Paradoxical low-flow, low-gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival

Deterioration of myocardial function in paradoxical low-flow severe aortic stenosis: two-dimensional strain analysis

BACKGROUND

The diagnosis and management of paradoxical low-flow (PLF) aortic stenosis (AS) is challenging in clinical practice. In addition, its pathophysiology has not been fully understood. The aim of this study was to test the hypothesis that left ventricular (LV) myocardial function is deteriorated in PLF AS and that it is closely related to global LV afterload.

METHODS

Echocardiographic data from 103 patients with severe AS (aortic valve area < 1.0 cm(2)) with normal LV ejection fractions were prospectively collected. Global longitudinal and circumferential myocardial strain was analyzed using two-dimensional speckle-tracking imaging. PLF AS was defined as a stroke volume index < 35 mL/m(2).

RESULTS

Sixteen patients were classified as having PLF AS. Compared with those with normal-flow AS, patients with PLF AS were more likely to have worse functional status (mean New York Heart Association functional class, 2.38 ± 0.70 vs 1.96 ± 0.62; P = .02), worse global longitudinal strain (GLS) (-12.6 ± 4.4% vs -16.4 ± 4.0%, P < .01), lower aortic valve area (0.53 ± 0.15 vs 0.78 ± 0.19 cm(2), P < .01), and higher valvuloarterial impedance (5.62 ± 1.33 vs 3.65 ± 0.83 mm Hg · m(2)/mL, P < .01). GLS showed a significant negative linear relationship with stroke volume index (r = -0.324, P = .001) and a positive relationship with E/E' ratio (r = 0.367, P < .001). Multivariate analysis showed that age (β = 0.08, P = .07) and valvuloarterial impedance (β = 1.54, P < .01) were significant predictors of GLS.

CONCLUSIONS

GLS is depressed in patients with PLF AS. This implies that subclinical myocardial dysfunction may be more prominent in PLF AS compared with normal-flow AS and suggests the possible diagnostic and prognostic value of two-dimensional global strain in identifying PLF AS. In addition, global LV afterload is an important determinant of myocardial dysfunction in patients with severe AS.

WITHDRAWN: Very Early Improvement in Valvuloarterial Impedance Induced by Transcatheter Aortic Valve Implantation (CoreValve) in Symptomatic Aortic Stenosis

The editors have requested that the article be withdrawn because of concern that some of its contents appear quite similar to portions of another publication from the same group of investigators. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Comparison between cardiovascular magnetic resonance and transthoracic Doppler echocardiography for the estimation of effective orifice area in aortic stenosis

BACKGROUND

The effective orifice area (EOA) estimated by transthoracic Doppler echocardiography (TTE) via the continuity equation is commonly used to determine the severity of aortic stenosis (AS). However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance (CMR) has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA.

METHODS AND RESULTS

31 patients with mild to severe AS (EOA range: 0.72 to 1.73 cm2) and seven (7) healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract (LVOT) cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area (ALVOT, 3.84 ± 0.80 cm2) compared to CMR (4.78 ± 1.05 cm2). On the other hand, TTE overestimated the LVOT velocity-time integral (VTILVOT: 21 ± 4 vs. 15 ± 4 cm). Good concordance was observed between TTE and CMR for estimation of aortic jet VTI (61 ± 22 vs. 57 ± 20 cm). Overall, there was a good correlation and concordance between TTE-derived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = 0.06 ± 0.29 cm2). The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.

CONCLUSION

Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.

Outcomes and survival with aortic valve replacement compared with medical therapy in patients with low-, moderate-, and severe-gradient severe aortic stenosis and normal left ventricular ejection fraction

BACKGROUND

This study determined outcomes and survival with aortic valve replacement (AVR) versus medical therapy in patients with normal left ventricular ejection fraction (LVEF) with severely reduced aortic valve areas (AVA) but nonsevere mean gradients.

