Uses and limitations of exercise Doppler echocardiography in the diagnosis of ischemic heart disease

This study tested the hypothesis that coronary artery disease might be identified by a decrease in Doppler measurements of flow velocity and acceleration. The response of aortic blood flow velocity and acceleration to exercise was determined in 102 subjects (28 young control subjects and 74 older patients) who underwent continuous wave Doppler echocardiographic examination before, during and immediately after near maximal treadmill exercise. Patients were grouped according to the results of thallium perfusion imaging: Group I = normal, Group II = ischemia with or without prior infarction and Group III = prior infarction only. A significant decrease in the level of velocity and acceleration achieved with exercise was observed both in patients in Group I (normal thallium study) (1.2 +/- 0.3 m/s and 36.8 +/- 14 m/s per s, p less than or equal to 0.005) and in patients in Group II (ischemia) (1.1 +/- 0.3 m/s and 27.7 +/- 11 m/s per s, p less than or equal to 0.0005) compared with values in young control subjects (1.4 +/- 0.2 m/s and 52.7 +/- 16 m/s per s). When groups of patients of similar age who differed in the presence (Group II) or absence (Group I) of ischemia on thallium scintigraphy were compared, no difference was found for maximal velocity (1.1 +/- 0.3 versus 1.2 +/- 0.3 m/s, p = NS), but acceleration was significantly lower in Group II (27.7 +/- 11 versus 36.8 +/- 14 m/s per s, p less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of and variables associated with silent myocardial ischemia on exercise thallium-201 stress testing

The prevalence of silent myocardial ischemia was prospectively assessed in a group of 103 consecutive patients (mean age 59 +/- 10 years, 79% male) undergoing symptom-limited exercise thallium-201 scintigraphy. Variables that best correlated with the occurrence of painless ischemia by quantitative scintigraphic criteria were examined. Fifty-nine patients (57%) had no angina on exercise testing. A significantly greater percent of patients with silent ischemia than of patients with angina had a recent myocardial infarction (31% versus 7%, p less than 0.01), had no prior angina (91% versus 64%, p less than 0.01), had dyspnea as an exercise test end point (56% versus 35%, p less than 0.05) and exhibited redistribution defects in the supply regions of the right and circumflex coronary arteries (50% versus 35%, p less than 0.05). The group with exercise angina had more ST depression (64% versus 41%, p less than 0.05) and more patients with four or more redistribution defects. However, there was no difference between the two groups with respect to mean total thallium-201 perfusion score, number of redistribution defects per patient, multi-vessel thallium redistribution pattern or extent of angiographic coronary artery disease. There was also no difference between the silent ischemia and angina groups with respect to antianginal drug usage, prevalence of diabetes mellitus, exercise duration, peak exercise heart rate, peak work load, peak double (rate-pressure) product and percent of patients achieving greater than or equal to 85% of maximal predicted heart rate for age. Thus, in this study group, there was a rather high prevalence rate of silent ischemia (57%) by exercise thallium-201 criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prediction of the frequency and duration of ambulatory myocardial ischemia in patients with stable coronary artery disease by determination of the ischemic threshold from exercise testing: importance of the exercise protocol

The relation between ambulatory myocardial ischemia and the results of exercise testing in patients with ischemic heart disease remains undefined, because of the dissimilar results of previous reports. To further investigate this issue and, in particular, to ascertain the importance of the exercise protocol in determining that relation, 70 patients with stable coronary artery disease underwent 48 h ambulatory electrocardiographic (ECG) monitoring and treadmill exercise tests after withdrawal of medications. Patients exercised using two different protocols with slow (National Institutes of Health [NIH] combined protocol) and brisk (Bruce protocol) work load increments. Exercise duration was longer with the NIH combined protocol (14.1 +/- 5 versus 6.8 +/- 2 min; p less than 0.0001), but the maximal work load and peak heart rate achieved were greater with the Bruce protocol (9.8 +/- 2 versus 6.5 +/- 2 METs, and 142 +/- 19 versus 133 +/- 22 beats/min, respectively; p less than 0.0001). A close inverse correlation between exercise testing and the results of ambulatory ECG monitoring was observed using the NIH combined protocol; the strongest correlation was observed between time of exercise at 1 mm of ST segment depression and number of ischemic episodes (r = -0.86; p less than 0.0001). With the Bruce protocol a significantly weaker inverse correlation was found (r = -0.35). The mean heart rate at the onset of ST segment depression was similar during monitoring and during exercise testing with the NIH combined protocol (97.2 +/- 13 versus 101.0 +/- 17 beats/min, respectively) but it was significantly higher (110.4 +/- 13) when using the Bruce protocol (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Patients with symptomatic ischemia have larger thallium perfusion abnormalities and more adverse prognosis than patients with silent ischemia.

