Echocardiography of cardiac aging in wild-type (WT) and mCAT mice (A-D) and Polgm/mmice in the presence or absence of mCAT (E-H). (A, E) Left ventricular mass index (LVMI), (B, F) % FS (fractional shortening), (C, G) Ea/Aa by tissue Doppler imaging (diastolic function), (D, H) the myocardial performance index (MPI). The increased linear trends across ages in WT mice were significant for all parameters (P <0.05 for all, left panels). The beneficial effect of mCAT versus WT was analyzed by the interaction between genotype and the linear age trend, and was significant in all cases (P <0.01 for all except fractional shortening, P = 0.03). *P <0.05 versus Polgm/m at age 4 to 6 months, #P <0.05 versus Polgm/m at age 13 to 14 months (right panels). LVMI, Left ventricular mass index; mCAT, catalase targeted to mitochondria. Modified from Dai et al. [25, 43].