METHODS

We identified 248 aortic stenosis (AS) patients with LVEF ≥ 50% and echocardiographic AVA < 1.0 cm(2). Group 1 had low-gradient: <30 mmHg mean gradient; group 2 (moderate: 30 to 40 mm Hg); and group 3 (severe: >40 mm).

RESULTS

There were 94, 87, and 67 patients in groups 1, 2, and 3. Incidence of death in groups 1, 2, and 3 were 55%, 39%, and 39% (P not significant). Incidence of AVR in groups 1, 2, and 3 were 23%, 53%, and 49% (P < 0.0001 for group 1 vs. 2; P = 0.0003 for group 1 vs. group 3). Incidence of AVR or death was 71%, 77%, and 76% (P not significant). AVR (hazard ratio = 0.30; 95% CI, 0.18, 0.51; P < 0.0001) and mitral annular calcification (hazard ratio = 2.33; 95% CI, 1.40, 3.88; P = 0.001) were independently associated with time to mortality. Kaplan-Meier curves for time to death did not differ significantly among the three groups. Kaplan-Meier survival curves for patients with and without AVR showed patients in all three groups who underwent AVR had significantly greater survival.

CONCLUSION

Among patients with normal LVEF and AVA < 1.0 cm(2), overall survival does not differ among those with low-, moderate-, or severe-aortic valve gradients. Survival is significantly improved with AVR, regardless of gradient.

Outcome of Patients With Low-Gradient “Severe” Aortic Stenosis and Preserved Ejection Fraction

Background—

Retrospective studies have suggested that patients with a low transvalvular gradient in the presence of an aortic valve area <1.0 cm 2 and normal ejection fraction may represent a subgroup with an advanced stage of aortic valve disease, reduced stroke volume, and poor prognosis requiring early surgery. We therefore evaluated the outcome of patients with low-gradient “severe” stenosis (defined as aortic valve area <1.0 cm 2 and mean gradient ≤40 mm Hg) in the prospective Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study.

Methods and Results—

Outcome in patients with low-gradient “severe” aortic stenosis was compared with outcome in patients with moderate stenosis (aortic valve area 1.0 to 1.5 cm 2 ; mean gradient 25 to 40 mm Hg). The primary end point of aortic valve events included death from cardiovascular causes, aortic valve replacement, and heart failure due to aortic stenosis. Secondary end points were major cardiovascular events and cardiovascular death. In 1525 asymptomatic patients (mean age, 67±10 years; ejection fraction, ≥55%), baseline echocardiography revealed low-gradient severe stenosis in 435 patients (29%) and moderate stenosis in 184 (12%). Left ventricular mass was lower in patients with low-gradient severe stenosis than in those with moderate stenosis (182±64 versus 212±68 g; P <0.01). During 46 months of follow-up, aortic valve events occurred in 48.5% versus 44.6%, respectively ( P =0.37; major cardiovascular events, 50.9% versus 48.5%, P =0.58; cardiovascular death, 7.8% versus 4.9%, P =0.19). Low-gradient severe stenosis patients with reduced stroke volume index (≤35 mL/m 2 ; n=223) had aortic valve events comparable to those in patients with normal stroke volume index (46.2% versus 50.9%; P =0.53).

Conclusions—

Patients with low-gradient “severe” aortic stenosis and normal ejection fraction have an outcome similar to that in patients with moderate stenosis.

Heart failure with preserved left ventricular ejection fraction: concepts, misconceptions and future directions

Heart failure with preserved left ventricular ejection fraction (HFPEF) represents a huge medical problem, especially in light of an increasing elderly population. Dysfunction of both left ventricular filling and ejection, combined with adverse loading conditions related to advanced age, arterial hypertension, diabetes mellitus, obesity and atrial fibrillation are fundamental pathophysiological mechanisms. Hypertension is probably the most important modifiable risk factor. The diagnosis has largely been based on signs of increased left ventricular filling pressure. Additional matters of debate are the interpretation of left ventricular ejection fraction in concentric remodelling and the cut-off used for the definition of HFPEF, as well as inconsistencies related to prevalence and prognosis, and lack of benefit of drugs in randomized trials.

