Prediction of intrapulmonary right to left shunt with left atrial size in patients with liver cirrhosis

BACKGROUND: We screened a large number of liver transplant candidates with contrast echocardiography to detect intrapulmonary right to left shunt (IPS). We found that IPS is frequently present in patients with left atrial enlargement. This finding raises a question concerning the correlation between IPS and left atrial size in patients with liver cirrhosis. OBJECTIVES: The aim of this prospective study was to evaluate the possible correlation between left atrial size and IPS in patients with liver cirrhosis. METHODS: Adult patients (>18 years old) with documented liver cirrhosis underwent trans-thoracic contrast echocardiography with agitated saline. Left atrial dimension was measured by M-mode echocardiography. Stroke volume was calculated using left ventricular M-mode echocardiography. Patients with atrial fibrillation, intracardiac shunt, congenital heart defects, valvular heart disease and diastolic dysfunction were excluded. RESULTS: A total of 92 patients met all study criteria. Of these, 39 (42.3%) had IPS. Cardiac output was significantly greater in patients with IPS compared with those without IPS (5.68 +/- 0.83 L/min vs 4.75 +/- 0.76 L/min, P < 0.01). In a multi-variable model, after adjustment for body surface area and body mass index, left atrial enlargement was the strong predictor of IPS (area under the curve = 0.66) but when controlling for cardiac output, left atrial size was not an independent predictor of IPS. CONCLUSION: In the context of liver cirrhosis, patients with IPS have greater cardiac output compared with those without shunt. Left atrial enlargement, which reflects one aspect of increased cardiac output, is an indirect marker of IPS and greater left atrial dimension is associated with the presence of intrapulmonary right-to-left shunt.