Abstract 2819: Cross-correlation Analysis of Myocardial Velocity is Superior to Conventional Time-to-Peak Parameters for Quantifying Left Ventricular Dyssynchrony
Background-A recent study showed that the most commonly used Tissue Doppler imaging (TDI) parameters to diagnose left ventricular dyssynchrony agree only 50% of the time. Most of these parameters require calculation of the ``time-to-peak” myocardial velocity. This ``time-to-peak” based analysis utilizes only one of >100 data points collected per heart cycle.
Methods-We developed and tested a new dyssynchrony parameter, cross-correlation delay (XCD), that utilizes all velocity data points from 3 consecutive beats (~420 points). We hypothesized that XCD would be superior to existing methods at diagnosing dyssynchrony. We tested XCD on 11 members of a positive control group (echocardiographic responders to cardiac resynchronization therapy) and 12 members of a negative control group (normal echocardiogram and 12-lead ECG). We compared XCD to septal-to-lateral delay in time-to-peak (SLD), maximum difference in the basal 2- or 4-chamber times-to-peak (MaxDiff) and standard deviation of the 12 basal and mid-wall times-to-peak (Ts-SD).
Results-An XCD threshold of 31ms discriminated between positive and negative controls with 100% sensitivity and specificity (Figure 1⇓). SLD, MaxDiff and Ts-SD showed sensitivities of 36, 55 and 100% and specificities of 50, 42 and 50%, respectively. ROC analysis showed XCD and Ts-SD were superior to SLD and MaxDiff in discriminating between positive and negative controls (p<0.01). XCD was the only parameter which decreased after resynchronization in the positive controls (from 160±88ms to 69±61ms, p=0.003).
Conclusion-XCD is superior to existing parameters at discriminating patients with LV dyssynchrony from those with normal function.