Two-Dimensional Strain for the Assessment of Left Ventricular Function in Low Flow–Low Gradient Aortic Stenosis, Relationship to Hemodynamics, and Outcome

Impact of Stress Echocardiography on Aortic Valve Stenosis Management

Rest and stress echocardiography (SE) play a fundamental role in the evaluation of aortic valve stenosis (AS). According to the current guidelines for the echocardiographic evaluation of patients with aortic stenosis, four broad categories can be defined: high-gradient AS (mean gradient ≥ 40 mmHg, peak velocity ≥ 4 m/s, aortic valve area (AVA) ≤ 1 cm2 or indexed AVA ≤ 0.6 cm2/m2); low-flow, low-gradient AS with reduced ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, left ventricle ejection fraction (LVEF) < 50%, stroke volume index (Svi) ≤ 35 mL/m2); low-flow, low-gradient AS with preserved ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, LVEF ≥ 50%, SVi ≤ 35 mL/m2); and normal-flow, low-gradient AS with preserved ejection fraction (mean gradient < 40 mmHg, AVA ≤ 1 cm2, indexed AVA ≤ 0.6 cm2/m2, LVEF ≥ 50%, SVi > 35 mL/m2). Aortic valve replacement (AVR) is indicated with the onset of symptoms development or LVEF reduction. However, there is often mismatch between resting transthoracic echocardiography findings and patient's symptoms. In these discordant cases, SE and CT calcium scoring are among the indicated methods to guide the management decision making. Additionally, due to the increasing evidence that in asymptomatic severe aortic stenosis an early AVR instead of conservative treatment is associated with better outcomes, SE can help identify those that would benefit from an early AVR by revealing markers of poor prognosis. Low-flow, low-gradient AS represents a challenge both in diagnosis and in therapeutic management. Low-dose dobutamine SE is the recommended method to distinguish true-severe from pseudo-severe stenosis and assess the existence of flow (contractile) reserve to appropriately guide the need for intervention in these patients.

Position Statement on the Use of Myocardial Strain in Cardiology Routines by the Brazilian Society of Cardiology's Department Of Cardiovascular Imaging - 2023

Central Illustration : Position Statement on the Use of Myocardial Strain in Cardiology Routines by the Brazilian Society of Cardiology's Department Of Cardiovascular Imaging - 2023 Proposal for including strain in the integrated diastolic function assessment algorithm, adapted from Nagueh et al.67 Am: mitral A-wave duration; Ap: reverse pulmonary A-wave duration; DD: diastolic dysfunction; LA: left atrium; LASr: LA strain reserve; LVGLS: left ventricular global longitudinal strain; TI: tricuspid insufficiency. Confirm concentric remodeling with LVGLS. In LVEF, mitral E wave deceleration time < 160 ms and pulmonary S-wave < D-wave are also parameters of increased filling pressure. This algorithm does not apply to patients with atrial fibrillation (AF), mitral annulus calcification, > mild mitral valve disease, left bundle branch block, paced rhythm, prosthetic valves, or severe primary pulmonary hypertension.

Clinical Value of Stress Transaortic Flow Rate During Dobutamine Echocardiography in Reduced Left Ventricular Ejection Fraction, Low-Gradient Aortic Stenosis: A Multicenter Study

BACKGROUND

Low rest transaortic flow rate (FR) has been shown previously to predict mortality in low-gradient aortic stenosis. However limited prognostic data exists on stress FR during low-dose dobutamine stress echocardiography. We aimed to assess the value of stress FR for the detection of aortic valve stenosis (AS) severity and the prediction of mortality.

METHODS

This is a multicenter cohort study of patients with reduced left ventricular ejection fraction and low-gradient aortic stenosis (aortic valve area <1 cm² and mean gradient <40 mm Hg) who underwent low-dose dobutamine stress echocardiography to identify the AS severity and presence of flow reserve. The outcome assessed was all-cause mortality.

RESULTS

Of the 287 patients (mean age, 75±10 years; males, 71%; left ventricular ejection fraction, 31±10%) over a mean follow-up of 24±30 months there were 127 (44.3%) deaths and 147 (51.2%) patients underwent aortic valve intervention. Higher stress FR was independently associated with reduced risk of mortality (hazard ratio, 0.97 [95% CI, 0.94-0.99]; P=0.01) after adjusting for age, chronic kidney disease, heart failure symptoms, aortic valve intervention, and rest left ventricular ejection fraction. The minimum cutoff for prediction of mortality was stress FR 210 mL/s. Following adjustment to the same important clinical and echocardiographic parameters, among the three criteria of AS severity during stress, ie, the guideline definition of aortic valve area <1cm² and aortic valve mean gradient ≥40 mm Hg, or aortic valve mean gradient ≥40 mm Hg, or the novel definition of aortic valve area <1 cm² at stress FR ≥210 mL/s, only the latter was independently associated with mortality (hazard ratio, 1.72 [95% CI, 1.05-2.82]; P=0.03). Furthermore aortic valve area <1cm² at stress FR ≥210 mL/s was the only severe aortic stenosis criterion that was associated with improved outcome following aortic valve intervention (P<0.001). Guideline-defined stroke volume flow reserve did not predict mortality.

