Resting Wall Motion Abnormalities Research Articles

Significance of Resting Wall Motion Abnormalities in 2-Dimensional Echocardiography in Patients Without Previous Myocardial Infarction Referred for Pharmacologic Stress Testing

Significance of Resting Wall Motion Abnormalities in 2-Dimensional Echocardiography in Patients Without Previous Myocardial Infarction Referred for Pharmacologic Stress Testing

258 Increased detection of viable myocardium using myocardial perfusion analysis in patients with resting wall motion abnormalities

258 Increased detection of viable myocardium using myocardial perfusion analysis in patients with resting wall motion abnormalities

258 Increased detection of viable myocardium using myocardial perfusion analysis in patients with resting wall motion abnormalities

258 Increased detection of viable myocardium using myocardial perfusion analysis in patients with resting wall motion abnormalities

Cardiac evaluation in hypotension-prone and hypotension-resistant hemodialysis patients

Hypotension during hemodialysis occurs frequently, but the precise mechanism remains unclear. In this study, the presence of myocardial ischemia and myocardial contractile reserve during infusions of the beta-adrenergic receptor agonist dobutamine was assessed by means of dobutamine-atropine stress echocardiography (DSE) in hypotension-prone (HP) and hypotension-resistant (HR) hemodialysis patients. Eighteen HP patients (age 53 +/- 6 years) were compared with 18 HR patients (age 53 +/- 3 years), matched with respect to the duration of hemodialysis and cardiovascular history. New wall abnormalities during dobutamine stress reflect the presence of myocardial ischemia, whereas the increase in stroke index and cardiac index reflects myocardial contractile reserve. Wall motion score at rest (1.42 +/- 0.53 vs. 1.44 +/- 0.57) and dobutamine-induced new wall motion abnormalities (4 vs. 3 patients) between HP and HR patients were similar, but responses of cardiac index, stroke index, and systolic blood pressure to do butamine between the two groups were different. Not withstanding a similar cardiac index at rest (2.4 +/- 1.1 liter/min/m2 in HP and 2.8 +/- 1.2 liter/min/m2 in HR patients), dobutamine-induced increments in the cardiac index were considerably smaller in the former (0.8 +/- 1.3 liter/min/m2) than in the latter patients (2.3 +/- 1.6 liter/min/m2, P = 0.002), predominantly because of a progressive decrease in the stroke index in the HP patients. Impaired myocardial contractile reserve rather than ischemia is predominant in HP patients. This impaired myocardial contractile reserve may play a role in the development of hemodialysis-induced hypotension.

The functional significance of chronotropic incompetence during dobutamine stress test

OBJECTIVETo investigate the functional significance of chronotropic incompetence during dobutamine stress echocardiography.PATIENTS AND METHODSThe functional significance of chronotropic incompetence was evaluated during dobutamine stress echocardiography in 512 patients without β...

Nonexercise stress transthoracic echocardiography: transesophageal atrial pacing versus dobutamine stress

