Echocardiographic evaluation of ventricular dyssynchrony: a comparison between strain Doppler echocardiography and radionuclide angiocardiography

Background. Several parameters have recently been proposed to assess mechanical dyssynchrony both in tissue Doppler / strain Doppler imaging (TDI/SRI) and radionuclide angioscintigraphy (RNA). It is unknown whether large differences exist between SRI and RNA to evaluate inter- and intra-ventricular dyssynchrony and whether the results are interchangeable. Methods. Thirty-two patients with dilated cardiomyopathy (NYHA class II or greater), left bundle branch block (QRS >120ms), and LV ejection fraction <35% were studied with SRI echocardiography and RNA before and after biventricular pacing (BP). Intraventricular dyssynchrony was determined as the difference between the longest and shortest electromechanical coupling times in the basal septal, lateral, and posterior LV segments. Interventricular dyssynchrony was determined as the difference between electromechanical coupling times in the basal lateral RV segment and the most delayed LV segment. On line continuous LV volume changings were recorded using RNA and interventricular delay and basal-apical contraction were obtained. Results. At six months follow-up after BV implantation, patients functional status improved by one NYHA class or more and LVEF improved overall from 20.4 +/- 7.9% to 28.9 +/- 13.2%. Interventricular dyssynchrony by SRI was reduced from 79.3 +/- 38 ms to 34.7 +/- 27.2 ms (p<0.005) and intraventricular dyssynchrony from 74 +/- 32.4 ms to 24.6 +/- 17.8 ms (p<0.001). Interventricular dyssynchrony by RNA was reduced from 72 +/- 39 ms to 13.9 +/- 37.2 ms (p<0.001) and apicobasal intraventricular dyssynchrony from 67.4 +/- 31.2 ms to 16.8 +/- 22.7 ms (p<0.001). SRI and RNA parameters had optimal predictive accuracy of the effects of BP on LV function and a larger area under the receiver operating characteristic curve than the QRS duration. Overall agreement between SRI and RNA was 89% (k= 0.62). Conclusion. SRI and RNA dyssynchrony measurements have an acceptable observer variability and values are largely comparable in pts with poor LV function and broad QRS.