Type 3 long QT syndrome: Is the effectiveness of treatment with beta-blockers population-specific?

BACKGROUND

The efficacy of beta-blocker treatment in type 3 long QT syndrome (LQT3) remains debated.

OBJECTIVES

The purpose of this study was to test the hypothesis that beta-blocker use is associated with cardiac events (CEs) in a French cohort of LQT3 patients.

METHODS

All patients with a likely pathogenic/pathogenic variant in the SCN5A gene (linked to LQT3) were included and followed-up. Documented ventricular tachycardia/ventricular fibrillation, torsades de pointes, aborted cardiac arrest, sudden death, and appropriate shocks were considered as severe cardiac events (SCEs). CEs also included syncope.

RESULTS

We included 147 patients from 54 families carrying 23 variants. Six of the patients developed symptoms before the age of 1 year and were analyzed separately. The 141 remaining patients (52.5% male; median age at diagnosis 24.0 years) were followed-up for a median of 11 years. The probabilities of a CE and an SCE from birth to the age of 40 were 20.5% and 9.9%, respectively. QTc prolongation (hazard ratio [HR] 1.12 [1.0-1.2]; P = .005]) and proband status (HR 4.07 [1.9-8.9]; P <.001) were independently associated with the occurrence of CEs. Proband status (HR 8.13 [1.7-38.8]; P = .009) was found to be independently associated with SCEs, whereas QTc prolongation (HR 1.11 [1.0-1.3]; P = .108) did not reach statistical significance. The cumulative probability of the age at first CE/SCE was not lower in patients treated with a beta-blocker.

CONCLUSION

In agreement with the literature, proband status and lengthened QTc were associated with a higher risk of CEs. Our data do not show a protective effect of beta-blocker treatment.

ECG descriptors of ventricular repolarization are associated with cardiac events in a gene-specific manner in long QT syndrome patients

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Assistance Publiques Hôpitaux de Paris (APHP)

Background

Congenital long QT syndrome (LQTS) is still associated with syncope and a risk of sudden cardiac death despite the dramatic reduction in mortality associated with beta-blocker therapy. Current risk stratification tools are imperfect.

Objective

To assess the contribution of automated scalar ECG descriptors of ventricular repolarization for arrrhythmic risk stratification in genotyped LQTS patients.

Methods

Patients with genotyped type 1, 2 or 3 LQTS with at least 1 digital ECG recording have been included in the study. History at diagnosis, and follow-up data were collected. Cardiac events included syncope, aborted cardiac arrest, appropriate implantable cardioverter-defibrillator therapy in VF zone, and sudden death.

ECG were analyzed using the BRAVO algorithm embedded in the CalECG software, version 4.1.0. QT interval duration was manually checked but ECG descriptors of Ventricular Repolarization were fully automatic.

Multivariate cox regression analysis were performed to identify parameters associated with cardiac events.

Results

467 patients (58% female, median age at diagnosis=25, LQT1,2,3 54%, 39%, 7%) were followed-up during 15.2±9.2 years. Rate of cardiac event was 1.2/100 patients-year before diagnosis and 0.9/100 patients-year during follow-up.

QTc duration was associated with the occurrence of cardiac events in the whole study population (HR=1.01 95%CI 1.0-1.01, p=0.03). Ventricular repolarization parameters associated with cardiac events were different according to LQTS type. Cardiac events were associated with increased time to accumulate 50% of T-wave energy (HR=1.53 95%CI 1.04-2.26, p=0.03) in LQT1 but with a decrease in T-wave slopes (ascending slope HR=0.63 95%CI 0.17-0.75, p&lt;0.01) in type 2 LQTS patients. QTc duration was not independently associated with cardiac events in genotype specific multivariate models.

Conclusions

T-wave morphology parameters are associated with cardiac events in a gene-specific manner. Change in T-wave symmetry and T-wave flattening are associated with cardiac events in type 1 and type 2 LQTS respectively. The descriptors of ventricular repolarization are promising parameters or risk stratification beyond QTc duration in LQTS patients.

A new class of radiopeptides for PET imaging of neuromedin-B receptor: 68Ga-ranatensin analogs

The neuromedin B receptor NMB-R is frequently over-expressed in tumors of the lung, pancreas, colon, carcinoids (bronchial, intestinal) and also pruritus. We have developed a new class of radiopeptide for NMB-R targeting.

Correction: A new class of radiopeptides for PET imaging of neuromedin-B receptor: 68Ga-ranatensin analogs

Correction for ‘A new class of radiopeptides for PET imaging of neuromedin-B receptor: ⁶⁸Ga-ranatensin analogs’ by C. Morgat et al., Med. Chem. Commun., 2016, 7, 1217–1223.