End-tidal partial pressure of carbon dioxide (PetCO2) indicates the efficiency of respiratory function and gas exchange. It plays quite an important role in assessing patient’s condition and optimal treatment planning. The current article examines changes in PetCO2 as an important indicator for monitoring patients with cardiovascular disease (CVD), namely heart failure, coronary artery disease, arterial hypertension, and pulmonary hypertension. Such methods of PetCO2 monitoring, like capnometry in comparison with transcutaneous PCO2 measurement, are analyzed, and the diagnostic significance of these changes, and clinical application in the context of CVDs, are discussed. It provides high accuracy and speed of measurement, which is critical for effective monitoring of patients with CVDs. The methodology of capnogram registration by capnography and its phases for interpretation are described. Physiological mechanisms regulating changes in PetCO2 and the possibilities of using this indicator for individualized therapy implementation improvement of outcomes in patients with CVD are also being investigated. Changes in PetСО2 during exercise in patients with CVD are noted, as well as the effect of different types of physical exertion on PetСО2.