Restoration of frequency-dependent myocardial reserve after TAVI in severe aortic stenosis: an invasive hemodynamic...

Severe aortic stenosis (AS) and chronic pressure overload may impair frequency-dependent myocardial reserve despite preserved left ventricular ejection fraction (LVEF). We investigated whether acute afterload reduction with transcatheter aortic valve implantation (TAVI) restores force-frequency relationships (FFR) and relaxation frequency relationships (RFR). In this prospective study, patients with severe normal-flow, high-gradient AS and preserved LVEF underwent invasive left ventricular pressure recording during incremental atrial pacing at 80 and 100 beats/min before and immediately after TAVI. Systolic reserve was assessed using dP/dt_max and preload-adjusted indices [dP/dt_max/left ventricular end-diastolic pressure (LVEDP) and left ventricular peak systolic pressure (LVSP)/LVEDP], whereas lusitropic reserve was assessed using dP/dt_min, the relaxation constant τ, and LVEDP. Echocardiography was performed at baseline and 3 mo. Forty-six patients completed the pacing protocol. Before TAVI, pacing produced only a modest increase in dP/dt_max (Δ + 150 mmHg/s; P = 0.004), without improvement in dP/dt_min (P = 0.329) or τ (P = 0.182). Immediately after TAVI, pacing increased dP/dt_max (P < 0.001), dP/dt_max/LVEDP (P = 0.004), and LVSP/LVEDP (P = 0.031), while improving dP/dt_min (Δ + 56 mmHg/s; P = 0.050) and τ (P = 0.033) and reducing LVEDP (P = 0.017). Correlation analyses supported the emergence of physiological FFR and RFR after valve implantation. At 3 mo, echocardiography showed lower pulmonary artery systolic pressure (P = 0.002), improved left atrial reservoir strain, and lower diastolic dysfunction grade (P = 0.006). Thus, acute afterload relief with TAVI reveals preserved dynamic systolic and lusitropic reserve in severe AS, with subsequent group-level improvement in diastolic function.NEW & NOTEWORTHY This study provides direct invasive human evidence that frequency-dependent myocardial reserve is acutely restored after TAVI in severe aortic stenosis. Controlled atrial pacing revealed blunted force-frequency and relaxation-frequency responses before valve replacement, despite preserved ejection fraction, with rapid recovery after afterload relief. These findings show that impaired myocardial reserve in pressure-overload remodeling is functionally reversible and tightly linked to loading conditions.