OBJECTIVE: To evaluate the mechanism for silent ischemia and the effect on prognosis. DESIGN: To test the hypothesis that patients with silent (compared with symptomatic) ischemia have less severe ischemia and a more favorable prognosis, the authors prospectively evaluated 152 consecutive patients with a positive exercise electrocardiogram with exercise thallium scintigraphy and followed them for two years. SETTING: Tertiary care university-based hospital. RESULTS: Asymptomatic patients during the exercise test had a greater exercise duration (9.4 +/- 3.1 versus 6.3 +/- 2.5 mins, P < 0.01), maximal heart rate (155 +/- 20 versus 136 +/- 20 beats/min, P < 0.01), systolic blood pressure (184 +/- 21 versus 176 +/- 23 mmHg, P < 0.05) and double product than patients who were symptomatic with chest pain. Although there was no difference in the magnitude of ST depression, time to ST depression was greater in the asymptomatic (5.6 +/- 2.7 mins), compared with symptomatic (4.6 +/- 2.6 mins), group (P < 0.01). Thallium ischemic score was smaller during asymptomatic ischemia (2.1 +/- 2.7) compared with symptomatic ischemia (3.9 +/- 3.1, P < 0.01). These findings were also demonstrated in a subgroup of 107 patients with both a positive exercise electrocardiogram and positive thallium scan. The patients with asymptomatic ischemia had a two-year cardiac event rate of 5.1% compared with 13.8% in the symptomatic patients (P = 0.065). CONCLUSIONS: Patients with asymptomatic ischemia have less severe myocardial ischemia and a better prognosis than patients with symptomatic myocardial ischemia during exercise testing.     

Percutaneous transluminal coronary angioplasty in patients with reduced left ventricular ejection fraction: effects on myocardial perfusion and left ventricular response to exercise

Many patients with coronary artery disease treated by percutaneous transluminal coronary angioplasty (PTCA) have a history of previous myocardial injury resulting in a reduced left ventricular ejection fraction (EF). The effects of successful PTCA on myocardial perfusion and left ventricular function in these patients were compared to treatment in patients with normal left ventricular EF. There were 21 patients with a normal EF (mean EF 59 +/- 2%) (Group I) and 15 patients with reduced EF (mean EF 43 +/- 1%) (Group II). Before PTCA a similar degree of reversible myocardial ischemia was present on thallium scintigraphy. At peak exercise left ventricular EF in the Group I patients decreased by 4 +/- 1% compared to 8 +/- 1% in Group II. At one month following successful PTCA there was resolution of reversible myocardial ischemia in both groups. No changes in EF at rest were observed. At the same level of exercise as before PTCA the mean EF was 5 +/- 1% higher than the pretreatment value in Group I and 10 +/- 1% higher in Group II. Thus in this study reversible myocardial ischemia was associated with severe compromise in the left ventricular response to exercise which was substantially improved by PTCA.     

