Effect of age on cardiac index, stroke index and left ventricular ejection fraction at rest and during exercise as studied by radiocardiography.

Radiocardiography was used to measure cardiac output, stroke volume and left ventricular ejection fraction at rest and during muscular exercise in relation with age in 148 healthy subjects (age range: 6-78 years). A clear dependence of these parameters on age was found. The mean annual decrease at rest was 22 +/- 9 ml/min/m2 for cardiac index, 0.22 +/- 0.04 ml/m2 for stroke index and 0.0017 +/- 0.0003 for left ventricular ejection fraction. Male subjects had significantly (p less than 0.001) greater cardiac (9 +/- 4%) and stroke indices (11 +/- 3%) than females. During submaximal exercise cardiac index increased from 3.5 +/- 0.7 l/min/m2 to 8.1 +/- 1.6 l/min/m2 in male subjects (mean age: 32 years) and from 3.1 +/- 0.4 l/min/m2 to 7.2 +/- 1.2 l/min/m2 in female subjects (mean age: 29 years). The corresponding increases in stroke index and left ventricular ejection fraction were: from 52 +/- 7 ml/m2 to 62 +/- 9 ml/m2, from 46 +/- 7 ml/m2 to 51 +/- 9 ml/m2 and from 0.66 +/- 0.08 to 0.79 +/- 0.05 and from 0.64 +/- 0.10 to 0.72 +/- 0.10. In subjects who were 60 years and older the increases of these parameters during exercise were considerably smaller.