Effects of left ventricular dysfunction on left atrial performance in previous myocardial infarction and during pacing-induced myocardial ischemia in angina pectoris.

This study aimed to evaluate acute and chronic response of left atrial function to left ventricular dysfunction in patients with coronary artery disease. We studied simultaneous measurements of left atrial volume by biplane cineangiography and left ventricular pressure at rest and after pacing in 59 patients with coronary artery disease and 11 normal subjects. At rest, 35 patients with previous myocardial infarction (MI group) had low left ventricular filling rate of the first third in diastolic time, large left atrial volume before contraction (LA pre-ACV) and large left atrial ejection volume (LAEV), compared with control group. Left atrial ejection fraction (LAEF), the ratio of LAEV to LA pre-ACV, was similar between both groups. LAEF was maintained within a wide range of values in accordance with left ventricular peak A pressure, except for 3 patients who had high values of left ventricular peak A pressure and low values of LAEF. After a right atrial pacing stress test, time constant was prolonged and mean emptying rate of left atrial volume during early diastole decreased in 11 patients with angina pectoris who had an increase greater than 5 mmHg in left ventricular end-diastolic pressure after pacing. In these group, LA pre-ACV increased, LAEF decreased and LAEV was unchanged. These results suggest that left atrial performance responds differently to acute and chronic left ventricular dysfunction in patients with coronary artery disease.