Corrected Left Ventricular Electrical Delay Predicting Response to Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is a well-established treatment for patients with severe systolic heart failure (HF) and ventricular desynchronization. Despite the consistently observed structural and functional improvements as well as reductions in HF events and mortality in large multicenter randomized trials, 30% patients remain classified as nonresponders. Present evidences showed that QRS duration was the most effective parameter to predict responsivity of CRT in patients with severe HF. But some studies showed that QRS duration could be influenced by obesity and gender. Accordingly, the simple QRS interval width of body surface electrocardiograph should not be the most satisfactory parameter for screening patients suitable for CRT. Recent study showed that left ventricular electrical delay, as measured by the time from the onset of QRS to the LV electrogram peak (QLV), predicted CRT response. At long QLV intervals, atrioventricular optimization (AVO) can increase the likelihood of structural response to CRT. However, it is unclear whether it is suitable for Chinese patients. The investigators would like to validate this relation in a Chinese population and explore if a corrected QLV might do better to predict the responsivity of CRT.