Relation of myocardial histomorphometric features and left ventricular contractile reserve assessed by high-dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy

BACKGROUND: This study was designed to determine the relationship between histomorphometric features and contractile reserve assessed by high-dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy. METHODS: Twenty-four consecutive patients (21 men, aged 43.4+/-8.7 years) with idiopathic dilated cardiomyopathy underwent dobutamine stress echocardiography. Wall motion score index, ejection fraction, cardiac power output and end-systolic pressure/volume ratio were used as indices of left ventricular contractility. Left ventricular endomyocardial biopsy specimens (3-5 per patient) were routinely processed and stained with Masson trichrome, interstitial fibrosis and myocyte diameter were calculated quantitatively. RESULTS: Myocyte diameter and interstitial fibrosis showed strongest correlation with change in wall motion score index (r=-0.667, p<0.001, and r=-0.567, p=0.004, respectively), followed by change in ejection fraction (r=-0.603, p=0.002, and r=-0.467, p=0.021, respectively). Interstitial fibrosis showed no correlation with change of cardiac power output and end-systolic pressure/volume ratio, whereas myocyte diameter was associated with change of both indices (r=-0.565, p=0.004, and r=-0.455, p=0.025). CONCLUSIONS: Contractile reserve elicited by high-dose dobutamine is strongly related to the degree of histological disruption in patients with idiopathic dilated cardiomyopathy.     

Low dose dobutamine stress echocardiography predicts the improvement of left ventricular systolic function in dilated cardiomyopathy

OBJECTIVE: To determine whether dobutamine stress echocardiography can predict the improvement of left ventricular systolic function in patients with dilated cardiomyopathy (DCM). METHODS: Myocardial contractile reserve, as assessed by dobutamine stress echocardiography, was determined in 18 patients with DCM (mean (SD) age 53 (13) years, left ventricular ejection fraction (LVEF) 28 (10)%) and compared with changes in LVEF during a follow up period of 15 (8) months. The LVEF and regional left ventricular wall motion score (0, normal to 4, dyskinesis) of 12 segments in short axis and four chamber views were analysed before and after dobutamine infusion (5-20 microg/kg/min). RESULTS: During a follow up period of 15 (8) months, a significant improvement in LVEF (> 20%) was found in seven patients but not in the remaining 11. Baseline haemodynamic findings were similar in both groups. Patients with an improvement in follow up LVEF showed a greater change in wall motion score from baseline during dobutamine infusion than patients with no improvement (at rest, 1.7 (0.4) v 1.9 (0.2), NS; dobutamine 10 microg/kg/min, 0.6 (0.4) v 1.2 (0.4), p < 0.05). The percentage change in LVEF during dobutamine infusion was also significantly greater in patients who showed improvement than in those who did not. The change in LVEF during the follow up period (follow up LVEF/baseline LVEF) correlated well with the change in LVEF during dobutamine stress (LVEF at rest/LVEF at dobutamine 10 microg/kg/min; r = 0.74, p < 0.001). CONCLUSIONS: Changes in left ventricular systolic performance during low dose dobutamine stress echocardiography are a useful marker to predict the outcome of left ventricular systolic function in patients with DCM.     

Prediction of contractile reserve by cyclic variation of integrated backscatter of the myocardium in patients with chronic left ventricular dysfunction

OBJECTIVE—To clarify whether assessment of the acoustic properties of the myocardium at rest can predict contractile reserve in patients with chronic left ventricular dysfunction.
METHODS—23 patients (mean (SD) age 63 (12) years) with chronic left ventricular dysfunction were studied. The magnitude of cardiac cycle dependent variation of integrated backscatter (CVIB) of the myocardium was measured at rest in the basal and mid segment of the septum and posterior wall of the left ventricle, using a real time two dimensional integrated backscatter imaging system. The results were compared with the percentage wall thickening and the wall motion at rest and during low dose dobutamine infusion. The wall motion was graded as normal, hypokinetic, or akinetic and contractile reserve was considered present when an akinetic or hypokinetic segment improved during dobutamine infusion.
RESULTS—The CVIB at rest correlated with per cent wall thickening at rest and during dobutamine infusion (at rest, r = 0.61, p < 0.0001, during dobutamine, r = 0.76, p < 0.0001). Of the 76 segments examined, 27 showed contractile reserve. The mean CVIB at rest was significantly greater in segments with contractile reserve than in those without (p < 0.0001). CVIB above 3 dB at rest predicted segments with contractile reserve with a sensitivity and specificity of 81% and 60%, respectively (p < 0.0001).
CONCLUSIONS—CVIB reflected not only myocardial contractility but also the functional capacity of the myocardium. It predicted segmental contractile reserve in patients with chronic left ventricular dysfunction.


