Abstract 12935: Lack of Correlation Between Echocardiographic Parameters and Cardiac Hemodynamics in Patients With Severe Aortic Stenosis

Abstract

Introduction: Aortic stenosis (AS) affects ~10% of population over 65 years of age. Severe AS is defined as mean trans-aortic pressure gradient (MG) of ≥40 mmHg and/or aortic valve area (AVA) of <1.0 cm 2 . Patients’ symptoms correlate with cardiac output, and the ability to augment with exercise. However, the relationship between AVA/MG and stroke volume/cardiac output is not well defined. Hypothesis: We aimed to identify the relationship between conventional echocardiography-based parameters (i.e., AVA/MG) and non-echocardiography-based hemodynamics in AS. Methods: Consecutive patients with severe symptomatic AS undergoing TAVI between June and September 2020 at St. Boniface Hospital in Manitoba, Canada were recruited. Hemodynamics was measured using whole-body impedance-based Non-Invasive Cardiac System (NICaS). Evaluated hemodynamics include stroke volume index (Svi), cardiac output (CO), cardiac index (CI), and total peripheral resistance (TPR) and were compared to conventional parameters. Results: Thirty patients (37% females; mean age 79.0 ± 1.7 years) were enrolled. Average MG was 41.8 ± 2.2 mmHg (16.94 - 70.0) and mean AVA was 0.81 ± 0.04 cm 2 (0.30 - 1.10). A linear regression model revealed a poor correlation between AVA and both Svi and CI (r 2 =0.012 and 0.025, respectively). Similarly, MG correlated poorly with Svi and CI (r 2 =0.017 and 0.024, respectively). Interestingly, 60% patients displayed a low-flow state (defined as Svi <35 ml/m 2 ), despite a normal left ventricular ejection fraction (EF >50%, r 2 =0.011). Conclusions: There is incongruence between hemodynamics and conventional parameters defining severe AS. A subset of patients have low-flow state, despite normal left ventricular function. It is plausible that some of these patients, based on their hemodynamics, may benefit from valvular intervention earlier, even at a lower MG. Long-term hemodynamic assessment may guide identification of outcomes in AS patients post-TAVI.