Процена на левокоморна функција и миокардна деформација кај пациенти упатени на коронарна бајпас хирургија

Abstract

Introduction: Coronary artery disease (CAD) is one of the most common causes of death worldwide. Treatment of stabile CAD includes optimal medicament therapy, percutaneous coronary interventions and coronary artery bypass grafting (CABG). Successful CABG besides clinical improvement and prolonged life expectancy, leads to improved myocardial perfusion and subseqent functional recovery of the myocardium assessed by improvement of left ventricular (LV) function and LV strain evaluated by conventional and speckle tracking imaging (STI) echocardiography. Objectives: To evaluate changes in systolic and diastolic LV and right ventricular (RV) function after CABG, using conventional echocardiography and STI methods; To determine the relationship of conventional echocardiographic methods of assessment of myocardial function with methods of myocardial strain at any level; To determine independent predictors of myocardial strain in clinical, electrocardiographic, angiographic and / or conventional echocardiographic parameters before and after CABG and to determine the role of clinical, angiographic, surgical, conventional echocardiographic parameters and parameters of myocardial strain as independent predictors of improvement of LV systolic and / or diastolic, as well as RV function after performing CABG. Material and methods: Ninety one patients indicated for CABG were included in these prospective, cross-sectional study. Perioperative and postoperative management, as well as surgical treatment of patients was performed at the University Clinic for Cardiac Surgery in Skopje, and functional myocardial assessment using 2D transthoracic echocardiography (TTE) at the University Clinic of Cardiology in Skopje. Echocardiographic examinations were performed before and 4-6 months after surgery. We assessed clinical and operative characteristics of the patients, and with 2D TTE the following were assessed: cavity sizes and parameters of LV systolic and diastolic function, cavity sizes and function of RV and left atrium (LA), as well as myocardial strain by determining the longitudinal (GLS%), radial (GRS%) and circumferential strain (GCS%) of the LV and the longitudinal deformation of the RV (RV GLS%) and LA (PALS and PACS). Results: Mean age of the patients was 65 years with male predominance. The most prevalent comorbidities were arterial hypertension and dyslipidemia, and patients were predominantly overweight. The average EuroSCORE was 2.0 ± 1.5 and the average SYNTAX score was 31.0. The mean number of distal anastomoses per patient was 2.7, almost identical in all groups of patients regardless of LV ejection fraction (EF). There was no correlation between the number of distal anastomoses and the change in systolic and diastolic myocardial function after CABG. The mean cross clamp time was 61.5 ± 18.1 min and was significantly correlated with LV GLS% measured after CABG, but not with LVEF%. Although diabetes mellitus (DM) was not a risk factor for deterioration of systolic function after CABG, the presence of DM correlated with worse LVEF% and GCS% values after CABG. In patients with preserved LVEF% before CABG, there was a postoperatively statistically significant but clinically insignificant reduction in LVEF%. Except for MAPSE which improved significantly after CABG, the dimensions and volumes of LV in systole and diastole, stroke volume and wall motion score index (WMSI) stayed in normal range. GLS% improved statistically significantly, although it was within reference limits before CABG. In patients with deterioration of LVEF% below normal after CABG, the linear regression analysis found that for each percentage of deterioration of GLS% before CABG there is 1,2% reduction in LVEF% below normal after CABG. In patients with preoperatively impaired LVEF≤50%, postoperatively there was a significant improvement in LVEF% with a significant reduction in LV volumes. The group of patients with preoperatively impaired GLS <-17% showed an improvement in GLS% after CABG. In multivariate logistic (binary) regression analysis, an increase in GLS% of -17% after CABG is 0.955 times greater if the indexed LV end-systolic volume is lower (OR = 0.995; 95% CI 0.917-0.994; p = 0.025) and 0.03 times higher if the WMSI is lower (OR = 0.030; 95% CI 0.002-0.477; p = 0.030). These baseline parameters had high specificity (81%) and sensitivity (79%) in predicting GLS% growth of -17% after CABG. Our patients, as a group, had moderate basic diastolic dysfunction. Despite the statistically significant increase in e ’values and decrease in e/e’ ratio after CABG, diastolic dysfunction after CABG remained moderately impaired. In the whole group, there was a deterioration in the regional function of RV manifested through a statistically significant decrease in TAPSE and s’TDI after CABG. In patients with preserved LVEF> 50% and GLS ≥17% these parameters of RV function did not decreased below the normal range. Conclusion: Our study confirmed the hypothesis that there is an improvement in LV function in patients with preoperatively normal and impaired LVEF%, after CABG, assessed by the STI echocardiography method. Myocardial strain complements conventional methods of assessing LV systolic function and provides valuable information on the subclinical deterioration of LV function before it becomes apparent and before LVEF% is impaired. Such results create conditions for realistic evaluation of postoperative results and determination of prognostic expectations.