Comprehensive multimodal imaging of quadricuspid pulmonary valves: morphology, function, and mid-term prognosis.

Quadricuspid pulmonary valve (QPV) is a rare congenital anomaly with limited reports. This study characterizes QPV morphology and function by multimodal imaging, evaluates predictors of moderate-to-severe pulmonary regurgitation (PR), and assesses mid-term prognosis. Retrospective search of the imaging database at a tertiary medical center identified patients diagnosed with QPV between October 2004 and September 2024. Multimodal imaging was utilized to assess the characteristics of QPV and associated abnormalities. Among 1,367,280 cardiac CT and MR exams, 16 patients were diagnosed with QPV (38% male; mean age 43.4 ± 19.7 years). The most common morphology was type D (38%, one larger, two equal intermediate, and one smaller cusps), with cusp fusion in 25% and Becker's type Ⅲ in 13%. Associated congenital heart disease (CHD) occurred in 6 patients (38%). Moderate-to-severe PR was observed in 11 patients (69%), severe pulmonary valve stenosis (PS) in one, and pulmonary artery aneurysm (PAA) in eight (50%). Both regurgitant orifice area (ROA) and main pulmonary artery (PA) dilation increased the risk of moderate-to-severe PR (OR = 2.33, p = 0.048; OR = 1.57, p = 0.041; each 0.25-unit increase). No significant difference was found between QPV classification and PR severity or clinical outcomes. During a median follow-up of 16 (IQR: 2-66) months, no deaths occurred, and 5 patients (31%) underwent surgery. QPV is a rare congenital cardiac malformation with diverse morphologies, predominantly associated with PR and PAA. Approximately one-third of patients required surgery. Multimodal imaging is essential for diagnosis, functional assessment, and management planning for QPV.