Increased super-relaxed myosin underlies the tension deficit in RV myocytes from hfref patients

Right ventricular (RV) function in Heart Failure with Reduced Ejection Fraction (HFrEF) is variable. We recently found that depressed RV myocyte calcium activated tension (Tmax) in part explains this variance. Here, we sought to determine whether alterations in thick filament structure explain depressed Tmax and account for this variability. In a cohort of 21 HFrEF patients, we collected X-ray diffraction patterns from RV septum and quantified equatorial intensity ratios, intensity at myosin layer line 1 (MLL-1), and spacing between myosin heads (SM3).