The characters in Eugene Ionesco’s The Bald Soprano (one of the founding plays of the Theater of the Absurd) sit and talk, repeating the obvious until it starts sounding like nonsense. It is sometimes surprising how difficult it is to convince even scientists of the obvious.
In a well-conducted study in this issue of CHEST (see page 988), Rich et al1 remind us of the obvious and known fact that the estimation of pulmonary artery pressure (PAP) by Doppler echocardiography (DE) does not necessarily correlate with the measurement of PAP taken directly by right-sided heart catheterization (RHC). With a carefully conducted set of experiments and an appropriate statistical analysis, the authors show definitively that the estimated pulmonary artery systolic pressure (PASP), based on tricuspid regurgitant jet velocity (TRV), does not correlate with true PASP or mean PAP (mPAP) in a large cohort of patients with pulmonary hypertension. The authors examined the correlation and agreement between RHC and DE in a large cohort of 160 patients with pulmonary hypertension undergoing both tests within 30 days. In a smaller group of 23 patients, simultaneous measurements through RHC and DE were performed. In both instances, the authors found only a moderate correlation between RHC- and DE-derived PASP (r =0.7). Furthermore, Bland-Altman analysis revealed a >10-mm Hg difference 51% of the time. The study does not describe a novel finding. It is, however, a very important study because of its careful methodology and timing.