Combined assessment of left ventricular dyssynchrony and contractility by speckled tracking strain imaging: a novel index for predicting responders to cardiac resynchronization therapy.

BACKGROUND

Mechanical dyssynchrony is an important factor in the response to cardiac resynchronization therapy (CRT). However, no echocardiographic measure can improve prediction of case selection for CRT.

OBJECTIVE

The purpose of this study was to assess the efficacy of a newly combined echocardiographic index for ventricular dyssynchrony and contractility using speckled tracking strain analysis to predict responders to CRT.

METHODS

Forty-seven patients with severe heart failure in New York Heart Association functional class III/IV, left ventricular ejection fraction </=35%, and QRS duration >/=130 ms were included in the study. Echocardiography was performed, and a novel index (i-Index), the product of radial dyssynchrony and radial strain, was calculated. Responder to CRT was defined as a patient with a >/=15% decrease in left ventricular end-systolic volume at 6-month follow-up.

RESULTS

Thirty-two patients (68%) were classified as responders. The i-Index was significantly higher in responders than in nonresponders (3,450 +/- 1180 vs 1,481 +/- 841, P <.001). The area under receiver operator characteristic curve was 0.92 for the i-Index, which was better than the index of radial dyssynchrony only (0.74). A cutoff value of i-Index >2,000 predicted responders with 94% sensitivity and 80% specificity. The index using only radial dyssynchrony had 81% sensitivity and 53% specificity. Furthermore, i-Index decreased in responders (1,985 +/- 1261, P <.001) but not in nonresponders (1,684 +/- 866, P = .48).

CONCLUSION

Our findings suggest that a novel combined index by radial strain echocardiography might be a predictor of response to CRT. The value of this novel echocardiographic index requires further assessment in larger studies.