Low-dose Dobutamine Stress Research Articles

Low-Dose Dobutamine Stress Echocardiography for the Early Detection of Pulmonary Arterial Hypertension in Selected Patients with Systemic Sclerosis Whose Resting Echocardiography Is Non-Diagnostic for Pulmonary Hypertension.

Background: Dobutamine stress echocardiography (DSE) has limited application in systemic sclerosis (SSc). We examined DSE usefulness in revealing pulmonary arterial hypertension (PAH) in selected SSc patients whose resting echocardiography for pulmonary hypertension (PH) was non-diagnostic. Methods: Forty SSc patients underwent right heart catheterization (RHC) and, simultaneously, low-dose DSE (incremental doses up to 20 μg/kg/min). Inclusion criteria were: preserved left and right ventricular (RV) function (tricuspid annulus plane systolic excursion [TAPSE] ≥ 16 mm and tissue Doppler imaging-derived systolic velocity of tricuspid annulus [RVS’] > 10 cm/s), normal pulmonary function tests, and baseline maximal tricuspid regurgitation (TR) velocity of 2.7–3.2 m/s. Results: Of 36 patients who completed DSE, resting RHC diagnosed PAH in 12 patients (33.3%). At 20 μg/kg/min, patients with PAH had higher TR velocity, higher pulmonary arterial pressure measured by RHC, and lower RV inotropic response compared with patients without PAH. A cut-off value of maximal TR velocity >3.1 m/s had a sensitivity of 80%, a specificity of 84.2%, and an accuracy of 82.4% for the detection of PAH. Conclusions: Low-dose DSE has a satisfactory diagnostic accuracy for the early detection of PAH in highly selected SSc patients whose baseline echocardiographic measurements for PH lie in the gray zone.

Dobutamine stress testing for the evaluation of atrial and diastolic ventricular function in Fontan patients

ObjectiveTo assess the atrial and ventricular diastolic function response to dobutamine stress in Fontan patients, and to relate these measurements to exercise capacity and events during the follow-up.MethodsWe performed a...

Predictors of true-severe classical low-flow low-gradient aortic stenosis at resting echocardiography

BackgroundClassical low-flow, low-gradient (LF/LG) aortic stenosis (AS) is subclassified into a true-severe (TS) and a pseudo-severe (PS) subform using low-dose dobutamine stress echocardiography (DSE). In clinical practice a resting peak jet velocity (Vmax) >3.5 m/s or a mean transvalvular gradient (MPG) >35 mmHg suggests the presence of TS classical LF/LG AS, but there is no data to support this. The aim of this study was therefore to investigate whether a resting Vmax >3.5 m/s or MPG >35 mmHg reliably predicted diagnosis of TS classical LF/LG AS. MethodsOne hundred (100) consecutive patients with classical LF/LG AS were prospectively recruited. All patients underwent DSE for subcategorization. The impact of Vmax and MPG for the presence of the TS subform were analyzed. ResultsTS classical LF/LG AS was diagnosed in 72 patients. Resting Vmax and resting MPG predicted true-severity with an ROC-AUC of 0.737 (95%CI: 0.635–0.838; p < 0.001) and 0.725 (95%CI: 0.615–0.834; p < 0.001), respectively. The optimal positive predictive values (PPV) for the diagnosis of TS classical LF/LG AS were obtained with a resting Vmax >3.5 m/s or resting MPG >35 mmHg. In a multivariate logistic regression analysis, Vmax >3.5 m/s was independently associated with a 5.33-fold odds-ratio of TS classical LF/LG AS (OR 5.33; 95%CI: 1.34–21.18, p = 0.018). ConclusionsTS classical LF/LG AS can be reliably predicted by a resting Vmax >3.5 m/s or a resting MPG >35 mmHg. Further imaging for subclassification is not needed in this situation.

