Safety and efficacy of long-term Sodium Channel Blocker therapy for Early Rhythm Control: The EAST-AFNET 4 trial

Background and Aims Clinical concerns exist about the potential proarrhythmic effects of the sodium channel blockers flecainide and propafenone (SCB) in patients with cardiovascular disease. SCB were used to deliver early rhythm control (ERC) therapy in EAST-AFNET 4. Methods We analysed the primary safety outcome (death, stroke, or serious adverse events related to rhythm-control therapy) and primary efficacy outcome (cardiovascular death, stroke and hospitalization for worsening of heart failure or acute coronary syndrome) during SCB-intake for ERC patients (n = 1395) in EAST-AFNET 4. The protocol discouraged flecainide and propafenone in patients with reduced left ventricular ejection fraction and suggested stopping therapy upon QRS prolongation >25% on therapy. Results Flecainide or propafenone was given to 689 patients (age 69 (8) years; CHA2DS2-VASc 3.2 (1); 177 with heart failure; 41 with prior myocardial infarction, CABG or PCI; 26 with left ventricular hypertrophy >15 mm; median therapy duration 1,153 [237, 1,828] days). The primary efficacy outcome occurred less often in patients treated with SCB (3/100 (99/3,316) patient-years) than in patients who never received SCB (SCBnever 4.9/100 (150/3,083) patient-years, p < 0.001). There were numerically fewer primary safety outcomes in patients receiving SCB (2.9/100 (96/3,359) patient-years) than in SCBnever patients (4.2/100 (135/3,220) patient-years, adjusted p = 0.015). Sinus rhythm at 2 years was similar between groups (SCB 537/610 (88); SCBnever 472/579 (82)). Conclusion Long-term therapy with flecainide or propafenone appeared to be safe in the EAST-AFNET 4 trial to deliver effective ERC therapy, including in selected patients with stable cardiovascular disease such as coronary artery disease and stable heart failure. Clinical Trial Registration ISRCTN04708680, NCT01288352, EudraCT2010-021258-20, www.easttrial.org