Echocardiographic analysis
Transthoracic and transosephageal echocardiograpy were performed with Vivid E9 Ultrasound system (GE Healtcare, Waukesha, WI, USA), which had both multiplane 2 dimensional and real time 3 dimensional imaging capacity. In accordance with the guides of American Echocardiography Association, left ventricle end systolic diameters (LVESD) and end-diastolic diamaters(LVEDD) were measured in the parasternal long-axis view in resting state , using transthoracic echocardiography (TTE) . Left ventricle ejection fraction (LVEF) was calculated with three dimensional echocardiographic method. In order to determine the severity of MR, proximal isovelocity surface area (PISA) method was utilized. ERO (Effective regurgitant orifice area) and RV ( Regurgitant Volume ) measurements were carried out at both before CRT implantation and at the end of 3. month follow up control.
Responder / Non-responder Definiton: As recommended by the guides, over 0.1 cm2 decrease in ERO and 15ml and higher decrease in RV at the third month control TTE examination was regarded as improvement in MR and patients were divided into responder and non-responders according to this cutoff value.