Estimation of Left Ventricular Systolic Function Using Volume-Normalized Contractility Measures in Patients with Acute Myocardial Infraction

We propose three cardiac size-normalized contractility indexes in the work to investigate whether left ventricular (LV) systolic function in patients with acute myocardial infraction (AMI) after thrombolysis is enhanced or not. A cohort of 18 patients (17 men) aged 45-72 years received thrombolytic therapy within 24 hours after an AMI event, and their LV chamber function was determined using pressure-volume loops obtained by simultaneous conductance catheter volumetry and micromanometer pressure during catheterization examination at the first week and 3 months, respectively. A slope of the end-systolic pressure volume relation (Ees) was derived by reduced venous return. Three new contractility indexes (Esv, Edv, and Emv) were defined as the Ees divided by the end-systolic volume, end-diastolic and midrange of the LV volume, and then normalized to 100 ml, respectively. Using linear regression methods, we found high correlation coefficients of r = 0.835 at the first week and r = 0.826 at 3 months between the Ees and Esv after thrombolysis. Furthermore, Esv and Emv but not Ees were significantly higher measured at 3 months than at the first week after thrombolytic intervention. Thus, an increase in the volume- normalized contractility measures Esv and Emv implies the improvement of the left ventricular systolic function in the post- AMI human hearts long-term after thrombolytic treatment, in despite that there is a great coefficient of variation in cardiac chamber sizes at different recovery stages.