Real prevalence of pulmonary right-to-left shunt according to genotype in patients with hereditary hemorrhagic telangiectasia: a transthoracic contrast echocardiography study.

BACKGROUND: Transthoracic contrast echocardiography (TTCE) can detect pulmonary right-to-left shunting (RLS) and is used to screen for pulmonary arteriovenous malformations (PAVMs) in patients with hereditary hemorrhagic telangiectasia (HHT). We studied the prevalence and size of pulmonary RLS in HHT type 1, HHT type 2, and HHT-negative controls, and its positive predictive value (PPV) and negative predictive value (NPV) for PAVMs that can be treated by embolotherapy.

METHODS: In 343 consecutive persons referred for possible HHT as first-degree family members of index patients a TTCE and chest CT scan were performed. All persons were offered genetic analysis.

RESULTS: An HHT-causing mutation was confirmed in 92 (mean age 41 ± 15 y; 59% female) HHT1 relatives and in 97 (mean age 47 ± 14 y; 52% female) HHT2 relatives. TTCE showed a pulmonary RLS in 78 (85%) HHT1- and 34 (35%) HHT2-related mutation carriers, respectively (P < .0001). In HHT1 relatives, 29 of 53 (55%) PAVMs and in HHT2 relatives three of 17 (18%) PAVMS were treated, resulting in a PPV of TTCE for treatable PAVMs of 36.3% and 8.3%, respectively. The accompanying NPV was 100%. A minimal, moderate, or large shunt was present in 12 (13%), 24 (26%), and 42 (46%) HHT1-related, and in 20 (21%), 6 (6%), and 8 (8%) HHT2-related mutation carriers, respectively (P for trend < .0001). A large shunt predicted treatable PAVMs in 55.8% of HHT1 relatives and 37.5% of HHT2 relatives. TTCE was positive in four (6%) of 63 persons without HHT.

CONCLUSIONS: A pulmonary shunt on TTCE is more prevalent and larger in HHT1- compared with HHT2-related mutation carriers. Shunt grading is helpful to predict treatable PAVMs, particularly in the HHT2 group. TTCE is also positive in a small fraction of persons without HHT.