The relation of ventricular arrhythmia electrophysiological characteristics to cardiac phenotype and circadian patterns in hypertrophic cardiomyopathy

Most VAs are monomorphic ventricular tachycardias triggered by late-coupled PVCs. They are frequently terminated by ATP, but ATP does not reduce the frequency of ICD shocks. Younger HCM patients have more rapid VAs, which may explain the peak of sudden cardiac death in early adulthood. The circadian periodicity is different from that observed in ischaemic heart disease, and is likely to relate to the distinct character of the arrhythmogenic substrate in HCM and its modulators.