Keywords: contractile reserve; acoustic properties of myocardium; cyclic variation of integrated backscatter; left ventricular dysfunction     

Myocardial contractile reserve under low doses of dobutamine and improvement of left ventricular ejection fraction with treatment by carvedilol

To examine the ability of myocardial contractile reserve (MCR) assessment to predict the improvement of left ventricular ejection fraction with treatment by carvedilol, a prospective study was undertaken in 85 patients with chronic heart failure and left ventricular ejection fraction < 45%. Low dose dobutamine echocardiography (DSE), a 6-min walk test and measured brain natriuretic peptide (BNP) were assessed in all the patients. Patients were separated into two groups. Group A were patients without any myocardial reserve and group B patients with a myocardial contractile reserve defined as an increment of more than 20% of the resting left ventricular ejection fraction during dobutamine infusion. The two groups differed for percentage of ischemic cardiomyopathy (67.8 in group A vs. 29.7% in group B P = 0.028), 6-min walk test performance (respectively, 343 vs. 415 meters P < 0.05) and BNP plasma levels (respectively, 184.5 vs. 70.1 P < 0.02) but not for left ventricular ejection fraction or NYHA class. During DSE, MCR and heart rate variation was higher in group B than in group A. At the end of the follow up, LVEF increased and NYHA class decreased in group B but not in group A. In multivariate analysis the existence of MCR could predict the improvement of LVEF with treatment by carvedilol. In our study, studying MCR could help to predict patients who will improve their LVEF with carvedilol prior to the administration of the treatment.     

运动负荷超声评价主动脉瓣置换术后左心室收缩功能储备

目的:应用二维超声斑点追踪技术,评价主动脉瓣置换术后运动负荷试验中的左心室收缩功能储备。方法:21例因重度主动脉瓣狭窄进行瓣膜置换术的患者(左心室射血分数>50%)行运动负荷超声心动图检查,应用二维超声斑点追踪技术测量运动负荷试验中静息状态下及峰值负荷时的左心室收缩期长轴整体应变率(GLSRs),同时记录峰值负荷时的心肌摄氧量(pVO2)。结果与21例正常健康对照者进行比较。结果:静息状态下,病例组与对照组超声指标无明显差异。峰值负荷时,病例组pVO2低于正常组(P<0.05);GLSRs及二尖瓣环心肌收缩速度(Sm)均明显低于正常组(P<0.001)且与pVO2呈正相关(GLSRs:r=0.60,P=0.0007;Sm:r=0.65,P=0.002)。多重线性回归分析,病例组峰值负荷时的左心室收缩期应变率为pVO2的唯一影响因素。结论:主动脉瓣狭窄患者瓣膜置换术后,尽管静息状态下左心室功能正常,但运动负荷试验后,左心室收缩功能储备仍然低于正常。     

Assessment of myocardial viability with dobutamine stress echocardiography in patients with ischemic left ventricular dysfunction

The noninvasive assessment of myocardial viability has proved clinically useful for distinguishing hibernating and/or stunned myocardium from irreversibly injured myocardium in patients with chronic ischemic heart disease or recent myocardial infarction, with marked regional and/or global left ventricular (LV) dysfunction. Noninvasive techniques utilized for the detection of viability in asynergic myocardial regions include positron emission tomographic imaging of residual metabolic activity, single photon emission tomography (SPECT) of radioisotope uptake with thallium-201, low-dose dobutamine echocardiography assessment of inotropic reserve and myocardial contrast echocardiography for evaluation of microvascular integrity. Of these techniques, dobutamine stress echocardiography is a safe, widely available and relatively inexpensive modality for the identification of myocardial viability for risk stratification and prognosis. Low-dose dobutamine response can accurately predict improvement of dysfunctional yet viable myocardial regions, and thus identify a subset of patients whose LV function will improve following successful coronary revascularization.     

