UNSTABLE ANGINA PECTORIS OR UNSTABLE CORONARY SYNDROMES?

Abstract

Unstable angina pectoris (UA) is a variant of acute coronary syndrome without ST segment elevation (NSTEACS), which is characterized by the absence of biochemical criteria for myocardial damage, a change in the clinical picture of angina pectoris (an increase in the functional class of angina pectoris, the appearance of resting angina and a high probability of transformation of the process into myocardial infarction (MI). UA and the developed MI without ST segment elevation (NSTEMI) are not accompanied by the appearance of a pathological Q wave and are characterized by a general complex pathogenesis associated with progressive atherosclerosis, a non-occlusive thrombus in the area of erosion or rupture of an atherosclerotic plaque, vasospasm, coronary microcirculatory dysfunction or other causes of imbalance between oxygen intake and oxygen consumption resulting in myocardial ischemia, and are distinguished by increased levels of myocardial necrosis in the blood in case of NSTEMI. It is difficult to differentiate UA and NSTEMI in the first hours of the development of the process when a decision is made on reperfusion technologies and drug therapy without laboratory, and in some cases, additional examination with visualization of the probable new loss of viable myocardium, therefore, the diagnosis and management of these two clinical conditions are usually considered in the same clinical recommendations. A fairly common point of view that the risk of death in UA is significantly lower and the patient is less in need of an intensive strategy than with verified NSTEMI, is controversial given the likely cases of sudden cardiac death of ischemic genesis at the prehospital stage and the difficulties of differential diagnosis of these clinical states. The factors contributing to diagnostic errors include severity of the patient's condition, a variety of clinical atypical manifestations and pathophysiological mechanisms of myocardial ischemia, the presence of comorbid pathology. The article discusses various mechanisms of the development of myocardial ischemia, diagnostic and therapeutic invasive and non-invasive technologies that improve the prognosis of patients with UA. The optimal management tactics of NSTEACS includes early diagnosis and risk stratification, emergency hospitalization, monitoring, the use of non-invasive and invasive strategies, including coronary angiography and revascularization, as well as emergency and long-term treatment aimed at preventing acute cardiovascular events taking into account the age, gender differences and comorbid pathology. A differentiated approach to the administration of emergency therapy is the key to improving the prognosis of this high-risk category of patients. Due to the lack of the possibility of using revascularizing technologies in patients with obstructive coronary disease, non-pharmacological technologies that positively affect microcirculation processes are likely to be used: exposure of the patient’s blood to an alternating magnetic field (extracorporeal autohemomagnetotherapy) or to ultraviolet optical radiation (ultraviolet blood modification). In view of the difficulty in identifying the mechanism of myocardial ischemia in each individual patient with UA and a high likelihood of combination of various pathophysiological factors, myocardium rescue should be in the focus of therapeutic intervention, which dictates the validity and utility of all the recommended and available methods of pharmacological and non-pharmacological therapy and revascularization to reduce the effects of myocardial ischemia.