Contrast echocardiography for pulmonary arteriovenous malformations screening: does any bubble matter?

To evaluate diagnostic accuracy of contrast echocardiography (CE) as compared with CT, for the screening of pulmonary arteriovenous malformations (PAVMs) in hereditary haemorrhagic telangiectasia (HHT); to evaluate the clinical significance of semi-quantitative analysis of a shunt on CE. A blinded prospective study was conducted in 190 consecutive subjects at risk of HHT who underwent screening for PAVMs, including clinical evaluation, pulse oximetry, standard and CE, and chest multirow CT without contrast medium. A semi-quantitative analysis of the shunt size was performed according to the contrast echo opacification of the left-sided chambers: Grade 0, no bubbles; 1, occasional filling with < 20 bubbles; 2, moderate filling; 3, complete opacification. The first 100 patients were compared with 100 controls. A total of 119 (63%) patients had positive CE (32.2% Grade 1, 13.1% Grade 2, 11% Grade 3, 6.3% with patent foramen ovale). The overall diagnostic performance of CE was sensitivity 1.00, specificity 0.49, positive predictive value (PPV) 0.32, negative predictive value (NPV) 1.00. The PPV for the different grades was 0.00 for Grade 1, 0.56 for Grade 2, 1.00 for Grade 3; the NPV of Grade 0 was 1.00. A significant correlation was found between the CE grading and the number of PAVM, and complications (P < 0.0001). CE is an extremely sensitive procedure for the detection of PAVMs with substantial clinical impact.