Equilibrium contrast cardiovascular magnetic resonance for the measurement of diffuse myocardial fibrosis: preliminary validation in humans

BACKGROUND

Diffuse myocardial fibrosis is a final end point in most cardiac diseases. It is missed by the cardiovascular magnetic resonance (CMR) late gadolinium enhancement technique. Currently, quantifying diffuse myocardial fibrosis requires invasive biopsy, with inherent risk and sampling error. We have developed a robust and noninvasive technique, equilibrium contrast CMR (EQ-CMR) to quantify diffuse fibrosis and have validated it against the current gold standard of surgical myocardial biopsy.

METHODS AND RESULTS

The 3 principles of EQ-CMR are a bolus of extracellular gadolinium contrast followed by continuous infusion to achieve equilibrium; a blood sample to measure blood volume of distribution (1-hematocrit); and CMR to measure pre- and postequilibrium T1 (with heart rate correction). The myocardial volume of distribution is calculated, reflecting diffuse myocardial fibrosis. Clinical validation occurred in patients undergoing aortic valve replacement for aortic stenosis or myectomy in hypertrophic cardiomyopathy (n=18 and n=8, respectively). Surgical biopsies were analyzed for picrosirius red fibrosis quantification on histology. The mean histological fibrosis was 20.5+/-11% in aortic stenosis and 17.1+/-7.4% in hypertrophic cardiomyopathy. EQ-CMR correlated strongly with biopsy histological fibrosis: aortic stenosis, r(2)=0.86, Kendall Tau coefficient (T)=0.71, P<0.001; hypertrophic cardiomyopathy, r(2)=0.62, T=0.52, P=0.08; combined r(2)=0.80, T=0.67, P<0.001.

CONCLUSIONS

We have developed and validated a new technique, EQ-CMR, to measure diffuse myocardial fibrosis as an add-on to a standard CMR scan, which allows for the noninvasive quantification of the diffuse fibrosis burden in myocardial diseases.

Echo-tracking assessment of carotid artery stiffness in patients with aortic valve stenosis

BACKGROUND

There is little information about mechanical properties of large arteries in patients (pts) with aortic stenosis (AS).

METHODS

Nineteen patients with AS (aortic valve area: 0.88 +/- 0.29 cm(2)) and 24 control subjects without AS but with a similar distribution of risk factors were recruited. beta index, pressure-strain elastic modulus (Ep), arterial compliance (AC), augmentation index (AIx), and local pulse-wave velocity (PWV) were obtained at the level of right common carotid artery (CCA) by a real time echo-tracking system. Time to dominant peak of carotid diameter change waveform, corrected for heart rate (tDPc), and maximum rate of rise of carotid diameter (dD/dt) were measured. Systemic arterial compliance (SAC) was also calculated. Parameters of AS severity (mean gradient, valve area, stroke work loss [SWL]) were determined.

RESULTS

tDPc was higher in patients with AS than in controls (7.9 +/- 0.6 vs. 6.6 +/- 0.7, P < 0.0001) while dD/dt was lower (5.3 +/- 3.6 mm/s vs. 7.8 +/- 2.8 mm/s, P = 0.01). AIx was significantly higher in AS group (32.5 +/- 13.6% vs. 20.6 +/- 12.2%, P = 0.005) and had a linear correlation both with tDPc (r = 0.63, P < 0.0001) and with dD/dt (r =-0.38, P = 0.01). There was a significant correlation between carotid AC and SAC (r = 0.49, P = 0.03), but only carotid AC was related to SWL (r = 0.51, P = 0.02), while SAC was not (P = 0.26).

CONCLUSIONS

AIx was the only parameter of arterial rigidity found to be higher in patients with AS than in controls. Carotid AC showed a significant correlation with SAC and it seemed to be more closely related to AS severity than to SAC.

