Objective:
Left atrial (LA) enlargement and dysfunction have poor prognostic significance in heart failure and coronary artery disease. However, the correlation between LA diameter and World Health Organization (WHO) Group 2 pulmonary hypertension (PH) severity has not been well studied.
Hypothesis:
We hypothesized that LA enlargement as a marker of LA remodeling in response to pressure and volume overload may contribute to higher pulmonary arterial pressures (PAP) in this population, independent of comorbidities and left ventricular ejection fraction (LVEF).
Methods:
After exclusion for severe left-sided valvular disease, 100 patients with isolated or mixed WHO Group 2 PH defined by right heart catheterization were studied in a cross-sectional retrospective analysis at a single institution. Linear LA anteroposterior diameter was obtained from the parasternal long-axis view on two dimensional TTE. LVEF, LV E/A Ratio, and LV Mass Index were measured according to ASE guidelines. LV E/A and LV Mass Index was recorded in 80 subjects and 79 subjects, respectively. Mean PAP was assessed on RHC. TTE and RHC were performed within one year of each other.
Results:
LA diameter was significantly associated with mean PAP after adjustment for age, sex, body-mass index, presence of coronary artery disease, hypertension, atrial fibrillation, and LVEF in multivariable linear regression analysis. In this multivariable model, a one centimeter increase in LA diameter predicted an average increase in mean PAP of 2.78 mmHg (95% CI 0.10, 5.46, p = 0.0423). In a subset of this population, LVEF, LV E/A Ratio, and LV Mass Index were not significant predictors of mean PAP. Reduction in cardiac index was noted with increasing LA diameter but this trend did not reach statistical significance.
Conclusion:
LA enlargement is significantly associated with increased mean PAP in patients with WHO Group 2 PH. LA enlargement may be a proxy for LA dysfunction and our data suggests that increased LA diameter may be a predictor of WHO Group 2 PH severity. Further studies of LA dimension, volume, and function are warranted to further our understanding of the left atrium’s relationship to PH.
Models and Molecular Mechanisms of World Health Organization Group 2 to 4 Pulmonary Hypertension