Clinical value of stress transaortic flow rate during dobutamine echocardiography in low-gradient aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND/INTRODUCTION The clinical value of rest transaortic flow rate (FR) has been shown previously in low-gradient aortic stenosis (LGAS) for the prediction of outcome. However limited data exists on the prognostic value of stress FR in LGAS following low-dose dobutamine stress echocardiography (LDDSE). PURPOSE We aimed to assess the value of stress FR in patients with LGAS in the diagnosis of AS severity and the prediction of mortality. METHODS This is a multi-centre cohort study of patients with low left ventricular ejection fraction (LVEF) and LGAS (aortic valve area –AVA &amp;lt;1cm²) who underwent LDDSE. RESULTS Of the 287 patients (mean age: 75.1 ±10 years, males: 71%) over the mean follow-up of 24 ±30 months there were 127 (44.3%) deaths and 147 (51.2%) patients underwent aortic valve intervention. Lower stress FR was independently associated with increased risk of mortality (HR= 0.99, 95%CI= 0.99-0.999, p= 0.02) after adjusting for age, chronic kidney disease, presence of symptoms (NYHA II-IV), aortic valve intervention, rest LVEF and guideline-defined severe AS (AV mean gradient- AVMG ≥40mmHg with AVA &amp;lt;1cm² at peak stress). The minimum cut-off for prediction of mortality was stress FR 210ml/sec. Among the different criteria of AS severity during stress, i.e. guideline-defined criterion, or stress AVMG ≥40mmHg, or stress AVA &amp;lt;1cm² at stress FR ≥210ml/s, only the latter was independently associated with mortality (HR= 1.81, 95%CI= 1.04-3.2, p= 0.04) (Table 1) and was the parameter of AS severity that predicted improved outcome following aortic valve intervention (p &amp;lt;0.005) (Figure 1). Guideline-defined stroke volume flow reserve did not predict mortality. CONCLUSIONS Assessment of stress FR during LDDSE is important for the detection of both AS severity and flow reserve. Table 1 Multivariable analysis for prediction of all-cause mortality (N = 287) for the different criteria of aortic stenosis HR 95%CI p Age 1 0.98-1.03 0.84 Chronic kidney disease 1..84 1.13-2.99 0.01 Aortic valve intervention 0.37 0.22-0.61 &amp;lt;0.005 Presence of symptoms (NYHA II-IV) 1.87 0.66-5.31 0.24 Rest LVEF (by 1%) increase 0.97 0.95-1 0.06 Stress AVA &amp;lt; 1cm&amp;sup2; with stress AVMG≥40mmHg 1.02 0.31-3.34 0.97 Stress AVMG≥40mmHg 0.57 0.2-1.59 0.28 Stress AVA &amp;lt; 1cm&amp;sup2; at stress FR≥210mmHg 1.81 1.04-3.2 0.04 Abstract Figure 1

IMPACT OF TIME ON SHORT TERM OUTCOME FOR PERCUTANEOUS CORONARY INTERVENTION AFTER FAILED FIBRINOLYSIS FOR STEMI PATIENTS

Background: Although primary percutaneous coronary intervention (PPCI) is the most preferred reperfusion strategy for ST-segment-elevation in myocardial infarction (STEMI), fibrinolytic therapy is considered a valid alternative when PPCI is not feasible or cannot be done within 1 hour after the first medical contact. Objective: To assess the short-term outcome of anterior STEMI patients after failed fibrinolytic therapy, undergoing rescue PCI at 3 different timing scenarios, and to study the effect of delayed intervention on the outcome. Patients and Methods: This study included 63 patients with a diagnosis of anterior STEMI admitted to CCU in Nasser Institute hospital and Sayed Galal University Hospital from December 2016 to August 2018. They received thrombolysis by using streptokinase (1.500.000 IU) without clinical and/or electrocardiographic evidence of successful reperfusion within 90 minutes after the start of fibrinolysis. Patients were referred for rescue PCI within 24 hours. Patients were divided according to time delay from rescue PCI into 3 equal groups: Group A had PCI 3-6 hours after failed thrombolysis, group B had PCI 6-12 hours after failed thrombolysis and group C had PCI 12-24 hours after failed thrombolysis. Patients were studied for the incidence of major adverse cardiac events (MACE), i.e. death; reinfarction, target vessel revascularization (TVR), rehospitalization, symptomatic heart failure and LVEF in the acute stage and after 3 months follow up as primary end points. Left ventricular performance and viability were followed up using low dose dobutamine stress echocardiography as secondary endpoints. Results: Total 63 patients enrolled in the study with mean age 58.60 ± 10.42 years. 84.1% were males and 15.9% were females. Diabetic patients were 65%, hypertensives and smokers were 65% and 42.9% respectively. All patients underwent rescue PCI with bare metal stents (BMS). Three months follow up showed that group A patients had the lowest incidence of MACE (0.0% for Death, reinfarction, TVR, rehospitalization, and highest mean EF 54.14±6.80 (40 - 65) followed by group B (4.7% for death, 9.5% for re-infarction and 47.0% for rehospitalization) with mean EF 41.47±7.60 (30-85) while group C patient had the highest MACE rates and lowest mean LVEF 34.64±5.60 (20 - 40). There was non-significant increase in mortality and TVR rate between the 3 groups. Re-hospitalization showed a statistically significant difference that increased from 0% in group A to 47.0% in group B and 66.6% in group C. Concerning viability assessed by low dose DSE, there were significant difference between groups. In group A, only 4.7% had non-viable infarcted related area, while this percentage increased in group B and C to 38.0% and 100% respectively. Conclusion: Rescue PCI should be done as early as possible for favorable clinical outcome.

