Despite major breakthroughs that have recently been made in pacemakers implanted in heart failure (HF) patients, 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 pacemaker implanted HF patients. Therefore, investigators aimed to compare the aforementioned outcomes in patients and healthy controls.

Heart failure is a chronic, progressive condition in which the heart muscle is unable to pump enough blood through to meet the body's needs for blood and oxygen. Safeguarding HF patients at increased risk of sudden cardiac death due to ventricular arrhythmias and HF as a result of left ventricular systolic dysfunction and cardiac abnormal synchronization has continued to improve. Implantable cardioverter defibrillators (ICDs), which restore normal heart rhythm using pacing, cardioversion or defibrillation, and cardiac resynchronization therapy (CRT), which resynchronizes the contraction of the heart using biventricular pacing, are nowadays widely used to treat the aforementioned conditions.

New developments in medical treatments have focused on the primary affected organs, targeting reduced left ventricular ejection fraction in chronic HF. Although major breakthroughs in the treatments have occurred in recent years, especially implantable medical devices, it is clear that when drugs are optimally prescribed, even the latest technology used in pacemakers reported problems, especially functional impairments and symptoms often remain. In recent decades, it has become obvious that disease severity should not be estimated from cardiac function impairment alone. However, what has not hitherto been clearly investigated is the fact that even functional and maximal exercise capacity, respiratory and peripheral muscle strength and pulmonary function are impaired, and dyspnea in the activities of daily living and fatigue perception increased in HF patients with pacemakers.

Hence, investiators designed a prospective, cross-sectional study to compare the aforementioned outcomes in HF patients with pacemakers and healthy controls. Investigators hypothesized that functional and maximal exercise capacity, respiratory and peripheral muscle strength, and pulmonary function are impaired, and dyspnea in the activities of daily living, and fatigue perception increased in HF patients with pacemakers.

A cross-sectional study. 50 HF patients with pacemakers and 40 controls were compared. Functional (6-Minute Walking test (6-MWT)) and maximal exercise capacity (Incremental Shuttle Walking test (ISWT)), respiratory (MIP, MEP; Mouth pressure device) and peripheral muscle strength (Dynamometer), pulmonary function (Spirometry) dyspnea (Modified Medical Research Council Dyspnea scale) (MMRC)), and fatigue (Fatigue Severity scale (FSS)) were evaluated.

Inclusion criteria:

• Heart failure patients with ischemic or non-ischemic etiology,
• Aged between 18 and 80 years,
• Being clinically stable for at least 4 weeks,
• Having any type of implantable cardioverter-defibrillator (ICD), cardiac resynchronization therapy (CRT), New York Heart Association (NYHA) Class II-III,
• Having no change in medications over three months and all comorbid conditions, such as hypertension and diabetes, controlled.

Exclusion criteria:

• Having acute myocardial infarction, cognitive disorders, complex arrhythmias, uncontrolled hypertension, stroke or transient ischemic attack within the last six months prior to the study, angina pectoris, recent viral infections (six months prior to study), significant valvular disease,
• Having history of malignancy,
• Having orthopedic problems and rheumatologic diseases.

Prior to evaluation, all patients' clinical evaluation and echocardiographic measurements and pacemaker routine controls were conducted by a cardiologist. All patients and controls were tested by a physical therapist. Demographic characteristics were recorded. Functional and maximal exercise capacity, respiratory and peripheral muscle strength, pulmonary function, dyspnea and fatigue perception were evaluated and compared with age- and gender-matched healthy controls (without any chronic diseases) who volunteered to participate to the study.

There is not a plan to make individual participant data but when the statistical analyses of all data are made, all results will be shared.