Quantitation of aortic regurgitation by computer analysis of digital subtraction angiography

Quantitative aortography for assessment of aortic regurgitation in the era of percutaneous aortic valve replacement

Paravalvular leak (PVL) is a shortcoming that can erode the clinical benefits of transcatheter valve replacement (TAVR) and therefore a readily applicable method (aortography) to quantitate PVL objectively and accurately in the interventional suite is appealing to all operators. The ratio between the areas of the time-density curves in the aorta and left ventricular outflow tract (LVOT-AR) defines the regurgitation fraction (RF). This technique has been validated in a mock circulation; a single injection in diastole was further tested in porcine and ovine models. In the clinical setting, LVOT-AR was compared with trans-thoracic and trans-oesophageal echocardiography and cardiac magnetic resonance imaging. LVOT-AR > 17% discriminates mild from moderate aortic regurgitation on echocardiography and confers a poor prognosis in multiple registries, and justifies balloon post-dilatation. The LVOT-AR differentiates the individual performances of many old and novel devices and is being used in ongoing randomized trials and registries.

Paravalvular Aortic Regurgitation Severity Assessed by Quantitative Aortography: ACURATE neo2 versus ACURATE neo Transcatheter Aortic Valve Implantation

The new-generation ACURATE neo2 system was commercially released in September 2020. In this study, we sought to compare the aortic regurgitation (AR) severity of the ACURATE neo2 versus the ACURATE neo transcatheter heart valve, using quantitative videodensitometric angiography (qAR). This is a retrospective, Corelab analysis of final post-transcatheter aortic valve implantation (TAVI) aortograms of patients treated with the ACURATE neo2 and ACURATE neo systems. The ACURATE neo2 cohort comprised consecutive patients treated between September 2020 and January 2021 at two centers. The ACURATE neo cohort included consecutive patients treated before September 2020. Our primary objective was to compare AR severity on qAR following TAVI with ACURATE neo2 and ACURATE neo. Out of 401 aortograms, 228 (56.9%) were analyzable, with 120 in the ACURATE neo2 cohort, and 108 in the ACURATE neo cohort. The mean AR fraction was 4.4 ± 4.8% in the neo2 cohort, and 9.9 ± 8.2% in the neo cohort (p < 0.001). Furthermore, moderate or severe AR (qAR > 17%) was detected in 2 aortograms (1.7%) in the neo2 cohort and 15 aortograms (13.9%) in the neo cohort (p < 0.001). Quantitative aortography shows a lower rate of moderate or severe paravalvular AR in what is the first European experience of the new-generation, self-expanding ACURATE neo2 when compared to the first-generation ACURATE neo. Moreover, aortographic data need to be correlated and compared to Core Laboratory-adjudicated 30-day echocardiographic data.

Quantitative assessment of aortic regurgitation following transcatheter aortic valve replacement

Introduction: Transcatheter aortic valve replacement (TAVR) is expanding to lower risk and younger patients with severe symptomatic aortic valve disease. Despite clinical and technological improvements, post-procedural aortic regurgitation (AR) remains a limitation of TAVR, particularly when compared to surgical aortic valve replacement. Although several methods for AR quantification after TAVR are currently available, its exact graduation in everyday clinical practice remains challenging.Areas covered: This review describes the currently available evaluation methods of AR after TAVR, with a special emphasis on the quantitative assessment using videodensitometric angiography, echocardiography and cardiac magnetic resonance imaging.Expert opinion: In the majority of clinical scenarios, satisfactory evaluation of post-TAVR AR can be achieved with a combination of post-procedural angiography, hemodynamic indices and transthoracic echocardiography. Nevertheless, some TAVR patients show 'intermediate' forms of post-procedural AR, in which quantitative evaluation is mandatory for prognostic purposes and further decision-making. Notably, interpretation of quantitative measures early post-TAVR is challenging because of the lack of left ventricular enlargement. Video-densitometric angiography is an emerging method that appears to be clinically attractive for immediate post-TAVR assessment, but requires further validation in everyday clinical practice.

Validation of Prosthetic Mitral Regurgitation Quantification Using Novel Angiographic Platform by Mock Circulation

OBJECTIVES

This study aimed to validate a dedicated software for quantitative videodensitometric angiographic assessment of mitral regurgitation (QMR).

BACKGROUND

Quantitative videodensitometric aortography of aortic regurgitation using the time-density principle is a well-documented technique, but the angiographic assessment of mitral regurgitation (MR) remains at best semi-quantitative and operator dependent.

METHODS

Fourteen sheep underwent surgical mitral valve replacement using 2 different prostheses. Pre-sacrifice left ventriculograms were used to assess MR fraction (MRF) using QMR and MR volume (MRV). In an independent core lab, the CAAS QMR 0.1 was used for QMR analysis. In vitro MRF and MRV were assessed in a mock circulation at a comparable cardiac output to the in vivo one by thermodilution. The correlations and agreements of in vitro and in vivo MRF, MRV, and interobserver reproducibility for QMR analysis were assessed using the averaged cardiac cycles (CCs).