Comprehensive assessment of the aortic valve in critically ill patients for the non-cardiologist. Part I: Aortic stenosis of the native valve.

Aortic stenosis (AS) causes left ventricular outflow obstruction. Severe AS has major haemodynamic implications in critically ill patients, in whom increased cardiac output and oxygen delivery are often required. Transthoracic echocardiography (TTE) plays akey role in the AS severity grading. In this review, we will give an overview of how to use the simplified Bernoulli equation to convert the echo Doppler measured velocities (cm s-1) to AS peak and mean gra-dient (mm Hg) and how to calculate the aortic valve area (AVA), using the continuity equation, based on the principle of preservation of flow. TTE allows quantification of compensatory left ventricular (LV) hypertrophy, assessment of LV systolic function, and determination of LV diastolic function and LV loading. Subsequently, the obtained results from the TTE study need to be integrated to establish the AS severity grading. The pitfalls of echocardiographic AS severity assessment are explained, and how to deal with inconsistency between AVA and mean gradient. The contribution of transoesophageal echocardiography, low-dose dobutamine stress echo (in case of low-flow low-gradient AS), echocardiography strain imaging, cardiac magnetic resonance imaging, cardiac multidetector computed tomography and the relatively new concept of Flow Pressure Gradient Classification to the work-up for aortic stenosis is discussed. Finally, the treatment of AS is overviewed. Elective aortic valve replacement is indicated in patients with severe symptomatic AS. In the ICU, afterload reduction by vasodilator therapy and treatment of pulmonary and venous congestion by diuretics could be considered.

The clinical significance of the incorporation of tissue Doppler imaging into low-dose Dobutamine stress echocardiography in patients with aortic stenosis prior to Transcatheter aortic valve implantation

BackgroundLow-dose dobutamine stress echocardiography (DSE) is indicated in patients with low flow (stroke volume index [SVi] < 35 ml/m2) low gradient (mean pressure gradient < 40 mmHg) and left ventricular ejection fraction (LVEF) < 50% aortic stenosis (AS) to assess LV contractile reserve (> 20% increase in SVi) and severity grade of AS. Severe AS is defined by a mean pressure gradient of 40 mmHg occurring at any time during the test when aortic valve area remains < 1.0 cm2.Case presentationThis case report highlights the utility of mitral annular systolic velocity (S′) by tissue Doppler imaging and peak LV outflow tract (LVOT) velocity as markers of LV intrinsic contractile function during DSE in a patient with low flow low gradient AS and reduced EF prior to transcatheter aortic valve implantation (TAVI).ConclusionsMitral annular S′ and peak LVOT velocities are reliable markers of LV intrinsic contractile function and should be incorporated into routine low-dose DSE.

Safety and feasibility of dobutamine stress echocardiography in symptomatic high gradient aortic stenosis patients scheduled for transcatheter aortic valve implantation.

We aimed to study the safety and feasibility of low-dose dobutamine stress echocardiography in a symptomatic high gradient aortic stenosis population scheduled for transfemoral transcatheter aortic valve implantation (TAVI) and to quantify left ventricular (LV) flow reserve. Fifty patients underwent dobutamine stress echocardiography with 5 minutes increments of 5 μg/kg/min up to 20 μg/kg/min until the heart rate increased ≥20 beats/min from baseline or exceeded 100 beats/min. Other criteria for discontinuing the infusion were major adverse events: ventricular arrhythmia, persistent supraventricular arrhythmia, pulmonary edema, chest pain with significant ST-changes, or minor events: ST-changes, drop in systolic blood pressure >30 mmHg, mild chest pain, and/or dyspnea. LV flow reserve was defined as an increase in stroke volume ≥20% during the test. Of 50 patients, 45 completed the test according to protocol. No patient had major adverse event. Five patients experienced minor side effects: mild chest pain/dyspnea in three, self-terminating atrial flutter in one, and decrease in blood pressure in one. Significant LV flow reserve was observed in 20 patients (40%). Low-dose dobutamine stress test appeared safe and feasible patients with high gradient aortic stenosis, and showed LV flow reserve in a minority of them.

