Long QT Syndrome Patients With Mutations of the <i>SCN5A</i> and <i>HERG</i> Genes Have Differential Responses to Na ⁺ Channel Blockade and to Increases in Heart Rate

Abstract

This is the first study to demonstrate differential responses of LQTS patients to interventions targeted to their specific genetic defect. These findings also suggest that LQT3 patients may be more likely to benefit from Na+ channel blockers and from cardiac pacing because they would be at higher risk of arrhythmia at slow heart rates. Conversely, LQT2 patients may be at higher risk to develop syncope under stressful conditions because of the combined arrhythmogenic effect of catecholamines with the insufficient adaptation of their QT interval when heart rate increases.