Utility of the Ratio Between the Size of the Right Atrium and the Right Ventricle at End-Systole to Diagnose Atrial Secondary Tricuspid Regurgitation.

Background: In the multiparametric framework for diagnosing atrial secondary tricuspid regurgitation (A-STR), an end-systolic (ES) right atrial (RA)-to-right ventricular (RV) volume or area ratio ≥1.5 supports the diagnosis of A-STR over the ventricular secondary tricuspid regurgitation phenotype (V-STR). However, this threshold value has never been tested.

Methods: A single-center study was conducted, prospectively enrolling consecutive patients with secondary tricuspid regurgitation who underwent two- and three-dimensional echocardiography.

Results: A total of 350 patients were enrolled (mean age, 75 ± 13 years; 65% women). Although patients with A-STR and V-STR presented similar degrees of secondary tricuspid regurgitation and comparable RA size, the ES RA/RV volume ratio was significantly larger in A-STR than in V-STR (1.75 [interquartile range, 1.35-2.45] vs 1.18 [interquartile range, 0.81-1.66], respectively; P < .001). On receiver operating characteristic analysis, the ES RA/RV volume ratio showed a significantly higher predictive power for A-STR (area under the curve [AUC], 0.73; 95% CI, 0.68-0.78) compared with RA maximum volume (AUC, 0.6; 95% CI, 0.54-0.66; P = .01), RA minimum volume (AUC, 0.59; 95% CI, 0.53-0.65; P = .007), and ratio of RA minimum volume to RV end-diastolic volume (AUC, 0.57; 95% CI, 0.51-0.63; P < .001). However, the predictive power of the ES RA/RV volume ratio (AUC, 0.73; 95% CI, 0.68-0.78) and the ES RA/RV area ratio (AUC, 0.76; 95% CI, 0.71-0.81) for the diagnosis of A-STR was similar (P = .58). The threshold value for ES RA/RV volume ratio that best distinguished between A-STR and V-STR was 1.40 (AUC, 0.68; 95% CI, 0.63-0.73), whereas for ES RA/RV area ratio, it was 1.6 (AUC, 0.64; 95% CI, 0.59-0.69). A multivariable model that included either ES RA/RV volume ratio or ES RA/RV area ratio, along with LV ejection fraction, RV ejection fraction, RV ES volume, and pulmonary artery systolic pressure, resulted in an AUC of 0.97 for differentiating between A-STR and V-STR.

Conclusions: ES RA/RV volume ratio ≥ 1.4 and ES RA/RV area ratio ≥ 1.6 support the diagnosis of A-STR over V-STR.