Changes in Left Ventricular Performance from Early after Acute Myocardial Infarction to the Convalescent Phase

Left ventricular performance was assessed in 22 patients early (within the first 2 days) after acute myocardial infarction (AMI) and again during the convalescent phase (3-5 weeks later). Left ventricular end-diastolic pressure (LVEDP) fell from the early to the late study by an average of 10.7 mm Hg in the 12 (55%) group A patients. In these patients, cardiac index (CI) and left ventricular stroke work (LVSW) increased by an average of 0.65 liters/min/m2 and 63.8 g-m, respectively, and the mean right atrial pressure fell by 2.4 mm Hg. These changes were statistically significant (P < 0.05). Left ventricular (LV) function was improved in this group of patients.LVEDP increased in the other 10 patients and they were subdivided into groups B and C depending on whether CI increased or decreased. In six patients (27%), LVEDP increased by 5 mm Hg and CI increased by 0.4 liters/min/m2 (group B); the P value for these changes was < 0.05. Group B patients also had an increase of mean arterial pressure and left ventricular ejection time, and thus the alterations in LVEDP and CI could have resulted from an increase of arterial pressure. In four patients (18%), LVEDP increased by 11.5 mm Hg, CI decreased by 0.9 liter/min/m2, and LVSW was reduced by 34.5 g-m (group C). Although the decreases of CI and LVSW were not statistically significant in group C patients, LV function had deteriorated. In the follow-up period, three of the four patients in group C died and the fourth patient is in functional class IV.Therefore, in the convalescent period ventricular function had improved in 55%, and had deteriorated in 18% of cases. The changes in LV function could not have been predicted on the basis of the clinical features, systolic time intervals, or the initial hemodynamic findings. Patients whose ventricular function deteriorated during convalescence had a very poor prognosis.