Cardiac Resynchronization and Circulating Markers of Sarcoplasmic Reticulum Calcium Handling and Sudden Death Risk.

Cardiac resynchronization therapy (CRT) can improve heart function and decrease arrhythmic events. We tested whether CRT altered circulating markers of calcium handling and sudden death risk. Circulating cardiac sodium channel messenger RNA (mRNA) splicing variants indicate arrhythmic risk, and a reduction in sarco/endoplasmic reticulum calcium adenosine triphosphatase 2a (SERCA2a) is thought to diminish contractility in heart failure. CRT was associated with a decreased proportion of circulating, nonfunctional sodium channels and improved SERCA2a mRNA expression. Patients without CRT did not have improvement in the biomarkers. These changes might explain the lower arrhythmic risk and improved contractility associated with CRT.