Strategy for optimal aortic regurgitation quantification by Doppler echocardiography: agreement among different methods

Aortic Regurgitation: From Valvular to Myocardial Dysfunction

Chronic aortic regurgitation (AR) leads to volume overload in the left ventricle (LV), which is well tolerated for years. In this condition, the LV usually dilates with minimal reduction in the ejection fraction (EF), even in the absence of symptoms. Echocardiography is the primary imaging test used to quantify AR. However, no single assessment of Doppler measures is accurate and precise in individual patients; therefore, the integration of multiple parameters is necessary. Recent guidelines recommend surgical treatment for severe AR in patients who are symptomatic or have an LVEF < 55% and an end-systolic diameter > 50 mm. Nevertheless, advances in imaging technology have improved the quantification of AR and the assessment of LV subclinical dysfunction. It is widely recognized that patients who undergo aortic valve replacement/repair (AVR) due to symptoms or a low LVEF experience worse outcomes than those undergoing AVR for non-Class I indications. In fact, subclinical irreversible myocardial damage may occur in clinically well-compensated and closely monitored patients while awaiting formal surgical indications. This condition could be prevented by the use of multimodal imaging parameters, in particular longitudinal LV strain and magnetic resonance imaging. In addition, better cut-off values for mortality predictors should be established. This review aims to identify simple models that integrate several echocardiographic and cardiac magnetic resonance-derived parameters to predict the optimal timing of surgical treatment in asymptomatic patients with chronic severe AR.

Aortic regurgitation after transcatheter aortic valve implantation (TAVI) - Angiographic, echocardiographic and hemodynamic assessment in relation to one year outcome

BACKGROUND

Aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) remains a relatively frequent and life-limiting complication. However, the most prognostically discriminative (and therefore preferred) technique of AR evaluation after TAVI is not yet clearly defined. The aim of this study was to compare angiographic, echocardiographic and hemodynamic assessment of AR after TAVI in relation to one year outcome.

METHODS AND RESULTS

In this single center prospective cohort study, angiography (AR grading), echocardiography (AR quantification using color Doppler flow mapping) and invasive hemodynamics (AR index) were assessed before and after TAVI. All patients were followed up to at least one year. A total of 111 consecutive (very) high-risk patients with severe, symptomatic aortic valve stenosis underwent TAVI. No concordant relation could be demonstrated between angiographic, echocardiographic and invasive assessment of AR after TAVI. AR index <25 post TAVI was significantly influenced by left ventricular posterior wall thickness (odds ratio: 1.276, p=0.030) and AR index pre TAVI (odds ratio: 0.948, p=0.019). Neither angiographic nor hemodynamic AR assessments were able to discriminate between good or significantly decreased one year survival. In contrast, color Doppler flow mapping of AR after TAVI was highly reproducible, and able to differentiate between good or significantly decreased one year survival (AR grades 0-I: one year survival 87% vs. AR grades II-III-IV: one year survival 68%, p=0.035).

CONCLUSION

Echocardiography using color Doppler flow mapping is the preferred technique to assess prognostically relevant AR after TAVI.

Doppler-derived flow pattern in the descending aorta does not predict systemic to pulmonary arterial collateral flow in patients with single ventricle palliation: a cross-sectional study

BACKGROUND

Children with single ventricle heart disease are at risk for developing systemic to pulmonary arterial collateral vessels that adversely impact short-term outcomes, although the effect on long-term outcomes remains unclear. Collateral flow (CollF) can be quantified using cardiac magnetic resonance (CMR) flow quantification. The velocity-time integral (VTI), obtained from spectral Doppler tracings, has been used in "runoff" lesions like aortic regurgitation to quantify insufficiency. We hypothesized that the VTI ratio of the proximal descending aorta (DAo) after cavopulmonary anastomosis (CPA) would estimate CollF.

METHODS

A retrospective cross-sectional study was conducted. Patients who had a superior CPA or total CPA and underwent CMR between April 2008 and December 2012 were included. Those with greater than trivial semilunar valve insufficiency or aortic arch obstruction were excluded. In a subset (n = 88), spectral Doppler tracings of the DAo were analyzed to determine the VTI ratio. In another subset (n = 112), CMR was used to determine the ratio of retrograde to antegrade flow in the DAo.

RESULTS

There was no linear correlation between VTI ratio and CollF (r (2) = .006, P = .46). There was a weakly positive correlation with CollF (r (2) = .07, P = .007) and the CMR measured ratio of retrograde to antegrade flow. Holodiastolic flow reversal by echo did not predict higher CollF (P = .40), but those with holodiastolic flow reversal by CMR had significantly higher CollF (P = .04).

CONCLUSIONS

The ratio of reverse to forward flow in the DAo as determined by Doppler echo does not accurately reflect CollF in children with single ventricle after CPA.

