Carvedilol versus flecainide treatment in idiopathic ventricular extrasystoles and tachycardias (CARFLECT IV) trial: Rationale and design.

INTRODUCTION AND OBJECTIVES: Idiopathic symptomatic non-sustained ventricular arrhythmias (INVA), including premature ventricular contractions and non-sustained ventricular tachycardias, are generally considered benign. Symptoms and left ventricular dysfunction are indications for treatment with antiarrhythmic drugs. The SCN5A gene encodes part of the voltage-dependent sodium channel type V alpha, which is the primary target of flecainide. The H558R polymorphism of this gene has been associated with a better response to flecainide in atrial fibrillation. The aim of this study is to describe the protocol of the CARFLECT IV clinical trial, which will compare the efficacy of flecainide and carvedilol in reducing INVAs and their consequences, and to assess a potential interaction with the H558R polymorphism.

METHODS: A randomized, third party-blinded, crossover trial will be conducted in adults with frequent INVAs. Each treatment will be administered for 12 weeks. Thirty-two patients will be recruited. The primary objectives are to compare the reduction in arrhythmia burden before and after each treatment, as well as to perform a subsequent multivariate analysis that accounts for potential interactions with the H558R polymorphism. Multiple secondary objectives have been established: changes in quality of life, left ventricular ejection fraction, global longitudinal strain, and the occurrence of adverse events.

RESULTS: The results of the CARFLECT IV trial are not yet available.

CONCLUSIONS: This study will be the first clinical trial focused on adults with INVA. The information it provides may influence the choice of pharmacological therapy for the treatment of these arrhythmias.