Exercise echocardiography predicts development of left ventricular dysfunction in medically and surgically treated patients with asymptomatic severe aortic regurgitation

OBJECTIVE—To assess resting and exercise echocardiography for prediction of left ventricular dysfunction in patients with significant asymptomatic aortic regurgitation.
DESIGN—Cohort study of patients with aortic regurgitation.
SETTING—Tertiary referral centre specialising in valvar surgery.
PATIENTS—61 patients (38 men, 23 women; mean (SD) age 53 (14) years) with asymptomatic or minimally symptomatic aortic regurgitation and no known coronary artery disease; 35 were treated medically and 26 had aortic valve replacement.
INTERVENTIONS—Exercise echocardiography was used to evaluate ejection fraction, which was measured on the resting and post-stress images using the modified Simpson method. Patients with an increment of ejection fraction after exercise were denoted as having contractile reserve (CR+); those without an increment were labelled CR−.
MAIN OUTCOME MEASURES—Standard univariate and multivariate methods and receiver operating characteristic analyses were used to assess the ability of contractile reserve to predict follow up ejection fraction.
RESULTS—In the 35 medically treated patients, 13 of 21 (62%) with CR+ (mean (SD) ejection fraction increment 7 (3)%) had preserved ejection fraction on follow up. In the 14 patients with CR− (ejection fraction decrement 8 (4)%), 13 (93%) had a decrement of ejection fraction on follow up from 60 (5)% at baseline to 54 (3)% on follow up (p = 0.005). Age, resting left ventricular dimensions, medical treatment, aortic regurgitation severity, exercise capacity, and rate-pressure product were similar in both CR+ and CR− groups. Among the 26 surgical patients, 13 showed CR+ (ejection fraction increase 9 (5)%), all of whom had an increase in ejection fraction on follow up (from 49% to 59%). Of 13 surgical patients with CR− (ejection fraction decrease 7 (5)%), 10 (77%) showed the same or worse ejection fraction on postoperative follow up.
CONCLUSIONS—Contractile reserve on exercise echocardiography is a better predictor of left ventricular decompensation than resting indices in asymptomatic patients with aortic regurgitation. In patients undergoing aortic valve replacement, contractile reserve had a better correlation with resting ejection fraction on postoperative follow up. Measurement of contractile reserve may be useful to monitor the early development of myocardial dysfunction in asymptomatic patients with aortic regurgitation, and may help to optimise the timing of surgery.


Keywords: aortic regurgitation; contractile reserve; exercise testing; ejection fraction     

Rest left ventricular function and contractile reserve by dobutamine stress echocardiography in peripartum cardiomyopathy

AimsTo assess whether contractile reserve during dobutamine stress echocardiography (DSE) can predict left ventricular functional recovery in patients with peripartum cardiomyopathy and to assess myocardial fibrosis by magnetic resonance imaging (MRI) in these patients.MethodsNine patients with peripartum cardiomyopathy were enrolled. All patients underwent DSE and were followed for six months, when a rest Doppler echocardiogram was repeated. MRI was also performed at the beginning of follow-up to identify myocardial fibrosis.ResultsMean age was 29 ± 7.9 years and mean left ventricular ejection fraction at baseline was 39.4 ± 8.6% (range 24–49%). Eight of the nine patients showed left ventricular functional recovery with mean ejection fraction at follow-up of 57.1 ± 13.8%. The ejection fraction response to DSE did not predict recovery at follow-up. On the other hand, left ventricular ejection fraction at baseline correlated with ejection fraction at follow-up. Mild fibrosis was detected in only one patient.ConclusionLeft ventricular ejection fraction at baseline was a predictor of left ventricular functional recovery in patients with peripartum cardiomyopathy. Dobutamine stress echocardiography at presentation of the disease did not predict recovery at follow-up. Myocardial fibrosis appeared to be uncommon in this cardiomyopathy.     

