Relationship between MRI-based mechanical activation delays and direct intraoperative measurements of electrical delay in patients undergoing cardiac resynchronization

Background Magnetic Resonance Imaging (MRI) can be used to create maps of left ventricular (LV) mechanical activation delay by analyzing time-dependent radial motion of the myocardium. Local electrograms (EGM) can be obtained during the CRT procedure to measure local electrical activation delay in the LV myocardium. Preoperative MRI assessment of regional dyssynchrony would be useful to guide CRT lead placement. However, the relationship between electrical and mechanical dyssynchrony has not been studied in humans. We hypothesized that intraoperative electrical delay times will correlate with MR-based mechanical delay times.