What Is New in Low Gradient Aortic Stenosis: Surgery, TAVR, or Medical Therapy?

A significant proportion of patients with aortic stenosis (AS) have discordance in severity by mean gradient/peak velocity and aortic valve area. Low gradient aortic stenosis (LG-AS) is defined when the aortic valve area is < 1cm2 consistent with severe AS and mean aortic gradient is < 40mmHg consistent with non-severe AS. LG-AS represents a diagnostic and therapeutic challenge. To summarize the different categories, diagnosis, management, and prognosis of LG-AS. LG-AS is classified as classical (ejection fraction (EF) < 50%, indexed stroke volume (SVi) < 35ml/m2), paradoxical (EF > 50%, SVi < 35ml/m2), pseudo-severe (moderate AS with reduced EF), or normal flow low gradient AS. Recent findings emphasize the importance of low-dose dobutamine stress echocardiography and CT calcium score in the assessment of aortic valve. In addition, flow reserve (increase in SV > 50%) can be evaluated during dobutamine stress echocardiography and helps predict perioperative prognosis. Patients with LG-AS have better survival with aortic valve replacement (AVR) compared to medical therapy, irrespective of presence or absence of flow reserve. Some recent studies suggest that transcatheter aortic valve replacement (TAVR) may be superior to surgical AVR for patients with a lack of contractile flow reserve or those with paradoxical LG-AS, but further investigation is needed to clarify optimal treatment. The role of TAVR in patients with moderate AS and reduced EF is also under investigation.

ASSESSMENT OF MYOCARDIAL VIABILITY USING LOW DOSE DOBUTAMINE THREE DIMENSIONAL SPECKLE TRACKING STRESS TRANSTHORACIC ECHOCARDIOGRAPHY

Background: Three-dimensional speckle tracking echocardiography (3D STE) is used recently to assess many cardiac diseases; it is considered as natural growth of two-dimensional speckle tracking echocardiography (2D STE). The LV mechanics is in nature a 3D phenomenon and its accurate assessment requires a 3D imaging method. 3DSTE has been implemented for measuring 3D strain, and has emerged as a more physiologically sound tool for analyzing the complexity of LV mechanics, overcoming the inherent limitations of 2D STE. Objective: To determine the relative accuracy of area strain measured by 3D speckle-tracking echocardiography combined with low dose dobutamine for the detection of myocardial viability before coronary revascularization in comparison with MPI. Patients and Methods: The study included 40 patients referred to Bab El-She’riya University Hospital nuclear lab for assessment of myocardial viability by MPI before coronary revascularization. Then all patients were referred to Islamic Cardiac Center Echo lab where complete conventional transthoracic echocardiography was done followed by Low dose dobutamine (LDD) stress transthoracic echocardiography with 3D STE then comparing results of 3D strain of viable segments with that of nonviable segments and with corresponding segments in MPI studies. Results: The study showed that 241 segments in the 40 patients were assigned as abnormal segments, 114 were viable and 127 were nonviable, resting area strain (AS)was -18.7±2.5 for viable segments comparing to -12.6±5.3 for non-viable segment. A cut-off point of -16 was chosen to differentiate viable segments from non-viable ones with sensitivity 80.75% and specificity 83.1%. The average LDD AS value for viable segments was-24.5±2.7 and was -15.2±4.8 of non-viable segments with a cut-off point of -24 to differentiate viable segments from non-viable ones with sensitivity of 84.75% and a specificity of 89.1%. The average increase of AS of viable segments after LDD was -5.8±2.3 with a cut-off point to detect viability was a -0.24 increase in LDD from resting AS with a sensitivity of 95.75% and a specificity of 98.1%. Conclusion: AS obtained from 3D STE may be used clinically as an indicator to detect myocardial viability with higher sensitivity and specificity when combined with LDD.

