Right Atrial Coupling Index as a Novel Echocardiographic Marker in COPD: Associations With Prior Hospitalizations and...

Chronic obstructive pulmonary disease (COPD) frequently leads to right heart structural and functional alterations. This study evaluates the right atrial coupling index (RACI), calculated as the right atrial volume index (RAVI) divided by the tricuspid annular late diastolic velocity (a'), as a novel echocardiographic marker for discriminating patients with prior COPD-related hospitalizations and for assessing functional decline, measured via the six-minute walking distance (6MWD).

This cross-sectional study enrolled 76 stable COPD patients in sinus rhythm. Participants underwent transthoracic echocardiography to measure right heart parameters and performed a six-minute walk test. Hospitalization history was retrieved from electronic health records. RACI was analyzed using receiver operating characteristic (ROC) curves and correlation tests.

Of the 76 participants (83% male, mean age 67.6 ± 9.2 years), those with prior hospitalizations exhibited significantly higher RACI (2.51 ± 0.84 vs. 1.73 ± 0.63 cm³/m²/m/s, p < 0.001). In discriminating patients with prior hospitalizations, RACI achieved an AUC of 0.763 (95% CI: 0.652-0.853). For identifying functional decline (6MWD < 357 m), RACI showed an AUC of 0.844 (95% CI: 0.743-0.917) at a threshold of 1.99 cm³/m²/m/s. RACI consistently outperformed its individual components, RAVI and tricuspid a'.

RACI is significantly associated with a history of COPD-related hospitalizations and with reduced exercise capacity. As a cross-sectional discriminative marker, RACI outperformed its individual components and may serve as a useful echocardiographic index for characterizing right heart burden in stable COPD patients. Prospective longitudinal studies are warranted to establish its predictive validity for future exacerbation events.