Refining tricuspid regurgitation severity assessment with new corrected proximal isovelocity surface area threshold values

Aims Research has shown that the corrected proximal isovelocity surface area (PISA) method yields larger values for regurgitant volume (RegVol) and effective regurgitant orifice area (EROA) than conventional PISA method. However, it remains unclear whether new threshold values are needed for the corrected PISA method to effectively categorize the severity of secondary tricuspid regurgitation (STR). This study sought to identify threshold values for EROA and RegVol measured by the corrected PISA method for a three-grade classification of STR severity. Methods and results We used three-dimensional echocardiography to determine the volumetric regurgitant fraction (RegFr), calculated as the difference between the right (RV) and left ventricular (LV) stroke volumes (SV) divided by the RVSV. A total of 213 patients (78 ± 10 years; 64% women) with isolated STR were enrolled. Based on RegFr, we classified STR severity into mild (RegFr < 16%), moderate (RegFr 16–49%), and severe (RegFr > 49%) grades. EROA and RegVol were measured using conventional (EROACONV, RegVolCONV) and corrected (EROACORR, RegVolCORR) PISA methods. The threshold values for identifying patients with mild, moderate, and severe STR were <0.22, 0.22–0.46, and >0.46 cm² for EROACORR, respectively; and <18, 18–42, and >42 mL for RegVolCORR, respectively. The accuracy of these new threshold values in predicting STR severity based on RegFr was 99% for EROACORR and 94% for RegVolCORR. These accuracies were significantly higher than those of EROACONV (90%, P < 0.001) and RegVolCONV (41%, P < 0.001). Conclusion New threshold values for the corrected PISA method must be considered to improve the classification of STR severity.