ABSTRACT
One of the most challenging and important aspects of CPET performed for a patient with loss of exercise tolerance is to generate a broad diagnostic net, based on a history integrated with the findings of the CPET. This chapter stresses the importance of obtaining a history that may give clues to the onset of exercise impairment, such as periodicity, comorbidities, change of lifestyle, diet, etc. Additionally, the chapter describea the important diagnoses that belong in a thorough differential for loss of exercise tolerance. These include cardiac entities such as diastolic dysfunction, coronary artery disease, intermittent dysrhythmias such as atrial fibrillation, and postural orthostatic tachycardia syndrome (POTS). Respiratory abnormalities such as variable upper-airway dysfunction and exercise-induced bronchospasm are not uncommon. Other endocrinologic diseases, such as hyper- or hypothyroidism and hypo- or hyperadrenalism, must be considered along with hematologic abnormalities such as iron-deficiency with and without anemia. Other entities such as myopathies, chronic fatigue syndrome (systemic exertional intolerance), over-training syndrome, and deconditioning are other examples emanating from a broad differential diagnosis that a clinician must consider.