Dobutamine stress echocardiography and the effect of revascularization on outcome in diabetic and non-diabetic patients with chronic ischaemic left ventricular dysfunction

AIM: To evaluate the interaction between prognostic effect of revascularization and viability in diabetic and non-diabetic patients with ischaemic left ventricular dysfunction. METHODS: 612 patients with angiographically proven coronary artery disease and left ventricular ejection fraction <35% underwent dobutamine stress echocardiography to assess viability (peak-rest wall motion score index >0.4). 262 patients (75 diabetics, 187 non-diabetics) underwent revascularization and 350 (88 diabetics, 262 non-diabetics) were on medical therapy. RESULTS: During follow-up 215 patients died. Independent predictors of mortality in revascularized patients were resting left ventricular ejection fraction (HR=0.93, 95% CI 0.89-0.97, p<0.0001), Delta WMSI>40 (HR=0.44, 95% CI 0.23-0.85, p=0.01), and age (HR=1.03, 95% CI 1.00-1.06, p=0.04). In medically treated patients, independent predictors of mortality were diabetes mellitus (HR=1.64, 95% CI 1.13-2.38, p=0.009), number of diseased vessels (HR=1.27, 95% CI 1.03-1.56, p=0.02), and age (HR=1.02, 95% CI 1.00-1.04, p=0.03). In revascularized patients, 4-year mortality was 15% in those with viability and 26% in those without viability (p=0.04), there was no difference between diabetics and non-diabetics (24% vs 22%; p=0.24). CONCLUSIONS: Viability at dobutamine stress echocardiography independently predicts improved outcome following revascularization in non-diabetics as well as diabetic patients with ischaemic left ventricular dysfunction.     

NT-proBNP response to dobutamine stress echocardiography predicts left ventricular contractile reserve in dilated cardiomyopathy

BACKGROUND: Brain natriuretic peptide (BNP) and left ventricular (LV) inotropic reserve are major prognostic indexes in heart failure (HF). AIMS: To investigate the relationship between N-terminal-proBNP (NT-proBNP) changes in response to dobutamine stress echocardiography (DSE) and the LV inotropic reserve, in HF patients with dilated cardiomyopathy (DC). METHODS: We studied 41 patients with DC, LVEF 31.6+/-7.7%, NYHA class II-III and 15 controls. Plasma NT-proBNP levels were measured before and 60 min after three 5-min stages of dobutamine (5 to 15 microg/kg/min). RESULTS: Based on NT-proBNP changes in response to dobutamine, patients were categorized into two groups: In Group A circulating NT-proBNP levels fell (-16.6+/-7.8%), and in Group B they increased (8.4+/-9.1%). Group A had a marked improvement in WMSI compared to Group B (32.1+/-9.7% vs. 18.8+/-15.9%, p<0.001). Multivariate analysis showed that NT-proBNP changes were an independent predictor of LV inotropic reserve (b= -0.55, p<0.001). A reduction of 21.3% in plasma NT-proBNP levels in response to dobutamine predicted an improvement in WMSI of >25% with a sensitivity of 100% and a specificity of 92.3%. CONCLUSIONS: NT-proBNP changes in response to dobutamine reflect improvement in LV contractility and constitute an independent predictor of LV inotropic reserve in patients with DC.     

The prognostic value of myocardial viability recognized by low dose dipyridamole echocardiography in patients with chronic ischaemic left ventricular dysfunction.

