Long-term follow-up of hereditary hemorrhagic telangiectasia patients without significant pulmonary right-to-left shunt at screening

•HHT patients with low grade right-to-left shunt (RLS) at screening TTCE do not develop pulmonary arteriovenous malformations-related complications during long-term follow-up.•RLS rarely increases to grades ≥ 2 in HHT patients with initial grades 0–1 RLS at TTCE.•Extending rescreening to a period greater than 5 years could be justified in HHT patients without RLS at screening (grade 0). To describe the incidence of pulmonary arteriovenous malformations (PAVM)-related complications, right-to-left shunt (RLS) progression at transthoracic contrast echocardiography (TTCE) and development of treatable PAVM during long-term follow-up in hereditary hemorrhagic telangiectasia (HHT) patients with RLS grades 0–1 at screening TTCE. Observational prospective study including adult HHT patients with grades 0–1 RLS at screening TTCE. Those requiring previous embolization of PAVM were excluded. PAVM-related complications and RLS progression during follow-up were recorded. 183 patients were followed-up during 5.6 [IQR: 3.3–8.2] years. Seven (3.8 %) patients developed potentially PAVM-related complications, although all of them were considered unrelated to HHT after multidisciplinary assessment. Among 84 patients with a follow-up TTCE, RLS progressed to grades ≥2 in eight (9.5 %). Among patients with grade 0 RLS at screening, 31.6 % evolved to grade 1 RLS during follow-up and none progressed to grade ≥ 2. Among patients with grade 1 RLS at screening, RLS increased in 17.4 %, by one grade in most cases, and two (2.4 %) patients developed treatable PAVM. Grade 1 RLS and a higher epistaxis severity score were associated with RLS progression. In HHT patients with grades 0–1 RLS at screening, PAVM-related complications are rare. No patient with grade 0 RLS showed an increase in RLS of more than one grade on TTCE. Among patients with grade 1 RLS, rescreening every 5 years should be recommended because treatable PAVM can develop; follow-up with TTCE could be an alternative, as it would allow a better selection of patients for chest CT.