Equivalent contractility indexes for the assessment of left ventricular systolic function in post-AMI human hearts

We propose new contractility indexes, in the work, which are equivalent to the conventional contractility (Ees) determined with the slope of left ventricular (LV) end-systolic pressure-volume relation. Nineteen patients with acute myocardial infarction (AMI) were recruited in the study. They received thrombolytic therapy within 24 hours after the AMI event, and their LV pressures and volumes were measured with Millar and multi-electrode volume conductance catheters during catheterization examination at the first week and 3 months, respectively. The first equivalent contractility index (eEsv) submitted was defined as the Ees divided by the end-systolic volume (ESV) and normalized to 100 ml, the second (eEdv) as the Ees divided by the end-diastolic volume (EDV) and normalized to 100 ml, and the third (eEmv) as the Ees divided by the midrange of the LV volume and normalized to 100 m. Using linear regression methods, we found that a high correlation coefficient (r > 0.82) exists between the Ees and one of the three new contractility indexes. Furthermore, the eEsv but not Ees was significantly higher measured at 3 months than at one week after thrombolysis. In conclusion, an increase in the equivalent contractility eEsv implies the improvement of the left ventricular systolic function in the post-AMI human hearts long-term after thrombolytic intervention, as the size-dependence of contractility is taken into account.