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.

Design and rationale of the Danish trial of beta-blocker treatment after myocardial infarction without reduced ejection fraction: study protocol for a randomized controlled trial

Background

Treatment with beta-blockers is currently recommended after myocardial infarction (MI). The evidence relies on trials conducted decades ago before implementation of revascularization and contemporary medical therapy or in trials enrolling patients with heart failure or reduced left ventricular ejection fraction (LVEF ≤ 40%). Accordingly, the impact of beta-blockers on mortality and morbidity following acute MI in patients without reduced LVEF or heart failure is unclear.

Methods/design

The Danish trial of beta-blocker treatment after myocardial infarction without reduced ejection fraction (DANBLOCK) is a prospective, randomized, controlled, open-label, non-blinded endpoint clinical trial designed to evaluate the efficacy of beta-blocker treatment in post-MI patients in the absence of reduced LVEF or heart failure. We will randomize 3570 patients will be randomized within 14 days of index MI to beta-blocker or control for a minimum of 2 years. The primary endpoint is a composite of all-cause mortality, recurrent MI, acute decompensated heart failure, unstable angina pectoris, or stroke. The primary composite endpoint will be assessed through locally reported and adjudicated endpoints supplemented by linkage to the Danish national registers. A number of secondary endpoints will be investigated including patient reported outcomes and cardiovascular mortality. Data from similar ongoing trials in Norway and Sweden will be pooled to perform an individual patient data meta-analysis.

Discussion

DANBLOCK is a randomized clinical trial investigating the effect of long-term beta-blocker therapy after myocardial infarction in patients without heart failure and reduced LVEF. Results from the trial will add important scientific evidence to inform future clinical guidelines.

Trial registration

Clinicaltrials.gov, NCT03778554. Registered on 19 December 2018.

European Clinical Trials Database, 2018-002699-42, registered on 28 September 2018.

Beta-blocker therapy is associated with a lower incidence of syncope due to fast ventricular tachycardias among implantable cardioverter-defibrillator patients with left ventricular dysfunction: results from a multicenter study

INTRODUCTION

Among implantable cardioverter-defibrillator (ICD) patients, a substantial proportion of syncopes are due to fast ventricular tachycardias (FVTs). In the experimental models of ventricular tachycardias, the arterial vasoconstriction plays an important role in recovering the arterial pressure. Since beta-blockers increase vascular resistance, we hypothesized that beta-blockers could reduce the occurrence of syncope due to FVTs. Our objective was to determine the relationship between the beta-blocker therapy and the incidence of syncope in FVT (cycle length [CL] 250-320 ms) occurring in ICD patients. Slow VTs were excluded because of the lack of symptoms and VF episodes because of the small number.

METHODS AND RESULTS

In this multicenter study, 226 patients (LVEF 31 ± 10%) with single-chamber ICDs were followed. FVT programming was standardized, including antitachycardia pacing (ATP) as initial therapy. Symptoms were correlated with ICD-stored episode data of FVTs. The beta-blocker therapy was determined at each FVT presentation. We analyzed 289 FVTs (CL 291 ± 21 ms; 77% under beta-blockers; median of the duration:8 s) occurring consecutively in 52 ICD patients. The frequency of FVT-related syncope was 22 (7.6%). Beta-blockers were associated with a lower heart rate preceding FVT (85 ± 22 vs. 94 ± 23 bpm; p = 0.009), a higher ATP effectiveness (86 vs. 57%; p < 0.001), a lower duration of episodes (8 [2] vs. 10 [14] s; p < 0.001), and a lower incidence of FVT-related syncope (4.5 vs. 18%; p < 0.001). By logistic regression, a FVT > 8 s (OR = 21; p = 0.003) and the beta-blocker therapy (OR = 0.3; p = 0.012) were found as independent predictors of syncope.

CONCLUSION

Among ICD patients with left ventricular dysfunction, beta-blockers are associated with a lower incidence of FVT-related syncope.

; CHOICE-2 study investigators. Real-world Evidence for the Antianginal Efficacy of Trimetazidine from the Russian Observational CHOICE-2 Study

INTRODUCTION

The guidelines recommend a beta-blocker or calcium channel blocker as the first-line medication for angina, supplemented by other agents for additional symptoms. One such agent is trimetazidine (TMZ), which has been shown to reduce the frequency of anginal episodes and improve exercise performance without affecting haemodynamic parameters. However, extensive real-world evidence for its efficacy in combination with first-line therapies has been lacking.

METHODS

The aim of this large-scale, Russian, multicentre, 6-month, open-label, prospective observational study was to assess the effect of adding TMZ modified release 35 mg bid to background antianginal therapy in the real-world clinical setting.

RESULTS

The study included 896 patients: 54% women, aged 29-90 years (42.6% >65 years), 63% with class II angina, and receiving beta-blockers alone or in combination (93%). Add-on TMZ reduced angina frequency and short-acting nitrate use within 2 weeks (both p < 0.0001) regardless of background therapy and maintained this effect over 6 months. It increased the proportion of patients with class I angina sixfold while decreasing that of class 3 angina almost fourfold. It also improved walking distance and well-being at 6 months (both p < 0.0001). Treatment was well tolerated.

CONCLUSION

Add-on TMZ is a safe and rapidly effective treatment for reducing angina attacks and nitrate use in the real-world clinical setting. It also increases exercise capacity and well-being. These effects are observed within 2 weeks and persist for at least 6 months.