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 STR phenotype (V-STR). However, this threshold value has never been tested.

Methods: Single-center, prospective enrollment of consecutive patients with STR who underwent two- and three-dimensional echocardiography.

Results: We enrolled 350 patients (75±13 years, 65% women). Although patients with A-STR and V-STR presented similar degrees of STR and comparable RA size, the ES RA:RV volume ratio was significantly larger in A-STR than in V-STR (1.75 [interquartile range (IQR) 1.35-2.45] vs. 1.18 [IQR 0.81-1.66] respectively; p<0.001). On receiver operating characteristic (ROC) analysis, the ES RA:RV volume ratio showed a significantly higher predictive power for A-STR (AUC 0.73, 95%CI 0.68-0.78) compared to RA maximum volume (AUC 0.6, 95%CI 0.54-0.66, p=0.01), RA minimum volume (AUC 0.59, 95%CI 0.53-0.65, p=0.007), and RA minimum volume to RV end-diastolic volume ratio (AUC 0.57, 95%CI 0.51-0.63, p<0.001). 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 A-STR diagnosis were similar (p= 0.58). The threshold value for ES RA:RV volume ratio that best distinguished between the 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 of 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 left ventricular ejection fraction, RV ejection fraction, RA maximum volume, and pulmonary artery systolic pressure, resulted in an AUC= 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.