Cardiac Resynchronization Therapy Delivery Guided Non-Invasive Electrical and Venous Anatomy Assessment

Eligible subjects shall meet all following criteria: * Appropriately signed and dated informed consent. * Age ≥18 years at time of consent. * CRT indication according to the 2021 ESC guidelines on cardiac pacing and CRT (class I and IIA indication in patients with LBBB QRS morphology) or to 2017 AHA/ACC/HFSA guidelines (COR I). * Sinus rhythm * QRS duration ≥130 ms * Left bundle branch block * Left ventricular ejection fraction ≤35% * Symptomatic heart failure NYHA class ≥ II * Documented stable medical treatment for at least 6 months * No cardiovascular intervention during the last 6 month Exclusion Criteria are: * History of persistent or permanent atrial fibrillation * Previous pacemaker or ICD implantation * Indication to pacing due to bradycardia * Patients considered for His bundle pacing or cardiac conduction pacing * Patients with unstable angina * Subject experienced a recent myocardial infarction, within 40 days prior to enrollment * Subject underwent coronary artery bypass graft or valve surgery, within 90 days prior to enrollment * Subject is post heart transplantation, or is actively listed on the transplantation list, or has reasonable probability (per investigator's discretion) of undergoing transplantation in the next year * Subject is implanted with a left ventricular assist device * Subject is on continuous or uninterrupted infusion (inotropic) therapy for heart failure * Subject has severe aortic stenosis (with a valve area of \<1.0 cm2 or significant valve disease expected to be operated within study period) * Subject has congenital heart disease * Subject has a mechanical right-sided heart valve * Subject has a life expectancy of less than one year in the opinion of the investigator * Pregnant or breastfeeding women, or women of child bearing potential and who are not on a reliable form of birth control * Subject is enrolled in one or more concurrent studies that would confound the results of this study * Patients who have contraindications to CT scanning. * Patients with chronic kidney diseases and estimated glomerular filtration rate (eGMR) calculated based on CKD-EPI 2009 \< 40 ml/min/1.73m2