[Infleunce of heart cycle length on left ventricular ejection fraction in normals and patients with coronary artery disease].

The ejection fraction is a clinically valuable index of left ventricular pump function. We investigated the influence of a change in heart cycle length in normals (gr. I) and in patients with coronary artery disease without (gr. IIa) and after myocardial infarction (gr. IIb) (atrial pacing 80 and 120 min-1). In all subjects ejection time decreased by ca. 17%. There was no statistical difference between the groups. Ejection fraction (mean absolute values): gr. I (n = 7): - 3.4% (n. s.), gr. IIa (n = 8): - 8.4% (p is less than 0.01), gr. IIb (n = 12): - 6.5% (p is less than 0.01), Gr. IIa + IIb: - 7.2% (p is less than 0.001), gr. I +IIA + IIb: - 6.1% (p is less than 0.001). Compared to the control value the relative decrease for all subjects was -12.3 +/- 12.0% (n = 27). When left ventricular performance is evaluated by ejection fraction using invasive and noninvasive methods (contrast medium ventriculography, echocardiography and scintigraphy) heart cycle length has to be taken into account. The data cannot be normalized by a simple mathematical procedure.