Importance of left atrial function in patients with myocardial infarction.

Left atrial function was evaluated in patients with and without remote myocardial infarction. The simultaneous left atrial pressure recording and left atrial and left ventricular cineangiograms were obtained with a catheter-tip micromanometer. The pressure-volume curve of the left atrium was composed of an A-loop and a V-loop. The ratio of active atrial emptying to left ventricular stroke volume in patients with myocardial infarction was significantly larger than that in normal subjects (42 +/- 12% vs 29 +/- 10%, p less than 0.05). The left atrial work was also significantly greater in patients with myocardial infarction (1690 +/- 717 mm Hg X ml) than in normal subjects (940 +/- 426 mm Hg X ml, p less than 0.05). The ratio of active atrial emptying to left ventricular stroke volume and left atrial work were significantly related in both normal subjects and patients with myocardial infarction (gamma = 0.72, p less than 0.01). The left ventricular ejection fraction correlated inversely with left atrial work...