Previous studies have suggested that pulmonary hypertension (PH) in severe aortic stenosis (AS) is a risk factor for operative mortality with aortic valve replacement (AVR). Conversely, others have shown that patients with AS and PH extract a large symptomatic and survival benefit from AVR compared with those patients not treated surgically. We sought to evaluate the prevalence, severity, and mechanism of PH in an elderly patient cohort with severe AS. We prospectively evaluated 41 patients aged ≥80 years with severe AS. All patients underwent cardiac catheterization and transthoracic echocardiography within 24 hours. We found that PH was common in this cohort: 32 patients (78%) had PH; however, the predominant mechanism of PH was left heart congestion. Patients with PH had nearly double the pulmonary artery wedge pressure of patients without PH (23 vs. 13 mmHg; P ≤ 0.001). In patients with PH compared with those without, pulmonary vascular resistance was higher yet still under 3 Wood units (WU; 2.9 vs. 1.5 WU; P = 0.001), and the transpulmonary gradient (11 vs. 7 mmHg; P = 0.01) and diastolic pulmonary gradient (DPG; 3.0 vs. 2.7 mmHg; P = 0.74) were in normal range. Left ventricular diastolic abnormalities were more common in patients with severe AS and PH. Right ventricular (RV) dysfunction was common (13/41 patients, 32%), but the PH and non-PH groups had similar tricuspid annular plane systolic excursion (2.0 vs. 2.3 cm; P = 0.15). Only 2 subjects had both RV dysfunction and an elevated DPG. In conclusion, PH is common in elderly patients with severe AS. This occurs largely due to left heart congestion, with a relative absence of pulmonary vascular disease and RV dysfunction, and as such, PH may serve as a heart failure equivalent in these patients.