Dependency of Cardiac Resynchronization Therapy on Myocardial Viability at the LV Lead Position

OBJECTIVES: This study sought to analyze the effectiveness of cardiac resynchronization therapy (CRT) related to the viability in the segment of left ventricular (LV) lead position defined by myocardial deformation imaging. Echocardiographic myocardial deformation analysis allows determination of LV lead position as well as extent of myocardial viability.

METHODS: Myocardial deformation imaging based on tracking of acoustic markers within 2-dimensional echo images (GE Ultrasound, GE Healthcare, Horton, Norway) was performed in 65 heart failure patients (54 ± 6 years of age, 41 men) before and 12 months after CRT implantation. In a 16-segment model, the LV lead position was defined based on the segmental strain curve with earliest peak strain, whereas the CRT system was programmed to pure LV pacing. Non-viability of a segment (transmural scar formation) was assumed if the peak systolic circumferential strain was >-11.1%.

RESULTS: In 47 patients, the LV lead was placed in a viable segment, and in 18 patients, it was placed in a nonviable segment. At 12-month follow-up there was greater decrease of LV end-diastolic volumes (58 ± 13 ml vs. 44 ± 12 ml, p = 0.0388) and greater increase of LV ejection fraction (11 ± 4% vs. 5 ± 4%, p = 0.0343) and peak oxygen consumption (2.5 ± 0.9 ml/kg/min vs. 1.7 ± 1.1 ml/kg/min, p = 0.0465) in the viable compared with the nonviable group. The change in LV ejection fraction and the reduction in LV end-diastolic volumes at follow-up correlated to an increasing peak systolic circumferential strain in the segment of the LV pacing lead (r = 0.61, p = 0.0274 and r = 0.64, p = 0.0412, respectively). Considering only patients with ischemic heart disease, differences between viable and nonviable LV lead position group were even greater.

CONCLUSIONS: Preserved viability in the segment of the CRT LV lead position results in greater LV reverse remodeling and functional benefit at 12-month follow-up. Deformation imaging allows analysis of viability in the LV lead segment.

PMID: 21492811

Aortic Root Geometry in Aortic Stenosis Patients (A SEAS Substudy)

OBJECTIVES: To report aortic root geometry by echocardiography in a large population of healthy, asymptomatic aortic stenosis (AS) patients in relation to current vendor-specified requirements for transcatheter aortic valve implantation (TAVI).

METHODS: Baseline data in 1481 patients with asymptomatic AS (mean age 67 years, 39% women) in the Simvastatin Ezetimibe in AS study were used. The inner aortic diameter was measured at four levels: annulus, sinus of Valsalva, sinotubular junction and supracoronary, and sinus height as the annulo-junctional distance. Analyses were based on vendor-specified requirements for the aortic root geometry for current available prostheses, CoreValve and Edwards-Sapien.

RESULTS: The ratio of sinus of Valsalva height to sinus width was 1:2. In multivariate linear regression analysis, larger sinus of Valsalva height was associated with older age, larger sinus of Valsalva diameter, lower ejection fraction and smaller supracoronary diameter (multiple R(2) = 0.19, P< 0.01). The required annulus diameter for implantation of CoreValve was met in 61.9%, and for the Edwards-Sapien prosthesis in 66.9%. Overall, annular dimension feasible for TAVI using any available prosthesis was found in 78.2% of patients and in 77.7% of patients also the required minimum sinus of Valsalva height was found. Comparing the group of patients who met TAVI requirements to those who did not, the latter included more women and patients with lower body height and weight and significantly smaller aortic root diameters (all P < 0.05).

CONCLUSIONS: Among AS patients in the SEAS study, 27% of women and 19% of men did not have aortic root geometry fulfilling current requirements for TAVI.

PMID: 21508001

Prognostic Implication of Stress Echocardiography in 6214 Hypertensive and 5328 Normotensive Patients

OBJECTIVES:  To compare the prognostic implication of stress echocardiography (SE) in a large cohort of hypertensive and normotensive patients with known or suspected coronary artery disease (CAD). The relative prognostic meaning of the SE result in hypertensive and normotensive patients remains to be addressed.

