European Heart Journal Advance Access originally published online on September 13, 2007
European Heart Journal 2007 28(20):2554-2555; doi:10.1093/eurheartj/ehm373
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Effect of dynamic myocardial dyssynchrony on mitral regurgitation during supine bicycle exercise stress echocardiography in patients with idiopathic dilated cardiomyopathy and ‘narrow ’QRS: reply
Second University of Naples
Monaldi Hospital
Via G. Martucci 35 80121 Naples
Italy
Second University of Naples
Monaldi Hospital
Via L. Bianchi 6 80100 Naples
Italy
Tel: + 39 0817618525 Fax: + 39 0817145205 E-mail address: antonellodandrea{at}libero.it
E-mail address: raffaele.calabro{at}unina2.it
We thank Song very much for the interest in our manuscript.1 In our work, we demonstrated a significant increase in left ventricular (LV) intra-ventricular delay during physical effort, as well as a significant correlation of asynchronous activation of LV segments during effort and exercise-induced changes in mitral regurgitation and LV stroke volume, in a selected population of 60 patients with idiopathic dilated cardiomyopathy (DCM) and narrow QRS.
As properly underlined by Song, in our study, we did not report any correlation of changes of inter-ventricular myocardial delay with either mitral regurgitation or stroke volume during effort, because such correlations were not significant. Our results are not surprising, considering that in a whole population of 230 DCM patients studied during physical effort also in previous articles by Lancellotti et al., 2 Ennezat et al., 3 and Lafitte et al., 4 no significant correlation between inter-ventricular delay and dynamic mitral regurgitation was observed. Therefore, even admitting that septal displacement due to right ventricular overload during effort may increase both inter-ventricular delay and diastolic mitral regurgitation as a result of ventricular interaction,5 other mechanisms strongly associated with intra-ventricular delay such as systolic displacement of the mitral leaflet body into the LV cavity and changes in systolic tenting area and in synchronicity between the two papillary muscles could be more determinant in the worsening of functional mitral regurgitation.6
As for the evaluation of atrioventricular (AV) delay during effort, unfortunately from the letter, it is not clear which measurements should have been included in our study. In fact, Song reports the results of an interesting article by Breithardt et al., 7 who showed the acute effects of biventricular pacing on maximal rate of LV systolic pressure rise and the correlation between such increase in LV dP/dtmax and changes in mitral valve regurgitation. However, the echocardiographic method largely used for optimization of AV delay is the Ritter's mitral inflow method, which requires measurements derived from recordings of the pulsed Doppler mitral inflow velocity during different pacing modalities with long and short AV delay intervals.8 Considering that our study protocol included evaluation of electromechanical delay both at rest and during stress test, an accurate evaluation of changes in pulsed Doppler mitral flow during physical effort was not feasible, as an overlapping of E and A waves was strongly associated with the increase in the heart rate during stress. In fact, also in previous studies on this topic, the AV delay analysis during exercise was not considered.2–4
References
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