Increased QT variability in patients with hypertrophic cardiomyopathy

The purpose of this study was to examine QT interval variability in hypertrophic cardiomyopathy (HCM) by using frequency domain indices. Twenty-six subjects participated to the study: 16 had HCM (5 females, 9 males; mean age 39/spl plusmn/13 years), 10 were healthy volunteers (5 females, 5 males, mean age 35/spl plusmn/13 years), who served as controls. Twenty-four-hour Holter recordings of each subject were analysed on a homemade Holter analyser. The following spectral domain measures of QT interval variability were computed: ultra low (ULF), very low (VLF), low (LF) high frequency (HF) and total power. Spectral domain measures of QT interval variability were significantly higher in subjects with HCM than in controls. Further studies are required to evaluate whether analysis of QT variability on Holter recordings might have prognostic implications.