Development of a consensus document to improve multireader concordance and accuracy of aortic regurgitation severity grading by echocardiography versus cardiac magnetic resonance imaging

Current guidelines recommend a multiparametric echocardiographic assessment of aortic regurgitation (AR). However, the absence of a hierarchical weighting of discordant parameters could cause interobserver variability. In the present study, we sought to define and improve the interobserver variability of AR assessment. Seventeen level 3 readers graded 20 randomly selected patients with AR. The readers also provided a usefulness score for each parameter, depending on its influence on their decision of the AR severity grade. A consensus strategy was subsequently formulated and validated against cardiac magnetic resonance imaging in a separate group of 80 patients. The readers were updated with the consensus document and recalibrated using the same cases. Agreement was statistically assessed using Randolph's free-marginal multirater kappa. At baseline, no uniform approach was used to combine the individual parameters, contributing to the interobserver variability (overall kappa 0.5). A consensus strategy to categorize AR severity was developed in which the left ventricular volume took precedence over the other parameters and was used to differentiate chronic severe AR from less severe categories. Recalibration of the readers using this consensus strategy improved concordance (kappa increased to 0.7). The new strategy also improved the accuracy relative to cardiac magnetic resonance imaging, as evidenced by full agreement on severe AR between the consensus document-based grading and AR severity defined by cardiac magnetic resonance imaging in the separate validation group of 80 patients. In conclusion, grading of chronic AR using a multiparametric approach has suboptimal consistency between readers and a left ventricular volume-based consensus document improved concordance and accuracy.

Complex Plaques in the Proximal Descending Aorta

Background and Purpose— To investigate the incidence of retrograde flow from complex plaques (≥4-mm-thick, ulcerated, or superimposed thrombi) of the descending aorta (DAo) and its potential role in embolic stroke.

Methods— Ninety-four consecutive acute stroke patients with aortic plaques ≥3-mm-thick in transesophageal echocardiography were prospectively included. MRI was performed to localize complex plaques and to measure time-resolved 3-dimensional blood flow within the aorta. Three-dimensional visualization was used to evaluate if diastolic retrograde flow connected plaque location with the outlet of the left subclavian artery, left common carotid artery, or brachiocephalic trunk. Complex DAo plaques were considered an embolic source if retrograde flow reached a supra-aortic vessel that supplied the territory of visible acute and embolic retinal or cerebral infarction.

Results— Only decreasing heart rate was correlated (P <0.02) with increasing flow reversal to the aortic arch. Retrograde flow from complex DAo plaques reached the left subclavian artery in 55 (58.5%), the left common carotid artery in 23 (24.5%), and the brachiocephalic trunk in 13 patients (13.8%). Based on routine diagnostics and MRI of the ascending aorta/aortic arch, stroke etiology was determined in 57 and cryptogenic in 37 patients. Potential embolization from DAo plaques was then identified in 19 of 57 patients (33.3%) with determined and in 9 of 37 patients (24.3%) with cryptogenic stroke.

Conclusions— Retrograde flow from complex DAo plaques was frequent in both determined and cryptogenic stroke and could explain embolism to all brain territories. These findings suggest that complex DAo plaques should be considered a new source of stroke.

Echocardiography at diagnosis of antiphospholipid syndrome provides prognostic information on valvular disease evolution and identifies two subtypes of patients

The evolution of valvular disease in antiphospholipid syndrome (APS) is barely known. In order to evaluate whether the presence or absence of valvular disease at the time of diagnosis of APS, assessed by an initial echocardiogram, predicts its subsequent evolution, we performed a prospective cohort study. We included 53 patients with APS. An initial transthoracic echocardiogram was performed on patients at the time of diagnosis of APS. Serial echocardiograms were conducted along a 12-year follow-up. Final echocardiograms were used for comparative purposes. We started with 29 patients (54%) with and 24 (45%) without valvulopathy at initial echo. At the final echocardiogram, 27 of 29 patients with initial valvulopathy continued to have valvular disease (a 93% observed likelihood), and 22 of 24 patients without initial valvulopathy demonstrated an absence of valvular disease (a 91% observed likelihood). Patients with valvulopathy in comparison with those without presented more arterial thrombotic events (69% vs. 20%, P < 0.001), atherosclerotic risk factors (62% vs. 29%, P = 0.01), livedo (48% vs. 16%, P = 0.01) and migraine (41% vs. 12%, P = 0.02). We have identified two subtypes of APS patients with and without valvulopathy by defining differential clinical features and with little crossover in valvular involvement over a long follow-up period, giving a high prognostic value to the initial echocardiographic assessment. Lupus (2010) 19, 575—582.

