Background: Despite major breakthroughs that have recently been made in pacemakers implanted in patients with heart failure (HF), it is clear that functional impairments and symptoms often remain. However, only limited studies have investigated exercise capacity, muscle strength, pulmonary function, dyspnea, and fatigue in these patients. Therefore, we aimed to compare aforementioned outcomes in patients and healthy controls. Methods: A cross-sectional study. Fifty patients with HF with pacemakers (58.90 +/- 10.69 years, NYHA II-III, LVEF: 30.79 +/- 8.78%) and 40 controls (56.33 +/- 5.82 years) were compared. Functional (6-Minute Walking test (6-MWT)) and maximal exercise capacity (Incremental Shuttle Walk test (ISWT)), respiratory (Mouth pressure device) and peripheral muscle strength (Dynamometer), pulmonary function (Spirometry), dyspnea (Modified Medical Research Council Dyspnea scale), and fatigue (Fatigue Severity scale) were evaluated. ClinicalTrial number: NCT03701854. Results: 6-MWT (412.62 +/- 96.51 m versus 610.16 +/- 59.48 m) and ISWT (279.97 m versus 655 m) distances (p < 0.001), pulmonary function (p<0.001), respiratory and peripheral muscle strength (p < 0.001) were significantly lower; dyspnea (p < 0.001) and fatigue (p = .030) scores were higher in patients compared with controls. Conclusion: Maximal and functional exercise capacity is impaired in the majority of patients with HF with pacemakers, respiratory and peripheral muscles are weakened, dyspnea and fatigue perceptions are increased. Patients with pacemakers have to be included in cardiac rehabilitation programs to improve impairments.