Background: Echocardiography has long been established as the primary noninvasive method for diagnosing pulmonary hypertension (PH) prior to transcatheter aortic valve replacement (TAVR) in patients with severe aortic valve stenosis (AS). In recent years, radiological methods for diagnosing PH have been investigated. Measurements such as the computed tomography angiography (CTA)-derived pulmonary artery (PA) diameter and PA diameter/body surface area (PA/BSA) have shown promising results regarding their diagnostic strength. However, it has yet to be determined if a patient’s sex has any impact on the effectiveness of these diagnostic measurements. Methods: In all, 271 patients (51.3% male, mean age 82.6 ± 4.8 years) with severe AS undergoing TAVR were separated into male and female groups. The cut-off values for the diagnosis of PH were calculated for the CTA-derived PA diameter and PA/BSA based on different systolic pulmonal artery pressure values (40–45–50 mmHg). Patients were then subclassified according to measurements above or below these PA diameters and PA/BSA cut-off values. A PA diameter ≥29.5 mm and PA/BSA ≥ 15.7 mm/m2 qualified for PH. The 1–5 year survival rate in these cohorts was further analyzed. Results: Patients with a PA diameter ≥29.5 mm showed a significantly higher 1 year mortality rate (p = 0.014). This observation could only be confirmed for the male sex (p = 0.018) and not for the female sex (p = 0.492). As for the PA/BSA, in patients over the cut-off value, no significant increase in mortality was noted in the overall cohort. However, the male patients showed increased 3 year (p = 0.048) and 5 year mortality rates (p = 0.033). Conclusions: The CTA-obtained PA diameter and PA/BSA are both useful in the diagnosis of PH and mortality risk stratification in patients with severe AS undergoing TAVR, especially in males. Male patients with PA ≥ 29.5 mm or PA/BSA ≥ 15.7 mm/m2 seem to be at a higher risk of death during follow-up after undergoing TAVR. In females, no such correlation was observed.