CONCLUSIONS

Stress FR during low-dose dobutamine stress echocardiography was useful for the detection of both AS severity and flow reserve and was associated with improved prediction of outcome following aortic valve intervention.

Reduced Left Ventricular Global Longitudinal Strain Predicts Prolonged Hospitalization: A Cohort Analysis of Patients Having Aortic Valve Replacement Surgery

BACKGROUND

Left ventricular ejection fraction (LVEF) is often preserved in patients with aortic stenosis and thus cannot distinguish between normal myocardial contractile function and subclinical dysfunction. Global longitudinal strain and strain rate (SR), which measure myocardial deformation, are robust indicators of myocardial function and can detect subtle myocardial dysfunction that is not apparent with conventional echocardiographic measures. Strain and SR may better predict postoperative outcomes than LVEF. The primary aim of our investigation was to assess the association between global longitudinal strain and serious postoperative outcomes in patients with aortic stenosis having aortic valve replacement. Secondarily, we also assessed the associations between global longitudinal SR and LVEF and the outcomes.

METHODS

In this post hoc analysis of data from a randomized clinical trial (NCT01187329), we examined the association between measures of myocardial function and the following outcomes: (1) need for postoperative inotropic/vasopressor support; (2) prolonged hospitalization (>7 days); and (3) postoperative atrial fibrillation. Standardized transesophageal echocardiographic examinations were performed after anesthetic induction. Myocardial deformation was measured using speckle-tracking echocardiography. Multivariable logistic regression was used to assess associations between measures of myocardial function and outcomes, adjusted for potential confounding factors. The predictive ability of global longitudinal strain, SR, and LVEF was assessed as area under receiver operating characteristics curves (AUCs).

RESULTS

Of 100 patients enrolled in the clinical trial, 86 patients with aortic stenosis had acceptable images for global longitudinal strain analysis. Primarily, worse intraoperative global longitudinal strain was associated with prolonged hospitalization (odds ratio [98.3% confidence interval], 1.22 [1.01-1.47] per 1% decrease [absolute value] in strain; P = .012), but not with other outcomes. Secondarily, worse global longitudinal SR was associated with prolonged hospitalization (odds ratio [99.7% confidence interval], 1.68 [1.01-2.79] per 0.1 second(-1) decrease [absolute value] in SR; P = .003), but not other outcomes. LVEF was not associated with any outcomes. Global longitudinal SR was the best predictor for prolonged hospitalization (AUC, 0.72), followed by global longitudinal strain (AUC, 0.67) and LVEF (AUC, 0.62).

CONCLUSIONS

Global longitudinal strain and SR are useful predictors of prolonged hospitalization in patients with aortic stenosis having an aortic valve replacement.

Hemodynamic Changes During Physiological and Pharmacological Stress Testing in Healthy Subjects, Aortic Stenosis and Aortic Coarctation Patients-A Systematic Review and Meta-Analysis

Introduction: Exercise testing has become a diagnostic standard in the evaluation and management of heart disease. While different methods of exercise and pharmacological stress testing exist, only little is known about their comparability. We aimed to assess hemodynamic changes during dynamic exercise, isometric exercise, and dobutamine stress testing at different stress intensities in healthy subjects and patients with aortic stenosis (AS) and aortic coarctation (CoA).

Methods: A systematic literature search (PROSPERO 2017:CRD42017078608) in MEDLINE of interventional trials was conducted to identify eligible studies providing evidence of changes in hemodynamic parameters under different stress conditions acquired by MRI or echocardiography. A random effects model was used to estimate pooled mean changes in hemodynamics.

