Baxter, Christy

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.

Background: A key determinant of prognosis in pulmonary hypertension (PH) is the right ventricle’s (RV) ability to adapt to increased pulmonary vascular resistance. Consequently, markers of RV-pulmonary artery (PA) coupling may improve prognostic prediction in PH. The ratio of tricuspid annular plane systolic excursion (TAPSE) to systolic PA pressure (sPAP) has been proposed as a surrogate for RV-PA coupling and a reliable prognostic marker, however, the existing data on the prognostic value of the ratio between RV longitudinal strain (RVLS) and sPAP as a surrogate for RV-PA coupling is scarce. Hypothesis: To evaluate the prognostic role of RVLS/RVSP in PH patients and to compare this novel marker with established markers of RV-PA coupling. Methods: This is a single-center study that included adult patients with PH classified as group I or IV, all of whom had undergone a transthoracic echocardiogram (TTE) within one year prior to the initiation of PH-specific treatment. Certified sonographers procured RV strain measurements using a specific software (Epsilon Imaging, Ann Arbor, MI). Receiver operating characteristic (ROC) analysis was used to determine the best cutoff for predicting all-cause mortality at one-year for RVLS/RVSP and TAPSE/RVSP. The association of RVLS/RVSP and TAPSE/RVSP with mortality at one year was assessed using the Kaplan-Meier analysis and multivariate Cox regression analysis (adjusted for REVEAL LITE 2.0 risk score). Results: A total of 160 patients were included with a median age of 67.2 (56.8, 73.7) years and 47 (29.2%) were male . ROC analysis revealed optimal cutoffs of 0.265 (AUC = 0.83) for RVLS/RVSP and 0.185 (AUC = 0.77) for TAPSE/RVSP to predict all-cause mortality at one year. One-year cumulative incidence of all-cause mortality was lower among patients with RVLS/RVSP ≥ 0.265 (0 % vs 13.7 %, p = 0.001) and patients with TAPSE/RVSP ≥ 0.185 (1.8 % vs 16.7 %, p = 0.001) (Figure 1) . In the multivariate analysis, RVLS/RVSP < 0.265 was associated with higher risk of mortality at one year (HR: 2.38, 95 % CI: 1.05 to 5.38, p = 0.036) while TAPSE/RVSP < 0.185 was not (HR: 2.01, 95 % CI: 0.93 to 4.31, p = 0.072). Conclusions: RVLS/ RVSP may be a valuable prognostic marker in PH patients and could outperform conventional TTE parameters as a surrogate for detecting RV-PA coupling.