Features of interventional treatment of acute myocardial infarction without ST segment elevation

Abstract

Actuality of research topic. According to World Health Organization data, every year nearly 18 million people suffer from cardiovascular problems, which are the main cause of death in developing countries and constitute 31% in the overall mortality structure [1]. The highest proportion of cardiovascular mortality is asigned to acute coronary syndrom (SCA). The incidence of acute coronary syndrome without ST segment elevation (NST-SCA) is considerably more prevalent than that of acute coronary ST segment elevation syndrome (ST-SCA) (55 cases vs. 15 cases per 10000 inhabitants) [2]. Although in-hospital mortality of patients with acute myocardial infarction without STsegment elevation (NSTEMI) is lower than that of patients with acute myocardial infarction with ST-segment elevation (STEMI) (5% vs. 7%), the long-term estimated mortality in NSTEMI is higher [3]. Of a great importance is an adequate and timely treatment for acute myocardial infarction without ST-segment elevation in reducing overall mortality and disability both globally and particularily in the Republic of Moldova. Multiple randomized clinical trials and meta-analyzes have been demonstrated the superiority of the routine application of the invasive management strategy of NSTE-SCA over the selective application by decreasing the risk of death, as well as decreasing the number of repeated myocardial infarction, and the number of hospitalizations due to angina pectoris and repeated revascularizations [4, 5, 6]. Risks stratification by applying the criteria stipulated by the European Society of Cardiology (ESC), as wells as scores like GRACE (Global Registry of Acute Coronary Events), or TIMI (Thrombolysis in Myocardial Infarction) and other instruments is essential for choosing the optimal time window for implementing the strategy of invasive management. The current recommendations for the treatment of patients in the first 2 and 24 hours, considered in a group of very high and high risk, are based on large randomized clinical trials that have specifically investigated this issue [7, 8, 9]. And the current clinical practice has recorded a more favorable evolution of these patients in case of compliance with the recommended time windows. The clinical evolution of patients categorized as in intermediate and small risk groups ensure enough time to select the optimal therapeutic strategy. It is well known and demonstrated that emergency performed interventions have a higher rate of complications and less successful results than programed ones. The present research was conducted during 2015-2019 and was based on 2015 ESC Guidelline. This work amphasize and recommends the application of the invasive strategy in the first 72 hours of stabilizing the diagnosis of NSTE-SCA. In the condition of inaccessibility of coronary angiography performed in the specified time window, it is recommended to transfer patients to a center with interventional cardiology within [10]. This recommendation is based on two large meta-analyzes the aim of which and subsequently demonstrated result was the the concept of superiority of the routine invasive strategy over the optimal drug treatment and the selectively applied invasive strategy [5, 4]. Untill now, there was not yet perfoemed any randomized clinical trials to compare the benefits of invasive strategy applied in the first 72 hours associated with optimal medical treatment and coronary angiography with eventually angioplasty in patients with intermediate or low risk NSTEMI. According to many researches, both the anatomy and morphopathological structure of coronary heart disease, especially the target lesion in patients with NSTEMI has a high variability. Moreover, both the structure and the consistency of the atherosclerotic plaque that causes acute coronary syndrome vary throughout the course of the disease [11,12]. Over 80% of patients with acute coronary syndrome without ST-segment elevation are supposed to percutaneous myocardial revascularization (10-15% - drug treatment, 5-10% - aortocoronary bypass) [13]. Due to interventional cardiology development, there is observed a clear trend of decreasing the rate of patients to whom surgical treatment is applied and increasing rate of percutaneous vascular interventions cases. There are multiple interventional techniques used in the treatment of patients with acute coronary syndrome, and in case of considering the variability of anatomomorphological conditions during the evolution of the disease, each case requires the selection of the specific treatment technique. Also, it is constating a rising of applicability of the intracoronary imaging and functional diagnostic methods, such as optical coherence tomography, intracoronary ultrasonography and estimation of fractional flow reserve. Nowadays, this direction of research is still poor studied and not sufficiently reflected in the literature of speciality. Among patients with coronary injury that require increased attention and a specific therapeutic approach are those with diabetes mellitus (DM) considered as a basic disease. The presence of diabetes mellitus is an independent factor that assigns an overlapping risk to patients with SCA. The incidence of type 2 diabetes in patients who developed acute coronary syndrome is 37.6% according to the data published the researches in Beijing, China, and is approximately equal in patients who presented with or without ST-segment elevation ( 36.8 vs. 39.0%) [14]. Diabetes mellitus has a direct impact on the mortality of patients with acute coronary syndrome. Percutaneous myocardial reperfusion clearly improves the prognosis of the disease and significantly reduces mortality index even if the estimated death rate of patients with diabetes mellitus at 1 year after SCA reaches 7.2% [15], as well as in non-diabetic patients. The anatomical-morphological pattern of coronary lesions in patients with diabetes is distinguished as a rule by its severity and more massive spread, which in turn influences the impact of myocardial revascularization. Thus, for the success of an adequate reperfusion, the decrease of the complication rate and the improvement of the long-term prognosis is necessary the individualized interventional approach [16]. [...]