European Heart Journal Advance Access originally published online on April 24, 2007
European Heart Journal 2007 28(9):1174; doi:10.1093/eurheartj/ehm060
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Analysis of myocardial deformation based on ultrasonic pixel tracking to determine transmurality in chronic myocardial infarction: reply
Medical Clinic I
University RWTH Aachen
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Tel: +49 241 8088468, Fax: +49 241 8082414, E-mail address: rhoffmann{at}ukaachen.de
We read with great interest the letter by Ze-Zhou Song et al.1 Ze-Zhou Song et al. raise important issues on the impact of different disease conditions on segmental as well as global left ventricular function. Myocardial function may be impaired even without ischaemic events in hypertensive patients with left ventricular hypertrophy as has been shown in multiple studies. Similar impairment of myocardial function has been shown for several other conditions. Thus, the findings of our study have to be seen on the background of these well-known factors affecting global and regional left ventricular function even without ischaemic events. Some of these factors are not infrequent in clinical practice. However, the impact of most of these disease entities on left ventricular function is rather limited if extreme presentations are excluded in comparison with the impact of partial or complete transmural myocardial infarction. Nevertheless, these factors may impair the capacity to differentiate different transmurality states of myocardial infarction. The described diagnostic accuracy in our study to differentiate between transmural and non-transmural myocardial infarction was not optimal.2 The non-optimal diagnostic accuracy may in part be explained by ‘noise effects’ induced from comorbidities mentioned by the authors. A limitation of patient inclusion to patients without such comorbidities may have increased the diagnostic accuracy for the endpoint ‘definition of transmurality in myocardial infarction’. However, we intentionally decided not to limit our study to special patient subgroups. This approach is in accordance with other investigations, which evaluated the accuracy of new diagnostic modalities to define myocardial viability. Only an approach which does not exclude different patient subgroups warrants greater applicability of the study results to a wide variety of patients. We did not perform subanalysis on different patient subsets with specific comorbidities. Such subanalysis would have requested to account for different disease severity, inducing a high complexity of result reporting. We do not believe that this would have facilitated the application of the method in clinical practice. However, Ze-Zhou Song et al. are correct that the clinician applying deformation imaging methods for analysis of myocardial viability should consider potential conditions resulting in impaired function.
In addition, the authors correctly mention that myocardial contraction is a complex 3-dimensional process. Analysis of longitudinal motion has been possible using tissue Doppler imaging and was used by Zhang et al.3 for discrimination of different transmurality states of myocardial infarction. We applied a completely different echocardiographic modality which allows analysis of myocardial deformation based on tissue pixel tracking. It allows, based on short-axis views, the analysis of radial and circumferential deformation parameters. We did not analyse longitudinal motion that is not accessable from parasternal short-axis views. We agree that an analysis on the complementary value of the different deformation parameters may be desirable in the future.
References
- Ze-Zhou Song MM, Jing Ma MM. Analysis of myocardial deformation based on ultrasonic pixel tracking to determine transmurality in chronic myocardial infarction. Letter to Editor. Eur Heart J (2007).
- Becker M, Hoffmann R, Kühl HP, Grawe H, Katoh M, Kramann R, Bücker A, Hanrath P, Heussen N. Analysis of myocardial deformation based on ultrasonic pixel tracking to determine transmurality in chronic myocardial infarction. Eur Heart J (2006) 27:2560–2566.
[Abstract/Free Full Text] - Zhang Y, Chan AKY, Yu CM, Yip GWK, Fung JWH, Lam WWM, So NMC, Wang M, Wu EB, Wong JT, Sanderson JE. Strain rate imaging differentiates transmural from non-transmural myocardial infarction: a validation study using delayed-enhancement magnetic resonance imaging. J Am Coll Cardiol (2005) 46:864–871.
[Abstract/Free Full Text]
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