Comparison of atrial contribution to cardiac hemodynamics in patients with normal and severely compromised cardiac function.

The importance of atrial contribution to cardiac function in patients with congestive heart failure is controversial. Ten patients with severe congestive failure (Group A) and 10 patients with normal ventricular function (Group B) were studied during atrial and ventricular pacing. Left ventricular ejection fraction, baseline pulmonary capillary wedge pressure, and baseline cardiac index were different between Group A and Group B patients: 22 +/- 10 vs. 65 +/- 11 (p less than 0.01); 21 +/- 5 vs. 8 +/- 4, (p less than 0.01); and 2.8 +/- 0.5 vs. 3.5 +/- 1.0 (p = 0.05). Compared with atrial pacing, cardiac index decreased from 2.8 +/- 0.6 to 2.2 +/- 0.5 (p less than 0.01) in Group A and from 3.6 +/- 0.7 to 2.9 +/- 0.5 (p less than 0.01) in Group B, during ventricular pacing. Pulmonary capillary wedge pressure increased by similar amounts in both groups during ventricular pacing. The change in cardiac index, % change in cardiac index, and change in pulmonary capillary wedge pressure from atrial to ventricular pacing, were not different between Group A and Group B patients. By logistic regression analysis, no association was found between the % change in cardiac index and the following variables: left ventricular ejection fraction, left ventricular end-diastolic volume, baseline pulmonary capillary wedge pressure, change in pulmonary capillary wedge pressure, and baseline cardiac index. The atrial contribution to resting steady-state cardiac function is similar between patients with severe congestive failure and those with preserved ventricular function.