Clinical Investigation
Hypertrophic Cardiomyopathy
Delayed Left Ventricular Untwisting in Hypertrophic Cardiomyopathy

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Background

Almost all patients with hypertrophic cardiomyopathy (HCM) have some degree of left ventricular (LV) diastolic dysfunction. Nevertheless, the pathophysiology remains incompletely characterized. Conceptually, an ideal therapeutic agent should target the underlying mechanisms that cause LV diastolic dysfunction. Assessment of diastolic LV untwisting could potentially be helpful to gain insight into the mechanism of diastolic dysfunction. The purpose of this study was to investigate LV untwisting in patients with HCM and control subjects.

Methods

LV untwisting parameters were assessed using speckle-tracking echocardiography in 75 consecutive patients with HCM and compared with those from 75 healthy control subjects.

Results

Untwisting at 5%, 10%, and 15% of diastole was lower in patients with HCM (all P values < .001) compared with control subjects. Peak diastolic untwisting velocity (−92 ± 32°/s vs −104 ± 39°/s, P < .05) and untwisting rate from peak systolic twist to mitral valve opening (MVO) (−37 ± 20°/s vs −46 ± 22°/s, P < .01) were lower, while the for diastolic duration normalized time-to-peak diastolic untwisting velocity (17 ± 9% vs 13 ± 9%, P < .05) was higher in patients with HCM. Untwisting rate from peak systolic twist to MVO was negatively correlated with the E/A ratio (R2 = 0.15, P < .01). Peak diastolic untwisting velocity and untwisting rate from peak systolic twist to MVO were increased in mild but decreased in moderate and severe diastolic dysfunction compared with control subjects.

Conclusion

LV untwisting is delayed in HCM, which probably significantly contributes to diastolic dysfunction.

Section snippets

Study Participants

The study population consisted of 75 consecutive nonselected patients in sinus rhythm with HCM (mean age, 42 ± 15 years; 54 men) and good echocardiographic image quality that allowed for complete segmental assessment of LV rotation at both the basal and apical LV levels. During the enrollment of these 75 patients with HCM, 31 other patients (29%) were excluded because of suboptimal echocardiographic image quality not fulfilling this criterion. These patients were compared with 75 healthy

Characteristics of the Study Population

In Table 1, clinical and echocardiographic characteristics of patients with HCM and control subjects are shown. LA volume indexed by body surface area, LV mass, maximal LV wall thickness, interventricular septal, and LV posterior wall dimensions were higher, whereas LV end-diastolic and end-systolic dimensions were lower in patients with HCM (all P values < .001). Furthermore, E-wave velocity and septal Em were lower, whereas E-wave velocity deceleration time, E/Em ratio, and isovolumic

Discussion

Echocardiography has been used since its early days to gain insight into the complex pathophysiology of HCM, because it provides a practical and comprehensive assessment of cardiac structure and function.16, 17 HCM is usually associated with alterations in LV diastolic function, whereas global systolic function is preserved until the later stages of the disease. In the present study, delayed LV untwisting, reflecting ineffective diastolic uncoiling of the hypertrophic myocardium, was shown in

Conclusion

Speckle-tracking echocardiography offers novel, noninvasive indices to assess LV diastolic function. In patients with HCM, delayed LV untwisting is seen, which probably significantly contributes to diastolic dysfunction.

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    Copyright © 2009 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.