Prognostic effect of long-axis left ventricular dysfunction and B-type natriuretic peptide levels in asymptomatic aortic stenosis

In aortic stenosis (AS), the increased afterload results in progressive structural and functional changes that precede the development of symptoms. We hypothesized that the detection of abnormalities in left ventricular long-axis function could identify patients with asymptomatic AS at increased risk of events. We prospectively examined the outcome of 126 patients with asymptomatic AS who underwent a comprehensive echocardiographic examination, including tissue Doppler imaging. B-type natriuretic peptide (BNP) was measured in all patients. During a median follow-up period of 20.3 + or - 17.8 months, 6 patients died, 8 developed symptoms but did not undergo surgery, and 48 underwent aortic valve replacement. On multivariate Cox regression analysis, the parameters associated with the predefined outcome were gender (p = 0.048), left atrial area index (p = 0.011), systolic annular velocity (p = 0.016), E/Ea ratio (p = 0.024), late diastolic annular velocity (p = 0.023), and BNP (p = 0.012). Using receiver operating characteristics curve analysis, a left atrial area index of > or = 12.4 cm(2)/m(2), systolic annular velocity of < or = 4.5 cm/s, E/Ea ratio >13.8, late diastolic annular velocity of < or = 9 cm/s, and BNP of > or = 61 pg/ml were identified as the best cutoff values to predict events. In conclusion, in asymptomatic AS, tissue Doppler imaging and BNP measurements provide prognostic information beyond that from clinical and conventional echocardiographic parameters.

Key role of Doppler echocardiography in the emergency management of elderly patients

Owing to modern epidemiology in Western countries, ageing represents a growing health burden. In general, because of age itself and comorbid conditions, all clinical cardiovascular manifestations have a higher mortality rate and a worse outcome in older people compared with in younger individuals. Diagnosis of the disease in the elderly in an emergency setting is particularly challenging for the practitioner. Age-related cardiovascular changes and comorbid conditions may alter signs, symptoms and adaptation to the disease and response to treatment. Bedside Doppler echocardiography is likely to play a major role in guiding diagnosis, therapeutic strategies and prognosis. The purpose of this review is to appraise the application of echocardiographic examination in helping the clinician facing emergency situations that involve the cardiovascular system in the older population.

Natural history of very severe aortic stenosis

BACKGROUND

We sought to assess the outcome of asymptomatic patients with very severe aortic stenosis.

METHODS AND RESULTS

We prospectively followed 116 consecutive asymptomatic patients (57 women; age, 67 + or - 16 years) with very severe isolated aortic stenosis defined by a peak aortic jet velocity (AV-Vel) > or = 5.0 m/s (average AV-Vel, 5.37 + or - 0.35 m/s; valve area, 0.63 + or - 0.12 cm(2)). During a median follow-up of 41 months (interquartile range, 26 to 63 months), 96 events occurred (indication for aortic valve replacement, 90; cardiac deaths, 6). Event-free survival was 64%, 36%, 25%, 12%, and 3% at 1, 2, 3, 4, and 6 years, respectively. AV-Vel but not aortic valve area was shown to independently affect event-free survival. Patients with an AV-Vel > or = 5.5 m/s had an event-free survival of 44%, 25%, 11%, and 4% at 1, 2, 3, and 4 years, respectively, compared with 76%, 43%, 33%, and 17% for patients with an AV-Vel between 5.0 and 5.5 m/s (P<0.0001). Six cardiac deaths occurred in previously asymptomatic patients (sudden death, 1; congestive heart failure, 4; myocardial infarction, 1). Patients with an initial AV-Vel > or = 5.5 m/s had a higher likelihood (52%) of severe symptom onset (New York Heart Association or Canadian Cardiovascular Society class >II) than those with an AV-Vel between 5.0 and 5.5 m/s (27%; P=0.03).

CONCLUSIONS

Despite being asymptomatic, patients with very severe aortic stenosis have a poor prognosis with a high event rate and a risk of rapid functional deterioration. Early elective valve replacement surgery should therefore be considered in these patients.

