We tested the ability of cross-correlation analysis of myocardial systolic acceleration (XCA), a new marker of dyssynchrony based on tissue Doppler echocardiography, to predict long-term outcome of cardiac resynchronization therapy (CRT) and to discriminate between control patients and patients with dyssynchrony.Methods
XCA was performed by off-line analysis of digitally stored myocardial velocity curves in 44 patients treated with CRT and followed for 13 ± 2 months. We tested the ability of preimplant XCA to identify long-term responders to CRT (defined by a decrease in left ventricular end-systolic volume > 15%). Dyssynchrony findings were compared between CRT responders and 83 age-matched control patients with narrow QRS complexes and different levels of systolic cardiac dysfunction. XCA was compared with conventional dyssynchrony analysis based on differences in time-to-peak myocardial velocity.Results
XCA was able to discriminate between long-term responders and nonresponders to CRT (area under the curve [AUC] = 0.66), but not significantly better than conventional analysis (AUC = 0.58). XCA showed large differences between the control groups and the CRT group (P < .01 for all), and had a higher discriminatory ability between normal controls and responders to CRT than conventional analysis (AUC = 0.95 vs 0.75, P < .01).Conclusion
XCA significantly improves the assessment of intraventricular dyssynchrony, and dyssynchrony by this method is associated with positive long-term response to CRT.