ObjectivesTo compare transesophageal atrial pacing stress echocardiography with dobutamine stress echocardiography for feasibility, safety, duration, patient acceptance and concordance in inducing wall motion abnormalities.BackgroundTransesophageal atrial pacing is an effective method of increasing heart rate and has been used in the assessment of coronary artery disease.MethodsBoth tests were performed in sequence on the same patients in random order. Transesophageal atrial pacing stress echocardiography began at a heart rate of 10 beats/min above the baseline value and was increased by 20 beats/min every two min until 85% of the age-predicted maximum heart rate or another end point was reached. Dobutamine echocardiography was performed using three-min stages and a maximum dose of 40 μg/kg per min. Atropine (total dose ≤2 mg) was administered at the start of the 40 μg/kg per min stage if needed to augment heart rate or during pacing if Wenckebach heart block occurred.ResultsTransesophageal atrial pacing stress echocardiography was feasible in 100 of 104 patients (96%); the duration (8.6 ± 3.6 min) was significantly shorter than that of dobutamine stress echocardiography (15.1 ± 3.9 min) (p = 0.0001). With transesophageal atrial pacing stress echocardiography, the recovery period was shorter, symptoms and dysrhythmias were fewer, hypertension and hypotension were less common and target heart rate was more frequently achieved. No complications occurred with either test. Patient acceptance was satisfactory. Agreement between results of both tests was good for segmental wall motion scoring with a 16-segment model, scores 1 to 5 (kappa: rest, 0.79; peak, 0.57) and test interpretation (normal, ischemia, infarction or resting wall motion abnormality with ischemia) (kappa: 0.77).ConclusionsTransesophageal atrial pacing stress echocardiography is a feasible, well-tolerated alternative to dobutamine stress echocardiography. It can be performed rapidly and shows good agreement with dobutamine stress echocardiography in the induction of myocardial ischemia.

Effects of Low-Dose Dobutamine on Displacement of the Atrioventricular Plane and Assessment of Myocardial Viability in Patients with Acute Myocardial Infarction Treated with Thrombolysis.

Previous echocardiographic studies have highlighted the usefulness of atrioventricular (AV) plane displacement (the mitral annular motion) in assessing left ventricular function at rest. However, the effects of low-dose dobutamine on AV plane displacement in thrombolyzed patients with acute myocardial infarction (AMI) are unknown. Thirty-four patients with AMI treated with a thrombolytic agent and having rest wall motion abnormalities at the infarct site were studied with rest and low-dose dobutamine echocardiography before discharge. Thirty-one patients were followed up 18 months later with rest echocardiography. The systolic descent of the AV plane toward the apex at four different left ventricular sites (i.e., at the septal, anterior, lateral, and inferior walls) was recorded to assess left ventricular function. Compared with age-matched healthy subjects, the AV plane displacement was significantly reduced, especially at the infarct sites, in AMI patients at rest. During low-dose dobutamine, the AV plane displacement was increased at infarct sites (P < 0.001) in patients with signs of viability. A cutoff point of an increase in AV plane displacement of >/= 2 mm at the infarct sites during low-dose dobutamine stress had a sensitivity of 89% and a specificity of 87% in assessing myocardial viability. Using the same cutoff point of a spontaneous increase in the AV plane displacement of >/= 2 mm during the follow-up rest echocardiography, 87% of the patients with initial signs of viability and only 25% without signs of viability showed a spontaneous late recovery of initially stunned myocardium. Thus, the study shows that changes in the amplitude of the AV plane displacement during low-dose dobutamine stress echocardiography can easily be used to detect myocardial viability at an early stage with late potential spontaneous recovery.

Does Dobutamine Stress Echocardiography Induce Damage During Viability Diagnosis of Patients with Chronic Regional Dysfunction After Myocardial Infarction?

Experimental hibernating-model investigations of animals have shown that myocardial necrosis can be induced by longer-term intracoronary dobutamine infusion. This study was designed to determine whether myocardial infarction could be ascertained in patients with chronic regional wall motion abnormalities and greater than 75% stenosis in the supplying coronary artery through dobutamine stress echocardiography. Twenty patients with coronary artery disease and regional resting wall motion abnormalities were examined with a standard dobutamine protocol (5 to 50 μg/kg/min). Exclusion criteria were an acute coronary syndrome, severe heart failure, and severe hypertension. Creatine kinase (CK, CKMB), myoglobin, and troponine-I were measured before and at each of the first 7 hours after beginning of infusion. Fourteen of these 20 patients exhibited viable myocardium. The serum markers CK, CKMB, myoglobin, and troponin-I demonstrated no increase beyond the reference range, suggesting that with this protocol, no myocardial necrosis was induced. (J Am Soc Echocardiogr 1998;11:181–7)

Knowledge of perfusion and contractile reserve improves the predictive value of recovery of regional myocardial function postrevascularization: a study using the combination of myocardial contrast echocardiography and dobutamine echocardiography.

This study was designed to determine the value of myocardial contrast echocardiography (MCE) and dobutamine echocardiography (DE), alone or in combination, in predicting functional recovery in patients with resting wall motion abnormalities due to CAD. MCE and DE have been independently shown to be useful in detecting myocardial viability in the post-myocardial infarction setting. Thirty-nine patients with significant coronary artery disease and resting wall motion abnormalities underwent DE (2.5 to 20 microg x kg(-1) x min(-1)) and wall motion analysis (16-segment model). MCE was performed with selective intracoronary injections of sonicated meglumine (2 cm3). Myocardial viability was defined as presence of contrast effect by MCE and contractile reserve or an ischemic response by DE. Functional recovery (improvement in wall motion) was assessed after revascularization (percutaneous transluminal coronary angioplasty, n=20; coronary artery bypass surgery, n=19). When the two groups of patients were analyzed, MCE was associated with excellent sensitivities (84%) yet poor specificities (19% to 26%); DE had lower sensitivities (79% to 80%) but also poor specificities (30% to 36%). The combination of both was associated with excellent sensitivities (90% to 93%) and modest specificities (48% to 50%) for predicting functional recovery. A biphasic response with DE was infrequent (14% to 42%) but highly specific of functional recovery (84% to 94%). MCE had an excellent negative predictive value for functional recovery (83%). The prediction of functional recovery post-revascularization can be enhanced by combining MCE and DE.

Chronic myocardial hibernation in humans. From bedside to bench.

Since the pioneering work of Tennant and Wiggers,1 it has been known that total ischemia leads to a prompt cessation of contraction and eventually results in the appearance of cell damage and irreversible myocardial necrosis. Accordingly, in the minds of many cardiologists, the discovery of an abnormal regional contraction in a patient with coronary artery disease has long been equated with the presence of irreversible myocardial necrosis. With the advent of recanalization therapy, however, evidence progressively accumulated that prolonged regional “ischemic” dysfunction did not always arise from irreversible tissue damage and, to some extent, could be reversed by restoration of blood flow.2 3 4 5 These observations have led to the speculation that chronically hypoperfused myocardium, which is often referred to as “hibernating,”2 3 4 5 6 could maintain viability by simply reducing its metabolic demand to match the decreased supply for as long as myocardial perfusion was inadequate. The chronic impairment of contractile function in this setting has been regarded as a protective mechanism by which the heart spontaneously downgrades its myocardial function, minimizes its energy requirements, and prevents the appearance of irreversible tissue damage.2 4 5 The concept of chronic hibernation thus consists of two parts: a unique clinical observation that bears important implications for the management of patients with chronic coronary artery disease2 3 4 5 6 and a pathophysiological hypothesis, yet to be demonstrated, implying that the chronic dysfunction is due to a chronic reduction of resting MBF.4 5 Other aspects that were not included in the original description, ie, the rapidity of mechanical recovery after successful revascularization7 and the response of dysfunctional myocardium to inotropic stimulation, are now also considered to be integral parts of this condition. The purpose of this discussion is to review some of the …

Cardiac Risk Assessment before Vascular Surgery: A Prospective Study Comparing Clinical Evaluation, Dobutamine Stress Echocardiography, and Dobutamine Tc-99m Sestamibi Tomoscintigraphy

Preoperative evaluation for cardiac risk assessment before peripheral vascular surgery remains controversial. Between January and June 1994, a prospective open study was carried out in 156 patients scheduled for elective vascular procedures (63 carotid endarterectomies, 34 abdominal aortic aneurysms, 29 aortoiliac and 30 infrainguinal reconstructions) to compare the ability of clinical data, dobutamine stress echocardiography, and dobutamine Tc-99m sestamibi tomoscintigraphy to predict postoperative cardiac events. Pharmacological stress testing consisted of incremental dobutamine infusion (±1 mg atropine to achieve 85% of age-predicted maximal heart rate, with continuous echocardiographic monitoring, and injection of Tc-99m sestamibi after dobutamine infusion). Dobutamine echocardiography was abnormal in 36 patients (worsening resting wall motion abnormality in 11; new induced wall motion abnormality in 25). Dobutamine Tc-99m sestamibi tomoscintigraphy revealed a reversible perfusion defect in 34 patients, indicating the presence of myocardial ischaemia. As a result, eight patients underwent myocardial revascularization ( n = 5) or the proposed operation was cancelled ( n = 3). In the remaining 142 vascular procedures, there were eight (5.6%) adverse cardiac events: three myocardial infarctions (two fatal), three prolonged myocardial ischaemia, one acute congestive heart failure and one sustained ventricular arrhythmia in the post operative period. Univariate analysis selected unstable angina (relative risk (RR) 11.6), previous congestive heart failure (RR 6.4), Detsky's score of ≥15 (RR 3.0), positive dobutamine stress echocardiography (RR 3.7), and positive dobutamine tomoscintigraphy (RR 7.4) as significant predictors of postoperative cardiac events. In patients without clinical markers of coronary artery disease ( n = 66), non-invasive cardiac testing did not predict cardiac complications ( n = 2; one prolonged myocardial ischaemia; one infarction). In the subset of 76 patients with definite clinical or electrocardiographic evidence of ischaemic heart disease, dobutamine stress testing provided additional information, and optimized risk stratification: five of six patients who suffered a cardiac complication had a pathologic dobutamine stress test. Furthermore, a negative dobutamine stress test was characterized by a high negative predictive value (0.96 for echocardiography; 0.97 for tomoscintigraphy). The study further demonstrated that the cardiac response (ischaemic versus non-ischaemic) to dobutamine stress was concordantly classified by echocardiographic and tomoscintigraphic techniques in 96% of cases. It is concluded that complementary non-invasive cardiac stress testing by dobutamine is indicated only in patients with clinically apparent coronary artery disease.

Cardiac risk assessment before vascular surgery: a prospective study comparing clinical evaluation, dobutamine stress echocardiography, and dobutamine Tc-99m sestamibi tomoscintigraphy

Preoperative evaluation for cardiac risk assessment before peripheral vascular surgery remains controversial. Between January and June 1994, a prospective open study was carried out in 156 patients scheduled for elective vascular procedures (63 carotid endarterectomies, 34 abdominal aortic aneurysms, 29 aortoiliac and 30 infrainguinal reconstructions) to compare the ability of clinical data, dobutamine stress echocardiography, and dobutamine Tc-99m sestamibi tomoscintigraphy to predict postoperative cardiac events. Pharmacological stress testing consisted of incremental dobutamine infusion (±1 mg atropine to achieve 85% of age-predicted maximal heart rate, with continuous echocardiographic monitoring, and injection of Tc-99m sestamibi after dobutamine infusion). Dobutamine echocardiography was abnormal in 36 patients (worsening resting wall motion abnormality in 11; new induced wall motion abnormality in 25). Dobutamine Tc-99m sestamibi tomoscintigraphy revealed a reversible perfusion defect in 34 patients, indicating the presence of myocardial ischaemia. As a result, eight patients underwent myocardial revascularization ( n = 5) or the proposed operation was cancelled ( n = 3). In the remaining 142 vascular procedures, there were eight (5.6%) adverse cardiac events: three myocardial infarctions (two fatal), three prolonged myocardial ischaemia, one acute congestive heart failure and one sustained ventricular arrhythmia in the post operative period. Univariate analysis selected unstable angina (relative risk (RR) 11.6), previous congestive heart failure (RR 6.4), Detsky's score of ≥ 15 (RR 3.0), positive dobutamine stress echocardiography (RR 3.7), and positive dobutamine tomoscintigraphy (RR 7.4) as significant predictors of postoperative cardiac events. In patients without clinical markers of coronary artery disease ( n = 66), non-invasive cardiac testing did not predict cardiac complications ( n = 2; one prolonged myocardial ischaemia; one infarction). In the subset of 76 patients with definite clinical or electrocardiographic evidence of ischaemic heart disease, dobutamine stress testing provided additional information, and optimized risk stratification: five of six patients who suffered a cardiac complication had a pathologic dobutamine stress test. Furthermore, a negative dobutamine stress test was characterized by a high negative predictive value (0.96 for echocardiography; 0.97 for tomoscintigraphy). The study further demonstrated that the cardiac response (ischaemic versus non-ischaemic) to dobutamine stress was concordantly classified by echocardiographic and tomoscintigraphic techniques in 96% of cases. It is concluded that complementary non-invasive cardiac stress testing by dobutamine is indicated only in patients with clinically apparent coronary artery disease. © 1997 The International Society for Cardiovascular Surgery.

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.

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. One hundred and thirty two symptomatic patients with old myocardial infarction. 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. 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. 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.

Exercise echocardiography, angiography, and intracoronary ultrasound after cardiac transplantation

Fifty-one consecutive patients underwent exercise echocardiography, angiography, and intracoronary ultrasound (ICUS) 2.5 years (range 1 to 6) after cardiac transplantation. The average age of the donor was 29 years (range 13 to 50), and the average age of the recipient was 49 ± 12 years. In total, 78 studies were performed, as 25 patients had >1 annual evaluation and 2 patients had 3 consecutive annual evaluations. Of the 78 angiographic studies, 40 (26 patients) had evidence of coronary artery disease, defined as a focal stenosis (>20%, n = 4) or luminal irregularities (n = 36). However, by ICUS all 51 patients had intimal thickening at some point, with 34 patients possessing diffuse disease and 17 focal intimal thickening only. Of the 25 serial studies, 12 progressed by at least 1 Stanford class. The sensitivity of angiography for the determination of class III to IV intimal thickening was 64%, and the specificity was 76%. On exercise echocardiography, 6 examinations revealed resting wall motion abnormalities, whereas 6 had inducible wall motion abnormalities with exercise. The sensitivity of exercise echocardiography to determine class III to IV intimal thickening was 15%, and the specificity was 85%. In conclusion, exercise echocardiography is an insensitive method for predicting transplant-mediated coronary artery disease, whereas luminal irregularities on angiography may predict the presence of Stanford grade III to IV intimal thickening.

Technetium-99m sestamibi tomographic evaluation of residual ischemia after anterior myocardial infarction

This study investigated the value of sestamibi scintigraphy in assessing residual ischemia after anterior myocardial infarction. Serial imaging with sestamibi, the uptake and retention of which correlate with regional myocardial blood flow and viability, has been used to estimate salvaged myocardium and risk area after acute infarction. We recently documented that recovery of perfusion and contraction in the infarcted area may continue well after the subacute phase, suggesting myocardial hibernation. Some underestimation of viability in the setting of hibernating myocardium by sestamibi imaging has been reported. We studied 58 patients in stable condition after Q wave anterior infarction. Regional perfusion and function were quantitatively assessed by sestamibi tomography and two-dimensional echocardiography at 4 to 6 weeks and at 7 months after infarction. In sestamibi polar maps, abnormal areas with tracer uptake > 2.5 SD below our reference values were computed at rest and after symptom-limited exercise. On two-dimensional echocardiography the ejection fraction and extent of rest wall motion abnormalities were assessed by a computerized system. All patients had coronary angiography between the two studies. At 7 months the extent of rest sestamibi defect was significantly reduced in 40 patients (69%, group 1) and unchanged in 18 (31%, group 2). Rest wall motion abnormalities and ventricular ejection fraction significantly improved in group 1 but not in group 2. Underlying coronary disease, patency of the infarct-related vessel and rest sestamibi defect extent at 5 weeks were comparable between the two groups. At 7 months, an increase in the reversible (stress-rest defect) tracer defect was observed in group 1 (p < 0.05) despite a smaller stress-induced hypoperfusion (p < 0.05). Reversible sestamibi defects and stress hypoperfusion were unchanged in group 2. In 38 (95%) of 40 group 1 patients, the area showing reversible sestamibi defects at 7 months matched the area showing fixed hypoperfusion at 5 weeks. The reduction in the rest tracer uptake defect that can occur late after infarction may affect the assessment of ischemic burden by sestamibi imaging early after anterior myocardial infarction.

Relation between thallium uptake and contractile response to dobutamine. Implications regarding myocardial viability in patients with chronic coronary artery disease and left ventricular dysfunction.

Both thallium scintigraphy and dobutamine echocardiography have been used to assess myocardial viability. However, thallium uptake and the inotropic response to dobutamine are expressions of different cellular phenomena. The present study was undertaken to investigate the relation between the two methods in patients with chronic coronary artery disease and left ventricular dysfunction to derive insights into the mechanisms related to myocyte viability. Thirty patients (28 men and 2 women; age, 59 +/- 10 years) with chronic coronary artery disease and impaired left ventricular systolic function at rest (mean ejection fraction, 32 +/- 9%) were included in the study. Patients underwent transesophageal echocardiography during incremental doses of dobutamine from 2.5 to a maximum of 40 micrograms.kg-1.min-1 and single photon emission computed tomographic thallium scintigraphy using a stress-redistribution-reinjection protocol. The left ventricle was divided into 16 segments for analysis of echocardiographic and thallium images. Segmental myocardial contractile function was graded as normal, hypokinesis, akinesis, or dyskinesis at each incremental dose of dobutamine. Thallium uptake in each myocardial segment was graded on a 5-point scale from 0 (absent) to 2 (normal) for each of the stress, redistribution, and reinjection images. A segment was considered viable if the assigned thallium score was 1 or higher (normal uptake or only mild to moderate defect) in any of the stress, redistribution, or reinjection images. Among 472 myocardial segments available for analysis, 311 had resting wall motion abnormalities, of which 56% (173/311) showed contractile improvement with dobutamine (usually first observed at < or = 10 micrograms.kg-1.min-1) and 84% (262/311) were considered viable by thallium scintigraphy (P < .0001). Of the 262 segments considered viable by thallium, 167 (64%) had a contractile improvement with dobutamine; in contrast, only 6 of the 49 segments (12%) considered nonviable by thallium had a positive dobutamine response (P < .0001). Furthermore, a positive inotropic response to dobutamine was significantly related to the magnitude of thallium uptake: the proportion of segments with a positive dobutamine response rose with increasing magnitude of thallium uptake (P < .001). The disagreement between the two tests was related primarily to segments considered viable by thallium that did not show contractile improvement with dobutamine. These findings demonstrate the existence of a relation between thallium uptake and the inotropic response to dobutamine in patients with chronic coronary artery disease and left ventricular dysfunction. However, the proportion of segments showing a positive response to dobutamine is significantly lower than those with thallium uptake, suggesting that the cellular mechanisms responsible for a positive inotropic response to adrenergic stimulation require a higher degree of myocyte functional integrity than those responsible for thallium uptake.

Assessment of anatomic and physiological severity of single-vessel coronary artery lesions by dipyridamole echocardiography. Comparison with positron emission tomography and quantitative arteriography.

The aim of this study was to compare the results of dipyridamole-echocardiography test (DET: two-dimensional echo monitoring during dipyridamole infusion up to 0.84 mg/kg over a period of 10 minutes) with both anatomic and physiological parameters of coronary artery disease severity, assessed by computer-assisted quantitative coronary arteriography, and regional coronary flow reserve, measured by [13N]ammonia (13NH3) and dynamic positron emission tomography (PET), respectively. We studied 31 patients with a history of chest pain and neither previous myocardial infarction nor resting wall motion abnormalities. Eighteen patients had single-vessel disease (> 50% stenosis of one major coronary vessel), and 13 had normal coronary arteries. The criterion for DET positivity was the appearance of a new transient regional wall motion abnormality. In patients with a positive DET, two parameters were evaluated: the dipyridamole time (ie, the time from the beginning of drug infusion to the development of obvious dyssynergy) and the wall motion score index (WMSI, a semiquantitative integrated estimation of extent and severity of the stress-induced dyssynergy). WMSI was derived by summation of individual segment scores divided by the number of segments interpreted. Quantification of regional myocardial blood flow was obtained by PET measurements of 13NH3 arterial input function and left ventricular myocardial tissue concentration both at control and after dipyridamole (0.56 mg/kg over 4 minutes). Maximal regional blood flow after dipyridamole in the region supplied by the stenotic vessel was significantly lower in the 11 patients with coronary artery disease and positive DET than in the 7 patients with coronary artery disease and negative DET (1.08 +/- 0.33 versus 1.98 +/- 0.37 mL.min-1.g-1, P < .01). In patients with a positive DET, regional coronary flow reserve correlated well with dipyridamole time (r = .87, P < .01) but not with peak WMSI (r = .25, P = NS). Patients with dipyridamole-induced akinesia or dyskinesia (n = 6) had a greater reduction in regional coronary flow reserve than did those showing hypokinesia (n = 5): 1.38 +/- 0.51 versus 2.17 +/- 0.42, P < .05. Percent area reduction was more severe in patients with DET positivity than in those with DET negativity (93.7 +/- 8.7% versus 77 +/- 10.3%, P < .01), and it correlated with regional coronary flow reserve (r = .64, P < .01) and dipyridamole time (r = -.59, P < .01). In patients with single-vessel disease, DET shows an excellent specificity but a limited sensitivity; in these patients, DET positivity is associated with a physiologically important coronary stenosis. Severity of the anatomic stenosis and impairment in regional flow reserve are greater when the dipyridamole-induced dyssynergy appears earlier during the test. Therefore, a stratification of the anatomo-physiological severity of coronary artery disease can be obtained with DET, based mainly on the temporal allocation of the transient dyssynergy.

Dipyridamole thallium-201 imaging versus dobutamine echocardiography for the evaluation of coronary artery disease in patients unable to exercise

The present study used 51 patients in a prospective, crossover, blinded comparison of dipyridamole thallium-201 imaging and dobutamine echocardiography for (1) detection of coronary artery disease (CAD), (2) detection of inducible ischemia, and (3) determination of myocardial viability. The detection of CAD was based on quantitative defects on initial planar thallium-201 images and resting or inducible wall motion abnormalities on echocardiography. Detection of ischemia was based on redistribution on delayed thallium-201 images and inducible wall motion abnormality on echocardiography. The myocardium in a region with resting wall motion abnormality was considered viable if it showed either redistribution or >50% activity on delayed thallium-201 images, and if regional function either improved or worsened on echocardiography. The tests were comparable for the detection of CAD (53 and 59%, respectively, p = 0.23). Thallium-201 was superior to echocardiography for the detection of ischemia (35 vs 14%, respectively, p = 0.01). Although the incidence of viable myocardium was equivalent by the 2 tests (100 and 96%, respectively, p = 0.99) for each abnormally moving segment in the 24 patients with resting wall motion abnormality on echocardiography, it was greater on thallium-201 imaging (98 vs 68%, p < 0.01). It is concluded that because of its better ability to detect inducible myocardial ischemia and determine viability in myocardial segments showing reduced function, dipyridamole thallium-201 imaging appears to be superior to dobutamine echocardiography for the evaluation of CAD in patients unable to exercise.

Dobutamine stress echocardiography for cardiac risk assessment before aortic surgery

Purpose: This study evaluates dobutamine stress echocardiography (DSE) for perioperative cardiac risk assessment with elective aortic surgery.Methods: Dobutamine stress echocardiography was used to evaluate 81 patients before infrarenal aortic surgery. Patients were placed into three groups. Group I (n = 31) had normal DSEs. Group II (n = 25) had resting wall motion abnormalities without dobutamine-induced changes of ischemia. Group III (n = 25) had evidence of dobutamine-induced ischemia. Patient analysis revealed that of 46 patients with clinical indicators of coronary artery disease (CAD), only 23 had DSEs with inducible ischemia. Two of 35 patients without clinical indicators of CAD had DSEs with inducible ischemia.Results: The 56 patients in groups I and II underwent aortic reconstruction without cardiac complications or death. Of the 25 patients in group III, surgery was deferred in five (two patients with claudication and three with aneurysms ≤5 cm), and four underwent coronary artery bypass grafting. Outcome after coronary artery bypass grafting included one death from stroke, one aneurysm rupture, and two uncomplicated aortic reconstructions. The remaining 16 patients in group III underwent aortic surgery, with three postoperative myocardial infarctions (MI) and no deaths.Conclusions: Using DSE for preoperative assessment of cardiac risk allowed us to operate on 74 of 81 patients being considered for elective aortic reconstruction, with no operative deaths and a 4.1% rate of perioperative MI. Dobutamine stress echocardiography has the ability to identify patients with asymptomatic stress-induced ischemic myocardium and its increased risk for perioperative MI (p < 0.001). Equally important, for patients with clinical indicators of CAD but without DSE-inducible ischemia, no further cardiac evaluation is necessary.

Regional myocardial blood flow in stable angina pectoris associated with isolated significant narrowing of either the left anterior descending or left circumflex coronary artery

Myocardial perfusion measurements were obtained with positron emission tomography under basal conditions and after intravenous dipyridamole infusion (0.56 mg/kg over 4 minutes) to determine if myocardial perfusion is maximized in areas of resting wall motion abnormalities in patients with stable angina. Thirty-three patients with no history of myocardial infarction, and with coronary stenosis >50% involving the left anterior descending (n = 24) and left circumflex (n = 9) coronary arteries were evaluated. Quantitative perfusion images were recorded twice in each subject using nitrogen-13 ammonia at baseline and after intravenous administration of dipyridamole. Computer-assisted analysis of left ventriculograms showed abnormal wall motion in the stenosis-related regions in 16 patients (group 1), and normal regional function in 17 (group 2). The flow values in the anterior and posterolateral wall were considered to reflect left anterior and left circumflex coronary artery flow, respectively. Quantitative angiography showed that coronary stenosis severity was higher in group 1 than in group 2 (cross-sectional area reduction 94 ± 7% vs 87 ± 11%; p <0.05). Resting blood flow in the stenosis-related areas was significantly lower than in contralateral regions in group 1(0.66 ± 0.19 vs 0.77 ± 0.26 ml/min/r, p <0.05), but not in group 2 (0.73 ± 0.18 vs 0.78 ± 0.21 ml/min/g; p = NS). Dipyridamole significantly (p <0.01) increased myocardial blood flow in both stenotic and remote regions in both groups 1(0.95 ± 0.41 vs 1.57 ± 0.70 ml/min/10 and 2 (1.54 ± 0.53 vs 2.01 ± 0.84 ml/ min/g). Thus, in patients with stable angina and no previous myocardial infarction, chronic wall motion abnormalities may be associated with reduced myocardial blood flow. A residual vascular tone can be maintained in hypoperfused dysfunctioning myocardial areas, suggesting that further factors, in addition to the restriction in oxygen delivery, can downregulate the metabolic demand of hibemating myocardium.