Age-associated change in QRS axis: intrinsic or extrinsic ageing?

Human ageing is most usefully conceptualised as an interaction between intrinsic and extrinsic processes. Comparison of age-associated trends in populations living under different environmental conditions provides a method of recognising the effects of extrinsic influences. This paper compares the age-associated trend in mean frontal plane QRS axis in the male adult population of Pukapuka with the trend observed in an age-matched sample from a British population. The Pukapukans show no rise in mean blood pressure with age and have other features placing them at low risk of coronary heart disease. Although the British population showed the shift to the left in mean QRS axis characteristic of economically advanced populations there was no change in mean QRS axis with age among the Pukapukans. The conclusion is drawn that the shift with age in QRS axis observed in advanced populations is extrinsic in origin but is not necessarily a manifestation of coronary heart disease.