Echocardiographic determination of response to cardiac resynchronization therapy

Echocardiography not only plays a major role in quantifying cardiac mechanical dyssynchrony before cardiac resynchronization therapy (CRT), but also contributes to determining response to this important therapy. There has been increasing interest in refining patient selection for CRT, because the rate of non-responders may be 25-35%.^1,2 The definition of response to CRT has varied from study to study, including clinical response measures, such as New York Heart Association (NYHA) functional class, 6-minute walk distance, or a quality-of-life score questionnaire. These indices have been useful in several previous heart failure clinical trials. More objective measures of left ventricular (LV) structure and function have been promising following CRT in several investigations. Accordingly, this chapter will focus on the use of echocardiographic measures to quantify response to CRT.