AIMS: The aim of this study was to assess the prognostic value of myocardial viability recognized as a contractile response to vasodilator stimulation in patients with left ventricular dysfunction in a large scale, prospective, multicentre, observational study. METHODS AND RESULTS: Three hundred and seven patients (mean age 60 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction and severe left ventricular dysfunction (ejection fraction <35%; mean ejection fraction: 28 +/- 7%) were enrolled in the study. Each patient underwent low dose dipyridamole echo (0.28 mg x kg(-1) in 4 min). Myocardial viability was identified as an improvement of >0.20 in the wall motion score index. By selection, all patients were followed up for a median of 36 months. One-hundred and twenty-four were revascularized either by coronary artery bypass grafting (n=83) or coronary angioplasty (n=41). The only end-point analysed was cardiac death. In the revascularized group, cardiac death occurred in one of the 41 patients with and in 16 of the 83 patients without a viable myocardium (2.4% vs 19.3%, P<0.01). Outcome, as estimated by Kaplan-Meier survival, was better for patients with, compared to patients without, a viable myocardium, who underwent coronary revascularization (97.6 vs 77.4%, P=0.01). Using a Cox proportional hazards model, the presence of myocardial viability was shown to exert a protective effect on survival (chi-square 4.6, hazard ratio 0.1, 95% CI 0.01-0.8, P<0.03). The survival rate in medically treated patients was lower than in revascularized patients irrespective of the presence of a viable myocardium (79.7% vs 86.2, P=ns). CONCLUSION: In severe left ventricular ischaemic dysfunction, myocardial viability, as assessed by low dose dipyridamole echo, is associated with improved survival in revascularized patients.     

Comparison of dobutamine echocardiography and positron emission tomography in patients with chronic ischemic left ventricular dysfunction

Objectives. The aim of this study was to correlate dobutamine-induced contractile reserve as detected by echocardiography with findings on positron emission tomography in patients with chronic ischemic left ventricular dysfunction.

Background. Contractile reserve induced by low dose dobutamine infusion has been proposed as a marker of myocardial viability.

Methods. Sixty patients with stable coronary artery disease and left ventricular dysfunction (mean ejection fraction [± SD] 29 ± 10%) underwent transthoracic echocardiography with dobutamine infusion (up to 10 μg/kg body weight per min) and positron emission tomography with nitrogen-13 ammonia and fluorine-18 (F-18) fluorodeoxyglucose as a perfusion and a metabolic tracer, respectively. Regional wall motion, perfusion and metabolism were analyzed semiquantitatively by using a 16-segment model. Segments with F-18 fluorodeoxyglucose uptake > 50% were considered viable on positron emission tomography.

Results. After dobutamine infusion, hemodynamic variables changed significantly, and myocardial ischemia was evident in 17 patients. All 60 patients had dysfunctional myocardium considered viable on positron emission tomography (8 ± 4 segments/patient), whereas 52 patients had dysfunctional myocardium with contractile enhancement by dobutamine echocardiography (4 ± 2 segments/patient, P = 0.01). The extent of dysfunctional myocardium with contractile reserve appeared to correlate less closely with the total extent of viable dysfunctional myocardium identified by positron emission tomography than with the number of such segments associated with a pattern of perfusion-metabolism mismatch.

Conclusions. In patients with chronic ischemic left ventricular dysfunction, echocardiography can be used to identify enhancement in the contractile function of viable dysfunctional myocardium after infusion of low dose dobutamine. In this study, the presence and extent of such enhancement were relatively less than the values obtained from positron emission tomography.     

Presence of left ventricular contractile reserve, evaluated by means of dobutamine stress-echo test, is able to predict response to cardiac resynchronization therapy

Introduction  We evaluated whether the dobutamine stress-echo test can select responders to cardiac resynchronization therapy (CRT). Up to 50% of patients do not respond to CRT. Lack of response may be due to a significant amount of scar or fibrotic tissue at myocardial level. Methods and Results  We studied 42 CRT patients. After clinical and echocardiographic evaluation, all patients underwent a dobutamine stress-echo test to assess contractile reserve. Cut-off for the test was an increase of 25% of the left ventricular ejection fraction. Patients were implanted with a CRT–defibrillator and followed up at 6 months. Cut-off for CRT response was a reduction of 15% of left ventricular end-systolic volume. Twenty-five patients responded to CRT; all of them showed presence of contractile reserve. The test showed a sensitivity of 100% and a specificity of 88%. Conclusion  Contractile reserve was a strong predictive factor of response to CRT in the studied population.     

