A Feasibility Study Implant of the WiSE® CRT System With an Intracardiac Pacemaker to Achieve Totally Leadless CRT

Inclusion Criteria: * Patient with a class I or IIa (1) or (2) indication for implantation of a CRT device according to current available guidelines 1,2,4 (with additional QRS criteria on Class IIa (1)): * Class I: NYHA II, III, IV, EF ≤ 35%, LBBB, QRS ≥ 150 ms * Class IIa (1): NYHA II, III, IV, EF ≤ 35%, LBBB, QRS ≥ 130 to \< 150 ms * Class IIa (2): NYHA II, III, IV, EF ≤ 35%, non-LBBB, QRS ≥ 150 ms * Patient or legally authorized representative can provide written authorization and/or consent per institution requirements * Male or Female, aged 22 years or above * Meets criteria for one of the two patient groups * Group A: De novo totally leadless CRT implant in whom the physician believes a totally leadless approach would be beneficial (e.g., wish to avoid lifelong transvenous lead implant, anatomical constraints, history of device infection). * Patients with symptomatic AF and an uncontrolled heart rate who are candidates for AV node ablation (irrespective of QRS duration and LVEF), and in whom the physician believes a leadless pacing approach would be beneficial. * Patients with high degree AV block who have an indication for permanent pacing (with a LVEF ≤ 50%), are expected to require ventricular pacing more than 40% of the time, and in whom the physician believes a leadless approach would be beneficial. * Group B: Upgrade chronic intracardiac pacemaker to CRT * Patients with existing intracardiac pacemakers with greater than 20% RV pacing, who have developed symptomatic HF. Exclusion Criteria: * Patient who is or is expected to be inaccessible for follow-up visits * Female participant who is pregnant, lactating, or planning pregnancy during the course of the study * Inability to comply with the study follow-up or other study requirements * History of chronic alcohol/ drug abuse and currently using alcohol/ drugs * Non-ambulatory (or unstable) NYHA class 4 * Life expectancy less than 12 months * Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study. * Patient who is enrolled in another clinical study that could confound the results of this study (Note: patients enrolled in complementary study are eligible for enrolment)