Evaluation of aortic stenosis using cardiovascular magnetic resonance: a systematic review & meta-analysis

Abstract

Background As the average age of patients with severe aortic stenosis (AS) who receive procedural intervention continue to age, the need for non-invasive modalities that provide accurate diagnosis and operative planning is increasingly important. Advances in cardiovascular magnetic resonance (CMR) over the past two decades mean it is able to provide haemodynamic data at the aortic valve, along with high fidelity anatomical imaging. Methods Electronic databases were searched for studies comparing CMR to transthoracic echocardiography (TTE) and transoesophageal echocardiography (TEE) in the diagnosis of AS. Studies were included only if direct comparison was made on matched patients, and if diagnosis was primarily through measurement of aortic valve area (AVA). Results Twenty-three relevant, prospective articles were included in the meta-analysis, totalling 1040 individual patients. There was no significant difference in AVA measured as by CMR compared to TEE. CMR measurements of AVA size were larger compared to TTE by an average of 10.7% (absolute difference: + 0.14cm2, 95% CI 0.07–0.21, p < 0.001). Reliability was high for both inter- and intra-observer measurements (0.03cm2 +/− 0.04 and 0.02cm2 +/− 0.01, respectively). Conclusions Our analysis demonstrates the equivalence of AVA measurements using CMR compared to those obtained using TEE. CMR demonstrated a small but significantly larger AVA than TTE. However, this can be attributed to known errors in derivation of left ventricular outflow tract size as measured by TTE. By offering additional anatomical assessment, CMR is warranted as a primary tool in the assessment and workup of patients with severe AS who are candidates for surgical or transcatheter intervention.

Ageing, Hypertension and Aortic Valve Stenosis: A Conscious Uncoupling

“…VAL differs from Z VA and Z VA-INS on several fronts. VAL permits: (i) simultaneous acquisition of aortic pressure and flow; (ii) measures the combined LV afterload that is presented by both the systemic circulation and narrowing valve; (iii) samples the multiple flow profiles seen in patients with AS [46], and; (iv) estimates load in the frequency domain, a more common method of assessment and one that has a stronger basis in the physical sciences, albeit more difficult to apply [47]. The VAL method does not add valvular gradient (as in the case of Z VA and Z VA-INS ) as aortic valve haemodynamics are inherently coupled to the systemic arterial vasculature.…”

“…Simultaneous CMR/AT techniques are not without limitation, however. Cardiac magnetic resonance techniques to measure aortic valve gradient have been demonstrated to be heterogenous with varying approaches and tend to underestimate valve gradient when compared with echocardiography [46]. CMR study is frequently limited by the availability of a cardiac technician to check CMR compatible devices pre and post scanning as well as monitoring pacing function throughout.…”

Diagnosis and Management of Aortic Valve Stenosis: The Role of Non-Invasive Imaging

“…CMR emerged as an alternative and non-invasive method which avoids many of the pitfalls of other imaging techniques: sedation/anesthesia for TEE and contrast exposure of CT [43]. Moreover, CMR can offer a detailed identification and quantification of myocardial fibrosis, which has been implicated in prognosis post-SAVR or TAVI [44,45] and often predates a reduction in LVEF [46,47].…”

Multimodality Imaging for Discordant Low-Gradient Aortic Stenosis: Assessing the Valve and the Myocardium

“…Use of CMR phase-contrast to assess AS severity is challenging and -mainly due to partial volume averaging- leads to significant underestimation of peak aortic velocity and VTI, and thus, AVA and AS severity ( 16 , 80 , 81 ). A recent meta-analysis showed that planimetry (geometric orifice area) by CMR correlated well with TEE, but were up to 11% larger than AVA estimated by TTE ( 81 ).…”

“…Use of CMR phase-contrast to assess AS severity is challenging and -mainly due to partial volume averaging- leads to significant underestimation of peak aortic velocity and VTI, and thus, AVA and AS severity ( 16 , 80 , 81 ). A recent meta-analysis showed that planimetry (geometric orifice area) by CMR correlated well with TEE, but were up to 11% larger than AVA estimated by TTE ( 81 ). However, the methods used in CMR were heterogeneous (planimetric, hybrid and effective orifice area) and there are known differences between the effective and geometric orifice area due to flow contraction at the vena contracta.…”