Figure 2.

Non-linear relationship in the estimated rate of patients being free of cardiac events at 40 years of age and QT interval corrected for heart rate (QTc). The study included 647 patients from families with long-QT syndrome divided into four quartiles based on QTc interval. ‘Cardiac events’ were defined as the occurrence of syncope, cardiac arrest or sudden death, and these increased non-linearly with increasing QTc. Data were extracted from a Kaplan–Meier survival graph presented in Priori et al (2003) ⁸ using WebPlotDigitizer v3.9.