METHODS:  The study group was formed by 11 542 patients (6214 hypertensive patients; 5328 normotensive patients) who underwent exercise (n= 686), dobutamine (n= 2524), or dipyridamole (n= 8332) SE for evaluation of known (n= 4563) or suspected (n= 6979) CAD. Patients were followed up for a median of 25 months (1st quartile, 7; 3rd quartile, 57).

RESULTS: Ischaemia on SE (new wall motion abnormality) was detected in 3209 (28%) patients. During follow-up, 1587 events (924 deaths, 663 non-fatal infarctions) occurred. Patients (n= 2764) undergoing revascularization were censored. The annual event rate was 7.0% in hypertensive and 5.7% in normotensive patients (P = 0.02) with known CAD, and 3.7% in hypertensive and 2.4% in normotensive patients (P< 0.0001) with suspected CAD. Ischaemia on stress echo, resting wall motion abnormality (RWMA), age, male sex, and diabetes mellitus were multivariable prognostic predictors in both patient groups. Analysing data according to the interaction of prognostically important echocardiographic covariates, such as ischaemia on SE and RWMA, an effective risk assessment was obtained in hypertensive as well as normotensive patients. The annual event rate was markedly higher in hypertensive than in normotensive patients with no ischaemia and no RWMA (2.5 and 1.7%, P = 0.0001). Finally, the incremental prognostic value of inducible ischaemia over clinical evaluation and resting left ventricular function was greater in hypertensive than in normotensive patients both with known and suspected CAD.

CONCLUSIONS:  The SE result allows an effective prognostication in hypertensive and normotensive patients. However, a non-ischaemic test predicts better survival in normotensive than in hypertensive patients with no RWMA.

PMID: 21411815

Epicardial Fat: An Additional Measurement for Subclinical Atherosclerosis and Cardiovascular Risk Stratification?

OBJECTIVES:  The value of epicardial adipose tissue (EAT) thickness as determined by echocardiography in cardiovascular risk assessment is not well understood. The aim of this study was to determine the associations between EAT thickness and Framingham risk score, carotid intima media thickness, carotid artery plaque, and computed tomographic coronary calcium score in a primary prevention population.

METHODS:  Patients presenting for cardiovascular preventive care (n = 356) who underwent echocardiography as well as carotid artery ultrasound and/or coronary calcium scoring were included.

RESULTS:  EAT thickness was weakly correlated with Framingham risk score. The prevalence of carotid plaque was significantly greater in those with EAT thickness ≥5.0 mm who either had low Framingham risk scores or had body mass indexes ≥25 kg/m(2), compared with those with EAT thickness <5.0 mm. No significant association between EAT thickness and carotid intima-media thickness or coronary calcium score existed.

CONCLUSIONS:  EAT thickness ≥5.0 mm may identify an individual with a higher likelihood of having detectable carotid atherosclerosis.

PMID: 21185148

Current and Evolving Echocardiographic Techniques for the Quantitative Evaluation of Cardiac Mechanics: ASE/EAE Consensus Statement on Methodology and Indications Endorsed by the Japanese Society of Echocardiography

Echocardiographic imaging is ideally suited for the evaluation of cardiac mechanics because of its intrinsically dynamic nature.  Because for decades, echocardiography has been the only imaging modality that allows dynamic imaging of the heart, it is only natural that new, increasingly automated techniques for sophisticated analysis of cardiac mechanics have been driven by researchers and manufacturers of ultrasound imaging equipment.  Several such techniques have emerged over the past decades to address the issue of reader’s experience and inter-measurement variability in interpretation.  Some were widely embraced by echocardiographers around the world and became part of the clinical routine, whereas others remained limited to research and exploration of new clinical applications.  Two such techniques have dominated the research arena of echocardiography: (1) Doppler-based tissue velocity measurements, frequently referred to as tissue Doppler or myocardial Doppler, and (2) speckle tracking on the basis of displacement measurements.  Both types of measurements lend themselves to the derivation of multiple parameters of myocardial function.  The goal of this document is to focus on the currently available techniques that allow quantitative assessment of myocardial function via image-based analysis of local myocardial dynamics, including Doppler tissue imaging and speckle-tracking echocardiography, as well as integrated back- scatter analysis.  This document describes the current and potential clinical applications of these techniques and their strengths and weaknesses, briefly surveys a selection of the relevant published literature while highlighting normal and abnormal findings in the context of different cardiovascular pathologies, and summarizes the unresolved issues, future research priorities, and recommended indications for clinical use.