Relation of ultrasonic tissue characterization with integrated backscatter to contractile reserve in patients with chronic coronary artery disease

BACKGROUND: Previous studies have shown that viable but stunned myocardium displays contractile reserve and exhibits cardiac cycle-dependent variations of integrated backscatter (CVIB), whereas infarcted myocardium does not. HYPOTHESIS: This study was designed to clarify whether assessment of the acoustic properties of the myocardium can predict contractile reserve in patients with chronic coronary artery disease (CAD). METHODS: In all, 21 patients with chronic CAD and 19 normal control subjects were studied. The magnitude of CVIB of the myocardium was measured in the basal and mid segment of the anterior septum and posterior wall of the left ventricle, using a real-time, two-dimensional integrated backscatter imaging system. The results were compared with the percent systolic wall thickening and the wall motion before and after revascularization. The wall motion was graded as normal, hypokinetic, or akinetic, and contractile reserve was considered present when an akinetic or hypokinetic segment improved after revascularization. RESULTS: The average magnitude of CVIB was lower among dysfunctional segments of CAD than among normal segments of controls (3.73 +/- 1.71 vs. 6.35 +/- 0.69, p < 0.001). Of the 77 segments examined, 38 showed reversible dysfunction. Before revascularization, percent systolic wall thickening was similar among segments showing contractile reserve compared with those with persistent dysfunction myocardium (17.97 +/- 8.41 vs. 16.83 +/- 6.37%, p = 0.19), and the mean CVIB was significantly greater in segments with than in those without contractile reserve (4.73 +/- 1.47 vs. 2.75 +/- 1.31, p < 0.001). The CVIB above 3 dB before percutaneous transluminal coronary angioplasty predicted segments with contractile reserve with a sensitivity and specificity of 84.2 and 79.5%, respectively. CONCLUSIONS: Cardiac cycle-dependent variations of integrated backscatter reflected myocardial contractility and functional capacity of the myocardium. They predicted segmental contractile reserve in patients with CAD.     

Use of cyclic variation of integrated backscatter to assess contractile reserve and myocardial viability in chronic ischemic left ventricular dysfunction

The detection of viable myocardium has important implications for management, but use of stress echocardiography to detect this is subjective and requires exposure to dobutamine. We investigated whether cyclic variation (CV) of integrated backscatter (IB) from the apical views could provide a resting study for detection of contractile reserve (CR) and prediction of myocardial viability in 27 patients with chronic ischemic left ventricular (LV) dysfunction. Repeat echocardiography was performed after 6.7 +/- 3.8 months of follow-up; 14 patients underwent revascularization and 13 were treated medically. Using a standardized dobutamine echocardiography (DbE) protocol, images from three apical views were acquired at 80-120 frames/sec at rest and during stress. CR was identified if improvement of wall motion was observed at low dose (5 or 10 microg/kg/min) DbE. Myocardial viability was characterized by improvement at follow-up echocardiography in patients with revascularization. CVIB at rest and low dose dobutamine were assessed in 194 segments with resting asynergy (severe hypokinesis or akinesis), of which 88 (45%) were in patients who underwent revascularization. Of these, CVIB could be measured in 190 (98%) segments at rest and 185 (95%) at low dose dobutamine. Sixty-two (33%) segments had CR during low dose DbE and 50 (57%) segments showed wall-motion recovery (myocardial viability) at follow-up echocardiography. Segments with CR had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P = 0.005) than segments without CR. Using optimal thresholds of CVIB (> 8.2 dB) at rest, the accuracy of CVIB for detecting CR was 70%. Compared with nonviable segments, viable segments had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P < 0.001). Using optimal thresholds of CVIB (> 5.3 dB) at rest, the accuracy of CVIB for detecting myocardial viability was 85%, which was higher than that in conventional DbE (62%, P < 0.01). Thus, assessment of CVIB from the apical views is a feasible and accurate tool for detecting CR and predicting myocardial viability in chronic LV dysfunction.