Our main findings are that (i) univariate and multivariate analyses yield very similar results and low variability of parameters yields more reliable multivariate sensitivity analyses, (ii) despite exacerbating Ca2+ impairment in HF, fibroblast to myocyte coupling does not alter the role of the main mechanisms regulating Ca2+ dynamics in myocytes, and (iii) drug action on ICaL and SERCA enhancement and NCX block would help CaT restoration in HF regardless of fibrosis presence. Here, CAT is linked to hydrops fetalis.