Value of the exercise test in asymptomatic myocardial ischemia

To evaluate the predictive value of ischemic ST segment depression without associated chest pain during exercise testing, data were analyzed from 7305 studies. Two hundred thirty six patients were included in this study and were separated in 2 groups. Group A consisted of 169 patients without chest pain who, during exercise testing, showed a positive ST segment response (at least 1.5 mm of horizontal or downward ST segment depression for at least 0.08 second, compared with the resting baseline value), and Group B consisted of 67 patients who had both chest pain and a positive ST segment response. Selective coronary angiogram was performed on all patients. Each Group was separated into 3 sub-group according to the Cohn criteria: sub-group I (asymptomatic persons 8.3 vs 19.4%); sub-group II (patients with history of Myocardial Infarction 36.7% vs 19.4%); sub-group III (patients with chronic angina 55% vs 61.2%). The clinical characteristics, coronary risk factors, distribution of coronary artery disease, and exercise test response were similar in both groups. During treadmill exercise, the mean heart rate was 140.6 +/- 22 in group A versus 127.1 +/- 23 in the group B. The pressure-rate product was 2.4 +/- 0.8 versus 1.9 +/- 0.5, respectively (P less than or equal to 0.05). The predictive value for severe coronary artery disease of an exercise test in patients with asymptomatic ischemia was 77.5% as compared with 89.6% in the group with angina. This study confirms the high frequency of asymptomatic myocardial ischemia during exercise testing, compared with patients who had angina during exercise testing, with high percentage of prediction (77.5%) for coronary artery disease.     

Usefulness of severity of myocardial ischemia on exercise testing in predicting the severity of myocardial ischemia during daily activities

To determine the relation between myocardial ischemic indexes on exercise testing and on ambulatory Holter recording, 60 patients with stable coronary artery disease who exhibited an ischemic response to both testing procedures were studied. All patients performed a Bruce protocol exercise test and underwent 24-hour Holter recording within 2 weeks without antianginal medications. Mean exercise duration was 7.4 +/- 2.8 minutes, mean heart rate at 1-mm ST depression was 118 +/- 20 beats/min and mean maximal ST depression during exercise was 2.2 +/- 1 mm. During Holter recording the average number of ischemic episodes was 4.7 +/- 2.6 per patient, mean duration of daily ischemia was 62 +/- 54 minutes, mean maximal ST depression was 3.2 +/- 1.3 mm and average heart rate at 1-mm ST depression was 93 +/- 17 beats/min. Overall, the correlations between ischemic indexes on both testing procedures were very weak (mean r2 = 0.054). The only exercise variable that had a significant correlation (p less than 0.05) with all Holter variables was heart rate at 1-mm ST depression, yet it correlated very weakly (0.064 less than or equal to r2 less than or equal to 0.125) with most Holter covariates and had a better correlation (r2 = 0.256) only with average heart rate at 1-mm ST depression during Holter. Thus, ischemic indexes on exercise testing cannot accurately predict ischemic indexes on ambulatory Holter recording in patients with stable coronary artery disease who exhibit ischemic changes on both tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise-induced prolongation of the infarct-related Q-waves as a marker of myocardial viability in the infarcted area

OBJECTIVE: It is known that exercise-induced ischemia in patients with coronary artery disease (CAD) may produce QRS prolongation in the surface electrocardiogram (ECG). To investigate the presence of exercise-induced Q-wave prolongation in patients with single-vessel CAD and Q-wave myocardial infarction (MI), in association with the presence of reversible perfusion defects during thallium scintigraphy in the infarcted area. METHODS: 107 consecutive patients (89 males, mean age 56+/-8 years) were evaluated. All patients underwent coronary arteriography, maximal treadmill exercise testing and thallium-201 scintigraphy. Q-wave duration was measured both before exercise testing and during maximal heart rate from 12-lead ECGs recorded with a paper speed of 50 mm/s. RESULTS: Only 57 out of the 107 studied patients showed reversible perfusion defects in the infarcted area during thallium scintigraphy. Q-wave duration was significantly increased from the resting to the stress ECG (DeltaQ-wave duration) in patients with reversible perfusion defects in the infarcted areas (10+/-13 ms), but not in patients with fixed defects in the infarcted zone (-2.0+/-5 ms, p<0.01). The sensitivities and the specificities of Q-wave prolongation, ST segment elevation, and the combination of ST segment elevation with ST segment depression in the reciprocal leads for the detection of myocardial viability in the infarcted area were 82%, 48%, 29% and 88%, 50%, and 90%, respectively. CONCLUSIONS: Exercise-induced Q-wave prolongation is demonstrated in those patients with single-vessel CAD and a recent MI who show reversible perfusion defects in thallium scintigraphy. Exercise-induced Q-wave prolongation was found to be a sensitive and specific ECG marker for the detection of myocardial viability in the infarcted area.     

