Calcium Scoring to Classify Aortic Valve Stenosis Severity: What Is the Current Data?

Aortic Valve Calcium Score: Applications in Clinical Practice and Scientific Research-A Narrative Review

In this narrative review, we investigate the essential role played by the computed tomography Aortic Valve Calcium Score (AVCS) in the cardiovascular diagnostic landscape, with a special focus on its implications for clinical practice and scientific research. Calcific aortic valve stenosis is the most prevalent type of aortic stenosis (AS) in industrialized countries, and due to the aging population, its prevalence is increasing. While transthoracic echocardiography (TTE) remains the gold standard, AVCS stands out as an essential complementary tool in evaluating patients with AS. The advantage of AVCS is its independence from flow; this allows for a more precise evaluation of patients with discordant findings in TTE. Further clinical applications of AVCS include in the assessment of patients before transcatheter aortic valve replacement (TAVR), as it helps in predicting outcomes and provides prognostic information post-TAVR. Additionally, we describe different AVCS thresholds regarding gender and the anatomical variations of the aortic valve. Finally, we discuss various scientific studies where AVCS was applied. As AVCS has some limitations, due to the pathophysiologies of AS extending beyond calcification and gender differences, scientists strive to validate contrast-enhanced AVCS. Furthermore, research on developing radiation-free methods of measuring calcium content is ongoing.

Transcatheter aortic valve replacement outcomes in patients with low-flow very low-gradient aortic stenosis

AIMS

In patients with severe aortic stenosis (AS), low-flow low-gradient (LG) is a known predictor of worse outcomes. However, very LG may represent a distinct population with further cardiac dysfunction. It is unknown whether this population benefits from transcatheter aortic valve replacement (TAVR). We aimed to describe the patient characteristics and clinical outcomes of low-flow very LG severe AS.

METHODS AND RESULTS

This single-centre study included all patients with low-flow severe AS between 2019 and 2021. Patients were divided into groups with very LG [mean pressure gradient (MPG) ≤ 20 mmHg], LG (20 < MPG < 40 mmHg), and high-gradient (HG) (MPG ≥ 40 mmHg). Composite endpoint of all-cause mortality and heart failure rehospitalization was compared. A total of 662 patients [very LG 130 (20%); LG 339 (51%); HG 193 (29%)] were included. Median follow-up was 12 months. Very LG cohort had a higher prevalence of comorbid conditions with lower left ventricular ejection fraction (45% vs. 57% vs. 60%; P < 0.001). There was a graded increase in the risk of composite endpoint in the lower MPG strata (P < 0.001). Among those who underwent TAVR, very LG was an independent predictor of the composite endpoint (adjusted HR 2.42 [1.29-4.55]). While LG and HG cohorts had decreased risk of composite endpoint after TAVR compared with conservative management, very LG was not associated with risk reduction (adjusted HR 0.69 [0.35-1.34]).

CONCLUSION

Low-flow very LG severe AS represents a distinct population with significant comorbidities and worse outcomes. Further studies are needed to evaluate the short- and long-term benefits of TAVR in this population.

Aortic Valve Calcium Score by Computed Tomography as an Adjunct to Echocardiographic Assessment-A Review of Clinical Utility and Applications

Aortic valve stenosis (AS) is increasing in prevalence due to the aging population, and severe AS is associated with significant morbidity and mortality. Echocardiography remains the mainstay for the initial detection and diagnosis of AS, as well as for grading of severity. However, there are important subgroups of patients, for example, patients with low-flow low-gradient or paradoxical low-gradient AS, where quantification of severity of AS is challenging by echocardiography and underestimation of severity may delay appropriate management and impart a worse prognosis. Aortic valve calcium score by computed tomography has emerged as a useful clinical diagnostic test that is complimentary to echocardiography, particularly in cases where there may be conflicting data or clinical uncertainty about the degree of AS. In these situations, aortic valve calcium scoring may help re-stratify grading of severity and, therefore, further direct clinical management. This review presents the evolution of aortic valve calcium score by computed tomography, its diagnostic and prognostic value, as well as its utility in clinical care.