Hypertrophic cardiomyopathy is a heart disease that leads to a stressed, swollen heart muscle. Due to a poor understanding of underlying mechanisms, effective clinical treatments are not available. Patients receive generic heart medication and sometimes need open-heart surgery to remove excess tissue. Researchers have now successfully applied a new revolutionary technology (scRNA-seq) to uncover underlying disease mechanisms, including specifically those causing the swelling. The extensive 'big data' set is a treasure trove of novel observations that give insight in hypertrophic cardiomyopathy and potential new therapeutic venues.