Low-dose Dobutamine Stress Research Articles

Assessment of biventricular functional reserve and NT-proBNP levels in patients with RV volume overload after repair of tetralogy of Fallot at young age

Purpose To assess biventricular functional reserve (FR), NT-proBNP levels and exercise performance, in relation to right ventricular volume in patients with pulmonary regurgitation (PR) after repair of tetralogy of Fallot (TOF) at young age. Methods In 53 TOF patients (maximum age at repair 2.0 years, interval since repair 15 (5) years) without residual lesions except PR, biventricular FR (derived from magnetic resonance imaging with dobutamine stress), NT-proBNP levels, maximal workload, and peak oxygen uptake were assessed. Results Mean right ventricular end-diastolic volume was 140(38) ml/m 2. Median pulmonary regurgitant fraction was 37% (range 0–57%). Biventricular systolic stress response was normal: mean (SD) ESV decreased (ΔRVESV − 17(8) ml/m 2, ΔLVESV − 11(5)), SV increased (ΔRVSV + 12(9) ml/m 2, ΔLVSV + 9(6)), FR was positive in all (RV-FR + 11(5)%, LV-FR + 13(6)). No serious adverse effects to dobutamine were encountered. NT-proBNP was increased in 2 patients. Median level was 10 pmol/L (range 2–42). NT-proBNP correlated with PR-percentage but not with right ventricular size. High-risk levels of NT-proBNP indicated a smaller RV-FR and a smaller decrease of biventricular ESV. Mean (SEM) VO2 max was 96(3)%, mean Workload max 89(2)% of predicted. Conclusion At mid to long term follow-up overall NT-proBNP levels are normal and biventricular functional reserve and exercise tolerance are well preserved in TOF repaired at young age, irrespective of RV volume. This questions the validity of isolated PR or RV volume criteria for pulmonary valve replacement in this group. Low-dose dobutamine stress testing is well tolerated and may be a useful additional tool for clinical decision making.

Usefulness of Cardiac Magnetic Resonance Imaging Combined With Low-Dose Dobutamine Stress to Detect an Abnormal Ventricular Stress Response in Children and Young Adults After Fontan Operation at Young Age

After Fontan operation, patients are limited in increasing cardiac output and in exercise capacity. This has been related to impaired preload or other factors leading to decreased global ventricular performance with stress. To study these factors, the stress responses of functionally univentricular hearts were assessed at rest and during low-dose dobutamine stress using cardiovascular magnetic resonance imaging. Thirty-two patients after Fontan completion at young age were included (27 with total cavopulmonary connection, 5 with atriopulmonary connection; mean age 13.3 years, range 7.5 to 22.2; 23 male patients; median follow-up after Fontan operation 8.1 years, range 5.2 to 17.8). A multiphase short-axis stack of 10 to 12 contiguous slices of the systemic ventricle was obtained at rest and during low-dose dobutamine stress cardiovascular magnetic resonance imaging (maximum 7.5 microg/kg/min). With stress-testing, heart rate, ejection fraction, and cardiac index increased adequately (p <0.001). There was an abnormal decrease in end-diastolic volume and an adequate decrease in end-systolic volume (p <0.001). Stroke volume did not change with stress testing (p = 0.15). At rest, dominant left ventricles had higher ejection fractions than dominant right ventricles (p = 0.01), but this difference disappeared with stress testing. In conclusion, a functionally univentricular heart after Fontan completion at young age has an adequate increase in ejection fraction with beta-adrenergic stimulation. However, as a result of impaired preload with stress, cardiac output can be increased only by increasing heart rate.

O119 Identification of inducible ischemic myocardium by strain rate imaging during low-dose dobutamine stress echocardiography

O119 Identification of inducible ischemic myocardium by strain rate imaging during low-dose dobutamine stress echocardiography

Quantitation of Myocardial Borderzone Using Reconstructive 3-D Echocardiography After Chronic Infarction in Rats—Incremental Value of Low-Dose Dobutamine

