Volume-flow (V-Q) discordance occurs in nearly one-third of patients with aortic stenosis (AS) post TAVR and offers superior prognostic value over existing stroke volume index (SVi) and transaortic flow rate (TFR) thresholds, according to a recent study being presented at ESC Congress 2025 and simultaneously published Aug. 27 in JACC: Asia.

Sara L. Hungerford, MBBS, FACC, et al., evaluated registry data from 291 patients ≥65 years old who underwent TAVR and were followed over five years to evaluate the prognostic significance of V-Q discordance in patients with severe AS undergoing TAVR. Low V-Q discordance was defined as SVi <35 mL/m2 with TFR >210 mL/s and normal V-Q discordance as SVi >35 mL/m2 with TFR <210 mL/s. Additionally, aortic flow was assessed using Doppler echocardiography and TFR was calculated mathematically. A significant association between TFR, height, weight and BMI was observed.

Results showed that over the median three-year follow-up, V-Q discordance was observed in 29% of participants (15% low, 14% normal). Furthermore, discordance was more frequent in patients without hypertension (75% vs. 65%), coronary disease (57% vs. 35%) or diabetes (15% vs. 2%; all p<0.05) in participants with Svi <35 mL/m2. Arterial compliance was higher and diastolic blood pressure was lower, independent of Svi and LVEF.

Low V-Q discordance was a strong survival predictor and associated with improved three-year survival rates.

"Overall, our findings highlight the value of V-Q discordance in providing additional hemodynamic insights into systemic circulation properties in patients with low-flow AS," the authors write. "Further research is needed to establish standardized reference ranges, which will enable a more comprehensive understanding of the potential for TFR in improving diagnosis, risk stratification and prognostication in low-flow AS."