This Article Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Maron, B. J. Articles by Lesser, J. R. Search for Related Content PubMed PubMed Citation Articles by Maron, B. J. Articles by Lesser, J. R. Related Collections Myocardial cardiomyopathy disease CT and MRI Echocardiography Genetics of cardiovascular disease Related Article

(Circulation. 2007;115:e627-e628.)
© 2007 American Heart Association, Inc.

Images in Cardiovascular Medicine

Diagnostic Utility of Cardiac Magnetic Resonance Imaging in Monozygotic Twins With Hypertrophic Cardiomyopathy and Identical Pattern of Left Ventricular Hypertrophy

Barry J. Maron, MD; Tammy S. Haas, RN; John R. Lesser, MD

From the Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, Minn.

Correspondence to Barry J. Maron, MD, Minneapolis Heart Institute Foundation, 920 East 28th Street, Suite 60, Minneapolis, MN 55407. E-mail hcm.maron{at}mhif.org

Female, 18-year-old, monozygotic twins, had cardiac evaluations as a result of the suspicion of hypertrophic cardiomyopathy (HCM). Each was asymptomatic with active normal lifestyle. Both twins had normal 2-dimensional echocardiograms, which did not identify wall thickening in any segment of the left ventricular (LV) chamber (Figure). Mild systolic anterior motion of the mitral valve (associated with normal LV outflow tract velocities) and mitral regurgitation were present in both patients. LV end-diastolic cavity dimensions (40 and 34 mm, respectively) and left atrial dimension (20 and 28 mm, respectively) were similar. In each twin, 12-lead ECGs were abnormal but showed different patterns. Twin 1 had minor ST-T abnormalities and Twin 2 showed distinctively deep and narrow Q-waves in leads II, III, AVF, and V4–V6 (Figure).

View larger version (56K): [in this window] [in a new window]   Asymptomatic identical twins (18 years of age) with nonobstructive hypertrophic cardiomyopathy are depicted. Shown for Twin 1 are a representative CMR image (A), a 2-dimensional echocardiogram at mitral valve level (B), and a 12-lead ECG (C). The same studies are shown for Twin 2 in D, E, and F, respectively. Short-axis CMR images and echocardiograms are shown at the same cross-sectional level of the basal LV. Echocardiograms in both twins show normal LV wall thickness without evidence of hypertrophy (10 mm in Twin 1 (B) and 9 mm in Twin 2 (E), demarcated by solid white line at the 1 o’clock position). However, CMR imaging demonstrated virtually identical regions of segmental hypertrophy localized to the anterior LV free wall (white arrows), which measured 16 mm in each twin (A and D). Delayed enhancement was absent in both patients. The ECGs shown at the bottom are not identical; both twins show high voltages and T-wave inversion, but Twin 2 (F) also demonstrates deep and narrow Q-waves that are diffusely distributed. Calibration dots for echocardiogram are 10 mm apart. CMR indicates cardiovascular magnetic resonance; VS, ventricular septum.

Of note, cardiac magnetic resonance (CMR) imaging identified a virtually identical pattern of asymmetric LV wall thickening confined to the anterior free wall, undetected by echocardiography and measured at 16 mm in both twins (Figure). Therefore, because CMR imaging is more reliable than echocardiography in the definition of wall thickness in the anterolateral LV free wall,¹ only CMR imaging permitted recognition of LV hypertrophy (ie, the HCM phenotype) and ultimately the correct diagnosis in these twins.

These images are notable on 2 points. First, monozygotic twins show identical LV morphology (ie, magnitude and distribution of hypertrophy). These findings support the view that genetic background represents the primary determinant of the HCM phenotype, and also suggest that environmental factors probably have limited impact on the morphological expression of this disease. Second, in contrast to 2-dimensional echocardiography, only CMR imaging has the diagnostic power to reliably identify segmental hypertrophy confined to the anterior LV free wall in patients with HCM.

	Disclosures

Top Disclosures References

 
None.

	Footnotes

 
The online-only Data Supplement, which consists of Movies I and II, is available with this article at http://circ.ahajournals.org/cgi/ content/full/115/24/e627/DC1.

	References

Top Disclosures References

 

1. Rickers C, Wilke NM, Jerosch-Herold M, Casey SA, Panse P, Panse N, Weil J, Zenovich AG, Maron BJ. Utility of cardiac magnetic resonance imaging in the diagnosis of hypertrophic cardiomyopathy. Circulation. 2005; 112: 855–861[Abstract/Free Full Text]
   

Related Article:

Issue Highlights
Circulation 2007 115: 3039. [Full Text]

This Article Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Maron, B. J. Articles by Lesser, J. R. Search for Related Content PubMed PubMed Citation Articles by Maron, B. J. Articles by Lesser, J. R. Related Collections Myocardial cardiomyopathy disease CT and MRI Echocardiography Genetics of cardiovascular disease Related Article