The appearance of gallop rhythm after exercise stress testing

Background and hypothesis: Although it is generally assumed that the appearance of an early diastolic gallop, or third heart sound, appearing immediately after exercise during treadmill stress testing, indicates the presence of serious myocardial disease, no systematically collected data are available to test this hypothesis. Methods: The author performed auscultation on 3,679 patients undergoing routine treadmill testing together with thallium-201 perfusion scans. Exercise-induced diastolic sounds were related to the available clinical information and electrocardiographic and nuclear test results. These findings were compared with those of 665 randomly selected patients undergoing stress testing in whom such sounds were absent. Results: A total of 165 patients had audible third heart sounds (Group 1). In comparison with those patients lacking such sounds (Group 2), there was a considerably greater prevalence of myocardial scarring (68.5 vs. 26.9%), abnormal lung uptake of thallium (40 vs. 12.8%), diabetes mellitus (20.6 vs. 6.2%), and left bundle-branch block on the resting electrocardiogram (ECG) (15.1 vs. 1.2%). In addition, 65 patients (39.3%) had dilatation of the left ventricle after exercise;31 (18.8%) of these were also dilated at rest, but only 2 (1.2%) had a drop in blood pressure during stress. In those individuals also subjected to nuclear ventriculography, the average resting ejection fraction was 35%. Estimated exercise capacity was generally reduced in Group 1 (average peak of 6.6 METs), but 29 (17.6%) exceeded 9 METs. Sensitivity and specificity of electrocardiographic ST depression were relatively poor in the detection of perfusion defects within this group (36 and 62%, respectively). Of the 39 patients in Group 1 with a normal resting ECG, 19 (48.7%) had scar (usually posterior or lateral) on nuclear scans. In an additional 10 of this group, nuclear evidence of ischemia (often extensive) was found. Conclusions: An early or mid-diastolic gallop sound developing after exercise virtually always signifies myocardial disease with reduced myocardial function. Common associated findings are prior infarction (with or without associated ischemia), diabetes, and left bundle-branch block. When found in the presence of a normal resting ECG, this sound commonly signals the presence of an occult left ventricular scar and, less commonly, extensive myocardial ischemia. In those patients manifesting such sounds, electrocardiographic ST changes in response to exercise appear limited in the detection of coronary ischemia.     

Myocardial perfusion and left ventricular performance during exercise-induced ST-segment depression in apparently healthy subjects

Ischemic-like ST-segment depression seen during exercise in apparently healthy subjects has previously been noted, but the cause of this change is unknown. The aim of this study was to investigate the pathophysiology of this electrocardiographic change. Ten healthy subjects who developed an electrocardiographic "ischemic" pattern of ST change during treadmill exercise testing were studied. All subjects underwent both thallium-201 myocardial perfusion imaging and radionuclide angiocardiography at rest and during exercise at a time when abnormal ST changes appeared, and demonstrated a normal homogeneous pattern of thallium-201 distribution on both rest and exercise images. Overall, left ventricular ejection fraction rose from 0.60 +/- 0.06 (mean +/- SD) at rest to 0.65 +/- 0.07 with exercise. None of the subjects had regional wall motion abnormalities at rest or during exercise. These results are different from the findings observed in patients with coronary heart disease and angina pectoris in whom regional abnormalities in both perfusion and left ventricular performance have been noted during exercise. Therefore it would seem that myocardial ischemia is not likely to be a tenable explanation for the electrocardiographic "ischemic" changes in these apparently healthy subjects.     

