Does CAD Cause Tiredness?
Yes, coronary artery disease (CAD) can cause tiredness and fatigue through multiple mechanisms, including reduced cardiac output during exertion, muscle deconditioning, and the psychological burden of chronic disease.
Clinical Presentation of Fatigue in CAD
CAD patients commonly present with atypical symptoms beyond classic chest pain, and fatigue represents a significant manifestation:
- Athletes and active individuals with CAD may present with an overall reduction of exercise capacity and unusually elevated heart rate during exercise, rather than typical angina 1
- Fatigue can constitute the first clinical manifestation of cardiovascular disease and is responsible for deterioration of quality of life and prognosis 2
- In CAD patients, poor health-related quality of life is independently associated with greater fatigue, even after controlling for mental distress and disease severity 3
Pathophysiological Mechanisms
The tiredness experienced by CAD patients stems from both physical and mental components:
Physical Fatigue Mechanisms
- Physical fatigue relates to loss of muscle efficacy due to mismatch of cardiac output during exercise, muscle and microcirculatory deconditioning, neuroendocrine dysfunction, and associated metabolic disorders 2
- Myocardial ischemia during exercise is caused by a demand-supply mismatch, which can manifest as reduced exercise capacity rather than chest pain 1
- Diminished cardiovascular response to stress is directly associated with both global fatigue and mental fatigue in CAD patients after acute coronary syndrome 4
Mental Fatigue Component
- Mental fatigue corresponds to predominantly depressive mood disorders, with a particular entity called "vital exhaustion" 2
- Greater limitation due to emotional problems, decreased energy/vitality, and reduced mental component scores are independently associated with higher general fatigue in CAD patients 3
- Psychosocial stress independently contributes to CAD risk and symptom burden 5
Clinical Implications
Recognition and Assessment
- Fatigue should be recognized as a legitimate symptom of CAD, particularly in patients who may not experience typical angina 1
- Functional tests investigating both physical dimensions (exercise capacity) and mental dimensions (mood disorders) should be used to analyze their respective roles 2
- The absence of chest pain does not exclude significant CAD, as some patients present primarily with fatigue and reduced exercise tolerance 1
Impact on Outcomes
- Fatigue is responsible for deterioration of both quality of life and prognosis in cardiovascular disease 2
- In CAD patients undergoing rehabilitation, poor health-related quality of life associated with greater fatigue occurs independently from mental distress and CAD severity 3
- The diagnostic approach must eliminate other organic causes of fatigue while recognizing CAD as a primary contributor 2
Management Considerations
Exercise-Based Interventions
- Regular physical training reduces the risk of developing CAD and sudden cardiac death during vigorous exertion 1
- Exercise training promotes lower myocardial oxygen demand at any given workload through decreased heart rate, lower systolic blood pressure, and lower circulating catecholamines 1
- Rehabilitation has an essential role due to its global approach in reducing fatigue, with the threefold objective of improving independence, quality of life, and limiting morbidity and mortality 2
Important Caveats
- While regular moderate physical activity is beneficial, observational data indicate that intensive exercise training (beyond 7 times per week or 18 hours of strenuous exercise per week) increases mortality risk in patients with CAD 1
- The benefits of regular physical activity and sport participation outweigh by far the increased risk for coronary events triggered by acute, intensive physical activity 1
- Patients should engage in at least 30 minutes of moderate-intensity physical activity on most (preferably all) days of the week 1