[Ten questions about cardiopulmonary exercise testing: all that the cardiologist dares or dares not to ask].

In patients with cardiovascular, pulmonary, muscular and neurological diseases, cardiopulmonary exercise testing (CPET) is a valuable tool providing clinically-relevant diagnostic and prognostic information by evaluation of exercise response. CPET requires to be performed in dedicated centers able to correctly carry out the examination and to carefully evaluate the results. CPET analyzes functional capacity revealing both symptomatic and asymptomatic intolerance to exercise. One of the most important advantages for clinicians derived by the use of CPET, beyond standard exercise electrocardiography testing, is the capability not only to grade the severity of the disease, but also to distinguish between different causes of dyspnea and exercise impairment. Indications for CPET use in clinical practice are increasing in the last decades, evolving beyond the routine use as a training tool in athletes. In fact, CPET represents an important step in the management of patients with heart failure or pulmonary hypertension, as suggested by international guidelines. CPET role in helping for the selection of patients candidate to heart transplantation is also well known. Beyond its clinical usefulness, scientific interest in CPET is constantly expanding, mainly due to the safety of the exam and to the huge size of the pathophysiological information that it offers. The aim of this paper is to simply explain everyday applications and potential further purposes of CPET in clinical practice. Our review is intended both for physicians approaching CPET for the first time and for clinicians with an interest in expanding their knowledge in this field.