Myocardial perfusion imaging findings and the role of adenosine in the warm-up angina phenomenon

OBJECTIVES: This study examined the roles of myocardial perfusion and adenosine in warm-up angina. BACKGROUND: In warm-up angina, neither the role of an adenosine-mediated mechanism, as is found in experimental ischemic preconditioning, nor of increased myocardial perfusion is well defined. METHODS: In substudy A, a single-photon emission computed tomography (SPECT)-thallium-201 exercise test was performed by 12 subjects with ischemic heart disease on three occasions one week apart. The third test was preceded by a warm-up test. The extent of the thallium deficit and its intensity on the third test were compared with the baseline tests controlling for the heart rate-systolic blood pressure product (RPP) at thallium injection. In substudy B, 12 similar subjects did two successive exercise tests at two separate sessions and received the adenosine antagonist, aminophylline (intravenous 5 mg/kg bolus and 0.9 mg/kg/h infusion) at one session, and equivalent saline at the other session. Change in ischemic threshold (RPP at 1 mm ST segment depression) and in maximum ST depression adjusted for RPP were analyzed. RESULTS: In substudy A, despite a significant attenuation of electrocardiogram indexes of myocardial ischemia between the baseline and third (warmed-up) tests, the thallium extent deficits (20.8 +/- 15.1% and 16.8 +/- 12.4%) and intensity deficits (41.2 +/- 12.6% and 39.3 +/- 12.6%) did not differ significantly. In substudy B, the increase in ischemic threshold on re-exercise was unaffected by aminophylline. Adjusted maximum ST depression even decreased to a greater extent on re-exercise with aminophylline (by 51 +/- 21%) than with saline (by 32 +/- 19%) (p = 0.012). CONCLUSIONS: While warm-up angina is associated with a significant attenuation of exercise electrocardiogram indexes of ischemia, it is unaccompanied by significant changes in SPECT perfusion and does not appear to be mediated by an adenosine-dependent mechanism since it is not blocked by aminophylline. Thus, its mechanism, which appears distinct from experimental ischemic preconditioning, remains unidentified.     

Prognostic value of exercise thallium scintigraphy in patients with good exercise tolerance and a normal or abnormal exercise electrocardiogram and suspected or confirmed coronary artery disease.

Exercise thallium scintigraphy is widely used to assess prognosis in patients with suspected or proven coronary artery disease. The incremental prognostic value of this technique in patients who have good exercise tolerance has not been well studied. Two hundred ninety-nine patients with known or suspected coronary artery disease without prior myocardial infarction or revascularization procedure referred for exercise myocardial perfusion imaging and able to exercise to greater than or equal to stage III of the Bruce protocol were included. After a mean follow-up of 50 +/- 10 months, there were 15 cardiac events (5%). The incidence of cardiac events was 10 versus 3% (p less than 0.001) in patients with an abnormal versus normal thallium-201 scan, and 9 versus 3% (p = 0.03) for an abnormal versus normal exercise electrocardiogram. When the 185 patients with a normal exercise electrocardiogram were examined, the incidence of cardiac events was 3% (5 of 150) in patients with a normal scan versus 0% (0 of 35) in patients with an abnormal scan. In the 114 patients with an abnormal exercise electrocardiogram, an abnormal thallium-201 scan was predictive of cardiac events (18% [8 of 44] versus 3% [2 of 70]; p = 0.006). Stepwise logistic regression analysis selected an abnormal thallium-201 scan and abnormal exercise electrocardiogram, low peak exercise heart rate, and male gender as independent variables associated with a significant increased risk of cardiac events. Thus, in patients with known or suspected coronary artery disease and good exercise tolerance, the addition of thallium-201 imaging in patients with an abnormal exercise electrocardiogram provides useful prognostic information.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic significance of silent ischemia in the exercise test in patients with coronary disease

