Myocardial force and energy consumption as predictors of coronary flow recovery in patients with coronary artery disease

Objective. To evaluate the force and kinetic energy expenditure of myocardial contraction in patients with coronary artery disease (CAD) before and after restoration of coronary circulation. Material and methods. We examined 48 CAD patients (mean age 62.2±7.4 years) before surgery and 40 healthy subjects (mean age 42.0±3.4 years). In long-term postoperative period (3—6 years), 31 patients (mean age 63.4±5.1 years) were examined. Before surgery, all patients underwent coronarography and transthoracic echocardiography. Data were entered into the database and analyzed offline using EchoPAC workstation (GE). Left ventricular (LV) end-diastolic volume, end-systolic volume and ejection fraction (EF) were assessed. Intraventricular flow and pressure gradients, LV volume change (Vol), rate of volume change (dVol/dt) and acceleration (dVol/dt2) were processed in Multivox program as characteristics of contraction force. Myocardial contraction force was assessed considering acceleration of LV volume change. The last one was calculated using vector analysis and intraventricular blood flows throughout cardiac cycle. Results. Results were compared between patients with ischemic myocardial injury and healthy people. LV volume change acceleration may be interpreted as changes in hemodynamic forces developed by myocardium during cardiac cycle. We assessed force changes during cardiac cycle using plots of myocardial contraction along selected directions with fixed cardiac cycle and LV volume change acceleration. Restoration of coronary blood flow in long-term postoperative period was accompanied by 1.3—2 times higher kinetic energy in systole and diastole. The correlation between acceleration and LV EF was evaluated. Conclusion. Assessment of myocardial contraction force in CAD patients is based on volume change acceleration and intraventricular blood flow before and after restoration of coronary circulation. Left ventricular volume change rate and acceleration characterize myocardial force during cardiac cycle. Force estimation is one of the characteristics of myocardial function and can be used as an indicator of coronary flow recovery and normalization of myocardial function.