Key result
Long QT syndrome exhibits steeper heart rate dependence of QT duration than controls (0.347 vs 0.162; P<0.05), with LQT2 and LQT3 showing steeper dependence than LQT1 (0.623 vs 0.19; P<0.05).
Why the study?
How does the heart rate dependence of QT interval duration differ among long QT syndrome genotypes and control subjects?
Population
Patients with congenital long QT syndrome (LQT1, LQT2, LQT3) and control subjects
Design
Cross-sectional
Authors
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May refine noninvasive LQTS assessment; leaves open whether QT-heart rate slopes improve genotype-specific risk stratification.
Observational
How does the heart rate dependence of QT interval duration differ among long QT syndrome genotypes and control subjects?
Absolute Event Rate: 0.347% vs 0.162%
p-value: p=< 0.05
Individual long QT syndrome genotypes exhibit different QT interval dependence on heart rate, which may explain the propensity of LQT2 and LQT3 patients to develop arrhythmias during bradycardia.
Němec et al. (2004) conducted an observational in congenital long QT syndrome. Long QT syndrome vs. Control subjects was evaluated on Dependence of QT duration on heart rate at 100 beats/min (p=< 0.05). Long QT syndrome exhibits steeper heart rate dependence of QT duration than controls (0.347 vs 0.162; P<0.05), with LQT2 and LQT3 showing steeper dependence than LQT1 (0.623 vs 0.19; P<0.05).