Usefulness of the valvuloarterial impedance to predict adverse outcome in asymptomatic aortic stenosis

OBJECTIVES

This study was designed to examine the prognostic value of valvuloarterial impedance (Z(va)) in patients with aortic stenosis (AS).

BACKGROUND

We previously showed that the Z(va) is superior to standard indexes of AS severity in estimating the global hemodynamic load faced by the left ventricle (LV) and predicting the occurrence of LV dysfunction. This index is calculated by dividing the estimated LV systolic pressure (systolic arterial pressure + mean transvalvular gradient) by the stroke volume indexed for the body surface area.

METHODS

We retrospectively analyzed the clinical and echocardiographic data of 544 consecutive patients having at least moderate AS (aortic jet velocity > or =2.5 m.s(-1)) and no symptoms at baseline. The primary end point for this study was the overall mortality regardless of the realization of aortic valve replacement (AVR).

RESULTS

Four-year survival was significantly (p < 0.001) lower in the patients with a baseline Z(va) > or =4.5 mm Hg x ml(-1) x m(2) (65 +/- 5%) compared with those with Z(va) between 3.5 and 4.5 mm Hg x ml(-1) x m(2) (78 +/- 4%) and those with Z(va) < or =3.5 mm Hg x ml(-1) x m(2) (88 +/- 3%). The risk of mortality was increased by 2.76-fold in patients with Z(va) > or =4.5 mm Hg x ml(-1) x m(2) and by 2.30-fold in those with a Z(va) between 3.5 and 4.5 mm Hg x ml(-1) x m(2) after adjusting for other risk factors and type of treatment (surgical vs. medical).

CONCLUSIONS

Increased Z(va) is a marker of excessive LV hemodynamic load, and a value >3.5 successfully identifies patients with a poor outcome. These findings suggest that beyond standard indexes of stenosis severity, the consideration of Z(va) may be useful to improve risk stratification and clinical decision making in patients with AS.

Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction: implications for diagnosis and treatment

Paradoxical low flow, low gradient, severe aortic stenosis (AS) despite preserved ejection fraction is a recently described clinical entity whereby patients with severe AS on the basis of aortic valve area have a lower than expected gradient in relation to generally accepted values. This mode of presentation of severe AS is relatively frequent (up to 35% of cases) and such patients have a cluster of findings, indicating that they are at a more advanced stage of their disease and have a poorer prognosis if treated medically rather than surgically. Yet, a majority of these patients do not undergo surgery likely due to the fact that the reduced gradient is conducive to an underestimation of the severity of the disease and/or of symptoms. The purpose of this article is to review and further analyse the distinguishing characteristics of this entity and to present its implications with regards to currently accepted guidelines for AS severity.

Impact of myocardial fibrosis in patients with symptomatic severe aortic stenosis

BACKGROUND

In this prospective follow-up study, the effect of myocardial fibrosis on myocardial performance in symptomatic severe aortic stenosis was investigated, and the impact of fibrosis on clinical outcome after aortic valve replacement (AVR) was estimated.

METHODS AND RESULTS

Fifty-eight consecutive patients with isolated symptomatic severe aortic stenosis underwent extensive baseline characterization before AVR. Standard and tissue Doppler echocardiography and cardiac magnetic resonance imaging (late-enhancement imaging for replacement fibrosis) were performed at baseline and 9 months after AVR. Endomyocardial biopsies were obtained intraoperatively to determine the degree of myocardial fibrosis. Patients were analyzed according to the severity of interstitial fibrosis in cardiac biopsies (severe, n=21; mild, n=15; none, n=22). The extent of histologically determined cardiac fibrosis at baseline correlated closely with New York Heart Association functional class and markers of longitudinal systolic function (all P<0.001) but not global ejection fraction or aortic valve area. Nine months after AVR, the degree of late enhancement remained unchanged, implying that AVR failed to reduce the degree of replacement fibrosis. Patients with no fibrosis experienced a marked improvement in New York Heart Association class from 2.8+/-0.4 to 1.4+/-0.5 (P<0.001). Only parameters of longitudinal systolic function predicted this functional improvement. Four patients with severe fibrosis died during follow-up, but no patient from the other groups died.