To evaluate the prognostic significance of silent ischemia during exercise testing, 152 consecutive patients (143 males, 9 females) with a mean SD of 55 +/- 7 years (age range 32-73) who underwent exercise testing and coronary arteriography within 3 months were studied. All patients had the following characteristics: 1) a positive electrocardiographic exercise test response; 2) significant coronary artery disease on the arteriography; 3) uninterrupted clinical follow-up for a minimum of 6 months. The 152 patients were divided in 2 groups: group I: 56 patients (37%) with ischemic ST-segment depression during exercise testing without angina (silent ischemia); group II: 96 patients (63%) with ischemic ST-segment depression and angina (symptomatic ischemia). Patients in group I and group II showed similar time to ST-segment depression (3.6 +/- 1.5 min vs 3.2 +/- 1.4 min; p = NS), maximal ST-segment depression and peak heart rate-systolic pressure product (21,151 +/- 7,124 vs 20,456 +/- 6,024; p = NS). Exercise duration was longer in group I than in group II (5.6 +/- 2.1 min vs 4.8 +/- 1.5 min; p less than 0.001). The extent of coronary artery disease defined by the number of significant narrowed coronary vessels, left ventricular end diastolic pressure and ejection fraction were similar in the 2 groups. Sixty six patients who underwent coronary bypass surgery were not included in the analysis. The remaining 86 patients (40 in group I and 46 in group II) were medically treated. The mean follow-up period was 43,5 +/- 25 months (range 6-101).2+ myocardial ischemia during exercise testing.     

Objective assessment of coronary angioplasty for multivessel disease: results of exercise stress testing

The efficacy of coronary angioplasty in multivessel coronary artery disease was evaluated in a series of 145 consecutive patients in whom angioplasty had been successful and in whom a follow-up exercise stress test was performed within 2 months. Exercise stress test results of these patients with multivessel disease were compared with those of 177 patients with single vessel disease after successful coronary angioplasty. The postangioplasty exercise test showed ischemia in 13% of patients with single vessel and 29% of those with multivessel disease, although only 7 and 13%, respectively, experienced angina. The mean exercise duration was comparable for patients with multivessel disease (453 +/- 174 s) and single vessel disease (476 +/- 166 s). To assess the impact of the degree of revascularization in patients with multivessel disease on the results of exercise testing, 48 patients with completely revascularized vessels and 97 with incompletely revascularized vessels were evaluated. The mean exercise duration (459 +/- 178 versus 450 +/- 173 s), mean maximal heart rate (132 +/- 31 versus 136 +/- 25 beats/min) and mean systolic blood pressure (174 +/- 25 versus 170 +/- 26 mm Hg) were similar in completely and incompletely revascularized groups. Exercise-induced angina occurred in 13% of both groups. Ischemic ST segments were more common in the incompletely revascularized group (34 versus 19%, p = 0.06). Thus, exercise stress testing provides evidence that successful angioplasty can relieve electrocardiographic manifestations of ischemia as well as anginal symptoms in the majority of patients with either single or multivessel coronary artery disease who are suitable candidates for the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Outcome of patients with significant coronary stenosis but without ischemic evidence on exercise myocardial perfusion scintigraphy

OBJECTIVES: The rates of cardiac events and coronary revascularization were evaluated in patients with significant coronary stenosis of more than 75% by the American Heart Association (AHA) classification but no ischemic evidence by exercise myocardial perfusion scintigraphy. METHODS: Subjects were 171 patients (113 males, 58 females, mean age 66 +/- 9 years) undergoing coronary angiography and without scintigraphic evidence of myocardial ischemia. They were divided into two groups according to the severity of coronary artery stenosis based on AHA classification. Group A was composed of 139 patients with more than 75% stenosis (101 patients with 75% stenosis and 38 patients with more than 90% stenosis), and Group B was composed of 32 patients with 50% stenosis. Cardiac events including angina pectoris (n = 63), myocardial infarction (n = 1), heart failure (n = 2) and cardiac death (n = 0), coronary revascularization and predictive factors were evaluated during follow-up of 34 +/- 21 months. Furthermore, the interval between coronary revascularization and exercise myocardial perfusion scintigraphy was estimated. RESULTS: The rates of cardiac events (45%) and coronary revascularization (29%) in Group A were significantly higher than the rate of cardiac events (9%, p < 0.05) and coronary revascularization (6%, p < 0.05) in Group B. Only percentage stenosis and the number of diseased vessels affected the rates of cardiac event and coronary revascularization. CONCLUSIONS: Patients with significant coronary stenosis, but without ischemic evidence by exercise myocardial perfusion scintigraphy, have a relatively high rate of cardiac event and coronary revascularization, especially in patients with severe stenosis or multivessel disease. However, coronary revascularization should not be performed in all patients with significant coronary stenosis.     