PMID: 21385887

Assessment of Left Ventricular Regional Wall Motion and Ejection Fraction With Low-Radiation Dose Helical Dual-Source CT: Comparison to Two-Dimensional Echocardiography

OBJECTIVES: Electrocardiographic (ECG)-based tube current modulation during cardiac CT reduces radiation exposure but significantly increases noise in parts of the cardiac cycle where tube current is minimized. We evaluated the effect of maximal ECG-based tube current reduction on left ventricular (LV) regional wall motion assessment and ejection fraction (EF) by comparing low-radiation helical dual-source CT (DSCT) to 2-dimensional transthoracic echocardiography (2D-TTE).

METHODS: We studied 83 consecutive patients (15 with prior myocardial infarction) who underwent helically acquired DSCT coronary angiography with maximal ECG-based tube current modulation (low-radiation helical DSCT) and 2D-TTE within a 6-month period (median, 1 day), without any change in clinical status between the studies. In all patients, full tube current was applied only at 70% of the R-R interval, with minimal tube current (4% of maximum) in all other parts of the cardiac cycle. Reduced tube voltage (100 kVp) was combined with the maximal dose modulation in 34 patients. DSCT datasets were evaluated by a blinded, experienced cardiologist. Regional wall motion was assessed with the standard 17-segment model, with each segment scored as normal, hypokinetic, akinetic, and dyskinetic.

RESULTS: Mean effective radiation dose for the low-radiation helical DSCT was 5.2 ± 1.7 mSv. Regional wall motion was evaluable in all segments on low-radiation helical DSCT. There was excellent agreement of wall motion scoring by low-radiation helical DSCT and 2D-TTE in 1382 of 1411 segments (98%; Cohen’s κ value 0.83; 95% confidence interval, 0.76-0.89; P < 0.0001). Mean LVEF was 67.6% ± 10.3% on low-radiation helical DSCT and 61.8% ± 10.3% on 2D-TTE (P < 0.0001).

CONCLUSION: Low-radiation dose helical coronary CT angiography with maximal ECG-based tube current modulation is comparable to 2D-TTE for regional wall motion and EF assessment.

PMID: 21367686

Diagnostic Accuracy of Echocardiography for Pulmonary Hypertension: A Systematic Review and Meta-Analysis

OBJECTIVES: Right heart catheterization is the gold standard for the diagnosis of pulmonary hypertension. However, echocardiography is frequently used to screen for this disease and monitor progression over time because it is noninvasive, widely available, and relatively inexpensive. The objective of our study was to perform a systematic review and quantitative meta-analysis to determine the correlation of pulmonary pressures obtained via echocardiography versus right heart catheterization and to determine the diagnostic accuracy of echocardiography for pulmonary hypertension.

METHODS: MEDLINE, EMBASE, PapersFirst, and the Cochrane collaboration and the Cochrane Register of controlled trials were searched and were inclusive as of February 2010. Studies were only included if a correlation coefficient or the absolute number of true-positive, false-negative, true-negative, and false-positive observations were available, and the “reference standards” were described clearly. Quality was assessed with the Quality Assessment for Diagnostic Accuracy Studies (QUADAS). A random effects model was used to obtain a summary correlation coefficient and the bivariate model for diagnostic meta-analysis was used to obtain summary sensitivity and specificity values.

RESULTS: Twenty-nine studies were included in the meta-analysis. The summary correlation coefficient between systolic pulmonary arterial pressure estimated from echocardiography versus measured by right heart catheterization was 0.70 (95% CI: 0.67-0.73) (n=27). The summary sensitivity and specificity for echocardiography for diagnosing pulmonary hypertension was 83% (95% CI: 73-90) and 72% (95% CI: 53-85) (n=12), respectively. The summary diagnostic odds ratio was 13 (95% CI: 5-31).