Myocardial remodeling determines the degree of left ventricular dysfunction and mortality after transmural chronic myocardial infarction (CMI). Noninvasive characterization and quantitation of myocardial borderzone and collagenous scar are therefore parameters of clinical interest. The aims of this study were (i) to measure accuracy of reconstructive 3-D echocardiography (3DE) in scar and myocardial borderzone size assessment and (ii) to investigate the incremental value of low-dose dobutamine stress. 3DE was performed in 14 immunodeficient rats (rnu-rnu, 180–200 g) with anterior CMI 25 d after coronary ligation. Briefly, consecutive parallel short-axis cineloops were obtained electrocardiogram-gated starting from base to the apex. Morphology (mass, surface) and function (contractility, contractile reserve) of different compartments were assessed and correlated with 3-D histomorphometry. Histology was done using picrosirius red for collagen staining. 3DE left ventricular mass correlated closely with histomorphometry (y = 0.89x + 155, p < 0.0001, r = 0.80). Hypo- and akinetic myocardial surface correlated well with borderzone myocardium (y = 0.34x + 17, p = 0.009, r = 0.62) and collagenous scar (y = 1.9x + 4.4, p < 0.0001, r = 0.79), respectively. Extent of abnormal wall motion was closely related to borderzone and scar tissue area (y = 0.82x + 7, p < 0.0001, r = 0.77). 3DE quantitation of borderzone myocardium, but not collagenous scar, was more closely correlated to histomorphometry during inotropic stimulation. Global contractile reserve is positively associated with the size of myocardial borderzone. Regional contractile reserve of borderzone myocardium is not negatively associated with its collagen content. 3DE allows precise quantitation of myocardial borderzone and identification of transmural scar tissue noninvasively. Assessment of contractile reserve improves characterization and estimation of myocardial borderzone after CMI. (E-mail: ghanem@uni-bonn.de)

Cardiac Reserve in the Transplanted Heart: Effect of a Graft Polymorphism in the β 1-adrenoceptor

Polymorphism of the beta1-adrenoceptor (beta1-AR) affects outcome and beta-blocker efficacy in patients with heart failure. We studied the influence of the beta1-AR Ser49Gly polymorphism on cardiac reserve in transplanted hearts. Beta1-AR polymorphism was determined by allelic discrimination analysis. Patients were divided into two groups: either homozygous for Ser49 (n = 15) or with Gly49 in one or both alleles (Gly49; n = 5). Patients underwent a maximal bicycle exercise test and echocardiographic evaluation at rest and during low-dose dobutamine stress. Patients with Gly49 grafts had better physical endurance (144 +/- 26 vs 112 +/- 31 W, p = 0.03), a trend toward better chronotropic reserve (deltaHR 64 +/- 13 vs 47 +/- 16 bpm, p = 0.056) during exercise, and lower resting heart rate (82 +/- 7 vs 90 +/- 7 bpm, p = 0.04) than those homozygous for Ser49. There were no significant differences in left ventricular ejection fraction (LVEF), with the exception of a decrease in cardiac reserve in patients with the Gly49 variants at the lowest dose of dobutamine (deltaLVEF -4.4 +/- 1.5 vs 2.2 +/- 5.8%, p = 0.04). Doppler myocardial tissue velocities of early relaxation were increased in patients with the Gly49 variants compared with patients homozygous for Ser49, both at rest (14.5 +/- 3.2 vs 10.4 +/- 2.0 cm/s, p = 0.03) and during the lowest dose of dobutamine (15.0 +/- 3.7 vs 10.9 +/- 2.5 cm/s, p = 0.04). Heart transplant patients with the beta1-AR Gly49 variants had a lower heart rate, and better stress endurance and diastolic function compared with patients homozygous for Ser49. They also showed a trend toward better chronotropic reserve. These results provide a possible explanation for differences in cardiac reserve among patients with heart transplants.

Influence of Age, Hypertension, and Diabetes on Cardiac Reserve in a Rat Model

Cardiac reserve decreases with age1 and is impaired in heart disease both of ischemic and nonischemic cause.2 It correlates well with peak oxygen consumption per unit time during exercise, and measurement of cardiac reserve can be used as a tool to predict survival and outcome in patients with cardiomyopathy.3 Low-dose dobutamine stress echocardiography (DSE) is a well-established method to investigate cardiac reserve in human beings.4 DSE has also been used in several animal species since the early 1990s, but mostly at higher doses for evaluation of myocardial perfusion and ischemia.