Effectiveness of angiotensin-converting enzyme inhibitors in pediatric patients with mid to severe aortic valve regurgitation

The long-term benefit of angiotensin-converting enzyme inhibitors in pediatric patients with aortic valve regurgitation is under consideration. Eighteen patients with mid to severe aortic valve regurgitation were retrospectively evaluated. Echocardiographic parameters (left ventricular end-diastolic diameter, shortening fraction, left ventricular posterior wall thickness, and grade of aortic valve regurgitation) were analyzed before and during therapy with angiotensin-converting enzyme inhibitors. Data are given as standard deviation scores (Z-scores) derived from body surface-adjusted normal values. Median (interquartile range) age at start of therapy was 8.4 (5.4 to 10.0) years, and total follow-up 2.3 (0.9 to 5.4) years. Left ventricular end-diastolic diameter increased from 3.6 (2.3 to 4.5) to 3.7 (2.4 to 4.8), and left ventricular posterior wall diameter decreased from 1.9 (1.1 to 3.0) to 1.1 (0.5 to 2.3). Grade of aortic valve regurgitation increased from 3.5 (2.3 to 4.0) to 4.0 (2.0 to 4.0), and shortening fraction decreased from 39% (34% to 43%) to 37% (34% to 42%). No significant effect of angiotensin-converting enzyme inhibitors on left ventricular dimensions or function was found in our population of patients with mid to severe aortic valve regurgitation. Angiotensin-converting enzyme inhibitors may not alter left ventricular overload in pediatric patients with aortic valve regurgitation.

Accuracy of the flow convergence method for quantification of aortic regurgitation in patients with central versus eccentric jets

Proximal isovelocity surface area (PISA) has been proposed as a quantitative method to assess the severity of aortic regurgitation (AR). Yet the accuracy of this method in patients with eccentric AR jets is unknown. The aims of this study were to compare the accuracy of the PISA method for the quantification of AR severity in patients with central versus eccentric AR jets and to verify whether imaging from the left parasternal instead of the apical window improves the accuracy of the PISA method in patients with eccentric jets. Fifty patients with AR (21 with central jets and 29 with eccentric jets) underwent PISA and phase-contrast cardiac magnetic resonance (CMR) measurements of AR volume. In patients with eccentric AR jets, PISA measurements obtained from the left parasternal and apical windows were compared. In patients with central AR jets, CMR- and PISA-derived AR volumes were similar (28 +/- 19 vs 30 +/- 20 ml, p = 0.34), were strongly correlated (r = 0.92, p <0.0001), and differed minimally from each other (by 2 +/- 8 ml). In patients with eccentric AR jets, PISA-derived AR volumes underestimated those measured by CMR (38 +/- 22 vs 51 +/- 27 ml, bias -13 +/- 20 ml) and were correlated only fairly (r = 0.69, p <0.001). Imaging from the left parasternal window eliminated the differences between CMR- and PISA-derived AR volumes (51 +/- 27 vs 53 +/- 26 ml, p = 0.24) and improved the correlation between the 2 measures (r = 0.95). In conclusion, in patients with eccentric AR jets imaged from the apical window, the PISA method significantly underestimated AR severity. This was no longer the case when imaging was performed from the left parasternal instead of the apical window.

Prognostic value of preoperative indexed end-systolic left ventricle diameter in the outcome after surgery in patients with chronic aortic regurgitation

BACKGROUND

End-systolic diameter (ESD) is an important parameter in the prognosis and indication for surgery in chronic aortic regurgitation (AR). It has been suggested that ESD values noncorrected for body surface area (BSA) could be inappropriate in the management of patients with extreme BSA. The aim of the study was to assess the usefulness of indexed ESD (IESD) of the left ventricle in the management of patients with severe isolated chronic AR.

METHODS

One hundred forty-seven patients underwent surgery for chronic AR and were followed up for a mean of 8 +/- 6 years (1-22 years). A post hoc assessment was made of the prognostic value of preoperative ESD and IESD in different BSA percentiles: group 1, <or= 25th percentile (BSA 1.43-1.68 m(2), n = 40); group 2, >25th percentile and <or=75th percentile (BSA 1.69-1.91 m(2), n = 68); and group 3, >75th percentile (BSA 1.92-2.24 m(2), n = 39).

RESULTS

Age-adjusted preoperative ESD and IESD were independent predictors of mortality or heart failure in the entire population. Magnitude of the relative risk was slightly greater using preoperative IESD than ESD (HR 1.07, 95% CI 1.01-1.29, P = .017; HR 1.04, 95% CI 1.01-1.08, P = .016). In group 1, the age-adjusted expected mortality rate would drop if IESD of 25 mm/m(2) was used as a surgical criterion instead of ESD 50 mm, from 37.94% to 24.27% at 10 years (P = .002).

CONCLUSIONS

The use of IESD improves the prediction of unfavorable outcomes after surgery in patients with low BSA but not in those with high BSA. In patients with low BSA, IESD >or=25 mm/m(2) should be used as a cutoff point for surgery rather than ESD >50 mm.