RESULTS

In vivo derived MRF by QMR strongly correlated with in vitro derived MRF, regardless of the number of the CCs analyzed (best correlation: 3 CCs y = 0.446 + 0.994x; R = 0.784; p =0.002). The mean absolute difference between in vitro derived MRF and in vivo derived MRF from 3 CCs was 0.01 ± 4.2% on Bland-Altman analysis. In vitro MRV and in vivo MRV from 3 CCs were very strongly correlated (y = 0.196 + 1.255x; R = 0.839; p < 0.001). The mean absolute difference between in vitro MRV and in vivo MRV from 3 CCs was -1.4 ± 1.9 ml. There were very strong correlations of in vivo MRF between 2 independent analysts, regardless of the number of the CCs.

CONCLUSIONS

In vivo MRF using the novel software is feasible, accurate, and highly reproducible. These promising results have led us to initiate the first human feasibility study comprising patients undergoing percutaneous mitral valve edge-to-edge repair.

Feasibility study of a synchronized diastolic injection with low contrast volume for proper quantitative assessment of aortic regurgitation in porcine models

OBJECTIVES

To evaluate the in vivo feasibility of aortography with one accurately timed diastolic low-volume contrast injection for quantitative assessment of aortic regurgitation (AR) post transcatheter aortic valve replacement (TAVR).

BACKGROUND

With the rise of a minimalistic approach for TAVR, aortography (re)emerges as a pragmatic tool for AR assessment. In a mock circulation system, we have validated the accuracy of a single diastolic injection triggered by electrocardiogram (ECG) with low-contrast volume.

METHODS

Two-phase experiment: first, a series of aortograms were performed in a porcine model, with 8 mL of contrast using the synchronized (SYNC) and the conventional non-synchronized (NS) injections. In a second phase, we developed a model of AR by inserting partially unsheathed Wallstents of 6-10 mm of diameter across the pig's aortic valve, performing SYNC injections with 8 mL of contrast and NS injections with 8 mL and 15 mL (rate: 20 mL/sec). Respective accuracies of SYNC vs. NS were assessed using Passing-Bablock regression. An angiography core laboratory performed quantitative AR assessment with videodensitometry (VD-AR).

RESULTS

The SYNC injections produced higher opacification of the aortic root compared with NS injections (P = 0.04 for density). In the second phase, a regression line for predicting VD-AR based on the SYNC injection resulted in a lower intercept and a slope closer to the line of identity (y = 11.9 + 0.79x, P < 0.001, r²  = 0.94) with the NS-8 mL than with the NS-15 mL injection (y = 26.5 + 0.55x, P < 0.001, r²  = 0.81).

CONCLUSION

Synchronized diastolic injection with low contrast volume produced denser images in the aortic root and more accurate than the conventional injection; thus, may be an appealing alternative for assessment of AR post TAVR.

Detection and quantification of aortic regurgitation during aortic valvuloplasty

The degree of aortic regurgitation, before and after balloon aortic valvuloplasty, was assessed in 32 patients, using double indicator dilution curves: a) the forward curve was obtained by dye injection into the left ventricle and sampling in the aorta; b) the regurgitant curve was obtained by dye injection in the aorta and sampling in the left ventricle. A regurgitant index (RI) was calculated by obtaining the ratio of the areas of the triangles from regurgitant and forward curves. Eight-five percent of the patients were 70 years or older. After valvuloplasty, aortic valve area increased from 0.5 +/- 0.3 cm2 to 0.7 +/- 0.3 cm2 (P = .0002) while left ventricular to aortic gradient decreased from 77 +/- 32 to 51 +/- 24 (P = .0001). RI did not significantly change in 58% of patients, increased in 25%, and decreased in 15.2%. We conclude that in most patients undergoing aortic valvuloplasty, regurgitation does not change after the procedure. In some patients it may increase significantly, and in a few it may even decrease. Indicator dilution curves technique seems to provide a sensitive, accurate, and reproducible method to detect and quantify aortic incompetence before and after valvuloplasty.

Quantification of aortic regurgitation after balloon aortic valvuloplasty using videodensitometric analysis of digital subtraction aortography

The serial changes in aortic regurgitation (AR) after balloon aortic valvuloplasty have not been quantitatively evaluated. This study assessed the degree of AR by quantitative and qualitative techniques before and immediately after aortic valvuloplasty. Digital subtraction aortography was performed before and after valvuloplasty in 50 patients. The ratio of left ventricular to aortic contrast density during aortography was analyzed by videodensitometric techniques. A time-density curve was obtained by placing a 30 X 30 pixel region of interest over the aortogram and the left ventricular cavity. The ratio of left ventricular to aortic density at peak aortic density defined the videodensitometric ratio. Independent visual interpretation was also assessed and compared to videodensitometric methods. Quantitatively, no significant change in AR could be demonstrated in the mean videodensitometric ratio before or after balloon aortic valvuloplasty (0.33 +/- 0.21 vs 0.37 +/- 0.25, p = 0.07). Ten (20%) of the patients had a greater than or equal to 0.10 increase, and 4 (8%) patients a greater than or equal to 0.10 decrease in the AR ratio. Thus, serial quantitative and qualitative determinations of AR after balloon aortic valvuloplasty confirm that significant increases or decreases in AR severity are unusual after the procedure.