Congenital anomalies of the coronary arteries with associated ischemic ST depression on exercise: a report of three cases

This report presented evidence of myocardial ischemia as the etiology of angina pectoris in three patients with congenital anomalies of the coronary arteries but without arteriosclerotic disease. All of three cases showed angina pectoris and ST depressions on their exercise electrocardiogram. Case 1: This 58-year-old man developed angina pectoris at the age of 50 years. His treadmill exercise test precipitated chest pain and ST depression. His coronary arteriograms disclosed an ectopic origin of the right coronary artery just anterior to the origin of the left coronary artery in the left coronary sinus. No significant atherosclerotic stenosis was present. An apparent ischemic manifestation appeared to be caused by compression of an aberrant right coronary artery between the aorta and the right ventricular infundibulum. Case 2: A 49-year-old woman had a history of angina. Her treadmill exercise test induced chest pain and an abnormal exercise electrocardiographic finding. Her coronary arteriograms revealed a single left coronary artery. Insufficient perfusion was postulated as a cause of apparent myocardial ischemia in this case though angiographically, there was adequate perfusion. Case 3: This 31-year-old man had a six-year history of angina. His treadmill exercise electrocardiograms revealed ischemic changes accompanied by chest pain. Coronary arteriograms disclosed a coronary artery fistula. The ischemic manifestation was apparently caused by inadequate perfusion due to coronary steal. With the increasing use of coronary arteriography, unusual origins and courses of coronary arteries will be more frequently encountered. Precise knowledge of anomalies is prerequisite for evaluating variations in the location of the coronary artery ostia and their statistical probabilities.     

Relation between electrocardiographic and scintigraphic location of myocardial ischemia during exercise in one-vessel coronary artery disease

The purpose of this study was to determine the usefulness of exercise electrocardiography in predicting the site of myocardial ischemia. Fifty-two patients were studied who had angiographically documented 1-vessel coronary artery disease (CAD) and exercise-induced reversible thallium-201 perfusion defects. The patients were divided into 2 groups: group I (28 patients) had left anterior descending CAD and group II (24 patients) had left circumflex or right CAD. There were no significant differences between the 2 groups in severity of coronary stenosis, heart rate and systolic blood pressure during exercise. The size of the perfusion defect was larger in group I than II (28 +/- 12% vs 19 +/- 10%, p less than 0.02). There was no significant difference between the 2 groups in the frequency of ST depression in the anterior, inferior or lateral electrocardiographic leads. ST depression occurred in 16 patients (57%) in group I and 11 patients (46%) in group II (difference not significant). The sensitivity of the exercise electrocardiogram was 52% using 12 leads, 50% using 3 leads (V3, V5 and aVF) and 50% using V5 alone (difference not significant). Thus, the site of ST depression during exercise is not a good predictor of the site of exercise-induced perfusion defect or anatomic site of CAD. The use of 12 leads does not improve the sensitivity of exercise electrocardiography in patients with CAD.     

Effect of exercise training on multiple respiratory variables in patients with coronary artery disease: correlation with change in exercise capacity.

Multiple measurements of pulmonary function were performed during exercise testing in 29 patients with coronary artery disease (CAD) before and after exercise training. Following training, significant increases in oxygen consumption (VO2), carbon dioxide production (VCO2), and peak flow at maximal exercise were seen as compared with pretraining values (p less than .01), but not in any other respiratory variables. Only the peak respiratory exchange ratio (RER) achieved during pretraining exercise testing and peak values of minute ventilation (VT), respiratory rate, and VCO2 during a posttraining exercise test showed significant correlations with the change in maximum VO2 following exercise training (p less than .05). Significant correlations were also found among VT, VCO2, and peak flow at peak exercise following exercise training and the change in exercise duration between pretraining and posttraining stress tests. Of 22 patients evaluated with thallium 201 scintigraphy during their pretraining exercise test, 11 developed ischemic ST depression or a reversible perfusion defect. No significant differences in pulmonary function measurements during exercise testing were seen between patients who developed ischemia and those who did not. However, the change in peak metabolic equivalents (METS) achieved between pretraining and posttraining exercise was significantly greater in patients who developed ischemia (.836 +/- 1.003 versus .091 +/- .481, p less than .05). These results indicate that exercise training in patients with CAD is not associated with significant changes in most measurements of pulmonary function and, with the exception of RER at peak exercise, pretraining measurements do no show a significant correlation with changes in exercise capacity.     

