Left Bundle Branch Area Pacing or Biventricular Pacing in AF and Left Ventricular Dysfunction

INCLUSION CRITERIA In order to be eligible to participate in this study, a subject must meet all of the following criteria: * Adults ≥18 years with permanent AF and LVEF \< 50% who either require ventricular pacing because of bradycardia including patients undergoing AV junction ablation, or have an indication for cardiac resynchronization therapy. * Expected percentage of ventricular pacing \> 40% * ≥ 3 months of heart failure medication optimization Of note, patients who already have a device, but require an upgrade to a CRT device, can also be included EXCLUSION CRITERIA A potential subject who meets any of the following criteria will be excluded from participation in this study: * Age \< 18 years * Pregnancy or active pregnancy wish * Not eligible for implantation of an RV lead, LBBAP lead, or LV lead in the coronary sinus * Recent valve intervention/surgery or acute myocardial infarction (\< 6 months) * NYHA functional class IV heart failure, left ventricular assist device or cardiac transplant