 patients (75%) were female. 6/12 (50%) had bileaflet prolapse, while the other half had isolated posterior-leaflet prolapse. MR was mild in 7/12 (58%) patients. Mitral annular disjunction was present in 9/12 (75%) patients, while the Pickelhaube sign was detected in 4/12 (33%) of all patients. 10/12 (83%) patients had complex VAs, including nonsustained VT in 6/12 (50%) patients. Only 2/12 (16%) patients had a PVC burden >10%. Focal (or focal-on-diffuse) 18F-FDG uptake was seen in 10/12 (83%) patients and was localized to the papillary muscles and/or inferolateral wall and basal inferior segments of the left ventricle in 60% of these patients. 9/12 (75%) patients had concordance of myocardial 18F-FDG uptake and LGE.
Conclusions:
In patients with degenerative MVP with only mild or moderate MR and ventricular ectopy, focal (or focal-on-diffuse) uptake of FDG was seen in 83% of patients. Myocardial inflammation concordant with myocardial fibrosis/scar was detected in 75% of all patients. This suggests that chronic myocardial inflammation may contribute to myocardial injury in patients with classic MVP before they develop severe MR.
Perspective:
Known risk factors for sudden cardiac death in MVP with VAs include female sex, bileaflet prolapse, complex PVCs, mitral annular disjunction, and LGE on MRI. While severe MR confers the greatest risk, LGE is seen in a significant number of patients with mild and moderate MR. The majority of MVP-related sudden deaths occur in patients with less than severe MR. This small observational pilot study showed that both myocardial inflammation and fibrosis were already present in patients with MVP before they actually developed severe MR. This small number of patients was obviously subject to selection bias, given that they were recruited from an EP clinic. Nonetheless, there is a clinical need for better risk stratification in arrhythmic MVP, especially in patients with only mild or moderate MR who do not yet have an indication for valve intervention. Larger prospective assessment of MVP with all degrees of MR severity is needed. Furthermore, the assessment of the likely interplay of mitral annular disjunction to this paradigm is warranted.
Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, Valvular Heart Disease, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging, Mitral Regurgitation
Keywords: Arrhythmias, Cardiac, Death, Sudden, Cardiac, Diagnostic Imaging, Echocardiography, Doppler, Electrophysiology, Fibrosis, Fluorodeoxyglucose F18, Gadolinium, Heart Valve Diseases, Inflammation, Magnetic Resonance Imaging, Mitral Valve Insufficiency, Mitral Valve Prolapse, Positron-Emission Tomography, Prolapse, Tachycardia, Ventricular, Ventricular Premature Complexes
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