Ponych N. The changes in the structural and functional state of the myocardium in patients with aortic stenosis and reduced left ventricular ejection fraction after aortic valve replacement

The dissertation presents a new solution of the scientific problem of proving of the efficiency of surgical correction of aortic stenosis (AS) with reduced left ventricular ejection fraction (LV EF) based on the output of clinical characteristics, the evaluation of changes in the structural and functional state of the myocardium and prognosis of the results of aortic valve replacement (AVR). The results obtained from the study of clinical anamnestic and echocardiographic characteristics of patients with critical AS, selected for the AVR, indicate that LV volumes and LV EF show greater severity of heart disease in patients with isolated AS, who were referred for surgery at late stages of heart disease. Instead, in patients with AS and concomitant coronary atherosclerosis, who were on average about 10 years older, the problem was mostly diagnosed and corrected earlier, which was due to more pronounced clinical symptoms (primarily angina pectoris) and a more frequent detection of concomitant pathology, in particular, arterial hypertension, diabetes mellitus and renal dysfunction. One of the most important early indicators of the AVR outcome in patients with critical AS was the dynamics of LV EF. An increase in LV EF might be achieved rapidly in most patients with AS and LV systolic dysfunction within one week after the surgery: the median LV EF increased from 29 % to 43 %. A group of patients with an increase of LV EF by more than 30 % had a higher heart rate, lower LV EF level, more severe LV diastolic dysfunction (mainly type II or III), slightly smaller aortic valve area, higher Tei index and lower MAPSE. A smaller increase in LV EF was associated with a higher initial rate of atrial fibrillation and aortic regurgitation. The most powerful predictor of the favourable dynamics of the systolic function of LV in patients with critical AS in the postoperative period after 6-12 months was the initial LV EF. Other significant predictors of the growth of systolic function were the mean gradient of pressure on the aortic valve, the presence of mitral and tricuspid insufficiency in the preoperative period. The evaluation of the global longitudinal strain indicators shows more pronounced original changes and more favourable dynamics in the patients with AS and reduced EF LV compared with patients with preserved LV EF. Also, there have been identified the main factors of LV hypertrophy regression in patients with critical AS after AVR with 6 to 12 month observation period. The main factors that allowed to predict a significant decrease of the LV mass index of patients with AS after surgery were a larger LV myocardial mass index, low LV EF level, a small mitral regurgitation, an interval QTc>0,45 as well as the absence of concomitant multivessel coronary artery disease.