Scientific Session 18 — SS18: Cardiac Imaging - MRThursday, May 9, 2019
2323. Left Ventricular Wall Thickness and Mass Measurements Are Discrepant Between Echocardiography and Cardiac MRI in Patients With Fabry Disease
O'Brien C*, Karur G, Morel C, Iwanochko R, Hanneman K. Toronto General Hospital, University of Toronto, Toronto, Canada
Address correspondence to K. Hanneman (firstname.lastname@example.org)
Objective: Cardiac involvement is the leading cause of mortality in patients with Fabry disease, characterized by progressive left ventricular hypertrophy and myocardial fibrosis. Accurate assessment of maximum left ventricular (LV) wall thickness (LVWT) and LV mass is important in patients with Fabry disease, because these measurements may influence diagnosis, prognosis, and eligibility for disease-specific enzyme replacement therapy. Discordance between echocardiography and cardiac magnetic resonance imaging (MRI) measurements of maximum LVWT have recently been reported in patients with hypertrophic cardiomyopathy. The purpose of this study was to compare transthoracic echocardiography (TTE) and cardiac MRI measurements of maximum LVWT and LV mass obtained during routine clinical practice in patients with Fabry disease.
Materials and Methods: Seventy-eight patients with gene-positive Fabry disease (mean age, 45.6+/-14.3 years; 63% female) who underwent TTE and cardiac MRI within 6 months (median interval, 29 days) were included in this cross-sectional study. Maximum end-diastolic LVWT and LV mass indexed to body surface area (LVMI) were assessed by 2-dimensional TTE and by cardiac MRI according to current guidelines. Statistical analysis included Wilcoxon sign rank test. The relative discrepancy between modalities in LVWT and LVMI measurements were assessed at cut points of >=10% and >=25% of the mean.
Results: There were significant differences between TTE and MRI in maximum LVWT (12.7+/-4.8 mm vs 13.8+/-4.9 mm, p<0.001) and LVMI (105.5+/-51.2 g/m2 vs 81.6+/-36.3 g/m2, p<0.001). Maximum LVWT was identical between TTE and MRI in 17 patients (22%), larger by TTE than by MRI in 16 patients (21%), and smaller by TTE than by MRI in 45 patients (58%). The discrepancy between TTE and MRI measurements of maximum LVWT was >=10% in 48 patients (62%) and >=25% in 15 patients (19%). LVMI was larger by TTE compared to MRI in 69 patients (88%) and smaller by TTE compared to MRI in 9 patients (12%). The discrepancy between TTE and MRI measurements of LVMI was >=10% in 62 patients (79%) and >=25% in 39 patients (50%).
Conclusion: Although current guidelines recommend TTE or cardiac MRI to assess left ventricular hypertrophy in patients with Fabry disease, the results of this study demonstrate significant discrepancies between TTE and MRI measurements of LVWT and LVMI. TTE tends to underestimate LVWT and overestimate LVMI compared to MRI. Given the clinical importance of accurate measurements, the same modality should be used for longitudinal follow-up of LVWT and LVMI measurements in patients with Fabry disease. Further investigation is required to assess the reproducibility of measurements and sources of discrepancies between modalities.