Comparision the value of detecting myocardial viability between low dose dobutamine stress MRI and echocardiography

目的 对比小剂量多巴酚丁胺负荷MRI与负荷超声心动图检测存活心肌的价值.方法 对30例陈旧心肌梗死患者(急性心肌梗死发作后3个月以上,具有静息期室壁运动异常)分别行静息和负荷(5、10 μg ·kg-1·min-1)MR及超声心动图检查.24例进行了血运重建,经皮穿刺冠状动脉成形术(PTCA)16例,冠状动脉旁路搭桥术(CABG)8例.血运重建术后3～6个月,10例患者进行静息MR检查以观察节段心肌运动恢复情况.心肌节段划分采用16节段分法,MRI存活心肌的定义为:≥2个相邻的静息期无运动及反向运动的节段,负荷后节段心肌收缩≥2 mm;超声心动图心肌存活的定义为:≥2个相邻的静息期无运动及反向运动的心肌节段负荷后,室壁运动评分减少≥1分.结果 30例患者108个心肌节段静息期运动异常,多巴酚丁胺负荷MRI阳性65个节段,阴性43个节段;负荷超声心动图阳性56个节段,阴性52个节段.2种方法一致性Kappa值为0.75,符合率为88%,具有高度一致性.10例患者38个心肌节段进行了复查,其中24个节段运动增加,14个节段无改善.MRI及超声心动图检测陈旧心肌梗死存活心肌的敏感度、特异度、准确度分别为95.8%和79.2%(P＞0.05), 85.7%和85.7%(P＞0.05), 92.1%和81.6%(P＞0.05).结论 多巴酚丁胺负荷MRI与负荷超声心动图的诊断能力相当,MRI敏感度、准确度略高。

Clinical, serum cardiac troponin T and echocardiographic evaluation for prediction of late doxorubicin cardiotoxicity

9536 Background: To evaluate whether clinical signs or symptoms of congestive heart failure, serial assessment of systolic and diastolic cardiac function by low dose dobutamine stress echo (LDSE) and serum cardiac troponin T (cTnT) can predict doxorubicin (DOXO) cardiotoxicity. Methods: Twenty five patients with osteosarcoma enrolled in the Brazilian osteosarcoma treatment group study 2000, from january 2000 to may 2004, were studied with LDSE (&gt;5μg/kg/min) before chemotherapy, 160 mg/m2 DOXO and after 160 mg/m2 DOXO. cTnT were measured before and during DOXO infusion. Cardiotoxicity was defined as shortening fraction (SF) less than 30% assessed by rest echo 1 to 6 months off chemotherapy. Group A comprised those without cardiotoxicity (16 patients, 10 male, 14.3 ± 4.7 years) whereas group B included those with a SF &lt; 30% (9 patients, 6 male, 15.4 ± 3 years). Elevated serum cTnT was defined as seric levels above 0.01ng/ml. Results: Patients were submitted to a mean 3.4 LDSE and a mean of 32.5 serum cTnT. One patient (group B) presented clinical manifestation of cardiotoxicity. There was no statistical difference of elevated serum cTnT between the group B and group A (87.5% vs 46.2%; p=0,06). Left ventricular dimensions by M- MODE and transmitral Doppler inflow diastolic parameters were not significantly different between the two groups. Resting SF showed comparable values in both groups until cumulative doses of DOXO reached 160mg/m2, then the resting SF in group B was significant lower than group A (27% ± 2 and 34.1% ± 2, p&lt;0.01). During dobutamine infusion, SF and ΔSF (dobutamine-rest) were significantly lower in group B as compared to group A at a DOXO dose 160mg/m2 (SF 36.1%±3,4 and ΔSF 2.1±2.3 vs. SF 45.2%±4.9 and ΔSF 9.4±3; p&lt; 0.01 and p &lt; 0.01) as well as at a DOXO dose &gt; 160mg/m2 (30.3%±3 and 3.1±1.9 vs. 40.8%±5.9 and 7.2±4.2;p&lt;0.01 and p&lt;0.01). Conclusions: This study suggests that LDSE is more reliable than cTnT and clinical evaluation for predicting future subclinical cardiotoxicity,even at lower doxorubicin dose. No significant financial relationships to disclose.

