Diagnostic and prognostic value of blunted inferior vena cava respiratory variation during exercise stress echocardiography in patients suspected of heart failure with preserved ejection fraction

Background Early diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging, and patients identified by the HFA-PEFF score may have poor outcomes. If exercise stress echocardiography is inconclusive, invasive left atrial pressure measurement using a Swan-Ganz catheter is recommended. However, most hospitals are unable to perform such exercise testing with a Swan-Ganz catheter, highlighting the need for a simpler diagnostic approach. A previous study shows that an increase in left atrial pressure during exercise is accompanied by an increase in right atrial pressure. As right atrial pressure can be estimated from the inferior vena cava (IVC) , respiratory variation in the IVC during exercise may serve as a potential indicator of elevated left atrial pressure. Purpose We hypothesised that the absence of respiratory variation in the inferior vena cava (IVC) during low-intensity exercise stress echocardiography is associated with adverse prognosis in patients suspected of having HFpEF. To evaluate this hypothesis, we analysed patient data from our institution. Methods Among 184 consecutive patients who underwent exercise stress echocardiography at our institution between May 2023 and September 2024, 109 patients with an ejection fraction of ≥50% who underwent testing due to dyspnoea or elevated BNP levels were included in the analysis. Exercise stress testing was initiated at 0 watt (W) and increased in a stepwise manner by 25 W every three minutes. Respiratory variation in the IVC was assessed at 25 W, and its association with prognosis was examined. The primary outcome was worsening heart failure defined as diuretic use or hospitalisation due to acute heart failure. Survival analysis was performed using Kaplan–Meier curves and the log-rank test. Results The mean follow-up period was 298 days, during which eight events (7%) occurred among the 109 patients. IVC diameter was successfully measured at 25 W in 93 patients (85%). Patients without respiratory variation in the IVC at 25 W had higher BNP levels, which mean elevated left atrial pressure (92.3(52.8-226.6) vs. 55.9(29.4-114.1); p=0.033). In contrast, the HFA-PEFF score and H2FPEF score did not show a significant difference between the two groups (5(4-6) vs. 4(3-5), 3(2-5.5) vs. 3(1.75-4); p=0.19 and p=0.08, respectively). Kaplan–Meier analysis revealed a significantly higher incidence of events in the group without respiratory variation in the IVC (log-rank test; p < 0.001, Figure). Conclusion In patients suspected of having HFpEF, blunted respiratory variation in the IVC during low-intensity exercise stress echocardiography was associated with an increased incidence of heart failure events. These findings suggest that IVC respiratory variation may serve as a diagnostic and prognostic marker in this population.