Maximal Wall Thickness Measurement in Hypertrophic Cardiomyopathy

ISS OBJECTIVES The aim of this study was to define the variability of maximal wall thickness (MWT) measurements across modalities and predict its impact on care in patients with hypertrophic cardiomyopathy (HCM). BACKGROUND Left ventricular MWT measured by echocardiography or cardiovascular magnetic resonance (CMR) contributes to the diagnosis of HCM, stratifies risk, and guides key decisions, including whether to place an implantable cardioverter-defibrillator (ICD). METHODS A 20-center global network provided paired echocardiographic and CMR data sets from patients with HCM, from which 17 paired data sets of the highest quality were selected. These were presented as 7 randomly ordered pairs (at 6 cardiac conferences) to experienced readers who report HCM imaging in their daily practice, and their MWT caliper measurements were captured. The impact of measurement variability on ICD insertion decisions was estimated in 769 separately recruited multicenter patients with HCM using the European Society of Cardiology algorithm for 5-year risk for sudden cardiac death. RESULTS MWT analysis was completed by 70 readers (from 6 continents; 91% with >5 years’ experience). Seventy-nine percent and 68% scored echocardiographic and CMR image quality as excellent. For both modalities (echocardiographic and then CMR results), intramodality inter-reader MWT percentage variability was large (range –59% to 117% [SD 20%] and –61% to 52% [SD 11%], respectively). Agreement between modalities was low (SE of measurement 4.8 mm; 95% CI 4.3 mm-5.2 mm; r 1⁄4 0.56 [modest correlation]). In the multicenter HCM cohort, this estimated echocardiographic MWT percentage variability ( 20%) applied to the European Society of Cardiology algorithm reclassified risk in 19.5% of patients, which would have led to inappropriate ICD decision making in 1 in 7 patients with HCM (8.7% would have had ICD placement recommended despite potential low risk, and 6.8% would not have had ICD placement recommended despite intermediate or high risk). CONCLUSIONS Using the best available images and experienced readers, MWT as a biomarker in HCM has a high degree of inter-reader variability and should be applied with caution as part of decision making for ICD insertion. Better standardization efforts in HCM recommendations by current governing societies are needed to improve clinical decision making in patients with HCM. (J Am Coll Cardiol Img 2021;14:2123–2134) © 2021 by the American College of Cardiology Foundation. N 1936-878X/$36.00 https://doi.org/10.1016/j.jcmg.2021.03.032 Downloaded for Anonymous User (n/a) at Harvard University from ClinicalKey.com by Elsevier on December 06, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved. ABBR EV I A T I ON S