Dynamic Left Ventricular Dyssynchrony Assessed on 3-Dimensional Speckle-Tracking Area Strain During Dobutamine Stress Has a Negative Impact on Cardiovascular Events in Patients With Idiopathic Dilated Cardiomyopathy

BACKGROUND: Left ventricular (LV) dyssynchrony is not a stable phenomenon, but rather, changes dynamically. Given that the prognostic impact of dynamic dyssynchrony has not yet been elucidated, the objective was to investigate the clinical impact of dynamic dyssynchrony on patients with dilated cardiomyopathy (DCM). METHODS AND RESULTS: Seventy DCM patients with ejection fraction 32±9% were retrospectively recruited, and 3-dimensional speckle-tracking area strain was used to measure both contractile reserve and changes in dyssynchrony during dobutamine stress. The standard deviation of time-to-peak area strain was adopted as the systolic dyssynchrony index. Event-free survival was then tracked over a 13-month period. A ≥7.55% increase in systolic dyssynchrony index during dobutamine stress (Δsystolic dyssynchrony index) was the best predictor of cardiovascular events with 77% sensitivity and 88% specificity. Multivariate Cox analysis indicated that not only the absence of contractile reserve (Δglobal area strain ≤21.1%: hazard ratio [HR], 15.29; P=0.01), but the presence of dynamic dyssynchrony (ΔLV dyssynchrony ≥7.55%: HR: 7.591; P=0.003) was an independent predictor of cardiovascular events. Importantly, absence of dynamic dyssynchrony and presence of contractile reserve were associated with the most favorable outcome (98%), whereas the reverse condition was associated with the worst outcome (20%, P<0.001). CONCLUSIONS: Dynamic dyssynchrony is a potential predictor of cardiovascular events in patients with DCM, while assessment of dynamic dyssynchrony in combination with contractile reserve may further improve prognostic risk stratification.