3. METODOLOGIA
4.2 Género y construcción de la alteridad
4.2.3. Juego mixto
Several studies demonstrated the importance of the presence of significant baseline LV dys-
synchrony to predict response to CRT 4. Echocardiography and in particular tissue Doppler
and strain imaging have been extensively used to assess LV dyssynchrony and to predict
Chapter 9
182
response to CRT4,26. Nevertheless, the results of PROSPECT trial recently suggested that TDI
and conventional echocardiographic measures have limited value for prediction of response to CRT, when these techniques are applied in the community rather than in expert centers, indicating the need for sufficient training in data acquisition and analysis 13. In addition, novel techniques, such as 2D strain imaging and RT3DE, were not included in the PROSPECT trial and may provide complete and accurate information on LV dyssynchrony. In particular, RT3DE measures LV regional volumetric changes during the cardiac cycle, as a composite effect of longitudinal, radial and circumferential contraction. Kapetanakis et al demonstrated the feasibility of LV dyssynchrony assessment (SDI) with RT3DE in a large group of patients
and normal subjects 5; 26 patients underwent CRT implantation and responders to CRT had
significantly higher SDI at baseline than non-responders (16.6±1.1% vs. 7.1±2.0%, p <0.001). We obtained similar results: a higher baseline SDI was found in responders as compared to non-responders (9.7±3.6% vs. 5.1±1.8%, p <0.001), although the absolute SDI values were somewhat lower in the current study. This difference may be explained by the different software packages used for the 3D dataset analysis. In contrast to the TomTec software (used by Kapetanakis et al), the Q-Lab software uses a different contour tracing algorithm and does not permit the operator to change the point of Tmsv which is automatically detected, yield- ing a better reproducibility of the measurements but with a trend towards a lower SDI values. Direct comparisons are needed to elucidate these findings.
Furthermore, the cut-off value used by Kapetanakis et al for significant mechanical dys- synchrony was arbitrarily derived as an SDI >3SD above the mean value obtained in normal subjects (8.3%). We recently reported a cut-off value for SDI of 5.6% to optimally predict acute
echocardiographic response after CRT implantation 6, and a similar cut-off value (6.4%) was
obtained in the current study to predict response at 6 months follow-up.
study limitations
The patient cohort was relatively small and the predictive value of RT3DE needs to be as- sessed for clinical endpoints and confirmed in larger prospective studies.
Data on scar tissue and the exact LV lead position were not systematically available, which
have been shown to affect response to CRT 27,28. Also, the contribution of reduction in mitral
regurgitation on LA size and function after CRT should be explored in a larger group of patients.
183 RT3DE predicts LV and LA reverse remodeling after CRT
conclusIons
RT3DE allows assessment of the effects of CRT on LV and LA volumes and function. Baseline LV dyssynchrony (as measured with SDI) is predictive for echocardiographic response to CRT.
Chapter 9
184
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