Authors' Reply

Abstract

We appreciate the interest of Shizukuda et al. in our recent publication1Chetrit M. Roujol S. Picard M.H. Timmins L. Manning W.J. Rudski L.G. et al.Optimal technique for measurement of linear left ventricular dimensions.J Am Soc Echocardiogr. 2019; 32: 476-483.e1Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar on midventricular measurement of linear dimensions. Our derivation and validation experiments showed that midventricular dimensions yielded closer correlations with the reference standard for left ventricular (LV) mass, size, and systolic function compared with the traditionally recommended basal dimensions. We will address each of the points raised in their letter. First, with regard to the correlation coefficients, we recognize that the differences between the midventricular and basal levels were statistically small. Accordingly, the expected gains in accuracy by changing to the midventricular measurements would be modest in most cases and more marked in cases of focal basal septal hypertrophy or spherical LV remodeling. Given that the midventricular measurements do not require more time or effort to perform, even modest gains in accuracy may be worthwhile. Second, with regard to the Devereux method for the calculation of LV mass, we understand that it is common practice to sidestep focal anomalies in basal wall thickness (hypertrophy or thinning) by measuring a midventricular segment to obtain a more representative estimate of global mass. Although reasonable, this practice is not currently endorsed in the society's guidelines,2Lang R.M. Badano L.P. Mor-Avi V. Afilalo J. Armstrong A. Ernande L. et al.Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.J Am Soc Echocardiogr. 2015; 28: 1-39.e14Abstract Full Text Full Text PDF PubMed Scopus (6949) Google Scholar and our study is the first to empirically validate it in the presence (R = 0.87–0.97) and absence (R = 0.79–0.88) of basal septal hypertrophy. Third, with regard to the Teichholz method for the calculation of LV ejection fraction, we state that this method is not endorsed for clinical use in the society's latest guidelines. We further state that the rationale for using the Teichholz method was to compare linear-derived estimates of LV ejection fraction at two levels. Because the midventricular estimate was found to be more closely correlated with the reference standard, this strengthened our hypothesis about the true diameter of the ellipsoid left ventricle. Fourth, with regard to the acquisition of the three-chamber view by cardiac magnetic resonance, we would reassure Shizukuda et al. that this view was not planned from scout images but rather from a short-axis stack and two long-axis cines, ensuring that the interpreted images were from a nonforeshortened, three-chamber view with all of the appropriate landmarks. And finally, with regard to the diagnostic value of the basal septal wall thickness for dynamic LV outflow obstruction and other pathologies, we certainly agree that the left ventricle should always be interrogated in its entirety, and our intention was not to suggest ignoring the basal level by demonstrating the utility of the midventricular level. Linear dimensions continue to play a clinically relevant role in routine echocardiography, and our study provides empirical data to support the hypothesis (anecdotally affirmed by many seasoned echocardiographers) that midventricular dimensions better reflect the geometry of the LV cavity. Following this proof of concept, further research is needed to reproduce these findings in a larger multicenter cohort and to define normative reference values at the midventricular level. Letter to the Editor: Comments Regarding Recent Paper by Chetrit et al.Journal of the American Society of EchocardiographyVol. 32Issue 9PreviewWe have read with much interest the article “Optimal Technique for Measurement of Linear Left Ventricular Dimensions,” by Chetrit et al.,1 which indicates that the measurement of linear dimensions at the midventricular level better correlates with cardiac magnetic resonance imaging– (MRI-) driven left ventricular (LV) mass, size, and systolic function as compared with the traditionally recommended basal-level measurement. Although this study includes a somewhat small number of subjects, n = 75 for the first cohort and n = 100 for the second cohort, it is well designed using meticulous methods including the automated measurement software of cardiac MRI. Full-Text PDF