Low-dose dobutamine stress myocardial contrast echocardiography for the evaluation of myocardial microcirculation and prediction of overall cardiac function recovery.

The study aimed to investigate the role of low-dose dobutamine stress myocardial contrast echocardiography (MCE) in evaluating myocardial local microcirculation and predicting cardiac function recovery in patients with myocardial infarction. A total of 50 patients with acute myocardial infarction (AMI) were enrolled in the present study. Positron emission tomography was used as a gold standard to determine viable/non-viable myocardial segments in infarcted myocardial region. MCE and dobutamine stress MCE were carried out 72 h after PCI. MCE was carried out again to evaluate myocardial condition at 6 months after PCI. As compared with normal myocardial segments, resting MCE revealed a significant decrease of the values of A (the peak intensity of the time-perfusion intensity curve, reflecting the myocardial blood volume), β (the slope of the curve, reflecting the myocardial blood flow (MBF) velocity) and A x β (reflecting MBF) of viable and non-viable myocardial segments. After being challenged by dobutamine, the values of A, β and A x β of normal coronary blood supply areas were significantly increased; while the segments A and A x β of viable myocardium were markedly decreased. Patients were further divided into two groups based on the changes in the contrast-enhanced index (CSI) following dobutamine loading. In the dobutamine stress echocardiography-positive group (the CSI increased or decreased by >0.2), the left ventricular ejection fraction was significantly increased and pro-B-type natriuretic peptide significantly decreased at 6 months following intervention. Low-dose dobutamine stress MCE was indicated to be an effective method to evaluate myocardial microcirculation perfusion in patients with AMI following PCI. In addition, CSI, as a simple semi-quantitative index, may predict left ventricular function in patients with AMI.

Assessment of myocardial viability using echocardiographic strain imaging in patients with ST-elevation myocardial infarction: comparison with cardiac PET imaging.

A speckle tracking echocardiographic (STE) strain imaging can predict myocardial viability. The study compared the STE strain imaging using low-dose dobutamine stress with 18fluoro-deoxyglucose positron emission tomographic (18FDG-PET) imaging for the detection of myocardium viability. We studied 57 patients with ST-elevation myocardial infarction (STEMI) having angiographic evidence of total arterial cut off and akinetic myocardium. These patients underwent low-dose dobutamine echocardiography and 18FDG-PET imaging. The STE was used to measure the peak systolic longitudinal and circumferential strain and strain rate at rest and after low-dose dobutamine stress. A total of 298 akinetic segments were evaluated. The viable myocardium showed an increased strain and strain rate values following the dobutamine stress in comparison to the nonviable myocardium. The peak longitudinal strain rate [AUC 0.83 (95% confidence interval (CI) 0.67-0.99], p = 0.001; optimal cutoff - 0.64s-1 for sensitivity 0.87 and specificity 0.81), post-dobutamine peak longitudinal strain rate [AUC 0.94 (95% CI 0.87-1.00), p = 0.001; optimal cutoff - 0.85s-1 for sensitivity 0.89 and specificity 0.77), change in peak longitudinal strain rate [AUC 0.93 (95% CI 0.86-1), p = 0.001; optimal cutoff - 0.2s-1 for sensitivity 0.87 and specificity 0.87] predicted viability. The post-dobutamine peak circumferential strain rate [AUC 0.92 (95% CI 0.81-1.0), p = 0.001; optimal cutoff - 1.1s-1 for sensitivity and specificity 0.86], were predictor of viability. Both resting and post-dobutamine longitudinal and circumferential strain rate had better accuracy for the prediction of viability. The resting and post-dobutamine stress STE strain and strain rate parameters can assess the viability in akinetic segments.

Augmented left ventricular dyssynchrony by low-dose dobutamine stress suggested excellent cardiac resynchronization responses in low-flow low-gradient aortic stenosis.

Augmented left ventricular dyssynchrony by low-dose dobutamine stress suggested excellent cardiac resynchronization responses in low-flow low-gradient aortic stenosis.

