Clinical outcomes and haemodynamic response after blinded stress assessment of moderate aortic stenosis

Assessing aortic stenosis (AS) haemodynamics under stress may distinguish physiological responses beyond traditional severity metrics.

We aimed to evaluate symptomatic patients with moderate AS and preserved left ventricular ejection fraction (LVEF) using invasive and non-invasive assessments at rest and during stress, hypothesising that the stress aortic valve index (SAVI) would show only modest agreement with echocardiographic parameters of AS severity but would be associated with clinical outcomes.

We prospectively enrolled 52 patients with moderate AS and preserved LVEF but who were symptomatic without an alternative explanation. The SAVI, quantifying the relative reduction in maximal flow, was measured but remained blinded. Comprehensive assessment included echocardiography (at rest, bicycle and dobutamine stress), calcium scoring, and clinical outcomes. Patients were managed according to current standards without knowledge of the SAVI and followed for ≥1 year.

Invasive transvalvular gradient increased from 25±9 mmHg at rest to 42±14 mmHg during dobutamine. The aortic-to-left ventricular pressure ratio declined from 0.82 (interquartile range [IQR] 0.78-0.88) at rest to a SAVI of 0.70 (IQR 0.63-0.79) under stress. Resting aortic valve area (AVA) did not predict stress haemodynamics, underscoring physiological heterogeneity. Notably, 25/52 (48%) of patients demonstrated a SAVI ≤0.70, comparable with a severe AS cohort studied separately. Blinded SAVI scores independently predicted the need for clinical aortic valve (AV) intervention (hazard ratio 5.7; p=0.007), whereas AVA and sex-specific calcium thresholds did not.

Stress haemodynamic assessment in moderate AS unmasks a subgroup, not identified by conventional metrics, who are at significantly higher risk for AV intervention. Patients with abnormal stress physiology despite only moderate AS at rest may benefit from AV intervention, supporting this pilot study as the basis for a future randomised trial.