The right atrium and tricuspid annulus are cardinal structures in tricuspid regurgitation with or without pulmonary hypertension.

Background: Right heart structural abnormalities occur in both tricuspid regurgitation (TR) and pulmonary hypertension (PH). They may occur independently or together, but their joint effects on cardiac structure are incompletely described. This study examined the interactions of TR severity and PH on right heart structural changes.

Methods: The study evaluated 455 patients undergoing both echocardiography and CT angiography (CTA). Cases were divided into 3 groups by TR severity: trace (n=217), mild (n=174), and significant (moderate or severe, n=64). Each TR level was subdivided into two groups by PH absent or present. Cardiac structural measurements included tricuspid annulus area (TAA), right atrial (RA) and right ventricular volume (RV) indexed to body surface area.

Results: Analysis by TR and PH showed that indexed RA Volume and TAA were very sensitive to TR severity. RA volume was most affected by pulmonary hypertension when TR was trace or mild, while PH had less effect on TAA. In significant TR, neither RA volume nor TAA were changed by PH. Indexed RV volume was insensitive to trace and mild TR, and PH similarly had little effect.

Conclusions: RA volume and tricuspid annulus area enlarge in proportion to TR severity, trace through significant. PH impacts RA volume but only in trace and mild TR. RA volume best reflects TR impact on right heart structure, both with and without PH. Right atrial volume and tricuspid annulus area are the cardinal indices of TR-induced right heart structural disease et al.l severities.

Ultramini Abstract: Right heart structural effects of TR and PH were examined in this study. Patients were evaluated by echo and CTA, and grouped by TR severity as trace, mild, and significant, and were subdivided by PH absence/presence. Analysis by TR severity and PH showed that Indexed RA volume is the parameter most sensitive to TR severity, and PH causes incremental RA volume increases in trace/mild TR. Indexed tricuspid annulus area (TAA) similarly increases with TR severity, but was unaffected by PH at any TR severity. RV volume is insensitive to TR severity and PH. Indexed right atrial volume and tricuspid annulus area are cardinal indices for TR-induced right heart structural disease and increase proportionally to TR severity. RA volume is more sensitive to PH than is tricuspid annular area. TR severity may be more accurately assessed by increased RA volume and annulus area.

Perspective Statement: The right atrium (RA) and tricuspid annulus (TA) are the cardinal cardiac structures affected by tricuspid regurgitation (TR). They each enlarge with TR severity. The right ventricle exhibits minimal change across TR severity. Pulmonary hypertension (PH) enhances TR-mediated RA and TA dilation, but only in trace and mild TR. PH has no effect on RA, TA, or RV size in significant TR.

Central Message: Right atrial volume and tricuspid annulus area are the most sensitive to TR severity, and are also sensitive to pulmonary hypertension.