Echocardiographic Assessment of Aortic Stenosis under Sedation Underestimates Stenosis Severity

Correlation between pressure gradient from echocardiography and peak-to-peak pressure gradient from cardiac catheterization or surgery in patients with coarctation of aorta

The gold standard for assessing pressure gradients (PG) across coarctation involves measurements obtained through cardiac catheterization or surgical intervention. There has been ongoing discussion regarding the accuracy of non-invasive methods for estimating these gradients. This study sought to establish the correlation and agreement between the systolic blood pressure (SBP) gradient between the upper and lower extremities, as well as, the mean and maximum PG derived from echocardiography, in comparison to the peak-to-peak pressure gradient obtained from either cardiac catheterization or surgery. We conducted a retrospective study on patients < 18 years diagnosed with coarctation at Chiang Mai University Hospital from 2011 to 2022. The study involved the measurement of the SBP gradient between the upper and lower extremities, mean and maximum PG using echocardiography, peak-to-peak pressure gradient obtained from cardiac catheterization, and pressure gradient recorded during surgical procedures. The Spearman's correlation and Bland-Altman analysis were employed to assess correlation and agreement. Fifty-four patients with aortic coarctation were enrolled. The mean PG measured by echocardiography showed a significantly moderate correlation (r = 0.78, p < 0.001) and the highest level of agreement according to Bland Altman plots, in comparison to the peak-to-peak pressure gradient measured during both cardiac catheterization and surgical procedure. The max PG demonstrated a notable overestimation compared to the gold standard (mean difference + 13.14 with a slope of biases + 0.64, p < 0.001). The mean PG obtained through echocardiography has more potential to be applied in practical application in predicting pressure gradient in patients with coarctation.

Non-invasive myocardial work in aortic stenosis: validation and improvement in left ventricular pressure estimation

AIMS

The non-invasive myocardial work index (MWI) has been validated in patients without aortic stenosis (AS). A thorough assessment of methodological limitations is warranted before this index can be applied to patients with AS.

METHODS AND RESULTS

We simultaneously measured left ventricular pressure (LVP) by using a micromanometer-tipped catheter and obtained echocardiograms in 20 patients with severe AS. We estimated LVP curves and calculated pressure-strain loops using three different models: (i) the model validated in patients without AS; (ii) the same model, but with pressure at the aortic valve opening (AVO) adjusted to diastolic cuff pressure; and (iii) a new model based on the invasive measurements from patients with AS. Valvular events were determined by echocardiography. Peak LVP was estimated as the sum of the mean aortic transvalvular gradient and systolic cuff pressure. In same-beat comparisons between invasive and estimated LVP curves, Model 1 significantly overestimated early systolic pressure by 61 ± 5 mmHg at AVO compared with Models 2 and 3. However, the average correlation coefficients between estimated and invasive LVP traces were excellent for all models, and the overestimation had limited influence on MWI, with excellent correlation (r = 0.98, P < 0.001) and good agreement between the MWI calculated with estimated (all models) and invasive LVP.

CONCLUSION

This study confirms the validity of the non-invasive MWI in patients with AS. The accuracy of estimated LVP curves improved when matching AVO to the diastolic pressure in the original model, mirroring that of the AS-specific model. This may sequentially enhance the accuracy of regional MWI assessment.

Assessment of subclinical left ventricular systolic dysfunction in patients with asymptomatic severe aortic stenosis with preserved left ventricular systolic function by three-dimensional speckle tracking echocardiography

OBJECTIVES

Left ventricular dysfunction and remodeling can occur as a result of aortic valve stenosis (AS). Three-dimensional speckle tracking echocardiography (3D-STE) can detect early left ventricular myocardial dysfunction even before ejection fraction declines. The purpose of this study was to look at the relationship between various myocardial strain parameters measured by 3D-STE in asymptomatic severe AS patients from Bangladesh.

METHODS

This study included 46 patients with asymptomatic severe AS but preserved LV systolic function (mean age 50.11 ± 12.66 years, LVEF 63.78 ± 3.95%, AS group) and 33 healthy subjects with no cardiovascular disease (mean age 48.21 ± 4.53 years, LVEF 65.15 ± 3.13%, control group). 3D-STE was used to measure left ventricular global myocardial strain parameters such as peak systolic longitudinal strain (PSLS), circumferential strain, radial strain, and area strain.

RESULTS

The AS group had significantly thicker interventricular septum and posterior ventricular wall than the control group (1.49 ± .19 cm vs. .81 ± .09 cm, p < .001; 1.73 ± 1.71 cm vs. .81 ± .10 cm, p = .003, respectively.) In the AS group, the Indexed Aortic Valve Area (AVA) was significantly lower than in the control group. (.29 ± .10 vs. 2.03 ± .18, p < .001, respectively). In terms of LVEF (p = .102), left ventricular end diastolic volume (p = .075), or left ventricular end systolic volume (p = .092), no significant inter-group difference was found. However, global PSLS (-10.75 ± 2.27 vs. -16.42 ± 2.76, p < .001), circumferential strain (-14.26 ± 3.40 vs. -16.64 ± 2.56, p = .001), area strain (-22.70 ± 4.19 vs. -26.45 ± 9.90, p = .024) and radial strain (32.20 ± 8.77 vs. 41.00 ± 7.52, p < .001) in the AS group were significantly lower than in the control group.

