Abstract 19261: The Mechanism and Predictive Value of QRS Shortening in Cardiac Resynchronization Therapy in Patients With Heart Failure

Introduction: Cardiac resynchronization therapy (CRT) improves systolic function and decreases arrhythmic events in heart failure (HF). HF is known to be associated with a reduction in Sarco/Endoplasmic Reticulum Ca ATPase (SERCA2a) levels. Recently, we have shown that HF downregulates full-length cardiac sodium channel (SCN5A) mRNA and upregulates the splicing variant D (VD) encoding a nonfunctional channel. The ratio of circulating VD to full-length mRNA can predict the risk of sudden death. Hypothesis: We tested whether CRT altered circulating SERCA, full-length SCN5A mRNA and VD and further investigated its correlation with clinical parameters. Methods: HF patients with new implantable cardioverter-defibrillators (ICDs) for primary prevention were enrolled. Clinical parameters including native QRS width and left ventricular ejection fraction (LVEF) were measured. Circulating SERCA, SCN5A and VD levels at baseline and at a follow-up visit were measured and compared using the ratio of SERCA2a to β-actin...