Early improvement of left ventricular ejection fraction by cardiac resynchronization through His bundle pacing in patients with heart failure. - Moriña-Vázquez P; Moraleda-Salas MT; Manovel-Sánchez AJ; Fernández-Gómez JM; Arce-Léon Á; Venegas-Gamero J; Barba-Pichardo R (Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, 2020)