Results: One hundred and twenty-eight study arms with a total of 3,139 stress-examinations were included. In healthy subjects/(where available) in AS, pooled mean changes (95% CIs) during light dynamic stress were 31.78 (27.82–35.74) bpm in heart rate (HR) and 6.59 (2.58–10.61) ml in stroke volume (SV). Changes during light pharmacological stress were 13.71 (7.87–19.56)/14.0 (9.82–18.18) bpm in HR, and 5.47 (0.3–10.63)/8.0 (3.82–12.18) ml in SV. Changes during light isometric stress were 18.44 (10.74–26.14)/5.0 (−1.17–11.17) bpm in HR and −4.17 (−14.37–6.03)/−4.0 (−16.43–8.43) ml in SV. Changes during moderate dynamic stress were 49.57 (40.03–59.1)/46.45 (42.63–50.27) bpm in HR and 11.64 (5.87–17.42) ml in SV. During moderate pharmacological stress, changes in HR were 42.83 (36.94–48.72)/18.66 (2.38–34.93) bpm and in SV 6.29 (−2.0–14.58)/13.11 (7.99–18.23) ml. During high intensity dynamic stress changes in HR were 89.31 (81.46–97.17)/55.32 (47.31–63.33) bpm and in SV 21.31 (13.42–29.21)/−0.96 (−5.27–3.35) ml. During high pharmacological stress, changes in HR were 53.58 (36.53–70.64)/42.52 (32.77–52.28) bpm, and in SV 0.98 (−9.32–11.27)/14.06 (−1.62–29.74) ml. HR increase and age were inversely correlated at high stress intensities. In CoA, evidence was limited to single studies.

Conclusion: This systematic review and meta-analysis presents pooled hemodynamic changes under light, moderate and high intensity exercise and pharmacological stress, while considering the potential influence of age. Despite limited availability of comparative studies, the reference values presented in this review allow estimation of the expected individual range of a circulatory response in healthy individuals and patients with AS and may contribute to future study planning and patient-specific models even when stress testing is contraindicated.

Latent myopathy is more pronounced in patients with low flow versus normal flow aortic stenosis with normal left ventricular ejection fraction who are undergoing surgical aortic valve replacement: Multicenter study with a brief review of the literature

BACKGROUND

Midwall fibrosis and low stroke volume are independent predictors of mortality in severe aortic stenosis (AS) with preserved LV ejection fraction (LVEF). The role of speckle tracking echocardiography (STE) to identify latent myopathy pre- and post- aortic valve replacement (AVR) in high risk AS patients with normal LVEF is limited.

METHODS

Demographic, 2D echocardiographic, and STE data were analyzed in patients with severe AS and preserved LVEF who underwent tissue AVR. Velocity vector imaging (VVI) was used to assess regional and global peak systolic longitudinal strain (GLS). Low flow (LF) was defined as an indexed LV stroke volume <35 mL/m² .

RESULTS

Between December 2008 and May 2011, 37 patients (75 ± 9 years, 51% male) had both pre- and post-AVR echos within 6.6 ± 6.5 months (median = 4 months; range = 2.5-9.5) of surgery. Compared with pre-AVR, GLS (-6.9 ± 4.9% vs -11.1 ± 4.1%; P < .001) and strain rate (-0.72 ± 0.3s^-1 vs -0.87 ± 0.3s^-1 ; P = .01) improved post-AVR. Pre-AVR mid-segments showed a similar myopathy as the basal segments (-9.5 ± 4.3% vs -9.0 ± 4.2%;P = .3). The 16 (43%) LF patients in this study had lower pre- and post-AVR strain compared to NF patients (GLS Pre-AVR:LF vs NF: -5.1 ± 4.1% vs -8.4 ± 4.9% (P = .04) and GLS Post-AVR:LF vs NF: -9.2 ± 3.7% vs -12.5 ± 3.9% (P = .01)). However, there was no difference in absolute and %change improvement in GLS post-AVR (LF vs NF:∆ -4.2 ± 3.5% vs ∆-4.1 ± 5.3% (P = .90) and 193 ± 214% vs 143 ± 230% change (P = .5)). The lowest GLS was seen in LF/HG AS followed by LF/LG, NF/LG and NF/HG AS; P = .03.

CONCLUSIONS

Latent myopathy is more pronounced in LF AS both pre- and post-AVR. Our study provides evidence of improvement in myopathy in LF AS despite a persistent worse myopathy compared to NF patients post-AVR.

Impact of Right Ventricular Performance in Patients Undergoing Extracorporeal Membrane Oxygenation Following Cardiac Surgery

BACKGROUND

Extracorporeal membrane oxygenation following cardiac surgery safeguards end-organ oxygenation but unfavorably alters cardiac hemodynamics. Along with the detrimental effects of cardiac surgery to the right heart, this might impact outcome, particularly in patients with preexisting right ventricular (RV) dysfunction. We sought to determine the prognostic impact of RV function and to improve established risk-prediction models in this vulnerable patient cohort.

