Pulmonary arteriovenous malformation risks: Single-centre hybrid study of 1,149 cases re-emphasises hypoxemia without pulmonary hypertension, and paradoxical embolic/infective stroke etiologies

Pulmonary arteriovenous malformations (PAVMs) larger than 4mm in size are estimated to affect 38 per 100,000 individuals [95% confidence intervals 18-76]. They provide an anatomical right-to-left shunt such that each heartbeat, a proportion of the cardiac output bypasses the pulmonary capillary bed, preventing essential processing functions such as gas exchange and filtration of blood-borne emboli. Although large cohort series were published in earlier decades, more recent data series have been scant. Here we report features of 1149 consecutive patients with imaging-proven PAVMs, reviewed at a single UK centre between 1984-2026, including 813 [95% confidence intervals 0.68, 0.74] with clinical and/or genetically confirmed hereditary hemorrhagic telangiectasia (HHT). The median age was 47y, and 735 [0.64, 0.48] were female. We report 4348 oxygen saturation measurements at presentation and follow-up, and 810 pulmonary artery pressure (PAP) measurements made at angiography prior to treatment of PAVMs by embolisation. Together, these confirm that there is no risk of hypoxic pulmonary hypertension, with PAP measurements higher in patients with higher SaO ₂ . Massive hemoptysis or hemothorax affected 18/1,149 [0.007, 0.018] patients, confirmed ischemic strokes 125/1,149 [0.09, 0.13] patients, brain abscess 107/1,149 [0.08, 0.11] patients, and hemorrhagic strokes 23/1149 [0.01, 0.03] patients. These data will inform design of future work to evaluate etiologies, associations and implications for clinical practice.