Left Bundle Branch Area Pacing Using Conventional Stylet-driven Pacemaker Leads for Cardiac Resynchronization Therapy

Inclusion Criteria: * Aged 18 or above * Left Ventricular Ejection Fraction (LVEF) and NYHA meeting one off the previous indications documented with transthoracic echocardiography (TTE) no later than 3 months before randomization. * New York Heart Association (NYHA) class II-IV * Baseline left bundle branch block and QRS \>130ms or QRS \>150ms of any morphology or a wide paced QRS duration. Exclusion Criteria: * Younger than 18 years old * Pregnancy * Any unstable medical condition, life expectancy \< 12 months * Inability to provide consent or to undergo follow-up * Narrow QRS duration (≤130ms) or prolonged QRS duration with typical Right Bundle Branch Block (RBBB) morphology on 12 lead ECG and sinus rhythm. * Significant hypertrophic cardiomyopathy - any septum abnormality contra-indicating LBBAP implantation (according to physician's evaluation) * Patients who are unable to perform a 6 minute walk test (6MWT) Note: patients should be able to perform a 6 minute walk test, but it is not a requirement to have the test performed before the procedure (e.g. due to inability of planning).