METHODS AND RESULTS

Of 240 patients undergoing extracorporeal membrane oxygenation support following cardiac surgery, 111 had echocardiographic examinations at our institution before implantation of extracorporeal membrane oxygenation and were thus included. Median age was 67 years (interquartile range 60-74), and 74 patients were male. During a median follow-up of 27 months (interquartile range 16-63), 75 patients died. Fifty-one patients died within 30 days, 75 during long-term follow-up (median follow-up 27 months, minimum 5 months, maximum 125 months). Metrics of RV function were the strongest predictors of outcome, even stronger than left ventricular function (P<0.001 for receiver operating characteristics comparisons). Specifically, RV free-wall strain was a powerful predictor univariately and after adjustment for clinical variables, Simplified Acute Physiology Score-3, tricuspid regurgitation, surgery type and duration with adjusted hazard ratios of 0.41 (95%CI 0.24-0.68; P=0.001) for 30-day mortality and 0.48 (95%CI 0.33-0.71; P<0.001) for long-term mortality for a 1-SD (SD=-6%) change in RV free-wall strain. Combined assessment of the additive EuroSCORE and RV free-wall strain improved risk classification by a net reclassification improvement of 57% for 30-day mortality (P=0.01) and 56% for long-term mortality (P=0.02) compared with the additive EuroSCORE alone.

CONCLUSIONS

RV function is strongly linked to mortality, even after adjustment for baseline variables and clinical risk scores. RV performance improves established risk prediction models for short- and long-term mortality.

Early Left and Right Ventricular Response to Aortic Valve Replacement

BACKGROUND

The immediate effect of aortic valve replacement (AVR) for aortic stenosis on perioperative myocardial function is unclear. Left ventricular (LV) function may be impaired by cardioplegia-induced myocardial arrest and ischemia-reperfusion injury, especially in patients with LV hypertrophy. Alternatively, LV function may improve when afterload is reduced after AVR. The right ventricle (RV), however, experiences cardioplegic arrest without benefiting from improved loading conditions. Which of these effects on myocardial function dominate in patients undergoing AVR for aortic stenosis has not been thoroughly explored. Our primary objective is thus to characterize the effect of intraoperative events on LV function during AVR using echocardiographic measures of myocardial deformation. Second, we evaluated RV function.

METHODS

In this supplementary analysis of 100 patients enrolled in a clinical trial (NCT01187329), 97 patients underwent AVR for aortic stenosis. Of these patients, 95 had a standardized intraoperative transesophageal echocardiographic examination of systolic and diastolic function performed before surgical incision and repeated after chest closure. Echocardiographic images were analyzed off-line for global longitudinal myocardial strain and strain rate using 2D speckle-tracking echocardiography. Myocardial deformation assessed at the beginning of surgery was compared with the end of surgery using paired t tests corrected for multiple comparisons.

RESULTS

LV volumes and arterial blood pressure decreased, and heart rate increased at the end of surgery. Echocardiographic images were acceptable for analysis in 72 patients for LV strain, 67 for LV strain rate, and 54 for RV strain and strain rate. In 72 patients with LV strain images, 9 patients required epinephrine, 22 required norepinephrine, and 2 required both at the end of surgery. LV strain did not change at the end of surgery compared with the beginning of surgery (difference: 0.7 [97.6% confidence interval, -0.2 to 1.5]%; P = 0.07), whereas LV systolic strain rate improved (became more negative) (-0.3 [-0.4 to -0.2] s; P < 0.001). In contrast, RV systolic strain worsened (became less negative) at the end of surgery (difference: 4.6 [3.1 to 6.0]%; P < 0.001) although RV systolic strain rate was unchanged (0.0 [97.6% confidence interval, -0.1 to 0.1]; P = 0.83).

CONCLUSIONS

LV function improved after replacement of a stenotic aortic valve demonstrated by improved longitudinal strain rate. In contrast, RV function, assessed by longitudinal strain, was reduced.

Incremental Prognostic Use of Left Ventricular Global Longitudinal Strain in Asymptomatic/Minimally Symptomatic Patients With Severe Bioprosthetic Aortic Stenosis Undergoing Redo Aortic Valve Replacement

BACKGROUND

With improved survival of patients undergoing primary bioprosthetic aortic valve replacement (AVR), reoperation to relieve severe prosthetic aortic stenosis (PAS) is increasing. Timing of redo surgery in asymptomatic/minimally symptomatic patients remains controversial. Left ventricular (LV) global longitudinal strain (GLS) is a marker of subclinical LV dysfunction. In asymptomatic/minimally symptomatic patients with severe PAS undergoing redo AVR, we sought to determine whether LV-GLS provides incremental prognostic use.

