Effects of age and pulmonary arterial hypertension on the different phases of right atrial function

To evaluate the effects of age and pulmonary hypertension on phasic right atrial function we measured right atrial volumes at 3 different points in the cardiac cycle in 57 healthy subjects and 33 patients with pulmonary arterial hypertension. Right atrial reservoir function was assessed by systolic filling volume and passive and active emptying by passive and active emptying volume and fraction of total emptying. We compared these phases of right atrial function in 30 healthy subjects <60 and 27 ≥ 60 years old, and in a separate analysis, in 33 patients with pulmonary arterial hypertension and 33 matched controls. Healthy subjects ≥60 years had lower passive emptying fraction (46.0 ± 23.3% vs 59.9 ± 15.4%, P = 0.011) and larger active emptying volume (7.0 ± 3.5 vs 4.9 ± 2.5 ml/m², P = 0.013 ) and fraction (54.0 ± 23.3% vs 40.1 ± 15.4%, P = 0.011) compared to those <60. Patients with pulmonary arterial hypertension had larger right atrial volumes, systolic filling volume (18.3 ± 6.9 vs 12.3 ± 4.9 ml/m², P ≤ 0.001) and active emptying volume and fraction (11.2 ± 6.9 vs 5.4 ± 3.0 ml/m², P ≤ 0.001; 60.7 ± 29.9 vs 44.9 ± 19.0%, P = 0.017 ) and smaller passive emptying fraction (39.3 ± 29.9% vs 55.1 ± 19.0%, P = 0.017) compared to controls. Aging and pulmonary arterial hypertension are associated with a decrease in passive right atrial emptying and an increase in right atrial active emptying.