The effect of increased vascular afterload measures on flow rate and survival in severe aortic stenosis

Aims: Although an association between the systemic circulation and transaortic flow rate (TFR) is frequently hypothesized in patients with aortic stenosis (AS), it has not been demonstrated previously. We sought to explore the relationship between blood pressure (BP), vascular afterload measures, clinical history of hypertension, TFR, and survival in patients with severe AS (aortic valve area ≤ 1 cm²).

Methods and results: We studied 323 patients ≥ 65 years (110 prospective, 213 registry analysis) who underwent transcatheter aortic valve replacement over a 5-year period. Aortic flow was obtained by Doppler echocardiography, with TFR calculated using a mathematical derivation method. A BP ≥ 140/90 mmHg and/or mean arterial pressure ≥ 90 mmHg was considered hypertensive. Simultaneous pressure-flow analysis demonstrated that higher systolic BP (ß -0.545; P = 0.01†), pulse pressure (ß -0.545; P = 0.01†), vascular resistance (ß -0.02; P = 0.041), characteristic impedance (ß -0.27; P = 0.01), and lower arterial compliance (ß 32.73; P < 0.001†) were associated with reduced TFR in linear regression. In registry analysis, TFR was lower in those with a history of hypertension (223 ± 67 vs. 244 ± 77 mL/s; r -0.138; P = 0.045), coronary artery disease (CAD, P < 0.01), dialysis dependency (P < 0.01), and with increased anti-hypertensive medication use (P = 0.04), of which CAD (ß -28.5; P = 0.08†) and dialysis dependency (ß -68.5; P = 0.04†) remained significant in linear regression. A TFR ≤ 210 mL/s in normotensive patients was the strongest predictor of mortality (73.3% vs. 86.7%; P = 0.043; † denotes adjusted).

Conclusion: Elevated vascular afterload measures and comorbidities linked to arteriosclerosis and/or degenerative aortic stiffening independently reduce flow rates in severe AS. A TFR ≤ 210 mL/s predicts mortality but improves with BP assessment during evaluation.