2137: Novel myocardial viability index assessed by strain rate imaging correlates with left ventricular diastolic function in the early phase after acute coronary syndrome

Objectives: Experimental studies showed myocardial viability may influence on the diastolic function of left ventricle (LV) in the early phase after acute coronary syndrome (ACS). But there were few reports about this relationship in human. Methods: Ninety-three consecutive patients with ACS and akinetic wall motion in at least two segments underwent low dose dobutamine stress echocardiography to assess myocardial viability on 7 ± 2 days after the event. Myocardial viability was quantitatively evaluated by a strain rate imaging parameter, the percent change of time to the onset of regional relaxation (TR) as well as wall motion score index. Within 6 hours after the study, left and right heart catheterizations for recording of pressures were performed. Myocardial viability index (MVI) was newly devised in this study. Results: Patients (68.8% men, mean age 59.9 ± 1.3 years) tolerated stress echocardiography without complications. MVI showed significant linear correlations with left atrial volume index, deceleration time of transmitral E wave and E/E’ratio. Also, interestingly, MVI showed significant linear correlation with invasive pulmonary capillary wedge pressure (r = 0.72, p = 0.00). Conclusions: MVI acquired by strain rate imaging on low dose dobutamine stress echocardiography may provide a useful prognostic information for LV remodelling in the early phase of ACS.

Traditional and Color M-Mode Parameters of Left Ventricular Diastolic Function During Low-dose Dobutamine Stress Echocardiography: Relations to Contractility Reserve

Cross-sectional studies reported that left ventricular (LV) systolic and diastolic functions are correlated. However, whether changes in wall-motion score index (WMSI) or 2-dimensional ejection fraction (EF) predict changes of Doppler parameters of LV diastolic function is unclear. Patients with known or suspected history of coronary artery disease underwent assessment of LV systolic function (WMSI, EF) and diastolic function at baseline and during stress echocardiography by low-dose dobutamine (LDD) (peak infusion 10 microg/kg/min). Peak velocities of early (E) and late (A) LV filling waves and E wave deceleration time were measured according to standard protocol. E wave propagation rate (EVp) was assessed by color Doppler M-mode across the mitral valve. Tei index was calculated as: (A wave to E wave time - ejection time)/ejection time. Changes at LDD were calculated as: 100 x (value at LDD - value at baseline)/baseline. The study group comprised 66 patients, mean age 61 +/- 10 years, 80% men. Worse LV systolic function was associated with more severely impaired LV diastolic function both at baseline and at LDD. However, percent change of WMSI and change in EF did not correlate with percent change of EVp and E/E wave propagation rate, but with percent change of Tei index. At LDD, patients with myocardial viability did not show greater percent change of LV diastolic function parameters but significantly lower Tei index. In patients with suspected or known coronary artery disease, assessment of diastolic function reserve by LDD stress echocardiography using traditional and color M-mode Doppler may add quantitative information on myocardial function beyond traditional assessment of contractility reserve by WMSI or EF.

Low-dose dobutamine stress echocardiography predicts the improvement of left ventricular systolic function and long-term prognosis in patients with idiopathic dilated cardiomyopathy

It is unclear whether left ventricular (LV) contractile reserve assessed by low-dose dobutamine stress echocardiography (DSE) can predict the long-term prognosis together with LV functional changes in patients with idiopathic dilated cardiomyopathy (DCM). Contractile reserve was determined in 28 patients with DCM, and was then compared with changes in LV fractional shortening (FS) and cardiac events during a follow-up period of 68 ± 43 months. Nine events (2 sudden deaths, 5 heart failure deaths, and 2 rehospitalizations for heart failure) were observed. FS at peak dose was lower in patients with events (events group) than in those without events (no-events group) (20 ± 6 vs. 27 ± 7%; P < 0.05), although there were no differences in FS at baseline between the two groups. FS at follow-up was lower in the events group than in the no-events group (14 ± 7 vs. 21 ± 8%; P < 0.05). The change in FS during DSE (FS at peak dose/baseline) correlated with the change in FS during the follow-up time (FS at follow-up/baseline), and it was a predictor of events by multiple regression analysis. LV contractile reserve assessed by low-dose DSE is a useful marker not only to predict LV functional improvement, but also to determine the long-term prognosis in patients with DCM.