CONCLUSIONS: Echocardiography is a useful and noninvasive modality for measuring pulmonary pressures and for screening/diagnosing pulmonary hypertension.

PMID:

A New Method for Quantification of Left Ventricular Systolic Function Using a Corrected Ejection Fraction

OBJECTIVES: Left ventricular ejection fraction (EF) is a suboptimal measure of ventricular function. Recent mathematical modelling of left ventricular contraction has shown that the EF is determined by both myocardial shortening (strain) and by end-diastolic wall thickness. Increasing end-diastolic wall thickness resulted in augmented radial wall thickening. This may result in a significant ‘overestimation’ of ventricular systolic function as assessed by the EF. This study proposes a new measure of ventricular systolic function, the corrected EF (EF(c)) to allow for the presence of concentric left ventricular hypertrophy (LVH).

METHODS: The study uses a new two-layer, three-dimensional mathematical model of ventricular contraction. Changes in end-diastolic wall thickness in addition to long-axis and mid-wall circumferential strain were modelled.

RESULTS: Iso-strain lines were obtained where myocardial shortening (strain) is constant; EF increases with increasing end-diastolic wall thickness. The corrected EF is determined by following the iso-strain lines to the equivalent EF in the absence of hypertrophy (e.g. 9 mm thickness). For example, an individual with a mean end-diastolic wall thickness of 20 mm and measured EF of 60% has a corrected EF (EF(c)) of 37%.

CONCLUSIONS: The study shows that the EF is determined by absolute wall thickening and provides a nomogram for comparing EF when LVH is present. The EF(c) is a potential new measure of left ventricular systolic function. Its possible role will need validating in mortality trials.

PMID: 21216767

Transcatheter Approaches to Non-Valvar Structural Heart Disease

With advancement in transcatheter technology, numerous non-congenital structural heart lesions previously untreated, or treated with surgery are now amenable to transcatheter therapy. These therapies have centered on transcatheter valve replacement, however, other lesions are increasingly treated via the percutaneous approach. These procedures include patent foramen ovale closure, left atrial appendage occlusion, closure of post-infarct ventricular septal defects, occlusion of ruptured sinus of Valsalva aneurysm and treatment of paravalvar leaks. This review will outline indications for and approach to each of these procedures in the context of the current literature base with emphasis on pre- and intra-procedural imaging modalities.

PMID: 21331612

Comparison of the Structure of the Aortic Valve and Ascending Aorta in Adults Having Aortic Valve Replacement for Aortic Stenosis Versus for Pure Aortic Regurgitation and Resection of the Ascending Aorta for Aneurysm

OBJECTIVES: There is debate concerning whether an aneurysmal ascending aorta should be replaced when associated with a dysfunctioning aortic valve that is to be replaced.

METHODS: To examine this issue, we divided the patients by type of aortic valve dysfunction—either aortic stenosis (AS) or pure aortic regurgitation (AR)—something not previously undertaken.

RESULTS: Of 122 patients with ascending aortic aneurysm (unassociated with aortitis or acute dissection), the aortic valve was congenitally malformed (unicuspid or bicuspid) in 58 (98%) of the 59 AS patients, and in 38 (60%) of the 63 pure AR patients. Ascending aortic medial elastic fiber loss (EFL) (graded 0 to 4+) was zero or 1+ in 53 (90%) of the AS patients, in 20 (53%) of the 38 AR patients with bicuspid valves, and in all 12 AR patients with tricuspid valves unassociated with the Marfan syndrome. An unadjusted analysis showed that, among the 96 patients with congenitally malformed valves, the 38 AR patients had a significantly higher likelihood of 2+ to 4+ EFL than the 58 AS patients (crude odds ratio: 8.78; 95% confidence interval: 2.95, 28.13).

CONCLUSONS: These data strongly suggest that the type of aortic valve dysfunction—AS versus pure AR—is very helpful in predicting loss of aortic medial elastic fibers in patients with ascending aortic aneurysms and aortic valve disease.

PMID: 21321157

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.

