Pulmonary arteriovenous malformations (PAVMs) occur in 30–50% of hereditary hemorrhagic telangiectasia (HHT) patients. Some patients have no CT-detectable PAVMs but have intrapulmonary shunt (IPS) on contrast echocardiography (CE), possibly representing smaller PAVMs. We aimed to describe their clinical presentation and outcomes.
We identified patients from the Toronto HHT Database (1998–2008) with a definite HHT diagnosis according to the Curacao criteria. Patients with IPS on CE but negative CT scan for PAVMs were included. Retrospective chart and imaging review was performed.
Of 73 patients with isolated IPS, 43/73(59%) were female; mean age was 44 years (range: 20–73). ALK1 mutation was detected in 28/73 (38%), endoglin mutation in 11/73 (15%), variant of unknown significance in 4/73 (5%) and no detected mutation in 6/73 (8%). At initial assessment, dyspnea was reported in 25/73 (34%), migraine in 17/73(23%), previous minor hemoptysis in 6/73 (8%) and previous stroke in 3/73 (4%), though strokes occurred at ages 59–65 years and with multiple non-HHT risk factors. In 3/73 (4%) patients, significant PAVMs were detected on immediate pulmonary angiography following initial negative CT (all pre-helical CT use). Mean follow-up was 49 months (range: 0–120). PAVMs were detected on follow-up CT in 2/73 (3%), of which one was confirmed retrospectively on initial CT. There was 1 death (age 69); unrelated to PAVMs. There were no hemorrhagic or neurologic PAVM complications. Forty-nine/73 (67%) underwent serial CE. IPS severity increased in 12/49 (24%), remained unchanged in 16/49 (33%), and decreased in 21/49 (43%) of which 11 normalized.
Symptoms from isolated IPS are similar to PAVMs but occur at lower rates. Unlike patients with CT-detectable PAVMs, ALK-1 mutations might be more common than endoglin mutations. No PAVM-related complications were observed during follow-up, so risk of complications from isolated IPS is likely low. IPS severity remained unchanged or decreased over time in the majority of these patients.
Short-term risk appears to be low in these patients, but long-term follow-up is important to detect previously undetected and new PAVMs.
Harvey Wong, Grant monies (from sources other than industry) Nelson Arthur Hyland Foundation (M.E.F.); No Product/Research Disclosure Information