Study limitations
The present study did not validate the echocardiographic measurements
against invasive gold standard evaluation of the pulmonary circulation
by PAP, wedged PAP and cardiac output, and right ventricular function by
indices derived from pressure-volume loops. Thus accuracy and precision
were defined by comparison only with the core laboratory measurements.
The number of patients studied was relatively small (n = 10). However,
each of the 19 participating centers provided a total of 35 left and
right heart echo-Doppler variables at rest, peak exercise and after 5
minutes of recovery. Finally, it should be underlined that contrast
and/or agitated saline enhancement for tricuspid regurgitation (TR)
Doppler signal was not performed. The additional use of contrast and/or
agitated saline may further improve the reliability, particularly in
less experienced centers.