HFSA: Echo may not accurately assess PAH progression

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BOSTON—Repeated echocardiogram assessments are not sufficiently accurate to monitor progression of pulmonary arterial hypertension (PAH), according to results of the Registry to Evaluate Early And Long-term PAH disease management (REVEAL) presented Monday at the 2009 Heart Failure Society of America (HFSA) conference.

The correlation between cardiopulmonary hemodynamics estimated by echo and measured by right heart catheterization in patients with PAH is “controversial,” according to Harrison W. Farber, MD, from Boston University School of Medicine, and colleagues. Their group sought to correlate hemodynamic parameters evaluated by echo and right heart catheterization in patients with PAH enrolled in REVEAL.

The registry is a 54-center, observational, U.S.-based study designed to provide current data about demographics, course and management of nearly 2,000 patients with World Health Organization Group 1 PAH. Patients are followed for about five years from time of enrollment.

The researchers evaluated hemodynamics data collected from the first right heart catheterization and echo assessments within 12 months of one another. They found that similar results occurred when comparisons were restricted to echo/ right heart catheterization regardless of the time interval that separates them: on the same day, within one month of one another, within one to three months of one another, within three to six months of one another and within six to 12 months of one another.

The authors noted the consistent correlations may be due to combinations of the following:

  • There is good correlation between the two tests;
  • The variability of echo is so large that it overwhelms changes that might be observed if it were 100 percent accurate (where accuracy is defined as perfect correlation with a simultaneous right heart catheterization); and
  • Spontaneous biologic variation occurs at a pace such that the difference between two “accurate” tests is similar whether they are conducted within one day or within one year of one another.

However, Farber and colleagues also pointed out that there was “almost no correlation” of serial measurements between echo and right heart catheterization (right ventricular enlargement, right ventricular dysfunction, or left ventricular size vs. pulmonary vascular resistance index [PVRI], cardiac index, or mean right atrial pressure). They also reported that the P values from two sample t-tests comparing quantitative change in right heart catheterization compared with change in echo of “better” or “worse” were all less than 0.20.

For example, patients who experienced improvement from the first to the second assessment on the echo test for right ventricular enlargement reported an average decrease in PVRI of 3.8 Woods units x m2, while patients who experienced worsening right ventricular enlargement also reported a decrease in PVRI of 0.6 Woods units x m2. The difference, however, was not statistically significant.

The authors acknowledged the study’s limitations, including:

  • All patients were diagnosed with PAH using right heart catheterization.
  • All echos were not performed in a specialized center. However, they noted that the results “reflect real-life experience.”
  • The number of patients with serial echo and right heart catheterization assessments is small.
  • Though right systolic ventricular pressure (RSVP) is estimated from echo by the same technique, estimated right atrial pressure from echo may vary dependent on the operator and the method used to estimate it.

The Allschwil, Switzerland-based Actelion Pharmaceuticals supported REVEAL.