Stress echocardiography for selecting potential responders to cardiac resynchronisation therapy

In the current ESC/ACC/AHA guidelines, the selection of patients for cardiac resynchronisation therapy (CRT) is based upon the QRS duration, which reflects interventricular dyssynchrony. However, about 30% of patients do not respond to CRT. It has previously been demonstrated that the presence of left ventricular mechanical dyssynchrony is predictive of response to CRT after implantation. Most criteria assessing such dyssynchrony were derived from data obtained with resting Doppler echocardiography. The recently published PROSPECT (Predictors of Response to CRT) trial failed to identify echocardiographic measures of dyssynchrony that could routinely be recommended for patient selection before CRT implantation. Therefore, solutions may come from other echocardiographic modalities, such as dobutamine stress echocardiography and exercise echocardiography. The purpose of this review is to evaluate the usefulness of stress echocardiography to predict response to CRT. This review will show how exercise-induced changes in dyssynchrony and severity of mitral regurgitation and the role of preserved contractile reserve may help to better identify potential responders.