Stress Echocardiography: Ischemic and Nonischemic
Edgar Argulian
Farooq A. Chaudhry
1. A 77-year-old man with multiple cardiovascular risk factors complains of burning chest pain on exertion that is relieved by rest. During exercise echocardiography, which of the following is likely the latest event to be observed?
A. Chest pain.
B. Regional abnormality in myocardial relaxation.
C. Regional wall motion abnormality.
D. ST-segment depression on electrocardiogram.
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1. Answer: A. The use of stress echocardiography to diagnose flow-limiting coronary artery disease is based on a sequence of events known as the ischemic cascade as shown in Figure 14-14. The decrease in blood flow initially produces a perfusion abnormality, diastolic and systolic dysfunction, in that order, and then hemodynamic abnormalities occur. Electrocardiographic changes and symptoms occur late in the ischemic cascade; hence, the sensitivity of these parameters to identify ischemia is lower.
 Figure 14-14 |
2. Which of the following is normal global and regional response to dobutamine infusion during stress echocardiography?
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2. Answer: A. A normal response to dobutamine infusion during stress echocardiography starting with a low dose is a progressive increase in regional endocardial excursion, myocardial thickening, and left ventricular ejection fraction as well as a decrease in end-systolic left ventricular volume. A decrease in regional endocardial excursion and myocardial thickening at peak dose compared with a low dose (as described in option D) indicates myocardial ischemia. Cavity dilation and a decrease in left ventricular ejection fraction at peak dose (as described in option B) are uncommon and usually indicate a high ischemic burden.
3. Which of the following stress-testing modalities has been shown to have the highest specificity for detection of flow-limiting coronary artery disease?
A. Adenosine single-photon emission computed tomography (SPECT) myocardial perfusion imaging.
B. Exercise echocardiography.
C. Exercise electrocardiography.
D. Exercise SPECT myocardial perfusion imaging.
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3. Answer: B. Multiple studies comparing the test performance of different stress testing modalities yielded relatively consistent results. Sensitivity of nuclear perfusion imaging and stress echocardiography appear to be similar and exceed this for plain exercise electrocardiography although sensitivity may be higher for vasodilator nuclear perfusion imaging (close to 90%). At the same time, several meta-analyses have consistently shown a higher specificity for stress echocardiography, which could potentially contribute to its use as cost-effective diagnostic modality. One should realize that specificity of noninvasive imaging when using cardiac catheterization as a gold standard could be diminished in the current era due to test verification bias: patients with unrevealing stress test are less likely to undergo cardiac catheterization.
4. Which of the following is most likely to give a false-negative result during stress echocardiography?
A. Isolated left anterior descending artery disease.
B. Isolated left circumflex artery disease.
C. Marked increase in systolic blood pressure during stress.
D. Triple vessel disease with “balanced” ischemia. E. Use of atropine during dobutamine echocardiography.
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4. Answer: B. The sensitivity of stress echocardiography is proportionally related to the number of vessels involved, being the greatest for triple-vessel disease. This is especially true for left circumflex disease since it supplies a smaller amount of myocardium. False-negative results due to “balanced” ischemia as seen during nuclear perfusion imaging are not characteristic for stress echocardiography (option D). Hypertensive response to exercise can result in false-positive studies due to myocardial oxygen supply-demand mismatch (option C). Atropine is frequently used during dobutamine stress echocardiography when the peak heart rate is suboptimal, to improve the sensitivity and thus decrease the rate of false-negative studies (option E). Common causes of false-positive and false-negative results during stress echocardiography are listed in Table 14-1.
Table 14-1. Common Causes of False-Positive and False-Negative Results During Stress Echocardiography | ||||||||||||||||
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5. Which of the following can decrease the specificity of stress echocardiography?
A. Apical foreshortening.
B. Delay on image acquisition.
C. Hypertensive response to exercise.
D. Inadequate exercise with suboptimal peak heart rate.
E. Use of a beta-blocker before stress testing.
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5. Answer: C. Specificity of stress echocardiography is affected by the presence of false-positive results (Table 14-1). The list of conditions that can cause wall motion abnormalities during stress in the absence of flow-limiting coronary stenosis includes hypertensive response to exercise, abnormal septal motion caused by left bundle branch block, and nonischemic cardiomyopathy. Other options listed can potentially cause false-negative results and therefore affect sensitivity of stress echocardiogram.
