Changes in (A) body weight, (B) body surface area, (C) left atrium, (D) LV internal dimension at diastole, (E) LV internal dimension at systole, (F) aorta, (G) interventricular septum thickness at diastole, (H) interventricular septum thickness at systole, (I) left atrium:aorta ratio, (J) LV posterior wall thickness at diastole, and (K) LV posterior wall thickness at systole in both groups during the study. Data presented are means; error bars are SEM. The weeks represent time after SIV inoculation. Week 4 data represent the baseline data collected 4 weeks after SIV inoculation but immediately before starting the study interventions (ActRIIB.Fc or saline injections); week 16 data represent data collected after 12 weeks of intervention. LV, left ventricular; SIV, simian immunodeficiency virus.