Downloaded from www.ajronline.org by Univ of Penn Libr on 02/22/16 from IP address 165.123.34.86. Copyright ARRS. For personal use only; all rights reserved
Letters Reply to “Genetic, Myopathic, and Diagnostic Implications of Left Ventricular Noncompaction” We thank Dr. Finsterer and Dr. Stöllberger for their interesting comments [1] about our article titled “Left Ventricular Noncompaction: Imaging Findings and Diagnostic Criteria” [2]. In our article [2], my colleagues and I never refer to left ventricular noncompaction (LVNC) as “exclusively a congenital abnormality.” In the Cause and Pathogenesis section of our article, we explain that LVNC was first classified as primary genetic cardiomyopathy by the American Heart Association [3] but that LVNC is now grouped as an unclassified cardiomyopathy by the European Society of Cardiology [4]. We reported the following in our article [2]: There is controversy as to whether LVNC is congenital or acquired. In serial echocardiographic studies, LVNC was not diagnosed on the initial echocardiogram but was identified in subsequent examinations. Acquired hypertrabeculation or noncompaction has been reported in patients with neuromuscular disorders such as myotonic dystrophy [5, 6]. This suggests that noncompaction may be also acquired and may occur as part of a remodeling process of the myocardium secondary to pressure overload or myocardial damage to the ventricle [7]. We agree with the authors [1] that, in the case of vigorously training athletes, acquired hypertrabeculation may be present. The Multiethnic Study of Atherosclerosis [8] investigators emphasize that hypertrabeculation is probably caused by ventricular remodeling (as suggested in cases of acquired noncompaction) and that imaging diagnostic criteria actually used are too sensitive. In addition,
trabeculation can be influenced by race or ethnicity and, more importantly, by cardiac loading conditions and comorbidities [8]. LVNC has been reported in association with different gene mutations. Some of these mutations are associated with neuromuscular disorders, as the authors [1] mentioned, and others, such as sarcomeric mutations, are common with other cardiomyopathies (e.g., hypertrophic cardiomyopathy, dilated cardiomyopathy). These associations suggest that LVNC could be a phenotypic expression of these cardiomyopathies or neuromuscular disorders. As the authors assert, a causal relationship between a specific gene mutation and LVNC has not been proved. For this reason, LVNC cannot be classified as a “genetic cardiomyopathy.” We agree with the notion that LVNC does not follow “exclusively” an autosomal-dominant pattern of transmission. In our article [2], we reported that LVNC follows “predominantly” (not “exclusively”) an autosomal-dominant pattern of transmission; as the authors mentioned [1], autosomal-recessive transmission, X-linked transmission, and maternal transmission have been also reported. We agree with the authors that the reference standard for diagnosing LVNC should be anatomic studies; however, a diagnosis in vivo is important to prevent embolic or arrhythmogenic events that can lead to sudden death. Imaging plays a key role in the diagnostic process, and all imaging techniques present different advantages and limitations in this setting. My colleagues and I believe that cardiac MRI is the technique that presents more advantages than the other techniques. We agree with the authors that the quantification of trabeculated mass has limitations because the intertrabecular blood pool can be included in the trabeculated mass; however, the quantification of the trabeculated mass tends to be an objective value that can be useful in the diagnostic process, especially when all the other
imaging criteria are fulfilled. More data about a specific cutoff value to distinguish between a normal and abnormal amount of trabeculated mass are needed. Finally, we appreciate these relevant comments [1] about a topic as controversial as LVNC. Flavio Zuccarino Hospital del Mar Barcelona, Spain [email protected] DOI:10.2214/AJR.15.15562 WEB—This is a web exclusive article.
