Key result
Novel algorithm identifies ~20% lower left ventricular superposition index in CRT patients versus healthy volunteers.
Why the study?
Does a computed algorithm evaluating LV wall motion throughout the whole cardiac cycle accurately quantify LV asynchrony and optimize VV intervals in patients undergoing CRT?
Observational (n=60)
Does a computed algorithm evaluating LV wall motion throughout the whole cardiac cycle accurately quantify LV asynchrony and optimize VV intervals in patients undergoing CRT?
Absolute Event Rate: 63% vs 83%
p-value: p=<0.05
A novel computed algorithm using TDI throughout the entire cardiac cycle effectively quantifies LV dyssynchrony and shows excellent concordance with established methods for optimizing CRT programming.
May support LV asynchrony quantification in CRT; leaves open VV optimization utility pending prospective validation.
INTRODUCTION: Measurement of left ventricular (LV) asynchrony is usually determined on single time points from spectral tissue Doppler imaging (TDI) scans that are frequently difficult to identify or not representative of the whole cardiac cycle. Our aim was to validate a new asynchrony index that evaluates the motion of the LV walls throughout the whole cardiac cycle. METHODS AND RESULTS: Ten healthy volunteers and 50 patients undergoing cardiac resynchronization therapy (CRT) were studied with TDI. Wall displacement tracings from the septal and lateral LV walls were analyzed. Cross-correlation was calculated and 2 indices were obtained to assess LV asynchrony: the time delay and the superposition index (SI) between wall displacements. These results were compared between healthy volunteers and CRT patients, and between responders and nonresponders to CRT. Also, the optimal interventricular (VV) interval was based upon the best matching level. Volunteers showed lower asynchrony indices (83 +/- 2% SI, 17 +/- 8 ms time delay) as compared with CRT patients (63 +/- 15% SI, 73 +/- 60 ms time delay, P < 0.05). Responders also had more LV dyssynchrony than nonresponders (58 +/- 15% SI and 92 +/- 66 ms vs 68 +/- 12% and 48 +/- 34 ms, P < 0.05). The optimum VV interval selected by the computed algorithm showed an excellent concordance (Kappa = 0.90, P < 0.05) with that determined by other validated methods for optimizing the programming of CRT devices. CONCLUSIONS: This approach allows measurement of LV intraventricular asynchrony throughout the cardiac cycle, being useful to determine the optimum VV interval and to select candidates for CRT.
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Silva et al. (2009) conducted an observational in Heart failure requiring cardiac resynchronization therapy (n=60). Computed algorithm for left ventricular asynchrony (superposition index and time delay) vs. Healthy volunteers and CRT nonresponders was evaluated on Superposition index (SI) for left ventricular asynchrony (p=<0.05). A new computed algorithm measuring left ventricular asynchrony throughout the cardiac cycle identified greater dyssynchrony in CRT patients versus healthy volunteers (superposition index 63% vs 83%, P<0.05).
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