METHODS AND RESULTS

We studied 191 patients with severe bioprosthetic PAS (63±16 years, 58% men) who underwent redo AVR between 2000 and 2012 (excluding mechanical PAS, severe other valve disease transcatheter AVR, and LV ejection fraction <50%). Society of Thoracic Surgeons score was calculated. Standard echocardiography data were obtained. LV-GLS was measured on 2-, 3-, and 4-chamber views using velocity vector imaging. Severe PAS was defined as aortic valve area <0.8 cm², mean aortic valve gradient ≥40 mm Hg, and dimensionless index <0.25. A composite outcome of death and congestive heart failure admission was recorded. At baseline, mean Society of Thoracic Surgeons score, LV ejection fraction, mean aortic valve gradients, and right ventricular systolic pressure were 7±6, 58±6%, 54±10 mm Hg and 40±14 mm Hg, whereas 50% had >2+ aortic regurgitation. Median LV-GLS was -14.2% (-11.4, -17.1%). At 4.2±3 years, 41 (22%) patients met the composite end point (2.5% deaths and 1% strokes at 30 days postoperatively). On multivariable Cox survival analysis, LV-GLS was independently associated with longer-term composite events (hazard ratio, 1.21; 95% confidence interval, 1.10-1.33), P<0.01. The C statistic for the clinical model (Society of Thoracic Surgeons score, degree of aortic regurgitation, and right ventricular systolic pressure) was 0.64 (95% confidence interval 0.54-0.79), P<0.001. Addition of LV-GLS to the clinical model increased the C statistic significantly to 0.71 (95% confidence interval 0.58-0.81), P<0.001.

CONCLUSIONS

In asymptomatic/minimally symptomatic patients with severe bioprosthetic PAS undergoing redo AVR, baseline LV-GLS provides incremental prognostic use over established predictors and could potentially aid in surgical timing and risk stratification.

ANMCO/SIC/SICI-GISE/SICCH Executive Summary of Consensus Document on Risk Stratification in elderly patients with aortic stenosis before surgery or transcatheter aortic valve replacement

Aortic stenosis is one of the most frequent valvular diseases in developed countries, and its impact on public health resources and assistance is increasing. A substantial proportion of elderly people with severe aortic stenosis is not eligible to surgery because of the advanced age, frailty, and multiple co-morbidities. Transcatheter aortic valve implantation (TAVI) enables the treatment of very elderly patients at high or prohibitive surgical risk considered ineligible for surgery and with an acceptable life expectancy. However, a significant percentage of patients die or show no improvement in quality of life (QOL) in the follow-up. In the decision-making process, it is important to determine: (i) whether and how much frailty of the patient influences the risk of procedures; (ii) how the QOL and the individual patient's survival are influenced by aortic valve disease or from other associated conditions; and (iii) whether a geriatric specialist intervention to evaluate and correct frailty or other diseases with their potential or already manifest disabilities can improve the outcome of surgery or TAVI. Consequently, in addition to risk stratification with conventional tools, a number of factors including multi-morbidity, disability, frailty, and cognitive function should be considered, in order to assess the expected benefit of both surgery and TAVI. The pre-operative optimization through a multidisciplinary approach with a Heart Team can counteract the multiple damage (cardiac, neurological, muscular, respiratory, and kidney) that can potentially aggravate the reduced physiological reserves characteristic of frailty. The systematic application in clinical practice of multidimensional assessment instruments of frailty and cognitive function in the screening and the adoption of specific care pathways should facilitate this task.

Advanced imaging in valvular heart disease

Although echocardiography remains the mainstay imaging technique for the evaluation of patients with valvular heart disease (VHD), innovations in noninvasive imaging in the past few years have provided new insights into the pathophysiology and quantification of VHD, early detection of left ventricular (LV) dysfunction, and advanced prognostic assessment. The severity grading of valve dysfunction has been refined with the use of Doppler echocardiography, cardiac magnetic resonance (CMR), and CT imaging. LV ejection fraction remains an important criterion when deciding whether patients should be referred for surgery. However, echocardiographic strain imaging can now detect impaired LV systolic function before LV ejection fraction reduces, thus provoking the debate on whether patients with severe VHD should be referred for surgery at an earlier stage (before symptom onset). Impaired LV strain correlates with the amount of myocardial fibrosis detected with CMR techniques. Furthermore, accumulating data show that the extent of fibrosis associated with severe VHD has important prognostic implications. The present Review focuses on using these novel imaging modalities to assess pathophysiology, early LV dysfunction, and prognosis of major VHDs, including aortic stenosis, mitral regurgitation, and aortic regurgitation.

