Utility of E/e' Ratio During Low-Level Exercise to Diagnose Heart Failure With Preserved Ejection Fraction

E/e' ratio during exercise is the key parameter in identifying elevated pulmonary capillary wedge pressure (PCWP), and thus heart failure with preserved ejection fraction (HFpEF). However, its diagnostic value is limited when mitral inflow or tissue velocities are fused during elevated heart rate.

The authors hypothesized that E/e' ratio during low-level (20 W) exercise (E/e'_20W) can help diagnose HFpEF.

Ergometric exercise stress echocardiography was performed in 215 dyspneic patients with an EF ≥50%. The authors determined the feasibility of E/e' ratio at each stage (frequency of patients who had measurable E/e' without E-A fusion among 215 participants) and examined whether E/e'_20W could predict normal E/e' ratio during peak exercise (E/e'_peak ≤15). The authors also evaluated whether E/e'_20W could predict normal PCWP during exercise (PCWP <25 mm Hg) in a subset of participants (n = 45) who underwent exercise right heart catheterization.

The feasibility of the E/e' ratio decreased from 100% at rest to 96.3% during 20-W exercise and 74.9% during peak exercise caused by E-A fusion. In patients with E/e'_peak >15, there was an increase in E/e' ratio from rest to 20-W exercise (11.2 ± 2.1 to 16.3 ± 3.5; P < 0.0001), but it did not change significantly from 20-W exercise to peak exercise (P = 0.12). E/e'_20W predicted E/e'_peak ≤15 (AUC: 0.91; P < 0.0001) with the cutoff value of ≤12.4 showing high specificity (94%) and positive predictive value (98%). During 20-W exercise, 93% of the HFpEF patients developed PCWP ≥25 mm Hg. E/e'_20W predicted normal PCWP during exercise (AUC: 0.77; P = 0.01) with the cutoff value of ≤12.4 showing high specificity (83%).

E/e' ratio during low-level exercise is highly feasible and predicts normal E/e' ratio or PCWP during peak exercise with high specificity. These data suggest that E/e'_20W could be used as an alternative to the peak exercise value to rule out HFpEF in patients with dyspnea.