Right atrial strain associated with clinical outcomes in PAH
medwireNews: Study results suggest that right atrial (RA) strain could predict adverse outcomes among patients with pulmonary arterial hypertension (PAH).
“No longer the ‘forgotten chamber,’ the right atrium is now receiving more attention in the PAH and echocardiography literature,” say Nicole Bhave (University of Michigan Health System, Ann Arbor, USA) and study co-authors in The International Journal of Cardiovascular Imaging.
“Our findings add to a small but growing body of work illustrating the prognostic importance of RA size and function in this patient population,” they add.
The team found that 68% of 37 patients with PAH experienced the composite endpoint of prostacyclin initiation, lung transplantation, or death over a mean 5.3 years of follow-up. Mean RA strain, as measured by transthoracic echocardiography with speckle tracking, was significantly lower among patients who experienced the composite endpoint compared with those who did not, at 20% versus 33%.
RA strain was also lower in patients with PAH than in 14 healthy volunteers (24 vs 35%), but the PAH patients who did not experience the composite endpoint had similar strain measurements to the healthy individuals.
These findings suggest that the observed difference in RA strain between PAH patients and healthy controls “was driven largely by lower strain in patients who met the primary endpoint,” observe the authors.
However, they note that patients who did not meet the primary endpoint may have been “diagnosed and treated earlier in the disease process than patients who experienced adverse outcomes, such that significant right heart remodeling had not yet occurred.”
Bhave and colleagues also observed a negative correlation between RA strain and invasive hemodynamic measurements including RA pressure, pulmonary arterial pressure, and pulmonary vascular resistance (correlation coefficient = −0.31, −0.33, and −0.39, respectively), as well as a positive association between RA strain and cardiac index (correlation coefficient=0.44).
Furthermore, in receiver operating characteristic analysis, RA strain was not significantly different from RA volume, right ventricular (RV) fractional area change, RV basal diameter, or RV systolic pressure (RVSP) in its ability to distinguish patients meeting the primary endpoint from those without adverse outcomes.
Although the researchers point out that “RA strain assessment is straightforward and reproducible,” they note that their retrospective single-center study was limited by a small sample size, and that “larger studies are needed to determine whether RA strain has significant prognostic value when added to the simpler measurement of RA volume.”
And they add that “it remains to be seen whether RA strain is independently predictive of clinical outcomes in PAH, beyond measurements of RA size and estimated RVSP.”
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