Bridging integrator 1 (BIN1) is a membrane curvature protein which is richly spliced. We have identified a cardiac muscle splice variant (BIN1+13+17) now named cBIN1 1. In the past decade, it has been found that cBIN1 is responsible for calcium channel trafficking to carduac transverse-tubules (T-tubules) 2 as well as organizing microfolds of cardiac T-tubule membrane 1. The folds affect the local flow of ions 1 and help arrange cardiac dyads between L-type calcium channels and ryanodine receptors 3. In heart failure, cBIN1 is transcriptionally decreased 4, 5, affecting T-tubule architecture, and negative impacting calcium transients as well as cardiac function. Most recently, we found that normalization of cBIN1 in failing hearts can maintain microdomain structure, thereby preserving or even rescuing cardiac function. On the other hand, cBIN1-microfolds are externally released from normal cardiomyocytes 6. Using electron microscopy imaging with immunogold labeling, we found that cardiac origin cBIN1 exists in extracellular membrane vesicles known as microparticles. In human plasma, cBIN1 detection by an enzyme-linked immunosorbent assay (ELISA), is decreased in humans with heart failure, a condition with reduced cardiac muscle cBIN1. The clinical utility is significant. A cBIN1 Score (CS) based on plasma cBIN1 levels was studied in patients with heart failure. In our first cohort of heart failure with preserved ejection fraction, CS outperforms current biomarkers for the diagnosis of heart failure, and also can accurately predict future hospitalization in heart failure patients 7. The data indicate that myocardial cBIN1 not only can serve as a target for new heart failure therapy development, but also is continuously released into blood. The blood-based CS can therefore serve as a clinical biomarker of cardiomyocyte remodeling, aiding in the management of heart failure patients.