6. Which of the following is the most appropriate reason to terminate the stress test during dobutamine echocardiography?
A. Chest discomfort.
B. New wall motion abnormalities.
C. T-wave inversions on electrocardiogram.
D. Upsloping ST-segment depression on electrocardiogram. E. Ventricular ectopic beats.
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6. Answer: B. Dobutamine infusion can be associated with uncomfortable symptoms including chest discomfort and palpitations (choice A). Only if intolerable, these symptoms alone are the indication to terminate the test. Other end-points for dobutamine echocardiography include attainment of the target heart rate (85% of the age-predicted maximum heart rate) or protocol completion, hypotension, new or worsening significant wall-motion abnormalities (correct option, choice B), significant arrhythmias (not ventricular ectopic beats that are common during dobutamine infusion, option E), and severe hypertension.
7. The sensitivity of stress echocardiography to detect ischemia is greatest in which of the following coronary artery distributions?
A. Left anterior descending artery.
B. Left circumflex artery.
C. Ramus intermedius.
D. Right coronary artery.
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7. Answer: A. The sensitivity of stress echocardiography to detect flow-limiting lesions depends not only on the degree of coronary stenosis, but also on the number of vessels involved and the area of jeopardized myocardium. The sensitivity is higher for multivessel disease compared with single-vessel disease. Likewise, the sensitivity to detect stenosis in the left anterior descending artery and right coronary artery territory is superior to the sensitivity for the left circumflex. The highest sensitivity is for left anterior descending artery stenosis.
8. A 50-year-old woman complains of exertional shortness of breath and ankle swelling. She has no chest pain, cough, wheezing, palpitations, or syncope. She is treated for hypertension with a thiazide diuretic and irbesartan. Pulmonary function testing is unremarkable. Resting transthoracic echocardiogram shows left atrial dilation, mild concentric left ventricular hypertrophy with left ventricular ejection fraction of 60%, and normal right ventricular size and function. The estimated pulmonary artery systolic pressure is 35 mm Hg. Which of the following postexercise parameters is most likely to explain this patient’s symptoms?
A. Left ventricular ejection fraction.
B. Left ventricular outflow tract velocities.
C. Left ventricular wall motion analysis.
D. Right ventricular wall motion analysis. E. Transmitral flow velocities and tissue Doppler.
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8. Answer: E. Exertional dyspnea is a ubiquitous complaint and a relatively common reason for stress echocardiography referral. A significant number of dyspneic patients have diastolic dysfunction. In recent years, it has been shown that stress-induced diastolic dysfunction can be diagnosed in these patients using postexercise transmitral flow velocities, tissue Doppler velocities, and tricuspid regurgitant velocity. Semisupine bicycle is commonly used. In patients with diastolic heart failure, a postexercise increase in E/e′ ratio (>15) and tricuspid regurgitant velocity are commonly observed. Although coronary artery disease is a possibility in this patient, she reports no chest pain. Exertional dyspnea without chest pain is unlikely to be an angina equivalent in patients without known coronary artery disease or resting wall motion abnormalities (option C). Common noncoronary indications for stress echocardiography are listed in Table 14-2.
9. A 48-year-old woman complains of exertional dyspnea for the last several months. Her current exercise tolerance is about four blocks on a level ground, but she gets short of breath very easily when climbing stairs. Her medical history is insignificant, but she has a strong family history of coronary artery disease. Electrocardiogram shows normal sinus rhythm with T-wave inversions in leads I, avL, and V6. Transthoracic echocardiogram shows left atrial enlargement, and dilated left ventricle with global hypokinesis and ejection fraction of 20%. The right ventricle is normal in size and function, and the estimated pulmonary artery systolic pressure is 40 mm Hg. Which of the following is the best option in evaluating this patient?
