OPA1 and familial dilated cardiomyopathy: Interestingly, there were no differences in atrial myocyte width, length or area between Ntg and DCM-dnPI3K mice (Figure 3A−D), suggesting that differences in atrial weight (Figure 1) were due to an expansion of extracellular matrix or differences in the non-myocyte cell population within the atria rather than myocyte hypertrophy.