Section 13: Evaluation and Therapy for Heart Failure in the Setting of Ischemic Heart Disease

Section 13: Evaluation and Therapy for Heart Failure in the Setting of Ischemic Heart Disease

Utility of Combined Assessment of Coronary Flow Velocity and Myocardial Perfusion During Low-dose Dobutamine Stress Echocardiography in the Detection of Left Anterior Coronary Artery Disease

Background. Ischemia produces a sequence of events beginning with a decline in coronary flow reserve, myocardial perfusion abnormalities, and wall motion abnormalities. We hypothesized that low-dose dobutamine stress, combined with myocardial contrast echocardiography (MCE) and transthoracic Doppler echocardiography (TTDE), could detect myocardial ischemia preceding wall motion abnormalities according to this ischemic cascade.Methods. Ninety-six patients suspected of having stable angina pectoris underwent TTDE, MCE, and semi-quantitative dobutamine stress echocardiography (Semi-DSE). Wall motion was assessed using a scoring system. The contrast agent, Levovist, was injected intravenously to assess the coronary flow velocity (CFV) ratio in the left anterior descending coronary artery (LAD) and myocardial perfusion abnormalities in the LAD territory. The CFV ratio was calculated as the CFV during low-dose dobutamine stress divided by the baseline CFV. Time-intensity data for MCE were fitted for y = A (1-e-βt) from which the rate of the intensity rise (β) was calculated and the β ratio was derived at baseline and during stress.Results. Semi-DSE and low-dose dobutamine stress combined with TTDE and MCE were obtained successfully in 85 patients. The sensitivity and specificity of Semi-DSE for detecting ≥75% LAD stenosis were 79% and 93%, respectively. In the LAD territory, Semi-DSE showed 6 false negative and 4 false positive findings. However, failures of the CFV ratio and β ratio to increase >1.81 and >1.23 times that at baseline, respectively, indicated the presence of critical LAD stenosis, especially in 3 out of 6 false negative cases.Conclusions. Low-dose dobutamine stress combined with TTDE and MCE is a useful method for detecting critical LAD stenosis during Semi-DSE. This method overcomes the limitations of Semi-DSE.

Assessment of tissue viability for improvement of the left ventricular function after revascularization

Treatment of patients with heart failure following myocardial infarction is still a clinical challenge. Drug therapy in these patients is limited, and invasive revascularization is not always successful and does not guarantee desired results. The aim of this study was to compare the effectiveness of invasive revascularization procedures (coronary artery bypass grafting - CABG or percutaneous transluminal coronary angioplasty - PTCA) with conventional drug therapy in patients with heart failure after acute myocardial infarction in whom significant portion of viable myocardial tissue was detected during low dose dobutamine stress echocardiography. Using a prospective analysis, we investigated 66 patients with heart failure following myocardial infarction and reduced left ventricular ejection fraction (LVEF <35%). 34 patients underwent revascularization procedures including CABG or PTCA. The other 32 patients received only conventional drug therapy. The patients were followed during 12 months examing LVEF, left ventricular wall motion score index (WMSI), NYHA functional class, and cardiac death. After 12 months, patients undergoing revascularization procedures presented with significantly better functional improvement of LVEF (37.84% vs. 33.14%, p<0.05), better clinical status and significantly less cardiac deaths (8.82% vs. 21.87%, p<0.01) in comparison to patients who stayed on drug therapy. After 12 months WMSI was significantly better in patients who underwent interventional therapy (1.69 +/- 07 vs. 1.82 +/- 04, p<0.01). After a 12-month follow up period, patients with presence of viable myocardial tissue after myocardial infarction and undergoing revasculkatization procedures presented with better functional recovery and less cardiac events, including cardiac death, in comparison with patients who received only drug therapy.

