Paradoxical Low Flow Low Gradient Severe Aortic Stenosis—An Under-Recognized Entity

Phillip Crane,Naveen Sharma,Matias Yudi,Mandeep Singh Kalsi

doi:10.4236/crcm.2022.112006

Abstract

Some patients with severe aortic stenosis (AS), due to restrictive cardiac physiology, paradoxically have relatively low flow and low gradients across stenotic aortic valves despite preserved left ventricular (LV) systolic function. It results in symptoms and reduced quality of life and carries a high mortality. Whilst this form of severe AS, termed paradoxical low flow low gradient (pLFLG), is well reported, patients with this diagnosis experience inappropriate barriers to aortic valve replacement (AVR), the only efficacious treatment. We present the case of an 88-year-old female with 12 months of exertional dyspnoea on a background of hypothyroidism and hypercholesterolemia. Transthoracic echocardiogram (TTE) revealed LV hypertrophy, with a small LV cavity size and reduced stroke volume, yet normal systolic function. A heavily calcified aortic valve was identified with severe aortic stenosis, based on valve area, yet with incongruous mean transvalvular gradient of 25 mmHg (severe ≥ 50 mmHg). Following exclusion of other differential diagnoses, her symptoms were attributed to paradoxical LFLG severe AS. She was however declined definitive transcatheter aortic valve implantation (TAVI) due to her paradoxically low mean aortic gradient. Following further deterioration in her symptoms and supportive quantification of poor exercise performance, she was ultimately re-referred, accepted, and underwent TAVI. Following her AVR, the patient experiences significant improvement in both symptoms and quality of life after only one month. Paradoxical LFLG severe AS remains a well-documented yet under recognized disease. It carries high morbidity and mortality if untreated, yet is significantly less likely to be referred and accepted for intervention. With its prevalence expected to rise with an ageing population, this case serves as a timely reminder for clinicians to address the under recognition of important pathology.

Highlights

Aortic Stenosis is one of the most common and serious valvular disorders of the heart
Anatomical and clinical factors can contribute to the development of aortic stenosis, its progression to severe disease is associated with male sex, age, and the severity of narrowing and degree of aortic valvular calcification [1]
Severe aortic stenosis (AS) is defined by an indexed aortic valve area ≤ 0.6 cm2/m2, a mean transvalvular pressure gradient (MPG) ≥ 40 mmHg and dimensionless index of less than 0.25

Summary

Introduction

Aortic Stenosis is one of the most common and serious valvular disorders of the heart. It is a progressive, pathological narrowing of the aortic valve resulting in a hemodynamically significant left ventricular outflow tract obstruction. Pathological narrowing of the aortic valve resulting in a hemodynamically significant left ventricular outflow tract obstruction When untreated it results in characteristic symptoms of exertional angina, syncope and heart failure. Aortic valve replacement (AVR), surgical or transcatheter, is the only effective treatment, and is a Class I indication for severe AS with symptoms and/or systolic heart failure, with reduced LV ejection fraction [2]. Some patients have discordantly low MPG, in the setting of reduced, termed low-flow, low-gradient (LFLG), or preserved, termed paradoxical LFLG (pLFLG), LV systolic function. Outcomes for patients with pLFLG AS are at least as dire [3] [4] as patients with traditional high-gradient severe AS, yet are significantly less likely to be referred for and accepted for intervention [5] [6]

Past Medical History

Investigations

Management

Findings

Discussion