Calcific aortic stenosis

Calcific aortic stenosis (AS) is the most prevalent heart valve disorder in developed countries. It is characterized by progressive fibro-calcific remodelling and thickening of the aortic valve leaflets that, over years, evolve to cause severe obstruction to cardiac outflow. In developed countries, AS is the third-most frequent cardiovascular disease after coronary artery disease and systemic arterial hypertension, with a prevalence of 0.4% in the general population and 1.7% in the population >65 years old. Congenital abnormality (bicuspid valve) and older age are powerful risk factors for calcific AS. Metabolic syndrome and an elevated plasma level of lipoprotein(a) have also been associated with increased risk of calcific AS. The pathobiology of calcific AS is complex and involves genetic factors, lipoprotein deposition and oxidation, chronic inflammation, osteoblastic transition of cardiac valve interstitial cells and active leaflet calcification. Although no pharmacotherapy has proved to be effective in reducing the progression of AS, promising therapeutic targets include lipoprotein(a), the renin-angiotensin system, receptor activator of NF-κB ligand (RANKL; also known as TNFSF11) and ectonucleotidases. Currently, aortic valve replacement (AVR) remains the only effective treatment for severe AS. The diagnosis and staging of AS are based on the assessment of stenosis severity and left ventricular systolic function by Doppler echocardiography, and the presence of symptoms. The introduction of transcatheter AVR in the past decade has been a transformative therapeutic innovation for patients at high or prohibitive risk for surgical valve replacement, and this new technology might extend to lower-risk patients in the near future.

Paradoxical low-flow aortic stenosis is defined by increased ventricular hydraulic load and reduced longitudinal strain

AIMS

Patients with paradoxical low-flow severe aortic stenosis (PLF-AS) reportedly have higher left ventricular hydraulic load and more systolic strain dysfunction than patients with normal-flow aortic stenosis. This study investigates the relationship of systolic loading and strain to PLF-AS to further define its pathophysiology.

METHODS

One hundred and twenty patients (age 79 ± 12 years, 37% men) with an indexed aortic valve area (AVAi) of 0.6 cm/m or less and an ejection fraction of 50% or higher were divided into two groups based on indexed stroke volume (SVi): PLF-AS, SVi ≤ 35 ml/m, N = 46; normal-flow aortic stenosis, SVi > 35 ml/m, N = 74). Valvular and arterial load were assessed using multiple measurements, and strain was assessed using speckle-tracking echocardiography.

RESULTS

Patients with PLF-AS were found to have more valvular load (lower AVAi, P = 0.028; lower energy loss coefficient, P = 0.001), more arterial load [decreased arterial compliance and increased systemic vascular resistance (SVR), both P < 0.001] and more total hydraulic load [increased valvuloarterial impedance (Zva), P < 0.001]. Transvalvular gradients and arterial pressures were similar. Longitudinal strain was lower in PLF-AS (P < 0.001), but circumferential and rotation strains were similar. On adjusted regression, AVAi, SVR and longitudinal strain were associated with PLF-AS [odds ratio (OR) = 1.34, P = 0.043; OR = 1.31, P = 0.004; OR = 1.34, P = 0.011, respectively]. When SVR and AVAi were replaced with Zva, longitudinal strain and Zva (OR = 1.38, P = 0.015; OR = 1.33, P < 0.001 for both, respectively) were associated with PLF-AS.

CONCLUSION

Increased hydraulic load, from more severe valvular stenosis and increased vascular resistance, and longitudinal strain impairment are associated with PLF-AS and their interplay is likely fundamental to its pathophysiology.

Left ventricular global longitudinal strain is associated with cardiovascular risk factors and arterial stiffness in chronic kidney disease

Background

Global longitudinal strain (GLS) has emerged as a superior method for detecting left ventricular (LV) systolic dysfunction compared to ejection fraction (EF) on the basis that it is less operator dependent and more reproducible. The 2-dimensional strain (2DS) method is easily measured and integrated into a standard echocardiogram. This study aimed to determine the relationship between GLS and traditional and chronic kidney disease (CKD)-related risk factors of cardiovascular disease (CVD) in patients with CKD.

Methods

A cross sectional study of patients with moderate CKD stages 3 and 4 (n = 136). Clinical characteristics, anthropometric, biochemical data including markers of inflammation [C-reactive protein (CRP)], uremic toxins [indoxyl sulphate (IS), p-cresyl sulphate (PCS)], and arterial stiffness [pulse wave velocity (PWV)] were measured. Inducible ischemia was detected using exercise stress echocardiogram. GLS was determined from 3 standard apical views using 2-dimensional speckle tracking and EF was measured using Simpson’s rule. Associations between GLS and traditional and CKD-related risk factors were explored using multivariate models.

Results

The study population parameters included: age 59.4 ± 9.8 years, 58 % male, estimated glomerular filtration rate (eGFR) 44.4 ± 10.1 ml/min/1.73 m², GLS −18.3 ± 3.6 % and EF 65.8 % ± 7.8 %. This study demonstrated that GLS correlated with diabetes (r = 0.21, p = 0.01), history of heart failure (r = 0.20, p = 0.01), free IS (r = 0.24, p = 0.005) free PCS (r = 0.23, p = 0.007), body mass index (BMI) (r = 0.28, p < 0.001), and PWV (r = 0.24, p = 0.009). Following adjustment for demographic, baseline co-morbidities and laboratory parameters,GLS was independently associated with free IS, BMI and arterial stiffness (R² for model = 0.30, p < 0.0001).