Determination of ventricular volumes in coronary artery disease

Comparison of two gated SPECT analysis tools -- gated SPECT quantification (GSQ) and emory cardiac toolbox (ECT) -- in patients with coronary artery disease (CAD) and severely impaired left ventricular function (preoperative: EF <35% by cardiac catheter). A total of 56 gated SPECT examinations (one-day hybrid-protocol with (201)Tl-chloride for rest and (99m)Tc-sestamibi for stress applied during low-dose dobutamine stress MR-examination; temporal resolution; 8 phases per cardiac cycle) were performed in 36 patients (31 preoperatively, 25 postoperatively) and compared with MRI in 48 cases. Left ventricular end-diastolic (LV-EDV) and end-systolic (LV-ESV) volumes as well as the left ventricular ejection fraction (LV-EF) were calculated. The total volumetric assessment by both analysis algorithms (n = 56) showed good intraclass correlation coefficients preoperatively (n = 31), but even better postoperatively (n = 25). The mean reconstruction time was approximately 3 minutes ( +/- 2 SD) for GSQ and 15 minutes ( +/- 5 SD) for ECT. In comparison to MRI the results of both analysis tools also correlated well, but the agreement decreased in the presence of scared tissue. The mean LV-EF (MRI) preoperatively was 30.4%, in 6/36 patients above the values calculated from cardiac catheter, postoperatively 34.6%. Both gated SPECT analysis tools showed reliable volumetric assessments in high-risk patients with CAD and severely reduced LV-EF in comparison to MRI, with advantages for GSQ in terms of postprocessing time. However, for the calculation of LV-EF a markedly lower concordance with MR-results was observed for both methods depending on the presence of myocardial scars.

Effect of Atropine-dobutamine Stress Test on Left Ventricular Echocardiographic Parameters in Untrained Warmblood Horses

The aim of this study was to investigate the effect of combined atropine low-dose dobutamine stress test on left ventricular parameters in adult warmblood horses, to establish a potential protocol for pharmacological stress echocardiography. Seven healthy untrained warmblood horses aged 9 to 22 years were used. Heart rate (HR) and left ventricular B- and M-mode dimensions were recorded at baseline and during stress testing with 35 microg/kg atropine IV followed by incremental dobutamine infusion of 2 to 6 microg/kg/min. HR increased significantly (P < .05) during the pharmacological challenge, and a maximal HR of 156.6 +/- 12.5 bpm was reached at maximal dobutamine infusion rate. Systolic and diastolic interventricular septum thickness, systolic and diastolic left ventricular free wall thickness, and fractional shortening increased significantly and reached a maximum at the highest infusion rate (mean +/- SD: 4.51 +/- 0.27 versus 5.65 +/- 0.31 cm, 2.89 +/- 0.19 versus 3.78 +/- 0.10 cm, 3.72 +/- 0.34 versus 4.77 +/- 0.18 cm, 2.44 +/- 0.28 versus 3.11 +/- 0.34 cm, 34.98 +/- 3.82 versus 50.56 +/- 3.42%, respectively). Systolic and diastolic left ventricular internal diameter decreased significantly during dobutamine infusion. Left ventricular external and internal area were significantly lower at a dobutamine infusion rate of 2 microg/kg/min but no further decrease was observed during the subsequent steps. Systolic and diastolic myocardial area was significantly lower after the administration of dobutamine but not significantly different during dobutamine infusion, when compared to baseline values. This pharmacological stress test induced significant changes in left ventricular echocardiographic parameters in adult warmblood horses. Additional research should evaluate the value of this stress test in horses suffering from cardiac disease.

Low‐Dose Dobutamine Stress Echocardiography to Predict Reversibility of Mitral Regurgitation with CABG

The optimal management of moderate (grade 2-3+) ischemic mitral regurgitation (MR) in patients undergoing coronary artery bypass grafting (CABG) remains controversial. While CABG alone can reverse regurgitation in some patients with moderate MR, adjunctive mitral repair may be necessary in others. We performed low-dose dobutamine stress echocardiography (DSE) in 60 patients with moderate MR who were about to undergo CABG. Group I, 25 patients who demonstrated reduction in MR during DSE, had CABG alone. Group II, 35 patients in whom MR was unchanged during DSE, had mitral valve repair as well as CABG. MR was reduced postoperatively in both groups (P < 0.0001). Postoperative ejection fraction in Group I (12.2%) improved more than that in Group II (9.3%) (P < 0.01). We conclude that CABG alone may be sufficient to correct moderate MR when MR is reduced during DSE.

Quantification of valvular lesions in patients with left ventricular dysfunction

Echocardiography is the preferred method for assessment of aortic and mitral valvular lesions. The pressure gradient in aortic stenosis may be misleading in patients with poor left ventricular function. Aortic valve area planimetry by transesophageal echocardiography results in a flow independent anatomic measurement. Low-dose dobutamine stress echocardiography provides important prognostic information. Quantitative Doppler echocardiography allows accurate assessment of mitral regurgitation severity. However, the definition of what is severe mitral regurgitation is different in patients with left ventricular dysfunction.