A. Dipyridamole echocardiography using 0.84 mg/kg.
B. Dobutamine echocardiography using 2.5-40 &mgr;g/kg/min.
C. Dobutamine echocardiography using 10-40 &mgr;g/kg/min.
D. Treadmill exercise echocardiography using Bruce protocol.
E. Treadmill exercise electrocardiogram using Bruce protocol.
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9. Answer: B. Dobutamine echocardiography allows assessment of both viability and ischemia in patients with systolic left ventricular dysfunction and significant resting wall motion abnormalities. Dobutamine infusion is started at a lower dose (2.5 and 5 &mgr;g/kg/min) in these patients facilitating identification of viability in segments that are abnormal at rest. Viable segments will demonstrate inotropic contractile reserve. At higher doses, a biphasic response can be elicited, which is indicative of ischemia. Treadmill exercise electrocardiogram, treadmill echocardiography, and vasodilator stress echocardiography have poor sensitivity in identifying both viable and ischemic myocardium.
10. A 44-year-old woman complains of exertional substernal chest discomfort that limits her exercise capacity. She has type 2 diabetes mellitus and hypertension. Her BMI is 29 kg/m2. Coronary CT angiography shows mild nonobstructive coronary atherosclerosis. Coronary flow reserve assessment is planned using flow velocity measurements in the left anterior descending artery interrogated with pulse wave Doppler during echocardiography examination. Which of the following is the stress modality of choice?
A. Dipyridamole echocardiography using 0.84 mg/kg.
B. Dobutamine echocardiography using 2.5-40 &mgr;g/kg/min.
C. Dobutamine echocardiography using 10-40 &mgr;g/kg/min.
D. Semisupine bicycle exercise electrocardiogram.
E. Treadmill exercise echocardiography using Bruce protocol.
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10. Answer: A. Microvascular dysfunction without flow-limiting epicardial coronary disease can cause angina-like exertional chest pain in different patient subgroups including patients with diabetes mellitus, hypertension, and syndrome X. During exercise testing, typical symptoms can be provoked along with ischemic ST-segment changes. In contrast to coronary artery disease, wall motion abnormalities may not be an early event in these patients. Pulse wave Doppler examination of the mid-to-distal left anterior descending artery has been shown to be highly feasible in the low parasternal long-axis view under the guidance of color Doppler flow mapping and it allows assessment of the coronary flow reserve. Normally, there is at least twofold increase in the peak diastolic coronary flow velocities with vasodilator infusion (such as dipyridamole or adenosine) compared to rest. Abnormal coronary flow reserve (≤2) carries diagnostic and prognostic information in certain subgroups of patients. In a large study of patients with negative dipyridamole echocardiography by wall motion criteria abnormal coronary flow reserve provided independent prognostic information in both diabetic and nondiabetic patients (Cortigiani et al., J Am Coll Cardiol. 2007;50:1354-1361).
Table 14-2. Common Noncoronary Indications for Stress Echocardiography | ||||||||||||||
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11. A 70-year-old man complains of progressive exertional dyspnea over the last 6 months. Cardiac catheterization shows no obstructive coronary disease. Echocardiogram shows left atrial dilation and left ventricular dilation with ejection fraction of 30%. Aortic valve appears calcified with restricted motion. Peak velocity across the aortic valve is 3 m/s, mean gradient is 28 mm Hg, and estimated aortic valve area is 0.8 cm2. Which of the following findings during low-dose dobutamine infusion provides the strongest indication for aortic valve replacement in this patient?