Conclusions

In the CKD cohort, LV systolic function assessed using GLS was associated with uremic toxins, obesity and arterial stiffness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0098-1) contains supplementary material, which is available to authorized users.

Stress-echocardiography is underused in clinical practice: a nationwide survey in Austria

BACKGROUND

The wide area of application, including coronary artery disease, valvular heart disease, or pulmonary hypertension makes stress echocardiography (SE) a powerful, cost-effective imaging modality in cardiology. The role of this technique in clinical practice in Austria is unknown.

METHODS

A nationwide survey included all departments for cardiology and/or internal medicine in the years 2008 and 2013. By electronic questionnaire demographics, indication for the test, the numbers of examined cases per year, operators, and various applied techniques of SE were interrogated and completed by telephone interviews.

RESULTS

Data could be obtained from all 117 departments. In the year 2007 in 58 (50%) and in 2012 57 (49%) departments SE was available in Austrian hospitals. More than 100 SEs per year were performed by only four (7%) units in the year 2007 and by five (8%) in 2012. Physical exercise, dobutamine, and dipyridamole SE were available in 27 (46%), 52 (90%), and six (10%) units in 2007, and in 15 (27%), 52 (91%), and five (9%) units in 2012, respectively. In 2007 41 (71%) and in 2012 26 (46%) echo-labs administered contrast agents during SE. Transesophageal SE and 3D-echo was performed in one (2%) and three (5%) units in 2007, and in six (10%) and four (7%) echo-labs in 2012.

CONCLUSIONS

This representative survey demonstrates the underuse of SE in clinical practice in Austria. Even in established application fields performance is low, examination frequencies as recommended by the cardiology societies are fulfilled only by a minority of institutions.

Left Ventricular Global Longitudinal Strain (GLS) Is a Superior Predictor of All-Cause and Cardiovascular Mortality When Compared to Ejection Fraction in Advanced Chronic Kidney Disease

Background

Echocardiographic global longitudinal strain (GLS) is increasingly recognised as a more effective technique than conventional ejection fraction (EF) in detecting subtle changes in left ventricular (LV) function. This study investigated the prognostic value of GLS over EF in patients with advanced Chronic Kidney Disease (CKD).

Methods

The study included 183 patients (57% male, 63% on dialysis) with CKD stage 4, 5 and 5Dialysis (D). 112 (61%) of patients died in a follow up of 7.8 ± 4.4 years and 41% of deaths were due to cardiovascular (CV) disease. GLS was calculated using 2-dimensional speckle tracking and EF was measured using Simpson’s biplane method. Cox proportional hazard models were used to assess the association of measures of LV function and all- cause and CV mortality.

Results

The mean GLS at baseline was -13.6 ± 4.3% and EF was 45 ± 11%. GLS was a significant predictor of all-cause [Hazard Ratio (HR) 1.09 95%; Confidence Interval (CI) 1.02–1.16; p = 0.01] and CV mortality (HR 1.16 95%; CI 1.04–1.30; p = 0.008) following adjustment for relevant clinical variables including LV mass index (LVMI) and EF. GLS also had greater predictive power for both all- cause and CV mortality compared to EF. Impaired GLS (>-16%) was associated with a 5.6-fold increased unadjusted risk of CV mortality in patients with preserved EF.

Conclusions

In this cohort of patients with advanced CKD, GLS is a more sensitive predictor of overall and CV mortality compared to EF. Studies of larger populations in CKD are required to confirm that GLS provides additive prognostic value in patients with preserved EF.

The left ventricle in aortic stenosis--imaging assessment and clinical implications

Aortic stenosis has an increasing prevalence in the context of aging population. In these patients non-invasive imaging allows not only the grading of valve stenosis severity, but also the assessment of left ventricular function. These two goals play a key role in clinical decision-making. Although left ventricular ejection fraction is currently the only left ventricular function parameter that guides intervention, current imaging techniques are able to detect early changes in LV structure and function even in asymptomatic patients with significant aortic stenosis and preserved ejection fraction. Moreover, new imaging parameters emerged as predictors of disease progression in patients with aortic stenosis. Although proper standardization and confirmatory data from large prospective studies are needed, these novel parameters have the potential of becoming useful tools in guiding intervention in asymptomatic patients with aortic stenosis and stratify risk in symptomatic patients undergoing aortic valve replacement.

This review focuses on the mechanisms of transition from compensatory left ventricular hypertrophy to left ventricular dysfunction and heart failure in aortic stenosis and the role of non-invasive imaging assessment of the left ventricular geometry and function in these patients.