The presence of contractile reserve has no predictive value for the evolution of left ventricular function following atrio-ventricular node ablation in patients with permanent atrial fibrillation

Transcatheter ablation of the atrio-ventricular (AV) node followed by ventricular pacing has been shown to improve symptoms and quality of life (QOL) of patients with permanent atrial fibrillation (AF). In a considerable number of patients, cardiac function deteriorates after AV node ablation. We aimed to determine whether the absence of contractile reserve assessed by low dose dobutamine stress echocardiography (LDDSE) could identify those patients whose left ventricular (LV) function deteriorates after AV node ablation. All 25 patients studied had permanent AF for at least 12 months. LVEF was determined 6 days and 3 months after AV node ablation by radionuclide ventriculography (RNV), at a paced rate of 80 beats/min. Deterioration in cardiac function was defined as a decrease in LVEF>5%. LDSE was performed in all patients before and after ablation. The presence of contractile reserve was defined as an improvement in regional function of >or=1 grade at low dose dobutamine in at least 4 segments. QOL measurements were taken using Minnesota, NHBP and MPWB questionnaires. LVEF showed no improvement in the overall group (52.8+/-11.1% vs. 51.8+/-9.8%, p=NS). QOL showed significant improvement in all questionnaires (Minnesota: 4.1+/-2.1 vs. 2.5+/-2, p=0.001; NHBP: 54.8+/-43.3 vs. 34.2+/-34.3, p=0.002; MPWB: 22.2+/-4.6 vs. 19.4+/-6.2, p=0.03). There was no significant difference in change of LVEF between patients with and without contractile reserve (-0.4+/-8.7 vs. 1.6+/-11.3, p=NS). However, patients with a preserved LVEF at baseline showed more frequently a reduced LVEF after AV node ablation (62.2+/-10.4% vs. 47.5+/-7.6%, p=0.001). (1) The absence of contractile reserve does not predict deterioration of cardiac function after AV node ablation. (2) AV node ablation results in a significant improvement in QOL, which is not necessarily associated with improvement of LVEF. (3) Higher baseline LVEF predicts deterioration of cardiac function. These data suggest that although AV node ablation is an excellent way of controlling symptoms, it should be avoided in patients with normal LV function.

Cardioprotective effect of dexrazoxane during treatment with doxorubicin: A study using low‐dose dobutamine stress echocardiography

To assess the late cardioprotective effect of dexrazoxane associated with doxorubicin during treatment of osteosarcoma by means of low-dose dobutamine stress echocardiography (LDDSE) in non-relapsed asymptomatic children and teenagers. The study population included 58 patients with osteosarcoma divided in three groups, with equivalent age range, gender proportion and body surface area. Group I (21 patients, 14 males, 15 +/- 4 years) was analyzed before chemotherapy and considered the control group; Group II (19 patients, 11 males, 19.7 +/- 4 years) was treated with 348.4 +/- 18 mg/m2 of doxorubicin only and Group III (18 patients, 14 male, 16.8 +/- 5 years) treated with 396.5 +/- 55 mg/m2 of doxorubicin with dexrazoxane in the ratio 10:1. The patients were submitted to LDDSE (maximal dose 5 microg/kg/min). No major side effects were observed. Heart rate, blood pressure, left ventricular diameters, end systolic wall stress (ESWS), and other diastolic and systolic function indexes were assessed at rest conditions and during LDDSE and compared between the three groups. Group III received a doxorubicin dose significantly greater than Group II (P = 0.001). During LDDSE there were no significant changes in the diastolic function indexes in any of the groups, but there was a significant increase of systolic indexes and a decrease of ESWS in Group III compared to group II. There was no significant difference of any systolic functional parameters between Group I and III. Considering the ejection fraction (EF) at rest or at LDDSE, 13 patients (69.4%) in Group II and 5 patients (27.7%) in Group III were considered to have systolic dysfunction. (P = 0.02). Myocardial response to LDDSE in patients treated with doxorubicin and dexrazoxane was similar to patients without chemotherapy and better than those treated with doxorubicin only, suggesting less cardiotoxicity.