Evaluation of intrarenal vein flow patterns during routine echocardiography

Intrarenal vein flow (IRVF) abnormalities can predict cardiovascular events including heart failure. This study aimed to evaluate the utility of short IRVF scans during routine comprehensive transthoracic echocardiography (TTE) examinations in a standard TTE laboratory.

We screened consecutive patients who underwent elective TTE at our Ultrasound Imaging Laboratory between March 2018 and July 2019 and prospectively enrolled those who completed a 5 min IRVF scan during the 30 min TTE procedure.

Among the 2101 screened patients, 1326 were included in the study cohort (age: 73 ± 13 years, 756 men). IRVF abnormalities were detected in 13 (1.0%) patients. Twenty-one cardiac events were observed (1.6%, 21/1326): one myocardial infarction and 20 heart failures. Cumulative survival probability plots were generated using the Kaplan-Meier method within 6 months after the TTE index day and assessed using the log-rank test. The plots revealed significantly worse prognoses in patients with elevated right arterial pressure (RAP) and abnormal IRVF, when compared to normal RAP or normal IEVF (p < 0.0001 and p < 0.0001, respectively). In a receiver operating curve analysis to predict the occurrence of cardiovascular events, E/e' had moderate predictive potential (area under the curve: 0.795, p < 0.0001), and the combination of E/e' and IRVF abnormality had better predictive potential than did E/e' alone (p = 0.043).

Although rarely observed on TTE, IRVF abnormalities improve the ability of E/e' to detect cardiac events, especially heart failure. Further large-scale prospective studies are required to confirm our findings.