Echo Assessment of Intraventricular Dyssynchrony (IMPROVE)

Background. Clinical benefits of cardiac resynchronization therapy (CRT) have been clearly demonstrated in heart failure (HF) patients with severe left ventricular (LV) dysfunction and wide QRS at surface electrocardiogram. However, there is a growing evidence that QRS duration poorly predicts responses to CRT, and that ~30% of patients do not experience any benefit from CRT when pre-implant dyssynchrony is defined according to electrocardiographic criteria. A number of echocardiographic criteria have been proposed to assess mechanical LV dyssynchrony, but at present there is no consensus on their use to predict response to CRT.

Study Design. The Italian Multicenter PROject on echo assessment of left VEntricular (IMPROVE) dyssynchrony study is a prospective, multicenter, observational study aimed to assess feasibility and predictive power of mechanical dyssynchrony assessed by echocardiography in consecutive consenting patients candidate to CRT by clinical and electrocardiographic criteria. IMPROVE will enroll 120 healthy subjects and 216 HF patients in 6 sites in Italy. CRT response criteria will be based on improvement in NYHA class and LV reverse remodeling evaluated by 3D-echocardiography. Enrollment is expected to conclude early 2009.

Implications. CRT is today part of the therapeutic armamentarium for symptomatic HF patients refractory to medical therapy, with wide QRS complex and severe LV systolic dysfunction. The IMPROVE study has been designed to evaluate reference values of indexes of ultrasound mechanical dyssynchrony that have been proposed in the literature and compare their ability to predict response to CRT in HF patients.