Comparison of supine and erect bicycle exercise electrocardiography in coronary heart disease: Accentuation of exercise-induced ischemic ST depression by supine posture

Exercise-induced electrocardiographic ST depression was compared during supine and erect graded bicycle exercise in 43 patients with chest pain but no prior myocardial infarct; all had ≥1 mm of ST depression during either erect or supine exercise; 16 had multivessel, 24 had 1-vessel and 3 had no coronary artery disease. Supine exercise used 4 minutes/stage and erect exercise used either 4 minutes or 3 minutes/stage with identical graded work loads for both postures. Chest pain occurred in 31 patients during erect and in 29 during supine exercise. ST depression was ≥1 mm in 28 patients during erect exercise and in all 43 during supine exercise (p <0.001); mean maximal ST depression was 1.3 ± 0.2 mm during erect and 2.6 ± 0.2 mm during supine exercise (p <0.001). Maximal work load was higher during erect than supine exercise (745 ± 32 versus 678 ± 32 kpm/min; p <0.001). The accentuation of ST depression by supine posture was not attributable to the changes in heart rate, rate-pressure product or mean blood pressure during supine versus erect exercise. In the 10 patients who had 2 erect bicycle tests using work load durations of 3 and 4 minutes, the maximal ST depression was not significantly different (erect 3 minutes 1.3 ± 0.5 mm and erect 4 minutes 1.4 ± 0.4 mm). In 7 patients who also had a maximal treadmill exercise test, the maximal ST depression was significantly greater during supine exercise (2.3 ± 0.4 mm) than during either an erect bicycle test (0.6 ± 0.4 mm) or treadmill exercise (0.7 ± 0.4 mm) (p <0.05). Supine posture should be considered as an important potentiator of exercise-induced myocardial ischemia whem comparing indicators such as electrocardiography, radionuclide ventriculography and thallium-201 myocardial perfusion imaging during exercise.     

The differential response in atrial natriuretic peptide release during exercise in patients with and without ischemic heart disease

The elevation of cardiac filling pressure induces the release of atrial natriuretic peptide into the circulation. Ischemia during exercise in patients with coronary artery disease may manifest itself with elevation of cardiac filling pressure before the onset of electrocardiographic changes or chest pain. Thus, patients with ischemic heart disease might have an elevated circulating atrial natriuretic peptide after exercise. The present study investigated the effect of exercise on circulating atrial natriuretic peptide in patients with and without ischemic heart diseases. Group 1 was composed of five patients who had ischemic heart disease by clinical history, previous myocardial infarction, angina or angiographically proven coronary artery disease and positive electrocardiogram during exercise. Group 2 was composed of five patients without ischemic heart disease and negative electrocardiogram response. Heart rate, blood pressure, and atrial natriuretic peptide were measured during routine treadmill exercise testing using the Bruce protocol. Our results indicate that the rate of rise of heart rate (12.3 +/- 1.8 vs. 8.5 +/- 0.7 beats/min/min), blood pressure (7.1 +/- 1 vs. 4.2 +/- 0.8 mm Hg/minute), and atrial natriuretic peptide (4.1 +/- 1 vs. 1.4 +/- 0.3 pg/ml/min) was significantly elevated in patients with ischemic heart disease compared to the group 2 patients. These findings suggest that the disproportionate elevation of atrial natriuretic peptide after exercise in ischemia may be caused by elevation of cardiac filling pressure, which may provide a noninvasive method for the diagnosis of ischemic heart disease.