A. Peak velocity across the aortic valve of 4.2 m/s and estimated aortic valve area of 0.8 cm2.
B. Mean gradient across the aortic valve of 35 mm Hg and estimated aortic valve area of 0.8 cm2.
C. Mean gradient across the aortic valve of 35 mm Hg and an increase in stroke volume by 25%.
D. Mean gradient across the aortic valve of 41 mm Hg and estimated aortic valve area of 1.2 cm2.
E. No increase in stroke volume and no increase in mean gradient across the aortic valve.
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11. Answer: A. Dobutamine echocardiography is a useful diagnostic tool in patients with suspected severe aortic stenosis in the settings of severe left ventricular dysfunction. These patients typically have a depressed left ventricular ejection fraction, low mean aortic gradient (<40 mm Hg) and peak transvalvular velocity (<4 m/s), a calculated aortic valve area of <1.0 cm2, and a dimensionless index of <0.25. True severe aortic stenosis in this setting should be differentiated from “pseudo-severe” aortic stenosis created by a low-flow state and moderate or mild aortic stenosis. If the aortic stenosis is severe, the peak transvalvular velocity and the mean gradient augment during low-dose dobutamine infusion while the calculated aortic valve area does not change compared to baseline. Per current recommendations, aortic valve replacement should be considered in symptomatic patients with severe aortic stenosis with reduced left ventricular ejection fraction when a low-dose dobutamine stress study shows an aortic velocity ≥4.0 m/s (or mean pressure gradient ≥40 mm Hg) with an estimated aortic valve area ≤1.0 cm2 at any dobutamine dose. Also, dobutamine infusion can identify patients with lack of contractile reserve (an increase of stroke volume <20%) that have poor prognosis with either medical or surgical therapy (option E).
12. A 73-year-old woman with a history of hypertension is evaluated for atypical chest pain. Her exercise capacity is limited by chronic knee pain. Her resting echocardiogram is normal. She undergoes dobutamine echocardiography, which shows moderate ischemia in the apical segments, anterior wall, and anteroseptum. Subsequent coronary angiography shows mild luminal irregularities but no obstructive coronary artery disease. Her prognosis (overall survival) is most similar to which of the following patients?
A. Patient with markedly abnormal stress test and transient ischemic cavity dilation.
B. Patient with normal stress test and no significant (<50% stenosis) coronary disease.
C. Patient with similarly abnormal stress test and low baseline ejection fraction.
D. Patient with similarly abnormal stress test and obstructive (>50% stenosis) coronary disease.
E. Patient with similarly abnormal stress test undergoing exercise echocardiography.
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12. Answer: D. “False-positive” results on stress echocardiography are not uncommon as judged by coronary angiography. One study estimated that 33% of patients with abnormal stress echocardiogram have no obstructive disease on coronary angiography (From et al., J Am Soc Echocardiogr. 2010;23:207-214). In that study, the mortality in patients with abnormal stress test was influenced by age, stress modality (dobutamine echocardiography carrying a higher mortality), and resting left ventricular ejection fraction (<50% carrying a higher mortality). Patients with markedly abnormal stress echocardiogram also carried a higher mortality. Presence or absence of obstructive coronary artery disease (>50% stenosis) had no influence on mortality.
13. Which of the following statements is correct about the basic concepts of myocardial viability assessment?
A. Dobutamine stress echocardiography can differentiate viability in the endocardium versus epicardium.
B. No reflow indicates viable myocardium in the presence of an open epicardial vessel.
C. Nontransmural infarction of <50% of myocardial thickness does not impair wall thickening.
D. Q waves on electrocardiogram indicate absence of viable myocardium in the corresponding territory.
E. Stunned myocardium is a state of contractionperfusion mismatch that can be seen after successful reperfusion therapy.
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13. Answer: E. Stunned myocardium is a state of contraction-perfusion mismatch that can be seen in the setting of acute myocardial infarction after successful reperfusion. If recurrent chronic ischemia occurs, the dysfunctional but viable myocardium is called hibernating myocardium. Hibernating myocardium results from recurrent stunning of the myocardium (Fig. 14-15, basic concepts of viability). Dobutamine stress echocardiography cannot differentiate viability in the endocardium versus epicardium (option A). No reflow commonly results from capillary destruction and it is most consistent with no viability (option B). A nontransmural infarction of only 20% of the wall thickness can impair wall thickening (option C). Up to 40% of regions showing Q waves on the electrocardiogram are viable (option D).
