This book addresses an intriguing topic how myocyte nuclei of human hearts change in the end-stage cardiomyopathies. By means of image cytometric and confocal microscopic analyses, quantitative investigations were performed on myocardial cells from adult human hearts, as to explore the changes of myocyte nuclei in end-stage idiopathic dilated, ischemic and transplanted cardiomyopathies, which focused on the following issues about cardiomyocytes: DNA ploidy ranges, post-mortem changes in DNA content, degree of polyploidization and multinucleation, nuclear area, nuclear DNA ploidy patterns, mitoses, and chromatin bridge and extension. This book sheds lights on our understanding of the mechanisms for myocyte adaptation in pathological conditions and their dysfunction leading to cardiac deterioration.