CONCLUSION

Our findings showed reductions in left ventricular global myocardial strains, particularly PSLS in patients suffering from asymptomatic severe AS in Bangladesh; this is consistent with other studies. Reduced area strain, detectable with 3D-STE, is also consistent with that pattern.

Comparison of Echocardiographic and Catheter Mean Gradient to Assess Stenosis After Transcatheter Aortic Valve Implantation

Discordance exists between Doppler-derived and left heart catheterization (LHC)-derived mean gradient (MG) in transcatheter aortic valve implantation (TAVI). We compared echocardiographic parameters of prosthetic valve stenosis and LHC-derived MG in new TAVIs. In a retrospective, single-center study, intraoperative transesophageal echocardiogram (TEE)-derived MG, LHC-derived MG, and acceleration time (AT) were obtained before and after TAVI in 362 patients. Discharge MG, AT, and Doppler velocity index (DVI) using transthoracic echocardiogram (TTE) were also obtained. MG ≥10 mm Hg was defined as abnormal. During native valve assessment with pre-TAVI TEE and pre-TAVI LHC, Pearson correlation coefficient revealed a nearly perfect linear relation between both methods' MGs (r = 0.97, p <0.0001). Intraoperatively, after TAVI, Spearman correlation coefficient revealed a weak-to-moderate relation between post-TAVI TEE and LHC MGs (r = 0.33, p <0.0001). Significant differences were observed in categorizations between post-TAVI TEE MG and post-TAVI AT (McNemar test p = 0.0003) and between post-TAVI TEE MG and post-TAVI LHC MG (signed-rank test p <0.0001), with TEE MG more likely to misclassify a patient as abnormal. At discharge, 30% of patients had abnormal TTE MG, whereas 0% and 0.8% of patients had abnormal DVI and AT, respectively. Discharge TTE MG was not associated with death or hospitalization for heart failure at a median follow-up of 862 days. Post-TAVI Doppler-derived MG by intraoperative TEE was higher than LHC, despite being virtually identical before implantation. At discharge, patients were more likely to be classified as abnormal using MG than DVI and AT. Elevated MG at discharge was not associated with death or hospitalization for heart failure.

Bioprosthetic Aortic Valve Hemodynamics: Definitions, Outcomes, and Evidence Gaps: JACC State-of-the-Art Review

A virtual workshop was organized by the Heart Valve Collaboratory to identify areas of expert consensus, areas of disagreement, and evidence gaps related to bioprosthetic aortic valve hemodynamics. Impaired functional performance of bioprosthetic aortic valve replacement is associated with adverse patient outcomes; however, this assessment is complicated by the lack of standardization for labelling, definitions, and measurement techniques, both after surgical and transcatheter valve replacement. Echocardiography remains the standard assessment methodology because of its ease of performance, widespread availability, ability to do serial measurements over time, and correlation with outcomes. Management of a high gradient after replacement requires integration of the patient's clinical status, physical examination, and multimodality imaging in addition to shared patient decisions regarding treatment options. Future priorities that are underway include efforts to standardize prosthesis sizing and labelling for both surgical and transcatheter valves as well as trials to characterize the consequences of adverse hemodynamics.

Comparison of Simultaneous Transthoracic Versus Transesophageal Echocardiography for Assessment of Aortic Stenosis

Transthoracic echocardiography (TTE) is the gold standard for aortic stenosis (AS) assessment. Transesophageal echocardiography (TEE) provides better resolution, but its effect on AS assessment is unclear. To answer this question, we studied 56 patients with ≥moderate AS. Initial TTE (TTE1) was followed by conscious sedation with simultaneous TEE and TTE2. Based on conservative versus actionable implication, AS types were dichotomized into group A, comprising moderate and normal-flow low-gradient, and group B, comprising high gradient, low ejection fraction low-flow low-gradient, and paradoxical low-flow low-gradient AS. Paired analysis of echocardiographic variables and AS types measured by TEE versus TTE2 and by TEE versus TTE1 was performed. TEE versus simultaneous TTE2 comparison demonstrated higher mean gradients (31.7 ± 10.5 vs 27.4 ± 10.5 mm Hg) and velocities (359 ± 60.6 vs 332 ± 63.1 cm/s) with TEE, but lower left ventricular outflow velocity-time-integral (VTI₁) (18.6 ± 5.1 vs 20.2 ± 6.1 cm), all p <0.001. This resulted in a lower aortic valve area (0.8 ± 0.21 vs 0.87 ± 0.28 cm²), p <0.001, and a net relative risk of 1.86 of group A to B upgrade. TEE versus (awake state) TTE1 comparison revealed a larger decrease in VTI₁ because of a higher initial awake state VTI₁ (22 ± 5.6 cm), resulting in similar Doppler-velocity-index and aortic valve area decrease with TEE, despite a slight increase in mean gradients of 0.8 mm Hg (confidence interval -1.44 to 3.04) and velocities of 10 cm/s (confidence interval -1.5 to 23.4). This translated into a net relative risk of 1.92 of group A to B upgrade versus TTE1. In conclusion, TEE under conscious sedation overestimates AS severity compared with both awake state TTE and simultaneous sedation state TTE, accounted for by different Doppler insonation angles obtained in transapical versus transgastric position.

