ECHO was inaccurate for pulmonary artery pressure, compared to right heart cath
Rich et al from U. of Chicago add to the "we said, they said" record on echocardiography's accuracy in measuring PA pressures (and by implication, whether it can be used to justify oral therapy for PAH without invasive testing). They measured 160 people's PAP by right heart catheterization and ECHO, both tests within one month; they then measured 23 other people's PAP using ECHO at the end of RHC. Similar to some others' findings, they found ECHO was moderately correlated with right heart catheterization; however, paired ECHO/RHC measurements of PAP were rarely close in each person on Bland-Altman analysis. In the larger patient sample, ECHO-derived PAP was >10 mm Hg different than PAP on RHC 51% of the time (higher or lower in a 40/60 split); in the simultaneously-tested group, mean bias was 8 mm Hg. They remind us that correlation is not the same as reliability, accuracy or precision, and argue against using ECHO to guide management decisions for people with pulmonary hypertension. CHEST 2011;139:988-993.
An associated editorial by Paterson and Michelakis sounds a warning, telling the recent story on sickle cell disease-related PAH, whose apparent overdiagnosis by ECHO without heart catheterization in clinical trials may have led to a harmful rush to overtreatment with vasodilators.