P879Prospective comparison of valve regurgitation quantitation by cardiovascular magnetic resonance and transthoracic echocardiography


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Abstract

Purpose: Although both transthoracic echocardiography (TTE) and cardiovascular magnetic resonance imaging (CMR) allow evaluation of chronic aortic (AR) and mitral regurgitation (MR), we hypothesized that quantitation of regurgitation by CMR is more reproducible compared to TTE measures.Methods: TTE and CMR were performed on the same day in 56 prospectively enrolled adults (mean age 50 ± 14; 73% males, 31 with AR and 25 with MR). Causes of AR are 19 bicuspid valves, 6 aortic aneurysms, 2 endocarditis, 1 rheumatic, and 3 other. Causes of MR were 23 myxomatous valves, 1 endocarditis, and 1 ischemic. Exclusion criteria were atrial fibrillation, known poor acoustic windows, extreme claustrophobia and non-CMR compatible implanted devices. Both TTE and CMR studies were measured blindly by two independent experienced physicians. AR regurgitant volume was calculated on TTE (Acuson Sequoia, Siemens Medical Solutions) as Doppler left ventricular (LV) outflow minus inflow stroke volume (SV). MR regurgitant volume on TTE was calculated both using the proximal isovelocity surface area (PISA) method and as LV inflow minus outflow SV. CMR was performed on a 1.5-Tesla scanner (Achieva, Philips Medical) with a 5 channel phased array cardiac receiver coil. AR regurgitant volume was calculated directly by phase-contrast velocity mapping at the level of the aortic valve. MR regurgitant volume was calculated as LV total SV minus phase-contrast velocity forward aortic valve SV.Results: Mean AR regurgitant volume by CMR was 52 mL (range 6.5 to 140 mL) and by TTE was 62.5 mL (range -11.8 to 178 mL) with a Bland-Altman mean difference of -10 mL (95% CI -24 to 3 mL, p=NS). The Pearson correlation (r) for AR regurgitation volume was higher (p = 0.001) between the 2 CMR readers (0.998) than the 2 TTE readers (0.888). Mean MR regurgitant volume by CMR was 40.7 mL (range 9.0 to 96.8 mL) and by TTE was 79.1 mL (range -12.7 to 261 mL) with significant difference between these methods of -38 mL (CI -58 to -17 mL, p = 0.006). CMR interobserver variability (r) for MR quantitation was similar (0.938) to TTE using either the Doppler SV method (0.864) or the PISA method (0.897, p = NS for both).Conclusions: Compared to TTE, CMR has a lower interobserver variability for quantitation of chronic AR suggesting CMR may be superior for serial measurements. Although quantitation of MR is reproducible by TTE and CMR, differences in measured regurgitant volumes by these approaches suggest caution is needed in clinical practice.

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