PMID: 19737801

Transcatheter Aortic Valve Implantation in Aortic Stenosis: The Role of Echocardiography

Aortic stenosis is becoming an increasing health care problem as the population ages. Surgical aortic valve replacement remains the gold standard but is associated with high mortality and morbidity rates in elderly patients and those with multiple comorbidities. The authors explore transcatheter aortic valve implantation as an attractive alternative therapy in this high-risk population and outline its limitations and future directions, with a special emphasis on the role of echocardiography.

PMID: 21126855

Occurrence of Atrial Fibrillation During Dobutamine Stress Echocardiography: Incidence, Risk Factors, and Outcomes

OBJECTIVES: The reported incidence of atrial fibrillation (AF) occurring during dobutamine stress echocardiography (DSE) ranges from 0.5% to 4%. The aim of this study was to characterize the incidence, risk factors, and outcomes of AF precipitated during DSE.

METHODS: The clinical and echocardiographic data of consecutive patients over a 50-month period who were in sinus rhythm and underwent DSE were retrospectively reviewed.

RESULTS: A total of 11,806 consecutive patients underwent DSE and met all inclusion criteria. AF developed during DSE in 122 patients (1%), 71 of whom had histories of AF. The duration of AF was <1 hour in 74 patients (61%) and <24 hours in 117 patients (96%). Of the 47 patients who were still in AF when dismissed from the echocardiography laboratory, 21 had outpatient follow-up within 24 hours, eight were already inpatients, and 18 were triaged to the emergency department or hospital. Spontaneous cardioversion occurred in 114 patients (93%). There were no reported complications. The clinical characteristic most strongly associated with the development of AF during DSE was a history of AF (odds ratio, 18.4 if no history of congestive heart failure; P < .001). The presence or extent of stress-induced myocardial ischemia was not predictive of the development of AF.

CONCLUSIONS: AF is an infrequent complication of DSE. Most patients return to sinus rhythm spontaneously within 1 hour. Patients with persistent AF can be safely dismissed from the echocardiography laboratory to have outpatient follow-up within 24 hours unless they have suboptimal heart rate control, hypotension, significant symptoms, or markedly abnormal findings on DSE.

PMID: 21172598

Systolic and Diastolic Myocardial Mechanics in Patients With Cardiac Disease and Preserved Ejection Fraction: Impact of Left Ventricular Filling Pressure

OBJECTIVES: There are few data on the impact of left ventricular (LV) filling pressure on systolic and diastolic myocardial mechanics in patients with cardiac disease and preserved LV ejection fraction (LVEF) (≥50%).

METHODS: Patients referred for cardiac catheterization underwent comprehensive echocardiography within 20 minutes of catheterization. Strain and strain rate in longitudinal, radial, and circumferential directions and torsion were measured in systole and diastole. LV preatrial contraction pressure (pre-A) was measured and averaged over 10 cardiac cycles.

RESULTS: Sixty patients were studied (mean age, 55.3 ± 8.9 years). The 30 patients with LV pre-A ≥ 15 mm Hg had significantly lower longitudinal systolic strain and radial, circumferential, and torsional systolic strain rates than the 30 patients with LV pre-A < 15 mm Hg (P < .05 for all). Similar findings were seen for diastolic variables. There were significant correlations between several systolic and diastolic variables in multiple directions and LV pre-A. On multivariate analysis, the independent predictors of systolic and diastolic speckle-tracking parameters included LVEF and LV pre-A, depending on the specific parameter analyzed.

CONCLUSIONS: In patients with preserved LVEF and cardiac disease, several systolic and diastolic myocardial mechanical parameters significantly correlate with LV filling pressure. These data highlight the notion that patients with preserved LVEF and elevated LV filling pressures have significant abnormalities in systolic function as detected by speckle imaging, findings that may challenge the concept of “isolated diastolic dysfunction.” The extent of systolic and diastolic abnormalities in these patients may shed light on the mechanics of heart failure with preserved LVEF.

PMID: 20970305

Standardized Endpoint Definitions for Transcatheter Aortic Valve Implantation Clinical Trials: A Consensus Report from the Valve Academic Research Consortium

PMID: