Prediction of viability by pulsed-wave Doppler tissue sampling of asynergic myocardium during low-dose dobutamine challenge

Dobutamine stress echocardiography is widely used to predict reversible left ventricular dysfunction, but evaluation with this method is subjective. Pulsed-wave tissue Doppler imaging is a new technique that allows to obtain quantitative data on wall motion velocities of different myocardial segments through sample-volume placement. Therefore, this tool in combination with DSE may be suitable for identifying viability in asynergic myocardium. To evaluate this, in 40 patients (mean age 57+/-9) with resting dyssynergy (akinesis in 52, hypokinesis in 30) baseline wall motion scores and tissue Doppler variables were collected before and after 5 min infusion of 10 microg/kg per min dobutamine. Forty-six of 82 segments were classified as viable (a reduction in segmental score of at least one grade) according to follow-up echocardiography that was performed 4 weeks after revascularization. While myocardial S velocity percent increase in viable segments was 45+/-10, the increase was 25+/-12 in necrotic segments (n=36) during 10 microg dobutamine infusion (P=0.0001). Assuming 35% as a cut-off for viability the increase in S velocities by DSE yielded an 89% sensitivity and 86% specificity for predicting post-revascularization functional recovery. In conclusion, pulsed-wave tissue Doppler imaging of asynergic myocardium during dobutamine stress echocardiography can identify the viability quantitatively.     

Pulsed Tissue Doppler Imaging to Assess Myocardial Viability by Quantification of Regional Myocardial Functional Reserve

Dobutamine stress echocardiography (DSE) is used widely to evaluate myocardial viability, but is limited by the subjective nature of test interpretation. Assessment of systolic function by pulsed tissue Doppler imaging (TDI) during dobutamine stimulation may allow a more objective evaluation of myocardial functional reserve and, thus, myocardial viability. In 30 patients (58 +/- 9 years) with prior myocardial infarction, pulsed TDI with low dose dobutamine stress (10 microg/kg/min) was performed to assess myocardial viability. Qualitative assessment of two-dimensional (2-D) DSE and positron emission tomography (PET) were used for comparison. Peak systolic myocardial velocity was measured for each left ventricular segment (16 segments) at baseline and low dose dobutamine stress using pulsed TDI. The absolute and relative increases of peak systolic velocity from rest to low dose dobutamine stress were calculated. Three hundred sixty-four segments with adequate pulsed TDI tracing were divided according to either 2-D DSE or PET findings into normal, viable (mismatch), and nonviable (match) segments. The increase of peak systolic myocardial velocity from baseline to low dose dobutamine was significantly different between segments defined as normal, viable, and nonviable by 2-D DSE (2.71 +/- 1.91 cm/sec, 1.86 +/- 2.15 cm/sec, and 0.99 +/- 1.16 cm/sec, respectively; P < 0.001). The increase of peak systolic myocardial velocity from rest to low dose dobutamine for normal, mismatch, and match segments defined by PET was 2.72 +/- 1.96, 1.01 +/- 0.96 and 0.80 +/- 1.07 cm/sec, respectively (P < 0.001). In conclusion, the increase of peak systolic myocardial velocity during low dose dobutamine stimulation determined by pulsed TDI distinguishes between different myocardial viability states. It complements the standard interpretation of stress echocardiograms.     

Usefulness of dobutamine stress echocardiography in qualification of patients to angioplasty of infarct related artery

Late angioplasty of an infarct-related artery (IRA) performed weeks or months after myocardial infarction (MI) may restore blood flow in IRA and would result in improvement of regional wall motion. This study was designed to assess dobutamine stress echocardiography (DSE) in predicting the improvement of regional left ventricular (LV) function in patients after late PTCA of IRA. MATERIAL AND METHODS: 44 patients (36 M 8 F, mean age 54 +/- 7 year) who had a MI 15 +/- +/- 8 weeks earlier, were qualified to angioplasty of IRA when DSE showed the change in wall motion at the infarct zone--improved during low dose infusion (5-10 micrograms/kg/min) and/or worsened during a high dose dobutamine (up to 40 micrograms/kg/min). Regional wall motion was assessed by DSE performed at 2-7 days and 6-month after successful angioplasty. Wall motion score index (WMSI) decreased from 1.51 +/- 0.29 at rest to 1.31 +/- 0.28 at low-dose dobutamine infusion (p > 0.001) before angioplasty. Early after PTCA regional wall motion improves and baseline, exercise and rest values of WMSI decreased, compared with values before angioplasty. At baseline echocardiography 248 of segments were dyssynergic (112 hypokinetic, 125 akinetic and 10 dyskinetic). Viability during DSE was more frequent in segments with biphasic reaction during DSE than in segments showed monophasic reaction. In 34 patients control angiography (CA) was performed 6 month after successful PTCA. In this selected group CA showed significant restenosis of IRA in 12 pts (35% =, 9 of them showed positive DSE. Their base WMSI increased from 1.36 +/- 0.28 to 1.47 +/- 0.30 and peak stress WMSI from 1.32 +/- 0.29 to 1.60 +/- 0.30 (p < 0.001), respectively, between the exam just after PTCA comparing with the exam which detected restenosis. CONCLUSIONS: In some patients with infarction and a narrowed or occluded IRA the myocardium remains viable for a prolonged period. Improvement of wall motion during low-dose DSE and/or worsened during high dose DSE at infarct zone is a very useful tool in predicting of viable myocardium at infarct zone. DSE is an excellent method to demonstrate an immediate improvement in regional LV dysfunction after angioplasty of IRA. At 6 months' follow-up restenosis of IRA is often seen.     

Quantitative analysis of myocardial response to dobutamine by measurement of left ventricular wall motion using omnidirectional M-mode echocardiography

Although dobutamine stress echocardiography is important for assessing cardiac ischemia and viability, analysis of wall motion is qualitatively performed. We quantitatively evaluated left ventricular wall motion using a newly developed omnidirectional M-mode echocardiography that can depict the M-mode at the site of region of interest on the 2-dimensional image in real time, and established its usefulness for analyzing the myocardial response to dobutamine infusion. Dobutamine stress echocardiography with omnidirectional M-mode was performed in 57 patients with coronary lesions. In 38 of these patients, exercise stress single-photon emission computed tomographic thallium scintigraphy (Tl-201 SPECT) was performed. Endocardial excursion of 103 regions was measured from omnidirectional M-mode at baseline, low-dose (6 microg/kg/min), and at peak dose (30 microg/kg/min) dobutamine. A decrease and increase in wall excursion was scored (from -3 to 3) for a changes of every 2 mm, and a quantitative wall motion score (QWMS) was calculated as a summation of the scores from baseline to low dose and from low to peak doses. Quantitative coronary stenosis score (QCSS) was calculated as a summation of stenotic and collateral scores. The stenosis scores were graded as: 1 = 0% to 50%, 2 = 50% to 75%, 3 = 75% to 90%, 4 = 90% to 95%, 5 = 95% to 100%; collateral scores were graded as: -1 = poor collateral, -2 = good collateral. Based on the QWMS at each dose of dobutamine, the serial changes in wall motion were divided into 4 groups: augmented, biphasic, no change, and worsening. The QCSS was clearly different among these groups. QWMS was significantly correlated with QCSS (r = 0.657, p <0.001). The incidence of redistribution in Tl-201 SPECT was high in the region with low score of QWMS. In conclusion, omnidirectional M-mode is useful for quantitatively determining the grade of cardiac ischemia by assessing the serial change of ventricular wall motion during dobutamine infusion.     

Accuracy of dobutamine stress echocardiography in detecting coronary artery disease.

The diagnostic accuracy of dobutamine stress echocardiography (DSE) (incremental infused doses of 5, 10, 20 and 30 micrograms/kg/min) was evaluated in 141 patients who underwent coronary arteriography within 2 weeks of DSE. All patients were being evaluated for known or suspected coronary artery disease (CAD). DSE was interpreted blindly as normal or showing evidence of CAD, depending on the presence of resting or inducible wall motion abnormalities. Coronary arteriograms were reviewed in a blinded, quantitative fashion. DSE had a sensitivity of 96% for detecting patients with CAD, and a specificity of 66%. For the 53 patients with normal resting wall motion, sensitivity was 87% and specificity 91%. The protocol was well-tolerated by all patients. In comparison with wall motion analysis, 12-lead electrocardiograms during dobutamine infusion revealed ischemic changes in only 17% of patients with CAD. It is concluded that DSE is a clinically useful and accurate means for detecting CAD, its specificity is hindered in patients with resting wall motion abnormalities, and it can safely be used in patients with known cardiac disease.     

Determinants of contractile reserve in the infarction area. A quantitative study using dobutamine in contrast left ventriculography

AIM: The aim of this study was to relate the contractile reserve in infarction segments to the dysfunction at rest and to the residual coronary stenosis. METHODS: The study group consisted of 95 patients with a first myocardial infarction. Contrast left ventricular at baseline and after dobutamine infusion at 7.5 microg/kg/min and coronary angiograms were performed. The centerline method was used to quantify the extent of dysfunction (percentage of chords with dysfunction in the territory of the infarction artery) and its maximum severity (maximum units of standard deviation [SD] below the normal wall motion reference). Reduction of dysfunction extent with dobutamine was measured. RESULTS: On increasing baseline dysfunction severity, both the magnitude of the response to dobutamine ( 2 SD 3 SD 4 SD +/- 5 SD [n = 15] = 9+/-13%, > 5 SD [n = 13] = 3+/-4%, p = 0,0001), and the number of patients with a significant (> or =15%) positive response ( 2 SD 3 SD 4 SD 5 SD = 0%, p<0,0001) decreased. There were no differences in dobutamine improvement among the subgroups with (n = 84) or without (n = 11) significant stenosis in the infarction artery (18+/-15 vs. 16 +/-18%), or between the subgroups with a patent (n = 76, 18+/-19%) or occluded (n = 19, 11+/-11%) artery. CONCLUSIONS: Dobutamine response is related to dysfunction severity in the infarction area: when the severity is 5 (high negative response prevalence), dobutamine testing does not seem indicate. The existence of residual coronary stenosis does not attenuate contractile reserve at low dobutamine doses.     

Comparison of low-dose dobutamine echocardiography and thallium-201 reinjection for the determination of myocardial viability in the early post myocardial infarction period

OBJECTIVE: Determination of viability in the infarction zone in the early post Ml period is an important parameter in clinical decision making. METHODS: In an attempt to compare the places of low-dose dobutamine echocardiography (LDDE) and thallium-201 reinjection SPECT (TI-SPECT) in the determination of viability in dyssynergic myocardial segments, 17 patients (mean age: 54.6 +/- 12.8 years, 16 male, 1 female) with a recent myocardial infarction and an uneventful early clinical course underwent both tests within 5-13 days of infarction. The 16-segment model was utilised to evaluate the left ventricular wall motion and each segment was graded as 1) normokinetic, 2) hypokinetic, 3) akinetic and 4) dyskinetic or aneurysmal on a 4-scale basis. A dyssynergic segment of myocardium was considered to be viable by LDDE if it showed an improvement in wall motion of at least one grade with low-dose dobutamine infusion (10 microg/kg/min). On the other hand, mild to moderate (< 50%) fixed perfusion defects and reversible (at least a 10% improvement in perfusion on either redistribution or reinjection images) severe (50% or more) perfusion defects were considered positive for viability by TI-SPECT. RESULTS: Of the 76 segments with resting dyssynergy (10 dyskinetic/aneurysmal, 33 akinetic, 33 hypokinetic), 51 (67%) were shown to be viable by LDDE and 61 (80%) by TI-SPECT. There was an agreement of 76% (p = 0.03, K = 0.63) between the two methods. CONCLUSION: This study disclosed a moderate degree of agreement between LDDE and TI-SPECT for the determination of viability in dyssynergic myocardial segments in the early post-myocardial infarction period.     

Dobutamine stress echocardiography in hypertrophic cardiomyopathy

AIMS: Myocardial ischemia in the absence of coronary artery disease is common in patients with hypertrophic cardiomyopathy (HCM). Dobutamine stress echocardiography (DSE) induces left ventricular (LV) new wall motion abnormalities (NWMA) in some patients with HCM. We evaluated the effects of dobutamine on LV performance and hemodynamics in HCM. METHODS AND RESULTS: Eighteen patients with non-obstructive HCM underwent DSE. Dobutamine was administered at dosages of 5, 10, 20, 30 and 40 microg/kg/min with increments at intervals of 3 min. Seven patients developed NWMA, whereas the other 11 did not. During DSE, heart rate increased significantly more in NWMA patients,whereas LV outflow tract gradient (OTG) increased significantly and similarly in both groups. At peak dobutamine dose, NWMA patients had a significant increase in LV end-systolic diameter and volume and a significant decrease in LV fractional shortening and ejection fraction. Posterior wall thickening increased significantly, whereas septal thickening did not increase throughout DSE in both groups. CONCLUSIONS: In a subgroup of patients with HCM, DSE induces NWMA, associated with a greater increase in heart rate, irrespective of LVOTG. NWMA induce a depression of global LV systolic performance. The septum shows no contractile reserve, regardless of NWMA. These phenomena may be the result of induction of ischemia and/or impaired LV systolic function due to fast heart rate.     

Safety and feasibility of dobutamine stress echocardiography in patients with implantable cardioverter defibrillators

Coronary artery disease is the underlying etiology of left ventricular dysfunction and arrhythmias in most patients who receive implantable cardioverter defibrillators (ICDs). The aim of this study was to assess the safety and feasibility of dobutamine stress echocardiography (DSE) in patients with an ICD. DSE (dobutamine up to 50 microg/kg/min, atropine up to 2 mg) was performed in 87 patients with an ICD and known or suspected coronary artery disease. The ICD was inactivated before the stress test and reactivated after the study; no serious complications occurred. DSE is a safe and feasible method for evaluating myocardial ischemia in patients with an ICD.     

Long-term prognostic value of dobutamine stress echocardiography in patients with atrial fibrillation

STUDY OBJECTIVE: To assess the long-term prognostic value of dobutamine stress echocardiography (DSE) for cardiac events (cardiac death, myocardial infarction, and late revascularization) in patients with atrial fibrillation (AF). METHODS: Baseline ECGs were studied in patients undergoing DSE between 1989 and 1998. Sixty-nine patients had AF before DSE. Prognostic value of DSE in these patients was compared with a control group who had sinus rhythm (n = 1,664). The presence of stress-induced ischemia was noted for every patient. The mean follow-up period was 35 months (range, 6 to 84 months). Data are presented as hazards ratio (HR) with 95% confidence interval (CI). RESULTS: Heart rate at rest was higher in patients with AF (77 +/- 15 beats/min vs 73 +/- 14 beats/min; p = 0.04); however, double product at peak stress was not different between patients with AF and sinus rhythm (17,602 vs 17,169, respectively; p = 0.46). In patients with AF, target heart rate was achieved at a lower dobutamine dose (33 +/- 8 microg/kg/min vs 35 +/- 9 microg/kg/min; p = 0.01). Cardiac arrhythmias occurred more frequently (12% vs 5%; p = 0.001) in patients with AF during DSE. During a follow-up period of 7 years, cardiac death occurred in 5 patients, myocardial infarction in 2 patients, and late revascularization in 10 patients. Prognostic value of DSE for all late cardiac events was similar in patients with AF (HR, 3.0; 95% CI, 0.9 to 9.5) and sinus rhythm (HR, 3.4; 95% CI, 2.7 to 4.3; p = 0.85). CONCLUSION: The prognostic value of DSE for late cardiac events is maintained in patients with AF.     

Quantitative evaluation of left ventricular regional wall motion using a real-time wall thickness curve system with two-dimensional echocardiography

The real-time wall thickness curve system was newly developed for recording left ventricular (LV) wall thickening (WT) on a 2-dimensional echocardiogram recorded in an arbitrary direction because of the scarcity of quantitative data on wall motion change during dobutamine-induced ischemia. This study tested the feasibility of this system for quantitative evaluation of wall motion. In normal subjects, accuracy and reproducibility of measurements were evaluated by comparison with measurements on a conventional M-mode echocardiogram and examination of inter- and intraobserver variability. In 28 patients with coronary artery disease, percent systolic wall thickening (%WT) was measured during dobutamine infusion in incremental doses of 6 microg/kg/min, from 6 to 30 microg/kg/min. Percent change in %WT by dobutamine was compared with percent coronary stenosis derived from quantitative coronary angiography. Analysis of the mean difference and 95% confidence intervals demonstrated good accuracy and reproducibility: 0.0 mm and intervals of -0.5 to 0.5 mm in diastolic wall thickening of LV posterior wall (PW) between both methods, -1% and -4% to 2% in %WT of IVS and LVPW between both observers, and -1% and -3% to 2% in that between both measurements. During dobutamine infusion, the percent change in %WT was significantly correlated with percent stenosis (r = 0.75, p<0.0001). The WT curve system enabled us to assess regional wall function as %WT and was available for quantitative observation of wall motion change during pharmacologic intervention. This system may reduce the effects of heart movement and may be of great clinical benefit in evaluating regional wall function.     

Effect of dobutamine on regional left ventricular function measured by tagged magnetic resonance imaging in normal subjects

The effect of inotropic stimulation on the pattern and magnitude of regional left ventricular contraction was studied using tagged magnetic resonance imaging to assess whether dobutamine exacerbates variation in regional contraction at rest. Dobutamine stress testing defines a normal response as a homogeneous increase in regional wall motion. In 8 normal subjects, 4 equally spaced left ventricular short-axis levels were imaged through systole using tagged magnetic resonance imaging. The baseline imaging sequence was repeated with 5-, 10-, 15-, and 20-microg/kg/min dobutamine infusion. Regional myocardial displacement, radial thickening, and circumferential shortening were measured. The left ventricle was analyzed by level (base to apex) and wall (septum, inferior, lateral, anterior). Dobutamine did not alter baseline regional functional heterogeneity. Dobutamine infusion resulted in a uniform increase in displacement, radial thickening, and circumferential shortening from baseline to 10-microg/kg/min infusion without additional increases at higher doses.     

False positive ST segment elevation during dobutamine stress echocardiography due to left ventricular hypertrophy

The significance of ST segment elevation in dobutamine stress echocardiography (DSE) remains controversial. In patients with prior Q wave myocardial infarction (MI), it may reflect myocardial ischemia, contractile reserve in the infarct-related area, or dyskinesia of the infarcted areas of myocardium. In the nonpost-MI population, it has been attributed to vasospasm or strongly associated with coronary artery disease and ischemia. We hypothesized that ST segment elevation in the absence of inducible ischemia or prior MI is related to the presence of left ventricular hypertrophy (LVH). During DSE, dobutamine was infused from 5 microg/kg/min up to a maximum of 50 microg/kg/min. Echocardiographic images were obtained at baseline, low dose, peak dose, and recovery. Ischemia was defined as either the development of a new wall-motion abnormality or worsening wall motion at peak dose. We reviewed 682 consecutive DSE tests and found ST elevation in 42 patients (incidence = 6.1%). After excluding two patients for > 10% uninterpretable echocardiographic segments, the study population consisted of 40 patients. In 25 patients with ST elevation and without echocardiographic evidence for dobutamine-induced ischemia, 21 (84%) patients had LVH (P = 0.001). In 15 patients with inducible ischemia, only 4 (27%) patients had LVH. No other significant differences were found except that prior MI was more common in the inducible ischemia group. In the subgroup of 18 patients without prior MI, no inducible ischemia was found in 15 (83%). LVH was present in 14 (93%) of these 15 patients (P < 0.005), and all 14 had a normal baseline left ventricular ejection fraction. None of the three patients in the nonpost-MI subgroup with inducible ischemia had LVH. The 22 patients with prior MI had no significant association with LVH (P = 0.39). We conclude that ST segment elevation during DSE can occur without echocardiographic evidence for ischemia and is associated with LVH in the nonpost-MI population. This ST elevation may be related to transient electrocardiographic repolarization changes in the hypertrophied ventricle in the presence of altered loading conditions and/or altered catecholamine influences rather than true ischemia.     

Left ventricular remodeling can be predicted with left ventricular volume response during dobutamine echocardiography after acute myocardial infarction

OBJECTIVES: This study was performed to evaluate the significance of left ventricular (LV) volume response during dobutamine stress echocardiography (DSE) in the prediction of LV volume change during follow-up (F/U) in patients with acute myocardial infarction (AMI). METHODS: Forty-five patients with AMI (male 39, age 57+/-10 y, anterior myocardial infarction [MI] 29) underwent DSE 6+/-4 d after AMI. Revascularization of the infarct-related artery was performed if severe stenosis was present. A F/U echocardiography was performed 7.5+/-3.4 mo after DSE. The LV end-diastolic volume (EDV) and end-systolic volume (ESV) using the modified Simpson's method were measured at baseline echocardiography, low-dose (10 microg x kg(-1) x min(-1)) DSE, and F/U echocardiography. RESULTS: Patients were divided into 2 groups; Group I (n = 21) with an abnormal response (<10% decrease) in LVEDV during low-dose DSE; Group II (n = 24) with a normal response (> or =10% decrease) in LVEDV during low-dose DSE. At F/U echocardiography, the (%) change of LVEDV was significantly different between the 2 groups (-2.0+/-16.7 versus - 22.6+/-24.7%, p<0.01). Using multivariate analysis, the response of LVEDV (%) at low-dose DSE was the only significant independent predictor of the change of LVEDV (%) during F/U (y = 0.85 x - 0.03, r = 0.63, p<0.001). CONCLUSIONS: The response of LVEDV during DSE can be used as a predictor for the LV volume change after AMI.     

Early diastolic flow propagation velocity detects induced diastolic dysfunction during dobutamine stress echocardiography

Objective: Diastolic dysfunction precedes systolic dysfunction during the development of myocardial ischemia. Detecting diastolic dysfunction during stress test for coronary artery disease (CAD) could improve diagnostic sensitivity of the test. Flow propagation velocity (FPV) derived from color M‐mode Doppler has been proposed as a sensitive marker to detect diastolic dysfunction. Methods: The FPVs at baseline and at peak dobutamine infusion were measured using color M‐mode Doppler during dobutamine stress echocardiography in 90 patients. The results are compared among the groups divided on the results of coronary angiography. Results: The FPV was similar at baseline among the groups. At peak dobutamine infusion, the FPV increased significantly in the non‐CAD group (from 56 ± 19 cm/s to 66 ± 25 cm/s), whereas it failed to increase in the groups with CAD. As a result, the peak FPV was significantly lower in the groups with CAD than in the non‐CAD group. Receiver operating characteristic analysis showed that the peak FPV and ΔFPV had good diagnostic property to detect CAD (the areas under the curves were 0.77 and 0.73, respectively). Adopting these FPV criteria, sensitivity of DSE was improved. Conclusion: FPV measurement during DSE detects ischemic left ventricular diastolic dysfunction. Adding the assessment of peak FPV to conventional DSE increases the sensitivity and the ability to reliably exclude CAD. (Echocardiography 2011;28:335‐341)     

Usefulness of the ejection fraction response to dobutamine infusion in predicting functional recovery after coronary artery bypass grafting in patients with left ventricular dysfunction

Quantification of dysfunctional but viable myocardium has high prognostic value for improvement of left ventricular (LV) function after coronary artery bypass grafting (CABG). Dobutamine stress echocardiography (DSE) can assess viable myocardium by segmental wall motion changes during stress. However, analysis of wall motion is subjective with only moderate interinstitutional agreement (70%) and frequently overestimates functional improvement after CABG. In contrast, calculation of ejection fraction (EF) is less subjective and allows a more precise quantification of global contractile reserve. The aim of the study was to compare the prognostic value of EF response and segmental wall motion changes during DSE for the prediction of LV functional recovery after CABG. Forty patients underwent DSE before CABG. EF responses were assessed at rest, low-dose dobutamine, and at peak stress using the biplane disk method. Wall motion was scored using a 16-segment 5-point model. Resting radionuclide ventriculography (RNV-LVEF), performed before and 8 ± 2 months after CABG, was used as an independent reference. Five patients were excluded because of perioperative infarction or poor echo images. In 11 of 35 patients, RNV-LVEF recovered >5%. Improvement in EF during dobutamine infusion predicted RNV-LVEF recovery after CABG significantly better than segmental wall motion changes (72% vs 53%, p = 0.03). A biphasic EF response (i.e., improvement in ≥10% at low dose and subsequent worsening at peak stress) had the highest predictive value (80%) for late functional recovery. In conclusion, EF response to dobutamine infusion was superior to segmental wall motion changes in predicting RNV-LVEF recovery after CABG.     

Accuracy of dobutamine stress echocardiography for the diagnosis of coronary artery stenosis in patients with myocardial infarction: the impact of extent and severity of left ventricular dysfunction.

OBJECTIVES: To assess the value of dobutamine stress echocardiography (DSE) in the prediction of the extent and location of coronary artery stenosis in symptomatic patients with old myocardial infarction and to study the impact of the severity of resting wall motion abnormalities (WMA) on the diagnostic accuracy of the test. PATIENTS: One hundred and thirty two symptomatic patients with old myocardial infarction. METHODS: DSE (up to 40 micrograms/kg/min, with atropine up to 1 mg) was performed in all patients. Ischaemia was defined as new or worsened WMA. For each coronary artery, regional wall motion in the corresponding territory was classified as normal, mildly, moderately, or severely impaired according to the wall motion score index. Significant coronary stenosis was defined as > or = 50% diameter stenosis. RESULTS: A positive DSE for ischaemia occurred in 87 of 111 patients with and three of 21 patients without coronary artery stenosis (sensitivity = 78%; CI 71 to 86, specificity = 86%; CI 79 to 92, accuracy = 80%; CI 73 to 87). The accuracy for the diagnosis of individual coronary stenosis was 69% in the presence of normal wall motion and 74%, 74%, and 61% respectively when there was mild, moderate, and severe WMA in the corresponding territories (P = NS). The sensitivity was higher in presence of mild or moderate WMA (73%) than with normal wall motion (53%) or severe WMA (56%, P < 0.05 in both). In territories subtended by a stenotic artery, the regional wall motion score index was not different with or without ischaemia. CONCLUSION: DSE had a good overall accuracy for the diagnosis of coronary artery stenosis in symptomatic patients with old myocardial infarction. The presence of resting WMA did not limit DSE as a method of eliciting myocardial ischaemia and diagnosing significant coronary artery stenosis in patients with old myocardial infarctions.     

Enoximone coupled to very low dose dobutamine echocardiography detects myocardial viability in akinetic and dyskinetic post-myocardial infarcted areas.

Dobutamine and enoximone stimulate independently inotropic reserve by increasing intracellular cyclic adenosine monophosphate. The potential of enoximone (0.75 mg/kg body weight over 10 minutes) followed by very low dose (2.5 microg/kg/min) dobutamine echocardiography to predict recovery of ventricular function in akinetic and dyskinetic postinfarcted areas was studied. We enrolled 22 patients with previous Q-wave myocardial infarction and regional wall motion abnormalities related to left anterior descending arterial disease, left ventricular ejection fraction <40%, and all scheduled for myocardial revascularization. A 10 microg/kg/min dobutamine test was performed 48 hours before the study protocol. Test images obtained at peak of pharmacodynamic effects were compared with those obtained at 4 months after myocardial revascularization. We used a 16-segment ventricular model and a 5-grade scoring system. Resting regional myocardial dysfunction graded > or =2 was present in 267 of 352 segments evaluated. Contractile reserve (decrease in resting wall motion score > or =2 grades) at peak effect of enoximone infusion was present in 34 of 112 severely hypokinetic, 42 of 117 akinetic, and 14 of 38 dyskinetic segments. The inotropic reserve evaluated after very low dose dobutamine was observed in 34 of 112 severely hypokinetic, 49 of 117 akinetic, and 20 of 38 dyskinetic segments. After revascularization, recovery of function was observed in 31 of 112 severely hypokinetic, 49 of 117 akinetic, and 21 of 38 dyskinetic segments. Overall, there was a significant correlation between absolute score changes of segments which were abnormal at baseline (n = 267) to enoximone peak effects (r = 0.49, p <0.001) to predict absolute changes after revascularization; after dobutamine there was progress toward identity (r = 0.62, p <0.001) and the difference was significant among correlation slopes of dobutamine alone, enoximone alone, and enoximone plus very low dose dobutamine echocardiograophy (0.45+/-0.04, 0.51+/-0.04, and 0.63+/-0.04, respectively, F = 5.25, p = 0.005). Therefore, enoximone followed by very low dose dobutamine may assess myocardial viability of postinfarcted akinetic and dyskinetic areas. This test may be useful when evaluating patients with more severe cardiac failure and/or life-threatening arrhythmias.     

