Ventricular Stroke Work and Vascular Impedance Refine the Characterization of Patients with Aortic Stenosis

Aortic stenosis (AS) management is classically guided by symptoms and valvular metrics. Yet the natural history of AS is dictated by coupling of the left ventricle, aortic valve, and vascular system. We investigated if metrics of ventricular and vascular state add to the appreciation of AS state above valve gradient alone.

Seventy patients with severe symptomatic AS were prospectively followed from baseline to 30 days post-transcatheter aortic valve replacement (TAVR). Quality of life (QOL) was assessed by Kansas City Cardiomyopathy Questionnaire (KCCQ). Left ventricular stroke work (SW_LV) and vascular impedance spectrums were calculated noninvasively using in-house models based on central blood pressure waveforms, along with hemodynamic parameters from echocardiograms.

Patients with higher pre-procedural SW_LV and lower vascular impedance were more likely to experience improved QOL after TAVR. Patients fell into two categories – those who did and those who did not exhibit an increase in blood pressure 30-days post-procedure. In patients who developed hypertension (19%), vascular impedance increased and SW_LV remained unchanged (impedance at zeroth harmonic - Z₀, from 3964.4 to 4851.8 dyne·sec/cm³, P = 0.039; characteristic impedance – Zc, from 376.2 to 603.2 dyne·sec/cm³, p=0.033). SW_LV dropped only in patients who did not develop new hypertension post-TAVR (from 1.58 to 1.26 J, P < 0.001). Reduction in valvular pressure gradient after TAVR did not predict change in SW_LV (r=0.213, P = 0.129).

Reduction of SW_LV after TAVR may be an important metric in management of AS, rather than relying solely on the elimination of transvalvular pressure gradients.