Age-related increases in pulse pressure (PP) across the adult age-span, and the development of isolated systolic hypertension (ISH), the extreme form of high PP, are often presumed due to age-related arterial stiffening. However, stroke volume (SV) is a key physiological determinant of PP, but the impact of SV on age-related changes in PP and ISH is unclear. We sought to quantify the impact of age on the physiological determinants of PP and ISH.

Detailed haemodynamic data including blood pressure (BP), SV and aortic pulse wave velocity (aPWV) were available in 5496 individuals (2470 males), aged between 18–92 years. Data were stratified by gender. ISH was defined as SBP≥140mmHg and DBP<90mmHg.

SV and aPWV were independently associated with PP (P<0.001 for both) and there was a strong interaction with age, where PP and aPWV increased significantly across the adult age-span (P<0.001 for both) but SV declined significantly with increasing age (P<0.001). In younger individuals (<30 years), SV, but not aPWV, was associated with increasing quartiles of PP in both males and females (P<0.001 for both) and was elevated in subjects with ISH versus normotensives (P<0.001). However, the opposite pattern was evident in older individuals, with aPWV rather than SV associated with high PP and ISH (P<0.001 for all comparisons).

The haemodynamic mechanisms underlying elevated PP and ISH change across the adult life-span. Moreover, due to the age-related decline in SV, PP may underestimate the true age-related increase in aortic stiffness.