Dobutamine Stress Echocardiography Early After Heart Transplantation Predicts Development of Allograft Coronary Artery Disease and Outcome

Objectives. This study sought to determine the prognostic significance of serial dobutamine stress echocardiography (DSE) in new heart transplant recipients and to examine the relation between persistent wall motion abnormalities and the eventual development of coronary artery disease (CAD) as assessed by angiography.

Background. Allograft CAD is a major cause of graft failure. However, clinical diagnosis of the early disease remains difficult. The reasons for this include the diffuse nature of the disease and its predilection for the microvasculature, which are not easily detected by coronary angiography. Identifying patients at risk for the development of angiographic CAD early after transplantation may allow such patients to be targeted for aggressive treatment options to prevent subsequent cardiac events and early graft failure.

Methods. Twenty-two new heart transplant recipients were selected to undergo serial DSE at the time of their regularly scheduled endomyocardial biopsy. In addition, patients underwent scheduled annual coronary angiography. DSE was performed in 5-min stages with infusion of intravenous dobutamine at 5, 10, 20, 30 and 40 μg/kg body weight per min.

Results. Twenty-two patients had 91 DSE studies and 45 coronary angiograms. The patients were categorized into three groups based on the echocardiographic results. Group 1 (n = 7) had normal serial stress echocardiographic studies. Group 2 (n = 4) had transient inducible wall motion abnormalities. Group 3 (n = 11) developed persistent wall motion abnormalities. During a mean follow-up time of 32 ± 11 months (range 5 to 50), 8 (73%) of 11 patients in Group 3 developed events. The events included angiographic CAD (n = 7), myocardial infarction (MI) (n = 1) and cardiac death (n = 3). The patient who developed an MI had a normal coronary angiogram. No cardiac event or angiographic disease occurred in either Group 1 or 2 patients.

Conclusions. These results suggest that dobutamine-induced wall motion abnormalities, which are persistent in new heart transplant recipients, are predictive of the development of angiographic CAD, MI or death.     

Viability of hypokinetic segments: influence of tethering from adjacent segments: influence of tethering from adjacent segments

Hypokinetic myocardium is presumed to be reversibly dysfunctional. However, hypokinetic segments do not necessarily improve after revascularization since their outcome can be influenced by tethering effects of adjacent myocardium. To assess whether hypokinetic segments improve following revascularization, 24 patients underwent resting and dobutamine stress echocardiography (DSE), with a total of 420 (20 per patient) myocardial segments studied pre- and postrevascularization. One hundred fifty-five hypokinetic segments were identified prerevascularization. Postrevascularization, only 57% of these segments improved in wall motion, while 43% showed no improvement or worsening of wall motion. Low dose (5-10 microg/kg/min) DSE identified correctly 57 (65%) of 88 segments that improved, and falsely predicted improvement in 26 (39%) of 67 segments that ultimately did not improve postrevascularization. Of the hypokinetic segments that did not improve, 90% were adjacent to at least one severely hypokinetic or akinetic segment as compared with 73% of the segments that improved following revascularization (P = 0.009). Sixty-five percent of all true positive DSE responses were adjacent to at least one akinetic or severely hypokinetic segment, while 87% of all false negative DSE responses were adjacent to at least one akinetic or severely hypokinetic segment (P = 0.03). In conclusion, myocardial segments found to be hypokinetic do not necessarily improve after revascularization. This may be related to tethering influences of adjacent segments, which have a contrasting level of function.