Regional myocardial strain analysis via 2D speckle tracking echocardiography: validation with sonomicrometry and correlation with regional blood flow in the presence of graded coronary stenoses and dobutamine stress

BackgroundQuantitative regional strain analysis by speckle tracking echocardiography (STE) may be particularly useful in the assessment of myocardial ischemia and viability, although reliable measurement of regional strain remains challenging, especially in the circumferential and radial directions. We present an acute canine model that integrates a complex sonomicrometer array with microsphere blood flow measurements to evaluate regional myocardial strain and flow in the setting of graded coronary stenoses and dobutamine stress. We apply this unique model to rigorously evaluate a commercial 2D STE software package and explore fundamental regional myocardial flow-function relationships.MethodsSonomicrometers (16 crystals) were implanted in epicardial and endocardial pairs across the anterior myocardium of anesthetized open chest dogs (n = 7) to form three adjacent cubes representing the ischemic, border, and remote regions, as defined by their relative locations to a hydraulic occluder on the mid-left anterior descending coronary artery (LAD). Additional cardiac (n = 3) and extra-cardiac (n = 3) reference crystals were placed to define the cardiac axes and aid image registration. 2D short axis echocardiograms, sonometric data, and microsphere blood flow data were acquired at baseline and in the presence of mild and moderate LAD stenoses, both before and during low-dose dobutamine stress (5 μg/kg/min). Regional end-systolic 2D STE radial and circumferential strains were calculated with commercial software (EchoInsight) and compared to those determined by sonomicrometry and to microsphere blood flow measurements. Post-systolic indices (PSIs) were also calculated for radial and circumferential strains.ResultsLow-dose dobutamine augmented both strain and flow in the presence of mild and moderate stenoses. Regional 2D STE strains correlated moderately with strains assessed by sonomicrometry (Rradial = 0.56, p < 0.0001; Rcirc = 0.55, p < 0.0001) and with regional flow quantities (Rradial = 0.61, Rcirc = 0.63). Overall, correspondence between 2D STE and sonomicrometry was better in the circumferential direction (Bias ± 1.96 SD: − 1.0 ± 8.2% strain, p = 0.06) than the radial direction (5.7 ± 18.3%, p < 0.0001). Mean PSI values were greatest in low flow conditions and normalized with low-dose dobutamine.Conclusions2D STE identifies changes in regional end-systolic circumferential and radial strain produced by mild and moderate coronary stenoses and low-dose dobutamine stress. Regional 2D STE end-systolic strain measurements correlate modestly with regional sonomicrometer strain and microsphere flow measurements.

P1286 A retrospective clinical and anatomical characteristics study of transaortic extended left ventricular myectomy for obstructive hypertrophic cardiomyopathy

Abstract Objective Surgical septal myectomy is the gold-standard therapy for hypertrophic obstructive cardiomyopathy (HOCM). The aims of our study are to investigate anatomical characteristics and make clear effectiveness of transaortic extended left ventricular (LV) myectomy for HOCM. Methods This study enrolled 28 consecutive patients (age 66.7 ± 12.1 years, 46% Female) from 2012 to 2018 who met the following inclusion criteria: symptoms of heart failure persisting despite optimal medical therapy including beta blockers and Class I anti-arrhythmic agent, LV outflow tract gradient (LVOTG) &amp;gt; 50mmHg at rest or with provocation using stress echo (exercise TTE or low-dose dobutamine stress echo). We evaluated LV dimension, LVOTG, mitral regurgitation (MR), systolic anterior motion of mitral valve (SAM), Mitral complex morphology, high echoic region of endocardium and appearance of abnormal muscle bundles including apical-basal muscle bundle. These parameters were evaluated based on changes in LVOTG, MR and SAM at after LV myectomy. Also, intraoperative findings and cardiomyocytes pathological findings were evaluated. Stress echo were performed to investigate sustained reduction of LVOTG at medium term. Results All patients were successfully underwent transaortic extended LV myectomy. SAM was identified in all and moderate MR in 14 patients. The anterior mitral valve leaflet height was large in all patients and 16 patients had LV abnormal muscle bundles. Postoperative LVOTG were controlled in 10mmHg or less. SAM disappeared completely in all patients and MR were decreased mild or less. LVOTG were sustained good control in 10mmHg or less under stress echo at medium term. Conclusion LV myectomy provides excellent relief from LVOT obstruction. The appearance of mitral valve anterior leaflet and abnormal band may be important keys of LVOT obstruction.

Ventricular response to dobutamine stress cardiac magnetic resonance imaging is associated with adverse outcome during 8-year follow-up in patients with repaired Tetralogy of Fallot.

