Aortic Stenosis with High Gradients and Area >1: Just Follow Up?

Definig severe aortic stenosis (AS) rests upon Doppler parameters, and uses log-established cutoff values, which include peak velocity (PV) ≥ 4 m/s, mean gradient (MG) ≥ 40 mmHg and aortic valve area (AVA) ≤ 1 cm². However, there are value discrepancies in up to 30-40% of cases, which has given way to different clinical profiles. 

One of the discrepant phenotypes corresponds to patients with high gradients (HG) and AVA > 1 cm². Their management and prognosis has hardly been approached by clinical guidelines. The aim of this study was to look into the clinical and hemodynamic characteristics of this group and compare their mortality against other AS subtypes. 

This was a retrospective study on echocardiographic data from the Mayo Clinic (Minnesota, EE. UU.). It included patients with AS diagnosis classified according to AVA, PV and MG into four groups. Patients with prior valve surgery, left ventricular outflow tract obstruction, mitral or aortic insufficiency or mitral stenosis were excluded. Primary outcome was all cause mortality. 

Data from 3,209 were collected, distributed by hemodynamic characteristics as follows: 7.2% phenotype AG-AVA > 1, 45.9% phenotype HG-AVA ≤ 1, 14.3% low gradient phenotype with AVA ≤ 1 (LG-AVA ≤ 1), and 32.6% moderate AS.

HG-AVA > 1 patient mean age was 70.2 ± 12 years, making this the youngest of subtypes (P < 0.01), also presenting higher prevalence of male sex (85.7%), larger body surface and body mass index (BMI), and higher incidence of bicuspid aortic valve (39.6%). They had fewer comorbidities and lower levels of natriuretic peptide type B (BNP). PV and MG values were lower vs. phenotype AVA ≤ 1 (P < 0.01), while 115.0 ± 19 mL systolic volume (SV) and 54.8 ± 10.5 mL/m² indexed value (SV index) were higher.

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During a 944-day followup, there were 1,523 deaths (47.5%). Phenotype HG-AVA > 1 presented 38.9% mortality rate at 5 years, and 59.6% at 8 years. After adjusting for age, mortality in this group resulted similar to that of moderate AS patients, but lower vs. phenotype LG-AVA ≤ 1 (HR: 1.9 [CI 95%: 1.4-2.4]; P < 0.01).

As regards aortic valve replacement (AVR), mainly surgical (12.9% were TAVR), 67.4% of patients with HG-AVA > 1 were treated, vs. 69% of HG-AVA ≤ 1, 32.8% of LG-AVA ≤ 1 and 34.7% of moderate AS patients. Mortality in AVR patients, resulted higher in patients with AVA ≤ 1, both for HG (HR: 1.5 [CI 95%: 1.1-2.0]; P = 0.03) and LG patients (HR: 2.4 [CI 95%: 1.6-3.5]; P < 0.001).

Mortality rate for patients with HG-AVA > 1 undergoing AVR was superior to that of one controlled matched population, but significantly lower to that of HG-AVA > 1 patients not operated on (mortality rate 8.2 [CI 95%: 5.9-11.2]).

Conclusions

In this cohort of patients with AS, individuals with high gradients and > 1 cm² valve area were characterized for being younger, and have lower comorbidities vs. other phenotypes. Presented higher survival, expect for a matched population. Aortic valve replacement showed an 8-year survival benefit vs. the non-treated, which suggests a positive impact of surgery for this specific group. 

Original Title: High-Gradient Aortic Stenosis With Valve Area >1.0 cm2 The “Forgotten” Discordant Hemodynamic Phenotype.

Reference: Ito S, Oh JK, Michelena HI, Egbe AC, Connolly HM, Pellikka PA, Nkomo VT, Lewis BR, Miranda WR. High-Gradient Aortic Stenosis With Valve Area >1.0 cm2: The “Forgotten” Discordant Hemodynamic Phenotype. JACC Cardiovasc Imaging. 2024 Sep 5:S1936-878X(24)00315-2. doi: 10.1016/j.jcmg.2024.07.025. Epub ahead of print. PMID: 39297851.