CONCLUSIONS

Myocardial fibrosis is an important morphological substrate of postoperative clinical outcome in patients with severe aortic stenosis and was not reversible after AVR over the 9 months of follow-up examined in this study. Because markers of longitudinal systolic function appear to indicate sensitively both the severity of myocardial fibrosis and the clinical outcome, they may prove valuable for preoperative risk assessment in patients with aortic stenosis.

New concepts in valvular hemodynamics: implications for diagnosis and treatment of aortic stenosis

Aortic valve stenosis (AS) is the third-most frequent heart disease after coronary artery disease and arterial hypertension, and it is associated with a high incidence of adverse outcomes. Recent data support the notion that AS is not an isolated disease uniquely limited to the valve. Indeed, AS is frequently associated with abnormalities of the systemic arterial system, and, in particular, with reduced arterial compliance, which may have important consequences for the pathophysiology and clinical outcome of this disease. Moreover, AS may also be associated with left ventricular systolic dysfunction and reduced transvalvular flow rate, which pose important challenges with regards to diagnostic evaluation and clinical decision making in AS patients. Hence, the assessment of AS severity, as well as its therapeutic management, should be conducted with the use of a comprehensive evaluation that includes not only the aortic valve, but also the systemic arterial system and the left ventricle because these three entities are tightly coupled from both a pathophysiological and a hemodynamic standpoint.

Risk Score for Predicting Outcome in Patients With Asymptomatic Aortic Stenosis

Background— The management of patients with asymptomatic severe aortic stenosis remains controversial. We sought to develop a continuous risk score for predicting the midterm development of symptoms or adverse events in this setting.

Methods and Results— We prospectively followed 107 patients with asymptomatic aortic stenosis (aged 72 years [63 to 77]; 35 women; aortic-jet velocity, 4.1 m/s [3.5 to 4.4]) at a single center in France. Predefined end points for assessing outcome were the occurrence within 24 months of death or aortic valve replacement necessitated by symptoms or by a positive exercise test. Variables independently associated with outcome were used to build a score that was validated in an independent cohort of 107 patients from Belgium. Independent predictors of outcome were female sex, peak aortic-jet velocity, and B-type natriuretic peptide at baseline. Accordingly, the score could be calculated as follows: Score=[peak velocity (m/s)×2]+(natural logarithm of B-type natriuretic peptide×1.5)+1.5 (if female sex). Event-free survival after 20 months was 80% for patients within the first score quartile compared with only 7% for the fourth quartile. Areas under the receiver operating characteristic curve for the score were 0.90 and 0.89 in the development and validation cohorts, respectively.

Conclusions— If further validation is achieved, this score may be useful to predict outcome in individual patients with asymptomatic aortic stenosis to select those who might benefit from early surgery.

Hemodynamic energy dissipation in the cardiovascular system: generalized theoretical analysis on disease states

BACKGROUND

We present a fundamental theoretical framework for analysis of energy dissipation in any component of the circulatory system and formulate the full energy budget for both venous and arterial circulations. New indices allowing disease-specific subject-to-subject comparisons and disease-to-disease hemodynamic evaluation (quantifying the hemodynamic severity of one vascular disease type to the other) are presented based on this formalism.