AimsThe aim of this study was to evaluate the possible value of dobutamine stress cardiac magnetic resonance imaging (CMR) to predict adverse outcome in Tetralogy of Fallot (TOF) patients.Methods and resultsIn previous prospective multicentre studies, TOF patients underwent low-dose dobutamine stress CMR (7.5 µg/kg/min). Subsequently, during regular-care patient follow-up, patients were assessed for reaching the composite endpoint (cardiac death, arrhythmia-related hospitalization, or cardioversion/ablation, VO2 max ≤65% of predicted). A normal stress response was defined as a decrease in end-systolic volume (ESV) and increase in ejection fraction. The relative parameter change during stress was calculated as relative parameter change = [(parameterstress − parameterrest)/parameterrest] * 100. The predictive value of dobutamine stress CMR for the composite endpoint was determined using time-to-event analyses (Kaplan–Meier) and Cox proportional hazard analysis. We studied 100 patients [67 (67%) male, median age at baseline CMR 17.8 years (interquartile range 13.5–34.0), age at TOF repair 0.9 years (0.6–2.1)]. After a median follow-up of 8.6 years (6.7–14.1), 10 patients reached the composite endpoint. An abnormal stress response (30% vs. 4.4%, P = 0.021) was more frequently observed in composite endpoint patients. Also in endpoint patients, the relative decrease in right ventricular ESV decreased less during stress compared with the patients without an endpoint (−17 ± 15 vs. −26 ± 13 %, P = 0.045). Multivariable analyses identified an abnormal stress response (hazard ratio 10.4; 95% confidence interval 2.5–43.7; P = 0.001) as predictor for the composite endpoint.ConclusionAn abnormal ventricular response to dobutamine stress is associated with adverse outcome in patients with repaired TOF.

Imaging Strategies for Evaluating Low-Flow, Low-Gradient Aortic Stenosis with Reduced and Preserved Left Ventricular Ejection Fraction.

Aortic stenosis (AS) is one of the most common valvular heart diseases, and aortic valve replacement (AVR) provides both symptomatic and survival benefit in symptomatic severe AS patients. The purpose of this review is to discuss low-flow low-gradient AS which is still a challenging diagnostic entity. Thirty-forty percent of patients with AS have low flow which makes it difficult to differentiate truly severe AS that benefits from AVR compared to pseudo-severe AS which is currently managed conservatively. Patients with low-flow low-gradient AS (LF-LG AS) include those with reduced left ventricular systolic function (classical LF-LG AS) and those with preserved left ventricular systolic function (paradoxical LF-LG AS). Low-dose dobutamine stress echocardiography (DSE) helps to identify truly severe stenosis in patients with classical LF-LG AS. Aortic valve calcium scoring with multidetector computed tomography plays a major role in patients with paradoxical LF-LG AS and also among classical LF-LG AS patients who have reduced contractile reserve on DSE. This article will provide an overview of imaging strategies for evaluating LF-LG AS with reduced and preserved left ventricular ejection fraction.

Assessment of myocardial viability and contractile function in rabbits with different ischemic periods by stress echocardiography and multilayer strain

Objective To evaluate the changes of myocardial viability and systolic function in rabbits with different ischemic periods by layer-specific strain of ultrasound speckled tracking imaging (STI) and low dose dobutamine stress echocardiography(LDDSE). Methods Thirty-six rabbits were randomly divided into 3 groups(n=12): ①myocardial infarction group Ⅰ: coronary artery occlusion for 45 min; ②myocardial infarction group Ⅱ: coronary artery occlusion for 60 min; ③myocardial infarction group Ⅲ: coronary artery occlusion for 90 min. Echocardiography examinations were performed at baseline, after ligation and low dose dobutamine stress. After the experiment, rabbits were killed and the hearts were taken to assess viable or nonviable mycardium, triphenyl tetrazolium chloride and Evans blue staining were applied. Results ①After coronary artery ligation, left ventricular ejection fraction(LVEF) decreased in 3 groups(all P<0.05), the ventricular global endocardial longitudinal strain(GSLsys-endo), global myocardial longitudinal strain(GSLsys-mid), and global epicardial longitudinal strain(GSLsys-epi) decreased in 3 groups(all P<0.05), the longitudinal strain of endocardium(SLsys-endo), longitudinal strain of myocardium(SLsys-mid), longitudinal strain of epicardium(SLsys-epi) decreased in viable myocardial(all P<0.05); ②While low dose dobutamine stressing, the GSLsys and SLsys increased in each groups, and the GSLsys-endo, GSLsys-mid, GSLsys-epi and SLsys-endo of viable segments in each group were increased (P<0.05); ③After ligation and low dose dobutamine stress, the GSLsys in endocardium in three groups were different(P<0.05), and the SLsys in endocardium of viable segments in three groups were different (P<0.05). Conclusions Layer-specific strain of STI combined with LDDSE can accurately evaluate the changes of myocardial viability and systolic function in different ischemic periods, and the longitudinal strain of endocardium is more sensitive; moreover, with the increase of coronary artery occlusion time, the infarcted myocardium increases, myocardial viability and systolic function decrease. Key words: Echocardiography; Myocardial ischemia; Viable myocardium; Dobutamine stress