References
1. Finsterer J, Stöllberger C. Genetic, myopathic, and diagnostic implications of left ventricular noncompaction. (letter) AJR 2015; 260[web]:W46 2. Zuccarino F, Vollmer I, Sanchez G, Navallas M, Pugliese F, Gayete A. Left ventricular noncompaction: imaging findings and diagnostic criteria. AJR 2015; 204[web]:W519–W530 3. Maron BJ. The 2006 American Heart Association classification of cardiomyopathies is the gold standard. Circ Heart Fail 2008; 1:72–75; discussion, 76 4. Elliott P, Andersson B, Arbustini E, et al. Classification of the cardiomyopathies: a position statement from the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases. Eur Heart J 2008; 29:270–276 5. Stöllberger C, Finsterer J, Blazek G. Left ventricular hypertrabeculation/noncompaction and association with additional cardiac abnormalities and neuromuscular disorders. Am J Cardiol 2002; 90:899– 902 6. Finsterer J, Stöllberger C, Gaismayer K, Janssen B. Acquired noncompaction in Duchenne muscular dystrophy. Int J Cardiol 2006; 106:420–421 7. Ichida F. Left ventricular noncompaction. Circ J 2009; 73:19–26 8. Captur G, Zemrak F, Muthurangu V, et al. Fractal analysis of myocardial trabeculations in 2547 study participants: multi-ethnic study of atherosclerosis. Radiology 2015 Jun 10 [Epub ahead of print]
AJR 2016; 206:W47 0361–803X/16/2062–W47 © American Roentgen Ray Society
AJR:206, February 2016 W47
Letters Reply to “Genetic, Myopathic, and Diagnostic Implications of Left Ventricular Noncompaction” We thank Dr. Finsterer and Dr. Stöllberger for their interesting comments [1] about our article titled “Left Ventricular Noncompaction: Imaging Findings and Diagnostic Criteria” [2]. In our article [2], my colleagues and I never refer to left ventricular noncompaction (LVNC) as “exclusively a congenital abnormality.” In the Cause and Pathogenesis section of our article, we explain that LVNC was first classified as primary genetic cardiomyopathy by the American Heart Association [3] but that LVNC is now grouped as an unclassified cardiomyopathy by the European Society of Cardiology [4]. We reported the following in our article [2]: There is controversy as to whether LVNC is congenital or acquired. In serial echocardiographic studies, LVNC was not diagnosed on the initial echocardiogram but was identified in subsequent examinations. Acquired hypertrabeculation or noncompaction has been reported in patients with neuromuscular disorders such as myotonic dystrophy [5, 6]. This suggests that noncompaction may be also acquired and may occur as part of a remodeling process of the myocardium secondary to pressure overload or myocardial damage to the ventricle [7]. We agree with the authors [1] that, in the case of vigorously training athletes, acquired hypertrabeculation may be present. The Multiethnic Study of Atherosclerosis [8] investigators emphasize that hypertrabeculation is probably caused by ventricular remodeling (as suggested in cases of acquired noncompaction) and that imaging diagnostic criteria actually used are too sensitive. In addition,
trabeculation can be influenced by race or ethnicity and, more importantly, by cardiac loading conditions and comorbidities [8]. LVNC has been reported in association with different gene mutations. Some of these mutations are associated with neuromuscular disorders, as the authors [1] mentioned, and others, such as sarcomeric mutations, are common with other cardiomyopathies (e.g., hypertrophic cardiomyopathy, dilated cardiomyopathy). These associations suggest that LVNC could be a phenotypic expression of these cardiomyopathies or neuromuscular disorders. As the authors assert, a causal relationship between a specific gene mutation and LVNC has not been proved. For this reason, LVNC cannot be classified as a “genetic cardiomyopathy.” We agree with the notion that LVNC does not follow “exclusively” an autosomal-dominant pattern of transmission. In our article [2], we reported that LVNC follows “predominantly” (not “exclusively”) an autosomal-dominant pattern of transmission; as the authors mentioned [1], autosomal-recessive transmission, X-linked transmission, and maternal transmission have been also reported. We agree with the authors that the reference standard for diagnosing LVNC should be anatomic studies; however, a diagnosis in vivo is important to prevent embolic or arrhythmogenic events that can lead to sudden death. Imaging plays a key role in the diagnostic process, and all imaging techniques present different advantages and limitations in this setting. My colleagues and I believe that cardiac MRI is the technique that presents more advantages than the other techniques. We agree with the authors that the quantification of trabeculated mass has limitations because the intertrabecular blood pool can be included in the trabeculated mass; however, the quantification of the trabeculated mass tends to be an objective value that can be useful in the diagnostic process, especially when all the other
imaging criteria are fulfilled. More data about a specific cutoff value to distinguish between a normal and abnormal amount of trabeculated mass are needed. Finally, we appreciate these relevant comments [1] about a topic as controversial as LVNC. Flavio Zuccarino Hospital del Mar Barcelona, Spain [email protected] DOI:10.2214/AJR.15.15562 WEB—This is a web exclusive article.
References
1. Finsterer J, Stöllberger C. Genetic, myopathic, and diagnostic implications of left ventricular noncompaction. (letter) AJR 2015; 260[web]:W46 2. Zuccarino F, Vollmer I, Sanchez G, Navallas M, Pugliese F, Gayete A. Left ventricular noncompaction: imaging findings and diagnostic criteria. AJR 2015; 204[web]:W519–W530 3. Maron BJ. The 2006 American Heart Association classification of cardiomyopathies is the gold standard. Circ Heart Fail 2008; 1:72–75; discussion, 76 4. Elliott P, Andersson B, Arbustini E, et al. Classification of the cardiomyopathies: a position statement from the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases. Eur Heart J 2008; 29:270–276 5. Stöllberger C, Finsterer J, Blazek G. Left ventricular hypertrabeculation/noncompaction and association with additional cardiac abnormalities and neuromuscular disorders. Am J Cardiol 2002; 90:899– 902 6. Finsterer J, Stöllberger C, Gaismayer K, Janssen B. Acquired noncompaction in Duchenne muscular dystrophy. Int J Cardiol 2006; 106:420–421 7. Ichida F. Left ventricular noncompaction. Circ J 2009; 73:19–26 8. Captur G, Zemrak F, Muthurangu V, et al. Fractal analysis of myocardial trabeculations in 2547 study participants: multi-ethnic study of atherosclerosis. Radiology 2015 Jun 10 [Epub ahead of print]
AJR 2016; 206:W47 0361–803X/16/2062–W47 © American Roentgen Ray Society
AJR:206, February 2016 W47