 Figure 14-15. A normally perfused and functioning myocardium is depicted by normal coronary arteries and normal end-systolic and end-diastolic volumes. In the middle row on the right, a complete left coronary artery occlusion has occurred in the setting of plaque rupture with acute thrombosis. If the lack of perfusion is prolonged enough, a myocardial infarction ensues, with loss of function, depicted here by a regional increase in end-systolic volume (A). If reperfusion occurs, due to either recanalization or revascularization, the contractility initially abnormal due to ischemia may remain impaired in the acute and subacute stages, with subsequent improvement. This phenomenon is called stunning (B). Repetitive stunning leads to a state of chronic myocardial dysfunction called hibernation (C). A chronic flow-limiting coronary artery occlusion leads to downregulation of the regional wall motion abnormality, leading to hibernating myocardium (C). |
14. A 64-year-old man presents with intermittent chest pain. He has a strong family history of coronary artery disease. Transthoracic echocardiogram shows left atrial dilation, normal resting left ventricular wall motion, and left ventricular ejection fraction of 55%. Dobutamine echocardiography was ordered and global longitudinal strain values were obtained at baseline, low-dose, and peak dobutamine infusion. Which of the following set of values is most consistent with significant coronary artery disease as the cause of this patient’s chest pain?
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14. Answer: B. Global longitudinal strain reflects myocardial shortening in the longitudinal direction and therefore is a negative number. Normal values are commonly approximately -20%. Deformation analysis during dobutamine infusion can provide objective evidence of viability and ischemia. In one study, longitudinal strain analysis had a higher diagnostic accuracy than circumferential and radial strains and was comparable to visual wall motion assessment by an experienced echocardiographer in patients undergoing dobutamine echocardiography. Besides, a combination of longitudinal strain and visual assessment of wall motion resulted in a significant incremental increase in diagnostic accuracy (Ng et al., Am Heart J. 2009;158:836-844). Normally, global longitudinal strain increases with low-dose dobutamine (i.e., become more negative) followed by plateau at pre-peak and possible mild decrease at peak dobutamine dose (option C). Patients with flow-limiting coronary artery disease also show an increase in global longitudinal strain at low dose, but this is followed by a significant decrease in longitudinal strain at peak, sometimes below the baseline value (option B). Also, patients with coronary artery disease commonly have lower resting global longitudinal strain values compared with controls despite preserved left ventricular ejection fraction (Ng et al., Am Heart J. 2009;158:836-844).
15. A 62-year-old man is referred for stress echocardiography for chest pain and shortness of breath. Which of the following is unlikely to reduce accuracy of the test?
A. Left bundle branch block.
B. Pacemaker with A-sensed V-paced rhythm.
C. Right bundle branch block with first-degree atrioventricular block.
D. Right ventricular dilation and severe tricuspid regurgitation.
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15. Answer: C. Abnormal septal motion such as seen in certain conduction abnormalities can affect the accuracy of stress echocardiography. Specificity of image interpretation for obstructive epicardial coronary disease can be decreased. Both left bundle branch block and ventricular pacing create paradoxal septal motion, but abnormal perfusion and impaired wall thickening at higher heart rates can also be seen (options A and B). WPW syndrome can create dyssynchrony in contraction which can be interpreted as abnormal wall motion (option E). Right ventricular volume overload also results in abnormal septal motion (option D). Right bundle branch block with first-degree atrioventricular block should not impair image interpretation.
16. A 52-year-old female ex-smoker with a history of dyslipidemia and hypertension is referred for stress echocardiography due to exertional dyspnea and a recent episode of syncope. She exercises for 6 minutes on the Bruce protocol and has to stop because of shortness of breath. She reaches 86% of her maximum predicted heart rate (Fig. 14-1 and Video 14-1A-C). What is the most likely cause of this patient’s symptoms?
A. Dynamic pulmonary hypertension.
B. Hypertrophic obstructive cardiomyopathy.
C. Left anterior descending artery stenosis.
D. Multivessel coronary artery disease. E. Right coronary artery stenosis.
View Answer
16. Answer: A. This case illustrates the hemodynamic response to exercise in a patient with primary pulmonary hypertension who had only mild pulmonary hypertension at rest, with estimated pulmonary artery systolic pressure of 40 mm Hg that rose to 90 mm Hg during exercise (not shown). Poststress images demonstrate marked right ventricular enlargement and hypokinesis due to a dynamic rise in the rightsided pressures and D-shaped deformation of the interventricular septum with small and hyperdynamic left ventricle.
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