Myocardial Contractile Reserve and Mortality in Patients With Severe Aortic Stenosis With Impaired Left Ventricular Function Who Underwent Transcatheter Aortic Valve Implantation

Impact of Stress Echocardiography on Aortic Valve Stenosis Management

Rest and stress echocardiography (SE) play a fundamental role in the evaluation of aortic valve stenosis (AS). According to the current guidelines for the echocardiographic evaluation of patients with aortic stenosis, four broad categories can be defined: high-gradient AS (mean gradient ≥ 40 mmHg, peak velocity ≥ 4 m/s, aortic valve area (AVA) ≤ 1 cm2 or indexed AVA ≤ 0.6 cm2/m2); low-flow, low-gradient AS with reduced ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, left ventricle ejection fraction (LVEF) < 50%, stroke volume index (Svi) ≤ 35 mL/m2); low-flow, low-gradient AS with preserved ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, LVEF ≥ 50%, SVi ≤ 35 mL/m2); and normal-flow, low-gradient AS with preserved ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, indexed AVA ≤ 0.6 cm2/m2, LVEF ≥ 50%, SVi > 35 mL/m2). Aortic valve replacement (AVR) is indicated with the onset of symptoms development or LVEF reduction. However, there is often mismatch between resting transthoracic echocardiography findings and patient's symptoms. In these discordant cases, SE and CT calcium scoring are among the indicated methods to guide the management decision making. Additionally, due to the increasing evidence that in asymptomatic severe aortic stenosis an early AVR instead of conservative treatment is associated with better outcomes, SE can help identify those that would benefit from an early AVR by revealing markers of poor prognosis. Low-flow, low-gradient AS represents a challenge both in diagnosis and in therapeutic management. Low-dose dobutamine SE is the recommended method to distinguish true-severe from pseudo-severe stenosis and assess the existence of flow (contractile) reserve to appropriately guide the need for intervention in these patients.

Transcatheter aortic valve replacement in heart failure

Patients with severe aortic stenosis (AS) may develop heart failure (HF), the presence of which has traditionally been deemed as a final stage in AS progression with poor outcomes. The use of transcatheter aortic valve replacement (TAVR) has become the preferred therapy for most patients with AS and concomitant HF. With its instant afterload reduction, TAVR offers patients with HF significant haemodynamic benefits, with corresponding changes in left ventricular structure and improved mortality and quality of life. The prognostic covariates and optimal timing of TAVR in patients with less than severe AS remain unclear. The purpose of this review is to describe the association between TAVR and outcomes in patients with HF, particularly in the setting of left ventricular systolic dysfunction, acute HF, and right ventricular systolic dysfunction, and to highlight areas for future research.