It is known that IL11 is produced endogenously in the heart in mice following transverse aortic constriction and angiotensin II infusion45 and in humans with atrial fibrillation46 and heart failure.47 However, whether endogenous IL11 is toxic to CMs and negatively inotropic in heart failure syndromes is not known and we cannot extrapolate from the data seen with acute, high dose injection of recombinant protein. The gene discussed is IL11; the disease is heart failure.