Rafie, Nikita

Background In low-gradient severe aortic stenosis (AS), reduced left ventricular ejection fraction (LVEF <50%) is practically used to define low flow and prompt dobutamine stress echocardiography to discern pseudo-severe AS. In patients with preserved LVEF, stroke volume index (SVI) <35 mL/m² is typically used. However, both are volume-based surrogates. Transaortic flow rate (TAFR), calculated as stroke volume divided by left ventricular ejection time, may better reflect true flow. Nonetheless, comparative data between TAFR and established metrics remain limited. We aimed to evaluate the prognostic value of TAFR in symptomatic low-gradient severe AS. Methods We retrospectively identified patients with low-gradient severe AS (AVA ≤1 cm 2 and peak velocity (Vmax) <4 m/s or mean gradient (MG) <40 mm Hg) who underwent transcatheter aortic valve replacement at Mayo Clinic sites (2017–2023). The primary outcome was 1-year all-cause mortality. Survival was assessed using Kaplan-Meier and Cox proportional hazards models. Results Among 475 patients included (mean age 85±8 years; 49% women), 242 (51%) had TAFR <220 mL/s, 165 (35%) had EF <50%, and 221 (47%) had SVI <35 mL/m 2 . Low TAFR was significantly associated with higher 1-year mortality even after stratifying by EF or SVI. In multivariate analysis, TAFR was an independent predictor of mortality (HR 2.38; 95% CI 1.19 to 4.76, p=0.014) after adjusting for reduced LVEF, low SVI, gender, chronic kidney disease and mitral and tricuspid regurgitation. Conclusions In patients with symptomatic low-gradient severe AS, low TAFR, not SVI or LVEF, is independently associated with mortality and may offer more accurate measure of flow state for clinical staging.

Background: In patients with paradoxical low-gradient severe aortic stenosis (AS) based on aortic valve area (AVA) at rest (<1cm2) and normal left ventricular ejection fraction (LVEF >50%), the role of dobutamine stress echocardiography (DSE) is unclear. While current guidelines recommend assessing aortic valve calcium score in this context, DSE may still offer clinical value. Methods: We conducted a retrospective study on patients with paradoxical low gradient AS (LVEF >50% AVA <1cm 2 , MG < 40 mmHg) at rest who underwent DSE after Institutional Review Board approval. Data was extracted using an internal database. Patients > 18 yrs old with LVEF >50%, mean gradient (MG) < 40 mmHg, and valve area < 1 cm 2 at rest were included. Kruskal-Wallis test was used to identify which resting variables were associated with severe AS (MG >40 mm Hg and Valve area <1 cm 2 ) with DSE. Results: A total of 42 patients were included in the study and variables were reported as means (±SD). The mean age of patients was 78 years (±10) and 60% were female. The mean resting LVEF was 60% (±5%), MG at rest was 28 mmHg (±7) while it was 40 mmHg (±14) with DSE, and mean aortic valve area at rest was 0.9 cm 2 (±0.09) while it was 1.1 cm 2 (±0.23) with DSE. Of the 42 patients, 11 (26%) were found to have severe AS during DSE, defined by a MG >40 mmHg and AVA <1.0 cm 2 . Baseline AVA and MG at rest were significantly associated with severe AS on DSE (p=0.008 and p=0.024, respectively), while age, stroke volume index, and baseline LVEF were not. Univariate regression analysis showed that the area under the curve (AUC) for predicting severe AS was 0.73 for resting MG and 0.77 for resting AVA. A resting AVA cutoff of 0.78 cm 2 provided optimal sensitivity (0.63) and specificity (0.90). For resting MG, a cutoff of 29 mmHg gave a sensitivity of 0.91 and specificity of 0.68 for identifying patients with severe AS. Conclusion: Our study indicated that DSE remains useful in identifying severe AS in substantial number of patients (26%) who exhibit paradoxical low gradient severe AS. Additionally, AVA at rest and baseline mean gradient were statistically the reliable parameters to determine those who may benefit significantly from undergoing DSE. This is one of the first studies to our knowledge in the literature suggesting that DSE may still be useful in identifying severe AS patients despite “paradoxical low gradient severe AS” at rest. Further research is warranted to validate our findings.

Background: Patients with low gradient non-severe aortic stenosis (AS) at rest, in the context of reduced left ventricular ejection fraction (LVEF) (less than 50%), occasionally undergo dobutamine stress echocardiogram (DSE). However, limited data is available in the literature regarding the utility of DSE in this context. Methods: We conducted a retrospective study on patients with non-severe AS and LVEF less than 50% at rest who underwent DSE after Institutional Review Board approval. Retrospective data was extracted including rest and DSE parameters using an internal database. Only patients greater than 18 years old, who had an LVEF less than 50%, mean gradient (MG) less than 40 mmHg, and valve area greater than or equal to 1 cm 2 at rest were included in the study. Univariate and multivariate regression methods were used to identify which resting variables were associated with severe AS (MG greater than 40 mm Hg and valve area less than 1 cm 2 ) with DSE. Results: A total of 124 patients were included in the study. The mean age of patients was 78 years (±9) and 84% were male. The mean resting LVEF was 34% (±8%) while it was 40% (±12%) with DSE, mean stroke volume index at rest was 39 mL/m2 (±9) while it was 45 mL/m2 (±10) with DSE, MG at rest was 20 mmHg (±7) while it was 31 mmHg (±10) with DSE, and mean aortic valve area at rest was 1.27 cm 2 (±0.27) while it was 1.24 cm 2 (±0.29) with DSE. Of the 124 patients with non-severe AS at rest, 13 (10.5%) patients had severe AS with DSE. MG at rest was associated with severe AS (OR 1.3; 95% Cl: 1.1 - 1.5; p < 0.001) in a multivariate logistic regression model after adjusting for age, sex, LVEF at rest, SV index at rest. Resting aortic valve mean gradient also showed the highest AUC in relation to likelihood of having severe AS (0.87) (figure 1). Conclusion: Our study indicated that DSE remains useful in identifying severe AS in certain patients (up to 10%) who exhibit non-severe AS at rest in the setting of reduced LVEF. Additionally, MG at rest is the most reliable parameter to determine those who may benefit from undergoing DSE. This is one of the first studies to our knowledge in the literature suggesting that DSE may still be useful in identifying severe AS patients despite non-severe AS (i.e., valve area greater than or equal to 1 cm 2 ) at rest with reduced LVEF. Further research is warranted to validate our findings.

Since its inception, the electrocardiogram (ECG) has been an essential tool in medicine. The ECG is more than a mere tracing of cardiac electrical activity; it can detect and diagnose various pathologies including arrhythmias, pericardial and myocardial disease, electrolyte disturbances, and pulmonary disease. The ECG is a simple, non-invasive, rapid, and cost-effective diagnostic tool in medicine; however, its clinical utility relies on the accuracy of its interpretation. Computer ECG analysis has become so widespread and relied upon that ECG literacy among clinicians is waning. With recent technological advances, the application of artificial intelligence-augmented ECG (AI-ECG) algorithms has demonstrated the potential to risk stratify, diagnose, and even interpret ECGs—all of which can have a tremendous impact on patient care and clinical workflow. In this review, we examine (i) the utility and importance of the ECG in clinical practice, (ii) the accuracy and limitations of current ECG interpretation methods, (iii) existing challenges in ECG education, and (iv) the potential use of AI-ECG algorithms for comprehensive ECG interpretation.