Accuracy of agitated saline contrast echocardiography for assessment of intracardiac shunting in preoperative liver transplant patients
Swanson B, Salgia R, El-Bashir J, and Parikh S. Accuracy of agitated saline contrast echocardiography for assessment of intracardiac shunting in preoperative liver transplant patients. Journal of the American College of Cardiology 2020; 75(11):1600.
J Am Coll Cardiol
Background Patent Foramen Ovale (PFO) is a common clinical condition that is found in up to 20% of adults. Transthoracic Echocardiography (TTE) with agitated saline contrast imaging (ASCi) has become the screening test of choice for PFO with reported sensitivity of 99% and specificity of 85%. Exclusion of significant atrial level shunt is important prior to liver transplant but patients with end stage liver disease (ESLD) can be difficult to evaluate with ASCi given a high prevalence of intra-pulmonary shunting. We sought to evaluate if ASCi can accurately predict presence of atrial level shunting in patients with ESLD prior to transplant. Methods We performed a retrospective chart review of patients in our health system who underwent liver transplant between January 2016 and March of 2019. We screened for TTE with ASCi that was positive for presence of left sided microbubbles who also had a transesophageal echocardiogram (TEE). TTEs were reviewed and categorized as large if there were more than 20 left sided bubbles and early if they appeared within 5 cardiac cycles following opacification of right atrium. TEEs were then reviewed for presence of a PFO or atrial septal defect. Results Of the initial 317 patients that were screened, 124 had TTEs with ASCi performed of which, 51 (41%) were positive for shunt with rest or provocation. Of those, 25 (49%) had an adequate TEE performed in our system, of which 5 (20%) were found to have a PFO. Early vs. late positivity was not significantly associated with presence of PFO (19%vs 22% [p=0.84]) and of patients with early and large positive studies only 23% (3 of 13) had a PFO. Conclusion Our finding of only 20% of positive ASCi studies being associated with PFO is substantially lower than reported in prior literature. Furthermore, there does not seem to be any significant benefit utilizing early positivity or size of shunt to differentiate between PFO and intra-pulmonary shunting in ESLD patients. High prevalence of concomitant hepatopulmonary syndrome as well as high-flow states renders traditional measures of shunt localization and categorization inaccurate. These findings suggest that ASCi lacks adequate positive predictive value to assess for PFO in patients with ESLD.