Management of paradoxical low-flow, low-gradient aortic stenosis : need for an integrated approach, including assessment of symptoms, hypertension, and stenosis severity

In 2007, we reported that a substantial proportion of patients with severe aortic stenosis may have a low flow (LF) (i.e., reduced stroke volume), and thus, often have a low transvalvular pressure gradient (LG), despite a preserved left ventricular ejection fraction (LVEF) (1). The 2014 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines (2) classified this “paradoxical” LF/LG entity as a D3 stage of aortic stenosis, which is defined as an aortic valve area (AVA) of 50%, and a stroke volume index (SVi) of <35 ml/m2. Previous studies 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 reported that patients with paradoxical LF/LG aortic stenosis have worse outcomes than patients with moderate aortic stenosis or with severe aortic stenosis and a high-gradient (HG) and that their outcomes improve with aortic valve replacement (AVR). Accordingly, the 2014 ACC/AHA guidelines included a Class IIa (Level of Evidence: C) recommendation for AVR in these patients: “AVR is reasonable in symptomatic patients who have low-flow, low-gradient severe AS who are normotensive and have a LVEF =50% if clinical, hemodynamic, and anatomic data support valve obstruction as the most likely cause of symptoms” (2). The main findings of the retrospective study by Tribouilloy et al. (14) published in this issue of the Journal were: 1) patients with LF/LG and preserved LVEF have similar outcomes as patients with moderate aortic stenosis or with severe aortic stenosis and a HG; and 2) AVR does not improve these patients’ outcomes. The investigators should be commended for providing important data on the challenging subset of patients with paradoxical LF/LG aortic stenosis

Live longer and better without prosthesis-patient mismatch

In this issue of The Journal of Heart Valve Disease, Urso and co-workers (1) analyzed the impact of prosthesispatient mismatch (PPM) on survival and quality of life following aortic valve replacement (AVR) in 163 patients aged 75 years or more. Elderly patients currently represent a large proportion of the population undergoing AVR, and this proportion is expected to grow exponentially in the near future as the population ages. In this context, it becomes appropriate to determine the exact impact of PPM in this specific population in order to adopt the most appropriate strategies with regards to this age group. Indeed, these patients have often outlived their normal life expectancy, and their main motivation for consenting to surgery may be the expectation of an improved and/or maintained quality of life, rather than a prolonged survival. In this respect, the study by Urso et al. (1) is most interesting as these authors have analyzed the impact of PPM not only on the patients’ survival but also on their quality of life. Importantly, they found that, whereas moderate PPM had no impact on mid-term mortality in this cohort of elderly patients, it was nonetheless associated with a significant reduction in the quality of life

Assessment of low-flow, low-gradient aortic stenosis : multimodality imaging is the key to success

In patients with aortic stenosis (AS), a low-flow state may occur with reduced LV ejection fraction (LVEF) (i.e., classic low flow) or with preserved LVEF (i.e., paradoxical low flow) and it is often associated with low gradient because the gradient is highly flow-dependent. Low-flow, low-gradient (LF-LG) AS is a frequent clinical entity generally associated with worse outcomes. A multimodality imaging approach, including comprehensive resting echocardiography, dobutamine stress echocardiography (DSE), and multidetector computed tomography (MDCT), is the key to successful management of patients with LF-LG AS, who represent a highly challenging subset from both a diagnostic and a therapeutic standpoint. DSE and quantification of aortic valve calcification by MDCT provide important information that is crucial to differentiate true-severe from pseudo-severe AS and therefore select the most appropriate therapy (i.e., AVR vs. medical). The assessment of LV flow reserve by DSE is useful to stratify the operative risk and guide decision making between surgical and transcatheter AVR. Other imaging biomarkers, such as the global LV longitudinal strain measured during DSE or the amount of myocardial fibrosis assessed by cardiac magnetic resonance imaging, may provide incremental information for risk stratification and therapeutic management in LF-LG AS, but additional studies are needed to validate and refine these emerging biomarkers further

Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction: implications for diagnosis and treatment

Paradoxical low flow, low gradient, severe aortic stenosis (AS) despite preserved ejection fraction is a recently described clinical entity whereby patients with severe AS on the basis of aortic valve area have a lower than expected gradient in relation to generally accepted values. This mode of presentation of severe AS is relatively frequent (up to 35% of cases) and such patients have a cluster of findings, indicating that they are at a more advanced stage of their disease and have a poorer prognosis if treated medically rather than surgically. Yet, a majority of these patients do not undergo surgery likely due to the fact that the reduced gradient is conducive to an underestimation of the severity of the disease and/or of symptoms. The purpose of this article is to review and further analyse the distinguishing characteristics of this entity and to present its implications with regards to currently accepted guidelines for AS severity

Metabolic Syndrome: The Danger Signal in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by infiltration of blood vessels by lipids and leukocytes. There is a growing body of evidence that among risk factors that promote atherosclerosis, the metabolic syndrome is a powerful and prevalent predictor of cardiovascular events. The systemic inflammatory process associated with the metabolic syndrome has numerous deleterious effects that promote plaque activation, which is responsible for clinical events. Interactions between the innate immune system with lipid-derived products seem to play a major role in the pathophysiology of atherosclerosis in relation with the metabolic syndrome. The multiple links among adipose tissue, the vascular wall, and the immune system are the topics of this review, which examines the roles of oxidized low-density lipoprotein, inflammatory cytokines, and adipokines in triggering and perpetuating a danger signal response that promotes the development of atherosclerosis. Furthermore, therapeutic options that specifically target the metabolic syndrome components are reviewed in light of recent developments

On the evaluation of vorticity using cardiovascular magnetic resonance velocity measurements.

Vorticity and vortical structures play a fundamental role affect- ing the evaluation of energetic aspects (mainly left ventricle work) of cardiovascular function. Vorticity can be derived from cardiovascular magnetic resonance (CMR) imaging velocity measurements. However, several numerical schemes can be used to evaluate the vorticity field. The main objective of this work is to assess different numerical schemes used to evaluate the vor- ticity field derived from CMR velocity measurements. We com- pared the vorticity field obtained using direct differentiation schemes (eight-point circulation and Chapra) and derivate dif- ferentiation schemes (Richardson 4* and compact Richardson 4*) from a theoretical velocity field and in vivo CMR velocity measurements. In all cases, the effect of artificial spatial resolu- tion up-sampling and signal-to-noise ratio (SNR) on vorticity computation was evaluated. Theoretical and in vivo results showed that the eight-point circulation method underestimated vorticity. Up-sampling evaluation showed that the artificial improvement of spatial resolution had no effect on mean abso- lute vorticity estimation but it affected SNR for all methods. The Richardson 4* method and its compact version were the most accurate and stable methods for vorticity magnitude evaluation. Vorticity field determination using the eight-point circulation method, the most common method used in CMR, has reduced ac- curacy compared to other vorticity schemes. Richardson 4* and its compact version showed stable SNR using both theoretical and in vivo data