Evaluation of patients with myocardial infarction undergoing percutaneous coronary intervention (PCI) using low dose dobutamine stress echocardiography

Coronary artery disease (CAD) is a spectrum of heart diseases which has the highest mortality in the world. Systolic left ventricular (LV) function is an important predictor of outcome, and its precise assessment remains of great importance for the choice of treatment in populations with myocardial infarction (MI). This study was aimed to assess the function and viability of ischemic myocardium of LV before and after the percutaneous coronary intervention (PCI) by using 2dimentional (2D) STE with LDDSE and to know the usefulness of low dose dobutamine (LDD) test in detecting the viable ischemic LV area. The results of the current study revealed there was a significant decrease (improvement) in GLS before dobutamine from (-10.49±3.4) to (-12.87±3.44) after dobutamine. Then there was a significant increase (deterioration) in GLS from (-12.87±3.44) after giving 5 mg/kg/min dobutamine to (-11.56±3.29) after giving 10 mg/kg/min dobutamine (P value &lt; 0.001). While there were no significant differences in GLS after low dose dobutamine (-12.87±3.44) with the same parameters 3-6 months after PCI (-13.48±3.7). Left anterior descending artery (LAD) is the most common affected artery in our study. The study concluded that GLS provides a sensitive measure of LV function and appears reduced despite preserved LVEF also GLS can detect the viability of ischemic myocardium of LV with using LDD test which then assessed by PCI.

Comparison of Contrast Enhanced Low-Dose Dobutamine Stress Echocardiography with 99mTc-Sestamibi Single-Photon Emission Computed Tomography in Assessment of Myocardial Viability.

INTRODUCTION:Dobutamine stress echocardiography (DSE) and myocardial perfusion scan are the commonly used modalities to detect viable myocardium. DSE is comparatively cheaper and widely available but has a lower sensitivity.AIM:We aimed to compare contrast-enhanced low-dose dobutamine echocardiography (LDDE) and gated 99mTc-sestamibi myocardial perfusion scan (MPS) for the degree of agreement in the detection of myocardial viability.METHODS:We studied 850 left ventricular segments from 50 patients (42 men, mean age 55.5 years), with coronary artery disease and left ventricular systolic dysfunction (ejection fraction < 40%), using contrast-enhanced LDDE and 99mTc-Sestamibi gated SPECT. Segments were assessed for the presence of viability by both techniques and head to head comparisons were made.RESULTS:Adequate visualisation increased from 80% in unenhanced segments to 96% in contrast-enhanced segments. Of the total 850 segments studied, 290 segments (34.1%) had abnormal contraction (dysfunctional). Among these, 138 were hypokinetic (16.2% of total), 144 were severely hypokinetic or akinetic (16.9% of total), and 8 segments were dyskinetic or aneurismal (0.9% of total). Among 151 segments considered viable by technetium, 137 (90.7%) showed contractile improvement with dobutamine; in contrast, only 8 of the 139 segments (5.7%) considered nonviable by technetium had a positive dobutamine response. The per cent of agreement between technetium uptake and a positive response to dobutamine was 78.6% with kappa = 0.63, suggestive of a substantial degree of agreement between the two modalities.CONCLUSION:Use of contrast-enhanced LDDE significantly increased the adequate endocardial border visualisation. Furthermore, this study showed a strong degree of agreement between the modalities in the detection of viable segments. So, contrast-enhanced LDDE appears to be a safe and comparable alternative to MPS in myocardial viability assessment.