Rapid Fire Abstracts
Max King, BSc
Student
Thomas Jefferson University Hospital
Behzad Pavri, MD
Director, Cardiac Electrophysiology Fellowship Program
Thomas Jefferson University Hospital
Baskaran Sundaram, MD
Director, Division of Cardiothoracic Radiology
Thomas Jefferson University Hospital
Andrew Peters, MD
Assistant Professor, Cardiology
Thomas Jefferson University Hospital
Mitral annular disjunction (MAD) is increasingly studied, may accompany mitral valve prolapse (MVP), and is associated with risk of ventricular arrhythmias. Data also suggest that < 5 mm of disjunction may be normal. Cardiac MRI (CMR) detects MAD, offering precise anatomic measurement, assessment of the mitral annulus throughout the cardiac cycle, and myocardial fibrosis via late gadolinium enhancement (LGE). While ample echocardiographic literature exists, data using CMR is limited. Thus, we aimed to evaluate the changes in CMR metrics in patients (pts) with varying degrees of MAD compared to MVP alone.
Methods:
We developed a registry of pts with MAD ≥2mm or MVP-only on CMR. MAD length (Figure 1) and MVP height were measured using cine-MRI in the 3-chamber view during peak systole after excluding pseudo-MAD. Left ventricular end-diastolic and systolic volumes (LVEDV and LVESV), stroke volume (SV), left and right ventricular ejection fraction (LVEF and RVEF), cardiac output (CO), cardiac index (CI), mitral regurgitation (MR), and LGE were assessed. Pts were divided into two main groups: MAD vs MVP-only. The MAD group was further classified as < 5mm, ≥5mm, and ≥10 mm.
Results:
Total n=56 pts (33 F and mean age 61); MAD n= 41 and MVP-only n= 15. MAD < 5mm (n=13), MAD ≥5 mm (n=28), and MAD ≥10 mm (n=10). Pts with any MAD had a lower CI compared to the MVP-only group (mean difference -0.47 L/min/m2, p=0.03, Figure 2a, and Table 1). MAD ≥5mm had reduced CO (mean difference -0.99 L/min, p=0.04, Table 1, and Figure 2b) and CI (mean difference -0.44 L/min/m2, p=0.04, Table 1, and Figure 2a) compared to MVP-only. ANOVA revealed no differences in CO or CI across MAD subgroups (p=0.2 and 0.1, respectively). There were no differences in the incidence, volume, or fraction of mitral regurgitation between the MAD and MVP-only groups, nor amongst the MAD subgroups (except < 5mm) compared to MVP-only (Table 1). Strong correlation was found between MAD severity and MR severity, with correlation coefficients of 0.9 and 0.85 for MR volume and fraction, respectively. LGE was more common in MAD ≥10mm than in MAD < 10mm (p=0.028). Pts with MAD < 5mm had no significant differences in CMR parameters compared to MVP-only, aside from MR (Table 1).
Conclusion:
There were no differences in myocardial mechanics between the MVP-only and MAD < 5mm groups except for less MR. MAD of any degree was associated with a lower CI, and MAD ≥5mm correlated with reduced CO and CI. Mitral regurgitation could not account for differences between groups. There was also more myocardial fibrosis in severe MAD ≥10mm, suggesting a higher scar burden compared to MVP-only. We hypothesize that MAD may cause electromechanical disturbances in pts, impairing myocardial performance. Further research is necessary to determine the effect of these findings on clinical outcomes.
