There are no significant differences in clinical presentation, ECG parameters, and cardiac events among LQT1 patients with different locations of KCNQ1 mutations.
In 118 genetically-confirmed LQT2 patients (69 families, 62 KCNH2 mutations), the ECG parameters, Schwartz scores, and the incidence of cardiac events, defined as syncope, aborted cardiac arrest, and sudden cardiac death, were evaluated.
The risk of cardiac events is significantly higher among subjects with mutations at the LQT1 or LQT2 locus than among those with mutations at the LQT3 locus.
Excitement, exercises, and stress appear to be the triggers for developing cardiac events (syncope, sudden death) for LQTS patients with KCNQ1 mutations F275S, S277L, and G306V, and all three KCNH2 mutations L413P, E444D and L559H.
The purpose of this study was to investigate whether KCNQ1 mutations in highly conserved amino acid residues within the voltage-gated potassium channel family are associated with an increased risk of cardiac events.
This mutation, Ala561Thr, in the coding sequence of the fifth membrane-spanning domain (S5) of the HERG protein seems to convey a risk of cardiac events in affected family members.
The risk of cardiac events was significantly lower in LQT1 girls than boys≤12 years (HR, 0.55), whereas LQT2 female patients ≥13 years had the higher risk of cardiac events than male patients (HR, 4.60).
By correlating the clinical phenotype of 387 LQT1 patients with the cellular electrophysiological characteristics caused by an array of mutations in KCNQ1, we found that channels with a decreased rate of current activation are associated with increased risk of cardiac events (hazard ratio=2.02), independent of the clinical parameters usually used for risk stratification.
The risk varies by age among 3 genetic types of LQTS: LQT1 carriers are at higher risk of cardiac events between age 5 to 15 years than below age of 5 years, LQT2 carriers have the highest risk of cardiac events at age 10 to 15, and LQT3 carriers have infrequent cardiac events below age of 10 years.
The risk of cardiac events in LQT2 carriers with normal QTc is associated with abnormal T-wave morphology in women and pore location of mutation in men.
We provide evidence that the KCNQ1rs2074238 polymorphism is an independent risk modifier with the minor T-allele conferring protection against cardiac events in patients with LQTS.
The QTc duration and the frequency of cardiac events (syncope and LQTS-related cardiac arrest/death) were similar among carriers with the five HERG mutations.
The most common inherited cardiac arrhythmia, LQT1, is due to IKs potassium channel mutations and is linked to high risk of adrenergic-triggered cardiac events.
The risk varies by age among 3 genetic types of LQTS: LQT1 carriers are at higher risk of cardiac events between age 5 to 15 years than below age of 5 years, LQT2 carriers have the highest risk of cardiac events at age 10 to 15, and LQT3 carriers have infrequent cardiac events below age of 10 years.
Recent data showed that long QT syndrome (LQTS) patients with mutations in the pore region of the HERG (LQT2) gene have significantly higher risk of cardiac events than subjects with mutations in the non-pore region.
The LQTS score is a reasonable indicator for evaluating school-aged children with a b-LQT, and patients with a low LQTS score appear to be at low risk for cardiac events.
The risk of cardiac events was significantly lower in LQT1 girls than boys≤12 years (HR, 0.55), whereas LQT2 female patients ≥13 years had the higher risk of cardiac events than male patients (HR, 4.60).
The risk of cardiac events is significantly higher among subjects with mutations at the LQT1 or LQT2 locus than among those with mutations at the LQT3 locus.