METHODS AND RESULTS

Dimensional analysis of energy dissipation rate with respect to the human circulation shows that the rate of energy dissipation is inversely proportional to the square of the patient body surface area and directly proportional to the cube of cardiac output. This result verified the established formulae for energy loss in aortic stenosis that was solely derived through empirical clinical experience. Three new indices are introduced to evaluate more complex disease states: (1) circulation energy dissipation index (CEDI), (2) aortic valve energy dissipation index (AV-EDI), and (3) total cavopulmonary connection energy dissipation index (TCPC-EDI). CEDI is based on the full energy budget of the circulation and is the proper measure of the work performed by the ventricle relative to the net energy spent in overcoming frictional forces. It is shown to be 4.01+/-0.16 for healthy individuals and above 7.0 for patients with severe aortic stenosis. Application of CEDI index on single-ventricle venous physiology reveals that the surgically created Fontan circulation, which is indeed palliative, progressively degrades in hemodynamic efficiency with growth (p<0.001), with the net dissipation in a typical Fontan patient (Body surface area=1.0 m(2)) being equivalent to that of an average case of severe aortic stenosis. AV-EDI is shown to be the proper index to gauge the hemodynamic severity of stenosed aortic valves as it accurately reflects energy loss. It is about 0.28+/-0.12 for healthy human valves. Moderate aortic stenosis has an AV-EDI one order of magnitude higher while clinically severe aortic stenosis cases always had magnitudes above 3.0. TCPC-EDI represents the efficiency of the TCPC connection and is shown to be negatively correlated to the size of a typical "bottle-neck" region (pulmonary artery) in the surgical TCPC pathway (p<0.05).

CONCLUSIONS

Energy dissipation in the human circulation has been analyzed theoretically to derive the proper scaling (indexing) factor. CEDI, AV-EDI, and TCPC-EDI are proper measures of the dissipative characteristics of the circulatory system, aortic valve, and the Fontan connection, respectively.

Survival benefit of aortic valve replacement in patients with severe aortic stenosis with low ejection fraction and low gradient with normal ejection fraction

BACKGROUND

Aortic stenosis (AS) is becoming increasingly common with the aging population. Many of these patients have reduced left ventricular (LV) ejection fractions (EF) or low transvalvular gradients resulting in reluctance to offer aortic valve replacement (AVR).

METHODS

Our echocardiographic database for the period of 1993 to 2003 was screened for severe AS (aortic valve area [AVA]

RESULTS

Of the 740 patients with severe AS, 194 (26%) had severe LV dysfunction defined as EF 0.35 or less and 168 (23%) a mean transvalvular gradient of 30 mm Hg or less. Low ejection fraction was not a prerequisite for a low gradient. The Univariate predictors of higher mortality in both groups included higher age, lower ejection fraction, renal insufficiency, and lack of aortic valve replacement. Lack of aortic valve replacement was a strong predictor of mortality after adjusting for 18 clinical, echocardiographic, and pharmacologic variables. There were 72 patients with EF 0.20 or less, of whom 18 had AVR, which was associated with a large survival benefit similar to the entire cohort. In the 52 patients with EF 0.55 or less and mean gradient less than 30 mm Hg, the 5-year survival with AVR was 90% compared with 20% without AVR (p < 0.0001) which was supported by propensity score analysis as well.

CONCLUSIONS

Severe LV dysfunction or a low transvalvular gradient is seen in about a quarter of patients with severe AS and there is a reluctance to offer AVR in these patients. Aortic valve replacement is associated with a large mortality benefit in these patients.

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MESH Headings

• Aged
• Aged, 80 and over
• Aortic Valve Stenosis/diagnostic imaging
• Aortic Valve Stenosis/mortality
• Aortic Valve Stenosis/surgery
• Blood Vessel Prosthesis
• Blood Vessel Prosthesis Implantation/methods
• Blood Vessel Prosthesis Implantation/mortality
• Cohort Studies
• Echocardiography, Doppler
• Female
• Follow-Up Studies
• Humans
• Male
• Middle Aged
• Probability
• Proportional Hazards Models
• Reference Values
• Retrospective Studies
• Risk Assessment
• Severity of Illness Index
• Stroke Volume/physiology
• Survival Analysis
• Treatment Outcome
• Ventricular Dysfunction, Left/diagnosis
• Ventricular Dysfunction, Left/mortality

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Affiliation(s)

Ramdas G Pai Division of Cardiology, Loma Linda University Medical Center, Loma Linda, California, USA
Padmini Varadarajan
Anees Razzouk

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