Low gradient aortic stenosis

OPINION STATEMENT

Severe low-gradient (LG) aortic stenosis (AS) [aortic valve area (AVA) ≤ 1.0 cm(2), mean pressure gradient (MG) < 40 mmHg] represents a frequently encountered and challenging clinical dilemma. A systematic approach, which often requires several imaging modalities, should be undertaken to confirm the hemodynamic findings and rule out measurement error. Low-flow conditions often account for the discrepancy and can be present whether the left ventricular ejection fraction (LVEF) is depressed or normal. In patients with classical low-flow (LF), LG AS in which LVEF is reduced (<40-50 %), dobutamine stress echocardiography (DSE) should be used to distinguish patients with true severe AS and pseudo-severe AS, as well as to evaluate for the presence of left ventricular contractile or flow reserve. Surgical or transcatheter aortic valve replacement (AVR) should likely be reserved for those patients with true severe AS. Patient outcome with medical or surgical management generally relates to patient functional capacity, stenosis severity, and left ventricular functional reserve. Patients with severe LG AS with preserved LVEF can have a stroke volume that is either normal (>35 mL/m(2)) or low (<35 mL/m(2)). New data suggest that DSE can identify pseudo-severe AS in up to 30 % of patients with severe LF-LG AS with preserved LVEF. AVR should likely be restricted to those patients with true severe AS, although there is currently little data to support this strategy. Symptomatic patients with severe LG AS with preserved LVEF, whether they have normal or low flow, should be offered AVR. Transcatheter AVR provides an alternative therapeutic option in the high-risk patient.

First report on intraoperative vector flow imaging of the heart among patients with healthy and diseased aortic valves

The vector velocity method Transverse Oscillation (TO) implemented on a conventional ultrasound (US) scanner (ProFocus, BK Medical, Herlev, Denmark) can provide real-time, angle-independent estimates of the cardiac blood flow. During cardiac surgery, epicardial US examination using TO was performed on (A) 3 patients with healthy aortic valve and (B) 3 patients with aortic valve stenosis. In group B, the systolic flow of the ascending aorta had higher velocities, was more aliased and chaotic. The jet narrowed to 44% of the lumen compared to 75% in group A and with a vector concentration, a measure of flow complexity, of 0.41 compared to 0.87 in group A. The two groups had similar secondary flow of the ascending aorta with an average rotation frequency of 4.8 Hz. Simultaneous measurements were obtained with spectral Doppler (SD) and a thermodilution technique (TD). The mean difference in peak systolic velocity compared to SD in group A was 22% and 45% in B, while the mean difference in volume flow compared to TD in group A was 30% and 32% in B. TO can potentially reveal new information of cardiac blood flow, and may become a valuable diagnostic tool in the evaluation of patients with cardiovascular diseases.

Strain Echocardiography and Myocardial Mechanics: From Basics to Clinical Applications

The aim of this review is to summarize the recent developments in strain imaging, an evolving technique – from tissue Doppler to 3D echocardiography – for resolving the complex left ventricular mechanics. Following a brief overview of the different used technique to extract myocardial deformation data, the authors summarize the role of the technique in the assessment of cardiac mechanics and its role in the clinical arena.

Echocardiographic Evaluation of Aortic Stenosis - Normal Flow and Low Flow Scenarios

The echocardiographic evaluation of the patient with aortic stenosis (AS) has evolved in recent years, beyond confirming the diagnosis and measuring the resting mean pressure gradient or valve area. New echocardiographic approaches have developed to address the clinical dilemmas related to discordant haemodynamic data, asymptomatic haemodynamically severe AS and low-flow, low-gradient AS in order to better evaluate the disease severity, enhance the risk stratification of patients and provide important prognostic information. This article reviews the echocardiographic evaluation of the AS patient and focuses on the echocardiographic assessment of the haemodynamic severity, the prediction of clinical outcome and the use of echocardiography to guide patient management in the presence of normal flow and low flow scenarios.

Emerging role of echocardiographic strain/strain rate imaging and twist in systolic function evaluation and operative procedure in patients with aortic stenosis

Systolic function of the left ventricle is vital for patients with aortic stenosis. Unfortunately, the most widely used clinical parameter, the left ventricular ejection fraction, is not sensitive enough, especially for patients with left ventricular hypertrophy. Echocardiographic strain/strain rate and twist are emerging parameters for left ventricular systolic and diastolic function evaluation. Aortic stenosis could reduce strain/strain rate while magnifying twist. Furthermore, strain/strain rate correlates well with the prognosis of patients with aortic stenosis. Most importantly the circumferential strain, strain rate and twist also play a role in differentiating cardiac compensation or decompensation. In any case, these parameters could normalize after successful surgical aortic valve replacement or transcatheter aortic valve replacement. Regardless of these advantages, clinical evidence is needed to ensure their usefulness.