Usefulness of Cardiac Magnetic Resonance Imaging to Measure Left Ventricular Wall Thickness for Determining Risk Scores for Sudden Cardiac Death in Patients With Hypertrophic Cardiomyopathy

Abstract

Echocardiography-derived measurements of maximum left ventricular (LV) wall thickness are important for both the diagnosis and risk stratification of hypertrophic cardiomyopathy (HC). Cardiac magnetic resonance (CMR) imaging is increasingly being used in the assessment of HC; however, little is known about the relation between wall thickness measurements made by the 2 modalities. We sought to compare measurements made with echocardiography and CMR and to assess the impact of any differences on risk stratification using the current European Society of Cardiology guidelines. Maximum LV wall thickness measurements were recorded on 50 consecutive patients with HC. Sixty-nine percent of LV wall thickness measurements were recorded with echocardiography, compared with 69% from CMR (p <0.001). There was poor agreement on the location of maximum LV wall thickness; weighted-Cohen's κ 0.14 (p = 0.036) and maximum LV wall thicknesses were systematically higher with echocardiography than with CMR (mean 19.1 ± 0.4 mm vs 16.5 ± 0.3 mm, p <0.01, respectively); Bland-Altman bias 2.6 mm (95% confidence interval -9.8 to 4.6). Interobserver variability was lower for CMR (R 0.67 echocardiography, R 0.93 CMR). The mean difference in 5-year sudden cardiac death (SCD) risk between echocardiography and CMR was 0.49 ± 0.45% (p = 0.37). When classifying patients (low, intermediate, or high risk), 6 patients were reclassified when CMR was used instead of echocardiography to assess maximum LV wall thickness. These findings suggest that CMR measurements of maximum LV wall thickness can be cautiously used in the current European Society of Cardiology risk score calculations, although further long-term studies are needed to confirm this.

A case report and analysis of hypertrophic obstructive cardiomyopathy causing an illusion of aortic stenosis

“…[4–7] It is a useful technique in evaluating patients with hypertrophic cardiomyopathy and is preferred over other imaging modalities. [8,9] The present study revealed that hypertrophic obstructive cardiomyopathy could cause an illusion of aortic stenosis on imaging (cardiac MRI and transesophageal echocardiography). Cardiac physicians should always be vigilant and respond rationally to such patients.…”

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease

“…CMR provides high contrast between bright blood and dark myocardium, excellent spatial resolution, and full biventricular coverage. In addition, short-axis images, derived perpendicular to the true LV long axis, allows LVWT measurements by CMR to be more precise and reproducible [ 442 ], enabling a diagnosis of HCM which may be missed by TTE [ 400 – 402 ]. This holds true even in children, who have better acoustic windows than adults; a small study of pediatric HCM patients demonstrated that echocardiography derived measurements had poorer inter-observer and intra-observer reproducibility compared with CMR measurements [ 443 ].…”

Arrhythmic risk stratification by cardiac magnetic resonance tissue characterization: disclosing the arrhythmic substrate within the heart muscle

“…Careful LV wall thickness assessment is pivotal in HCM as the risk of VA has been reported to increase along with maximum wall thickness [6] and with global LV mass [90]. In this regard, CMR evaluation has proven to be more accurate compared to echocardiography, leading to reclassification into a lower risk class in about 10% of patients with HCM [91]. In particular, CMR enables to assess the presence of cardiac hypertrophy in segments difficult to image by echocardiography (i.e., the posterior wall and the apex of the LV) as well as to identify muscle bundles close to other cardiac structures (i.e., interventricular septum), preventing inaccurate wall thickness measurement.…”