1. To determine the most suitable exercise protocol for upper extremity aerobic exercise training, a widely used type of aerobic exercise to improve reduced upper extremity functional capacity in individuals with CIED and HF.
2. To investigate whether high-intensity intermittent upper extremity aerobic exercise training provides a more effective improvement in upper extremity functional capacity compared to moderate-intensity continuous upper extremity aerobic exercise training.
3. To determine the effectiveness of different types of upper extremity aerobic exercise training compared to lower extremity aerobic training alone in individuals with CIED and HF.

Inclusion Criteria:

• Patients aged 18 and over with heart failure who are receiving Implantable Cardioverter Defibrillator (ICD) or Cardiac Resynchronization Therapy (CRT)
• At least 3 months have passed since device implantation and there have been no complications at the last device control
• Being in New York Heart Association (NYHA) Class II-III
• Patients without cooperation problems
• Patients who volunteer to participate in the study

Exclusion Criteria:

• Patients who have previously participated in a cardiac rehabilitation program and those who have completed less than 1 year since the program,
• Patients with a primary diagnosis of cardiomyopathy and those with heart failure secondary to cardiomyopathy,
• Patients with a history of shoulder pathologies that may restrict upper extremity movement before device implantation (such as severe pain around the shoulder, edema, or shoulder dislocation that restricts upper extremity movement),
• Patients with a history of shoulder surgery (patients with limitations in range of motion),
• Patients who have undergone mastectomy on the affected side or a cerebrovascular event resulting in arm involvement,
• Patients with decompensated heart failure,
• Patients with a history of ICD-incompatible shock,
• Patients with a history of unstable angina pectoris, acute myocardial infarction, or cardiac surgery within the last 3 months,
• Patients who have experienced acute atrial fibrillation, ventricular tachycardia, and ventricular fibrillation within the last 3 months,
• Patients with actively treated malignancy or collagen tissue disease receiving systemic steroids
• Patients with chronic kidney disease undergoing dialysis where volume load is unstable,
• Persistent ventricular arrhythmias during baseline cardiopulmonary exercise testing.