The article "Hearts Apart: Sex Differences in Cardiac Remodeling in Health and Disease" by Thomas G. Martin and Leslie A. Leinwand highlights the significant role of biological sex in cardiac physiology and pathobiology. While heart disease is the leading cause of death worldwide, sex differences exist at both the organ and cellular levels, affecting clinical presentation, diagnosis, and treatment. The authors discuss baseline sex differences in cardiac structure, function, and cellular signaling, emphasizing the influence of sex hormones and chromosomes. They explore how the heart rapidly responds to physiological and pathological cues, with the extent and nature of cardiac remodeling often dependent on biological sex. The review covers organ- and molecular-level sex differences in adaptive and pathological cardiac remodeling, including conditions such as pressure and volume overload, ischemia, and genetic heart disease. Finally, the authors offer perspectives on future research directions, particularly in understanding the role of sex chromosomes in cardiac sex differences.The article "Hearts Apart: Sex Differences in Cardiac Remodeling in Health and Disease" by Thomas G. Martin and Leslie A. Leinwand highlights the significant role of biological sex in cardiac physiology and pathobiology. While heart disease is the leading cause of death worldwide, sex differences exist at both the organ and cellular levels, affecting clinical presentation, diagnosis, and treatment. The authors discuss baseline sex differences in cardiac structure, function, and cellular signaling, emphasizing the influence of sex hormones and chromosomes. They explore how the heart rapidly responds to physiological and pathological cues, with the extent and nature of cardiac remodeling often dependent on biological sex. The review covers organ- and molecular-level sex differences in adaptive and pathological cardiac remodeling, including conditions such as pressure and volume overload, ischemia, and genetic heart disease. Finally, the authors offer perspectives on future research directions, particularly in understanding the role of sex chromosomes in cardiac sex differences.