Long-term vasodilator therapy in patients with severe aortic regurgitation

BACKGROUND

Vasodilator therapy can reduce the left ventricular volume and mass and improve left ventricular performance in patients with aortic regurgitation. Accordingly, it has been suggested that such therapy may reduce or delay the need for aortic-valve replacement.

METHODS

We randomly assigned 95 patients with asymptomatic severe aortic regurgitation and normal left ventricular function to receive open-label nifedipine (20 mg every 12 hours), open-label enalapril (20 mg per day), or no treatment (control group) to identify the possible beneficial effects of vasodilator therapy on left ventricular function and the need for aortic-valve replacement.

RESULTS

After a mean of seven years of follow-up, the rate of aortic-valve replacement was similar among the groups: 39 percent in the control group, 50 percent in the enalapril group, and 41 percent in the nifedipine group (P=0.62). In addition, there were no significant differences among the groups in aortic regurgitant volume, left ventricular size, left ventricular mass, mean wall stress, or ejection fraction. One year after valve replacement, the left ventricular end-diastolic diameter and end-systolic diameter had decreased to a similar degree among the patients who underwent surgery in each of the three groups, and all the patients had a normal ejection fraction.

CONCLUSIONS

Long-term vasodilator therapy with nifedipine or enalapril did not reduce or delay the need for aortic-valve replacement in patients with asymptomatic severe aortic regurgitation and normal left ventricular systolic function. Furthermore, such therapy did not reduce the aortic regurgitant volume, decrease the size of the left ventricle, or improve left ventricular function.

Relation of N-terminal pro B-type natriuretic peptide to progression of aortic valve disease

AIMS

Recently an elevation of B-type natriuretic peptide (BNP) and its N-terminal fragment (NT-proBNP) in patients with aortic stenosis (AS) and aortic regurgitation (AR) has been described. The objective of this study was to evaluate the relation of NT-proBNP values to the progression of aortic valve disease.

METHODS AND RESULTS

One hundred and sixty-eight patients were included. NT-proBNP was elevated in patients with AS (n=109) and AR (n=37) linked to disease severity. Values for NT-proBNP, pressure gradient, and left ventricular mass were identical in patients (n=22) after previous valve replacement and in those patients with mild AS. NT-proBNP levels decreased in 86 patients after valve replacement (2292+/-353 vs. 785+/-101 pg/ml; P<0.01) but increased in 82 patients who were treated conservatively (616+/-120 vs. 1155+/-432 pg/mL; P=0.029), related to the progression of disease.

CONCLUSION

NT-proBNP is elevated in patients with aortic valve disease linked to disease severity and decreases after successful surgical therapy but increases in conservatively treated patients. These data underline the consistent relation of NT-proBNP to severity of aortic valve disease. Therefore, NT-proBNP should be considered as a biomarker for the monitoring of disease during follow-up, but further studies are warranted.

A new echocardiographic method for the assessment of the severity of aortic regurgitation: color M-mode flow propagation velocity

PURPOSE

Echocardiographic Doppler methods widely used in assessment of the severity of aortic regurgitation (AR) are considered sensitive and reliable. However, they all have limitations for quantitation of AR. The color M-mode Doppler flow propagation velocity (FPV) method has been shown to provide useful insights in the evaluation of left ventricular diastolic function and appears to be minimally affected with preload changes. Clinical data regarding the value of FPV in the determination of the significance of valvular insuffiencies are lacking. The purpose of this study was to evaluate the use of FPV in measurement of the severity of AR and to compare its reliability with angiography and other echocardiographic methods.

METHODS

Twenty-nine patients (13 male, 16 female) who had cardiac catheterization for various reasons before echocardiographic evaluation were included. The mean age was 53.6 +/- 13.4 years. At the time of cardiac catheterization, the degree of AR was assessed as mild in 10 patients, as moderate in 12, and as severe in 7. In all patients, FPV measurements of AR were obtained with color M-mode Doppler in the apical 5-chamber view. Regurgitation jet height and its ratio to left ventricular outflow obtained in the parasternal long axis with color flow Doppler, pressure half-time, and slope of AR obtained with continuous wave Doppler in apical 5-chamber view were other echocardiographic methods chosen for comparison.

RESULTS

The mean values of FPV were 93.1 +/- 18.4 cm/s, 49.8 +/- 8.0 cm/s, and 31.7 +/- 4.9 cm/s in severe, moderate, and mild AR groups, respectively (P <.001). Significant correlation was observed between angiographic grades, FPV, pressure half-time, slope, and jet height and ratio to left ventricular outflow (P <.0001, r = 0.93; P <.0001, r = -0.81; P <.0001, r = 0.76; P <.0001, r = 0.92, respectively).

CONCLUSION

FPV is a simple, practical, and reliable method for the quantification of AR.