Severe aortic stenosis echocardiographic thresholds revisited

BACKGROUND

In view of inconsistencies in threshold values of severe aortic stenosis (AS) hemodynamic indices, it is unclear what is the relative contribution of each variable in a binary classification of AS based on aortic valve replacement (AVR) indication. We aimed to assess relative discriminative value and optimal threshold of each constituent hemodynamic parameter for this classification and confirm additional prognostic value.

METHODS

Echocardiography studies of 168 patients with ≥ moderate AS were included. AS types were dichotomized into Group-A, comprising moderate and Normal-Flow Low-Gradient (NFLG), and Group-B, comprising High-Gradient(HG), Low Ejection Fraction Low-Flow Low-Gradient(Low EF-LFLG), and Paradoxical Low-Flow Low-Gradient(PLFLG) AS. Aortic valve area (AVA), Doppler velocity index (DVI), peak aortic velocity, mean gradient, stroke volume index and transaortic flow rate(TFR) were assessed for A/B Group discrimination value and optimal thresholds were determined. Dichotomized values were assessed for predictive value for AVR or death.

RESULTS

C-statistic values for binary AS classification was .74-.9 for the tested variables. AVA and DVI featured the highest score, and SVI the lowest one. AVA≤.81 cm² and DVI≤.249 had 87.6% and 86% respective sensitivity for Group B patients, and a similar specificity of 80.9%. During a mean follow-up of 9.1±10.1 months, each of the tested dichotomized variables except for SVI predicted AVR or death on multivariate analysis.

CONCLUSION

An AVA value ≤.81 cm² or a DVI ≤ .249 threshold carry the highest discriminative value for severe AS in patients with aortic stenosis, translating into an independent prognostic value, and can be helpful in making clinical decisions.

Comparison of Transvalvular Aortic Mean Gradients Obtained by Intraprocedural Echocardiography and Invasive Measurement in Balloon and Self-Expanding Transcatheter Valves

Background Concerns about discordance between echocardiographic and invasive mean gradients after transcatheter aortic valve replacement (TAVR) with balloon-expandable valves (BEVs) versus self-expanding valves (SEVs) exist. Methods and Results In a multicenter study, direct-invasive and echocardiography-derived transvalvular mean gradients obtained before and after TAVR were compared as well as post-TAVR and discharge echocardiographic mean gradients in BEVs versus SEVs in 808 patients. Pre-TAVR, there was good correlation (R=0.614; P<0.0001) between direct-invasive and echocardiography-derived mean gradients and weak correlation (R=0.138; P<0.0001) post-TAVR. Compared with post-TAVR echocardiographic mean gradients, both valves exhibit lower invasive and higher discharge echocardiographic mean gradients. Despite similar invasive mean gradients, a small BEV exhibits higher post-TAVR and discharge echocardiographic mean gradients than a large BEV, whereas small and large SEVs exhibit similar post-TAVR and discharge mean gradients. An ejection fraction <50% (P=0.028) and higher Society of Thoracic Surgeons predicted risk of mortality score (P=0.007), but not invasive or echocardiographic mean gradient ≥10 mm Hg (P=0.378 and P=0.341, respectively), nor discharge echocardiographic mean gradient ≥20 mm Hg (P=0.393), were associated with increased 2-year mortality. Conclusions Invasively measured and echocardiography-derived transvalvular mean gradients correlate well in aortic stenosis but weakly post-TAVR. Post-TAVR, echocardiography overestimates transvalvular mean gradients compared with invasive measurements, and poor correlation suggests these modalities cannot be used interchangeably. Moreover, echocardiographic mean gradients are higher on discharge than post-TAVR in all valves. Despite similar invasive mean gradients, a small BEV exhibits higher post-TAVR and discharge echocardiographic mean gradients than a large BEV, whereas small and large SEVs exhibit similar post-TAVR and discharge mean gradients. Immediately post-TAVR, elevated echocardiographic-derived mean gradients should be assessed with caution and compared with direct-invasive mean gradients. A low ejection fraction and higher Society of Thoracic Surgeons score, but not elevated mean gradients, are associated with increased 2-year mortality.