Low-Flow/Low-Gradient Aortic Stenosis

Abstract

Aortic stenosis (AS) is 1 of the most common valve disorders encountered in clinical practice and 1 of the most frequent indications for valve replacement surgery. Decades of research and clinical experience have resulted in the development of guidelines that provide the clinician with an evidence-based approach to the management of patients with valvular disease.1 Nonetheless, there remain patients with AS for whom management decisions are less clearly defined and who continue to pose significant diagnostic and therapeutic dilemmas. Severe AS has been defined as that associated with a valve area 40 mm Hg, and a peak flow velocity >4.0 m/s1. Patients with severe AS have a significant risk of cardiac morbidity and mortality2,3 and have improved symptoms and reduced mortality following aortic valve replacement (AVR).3 Traditionally, the decision to proceed with AVR in patients with AS has been based on the assessment of aortic valve area (AVA) and the presence of associated symptoms. However, as many as 30% of patients who have a calculated AVA in the severe range have other parameters suggesting mild or moderate disease (ie, mean gradient <30 mm Hg).4 These patients with low-flow/low-gradient AS (LF/LGAS) may truly have severe AS with resultant myocardial failure (true AS) or may have more moderate degrees of AS and unrelated myocardial dysfunction (pseudo-AS). In the latter setting, the aortic valve may appear severely stenotic as a result of the flow-dependent nature of the valve area calculation by either invasive or noninvasive techniques,5 and the inability of the myopathic ventricle to generate adequate force to fully open the valve. Distinguishing between these possibilities has important clinical implications in regard to prognosis and management options, as patients with true AS will likely benefit from …