Can noninvasive exercise test criteria identify patients with left main or 3-vessel coronary disease after a first myocardial infarction?

This study attempts to determine whether exercise treadmill testing with clinical, electrocardiographic, and thallium-201 myocardial perfusion imaging data can identify which patients have left main or 3-vessel (anatomically high-risk) coronary artery disease (CAD) after their first transmural myocardial infarct (MI). Twelve exercise test criteria for high-risk disease were compared in 40 patients referred for cardiac catheterization; 34 had a history of chest pain and 17 had angiographically defined high-risk CAD. A thallium image defect outside the vascular distribution of the MI was the most reliable criterion to distinguish patients with high-risk CAD (p = 0.00052 for Fisher's exact test of discrimination). Thallium imaging was somewhat more sensitive (92 versus 65%, p = 0.108) when patients with negative thallium imaging criteria who failed to achieve 85% of the age-predicted maximal heart rate were excluded. Failure to achieve 85% of predicted heart rate was by itself a useful criterion for detecting high-risk CAD (p = 0.017), especially in patients not taking propranolol (p = 0.004). Development of positive S-T segment depression at less than 70% predicted heart rate also discriminated left main or 3-vessel disease from less extensive CAD (p = 0.016). Other criteria failed to discriminate significantly between high-risk and less extensive CAD in patients after their first MI (p greater than 0.05). S-T segment depression (p = 0.199) or chest pain (p = 0.577) during exercise testing were particularly unreliable. Further, none of the criteria for high-risk CAD were influenced by irreversible left ventricular dysfunction. It is concluded that patients with thallium imaging defects outside the region of the infarct, decreasing blood pressure during exercise, failure to achieve 85% of predicted heart rate, or S-T depression at less than 70% of predicted heart rate have a high probability of having left main or 3-vessel disease. Patients without these criteria have a very low probability of having high-risk CAD and probably do not need coronary angiography for the purpose of excluding these high-risk coronary lesions after a first MI.     

Stress scintigraphy using single-photon emission computed tomography in the evaluation of coronary artery disease

Twenty-seven patients with angina pectoris, 24 with postmyocardial infarction angina and 7 with normal coronary arteries were examined by exercise thallium-201 emission computed tomography (SPECT) and planar scintigraphy. Exercise SPECT was compared with the reperfusion imaging obtained approximately 2 to 3 hours after exercise. The sensitivity and specificity of demonstrating involved coronary arteries by identifying the locations of myocardial perfusion defects were 96 and 87% for right coronary artery, 88 and 89% for left anterior descending artery (LAD) and 78 and 100% for left circumflex artery (LC). These figures are higher than those for planar scintigraphy (85 and 87% for right coronary artery, 73 and 89% for LAD and 39 and 100% for LC arteries). In patients with 3-vessel disease, sensitivity of SPECT (100, 88 and 75% for right coronary artery, LAD and LC, respectively) was higher than planar imaging (88, 63 and 31%, respectively), with a significant difference for LC (p less than 0.05). In 1, 2 and 0-vessel disease the sensitivity and specificity of the 2 techniques were comparable. Multivessel disease was more easily identified as multiple coronary involvement than planar imaging with a significant difference in 3-vessel disease (p less than 0.05). In conclusion, stress SPECT provides useful information for the identification of LC lesions in coronary heart disease, including 3-vessel involvement.     

Atrial pacing with two-dimensional echocardiography for evaluation of chest pain: comparison with thallium 201 scintigraphy

Atrial pacing was performed with two-dimensional (2-D) echocardiography and thallium 201 scintigraphy in 40 men with stable chest pain. Coronary angiography showed significant (one or more lesions greater than or equal to 50%) coronary artery disease (CAD) in 36 patients and no or insignificant CAD in 4. Two dimensional echocardiography showed a left ventricular wall motion abnormality (WMA) either at rest or with pacing in 28 (78%) patients with CAD, with 17 (47%) showing a new or worsened WMA with pacing. A thallium scan showing abnormality (reversible or fixed perfusion defect) was seen in 26 (72%) patients with CAD; 18 (50%) had a reversible defect. In all, 34 of the 36 patients with CAD (94%) had a WMA, a perfusion defect, or both (specificity 50%). Occurrence of both a WMA and a perfusion defect in individual segments ranged from 10 of 25 patients with septal abnormalities to 0 of 12 with abnormalities of the lateral segment. Sensitivity of 2-D echocardiography for identifying CAD in specific vessels was 81% for the left anterior descending (LAD) artery, 30% for the right coronary artery, and 20% for the circumflex artery (both p less than .001 compared with the LAD artery). Corresponding sensitivities for thallium 201 imaging were 54% (p less than .05 compared with 2-D echocardiography), 27%, and 8% (both p less than .05 compared with the LAD artery). When combined with atrial pacing, 2-D echocardiography and thallium 201 perfusion imaging are of similar value for diagnosing the presence of CAD in patients with stable chest pain. Two-dimensional echocardiography is superior to thallium 201 imaging for identifying the presence of significant CAD in the LAD artery, but both tests are limited in their ability to detect lesions of the right coronary or circumflex arteries.     

Assessment of coronary artery disease using single-photon emission computed tomography with thallium-201 during adenosine-induced coronary hyperemia

Thallium-201 myocardial imaging during dipyridamole-induced coronary hyperemia has been an accepted method for diagnosing coronary artery disease (CAD) and risk stratification. Adenosine is a powerful short-acting coronary vasodilator. Initial results of thallium imaging during adenosine infusion have been encouraging. In 132 patients with CAD and in 16 patients with normal coronary angiograms, adenosine was given intravenously at a dose of 0.14 mg/kg/min for 6 minutes and thallium-201 was injected at 3 minutes. The thallium images using single-photon emission computed tomography were abnormal in 47 of the 54 patients (87%) with 1-vessel, in 34 of 37 patients (92%) with 2-vessel and in 40 of 41 patients (98%) with 3-vessel CAD. The sensitivity was 92% in the 132 patients with CAD (95% confidence intervals, 86 to 96%). In patients with normal coronary angiograms, 14 of 16 patients had normal thallium images (specificity, 88%; 95% confidence intervals, 59 to 100%). The results were very similar when subgroups of patients were analyzed: those without prior myocardial infarction, elderly patients and women. The nature of the perfusion defects (fixed or reversible) was assessed in relation to whether the 4-hour delayed images were obtained with or without the reinjection technique. In patients who underwent conventional delayed imaging, there were more fixed perfusion defects than in patients with reinjection delayed imaging (16 vs 0%, p less than 0.0001). The adverse effects were mild, transient and well tolerated. Thus, adenosine thallium tomographic imaging provides a high degree of accuracy in the diagnosis of CAD. The use of the reinjection technique enhances the ability to detect reversible defects.     

Cardiac cinefluoroscopy as an inexpensive aid in the diagnosis of coronary artery disease

To compare the accuracy of cinefluoroscopy, exercise electrocardiography and thallium perfusion imaging in diagnosing coronary artery disease (CAD), these 3 studies were performed in 297 subjects without prior acute myocardial infarction who were referred for coronary angiography. Of the 137 patients who had more than 50% angiographic diameter narrowing in at least 1 major coronary artery, 91 (67%) were correctly identified by cinefluoroscopy, 90 (66%) by stress electrocardiography and 100 (73%) by thallium imaging. Of the 164 patients with no more than 50% diameter narrowing, the proportion of patients correctly identified as normal were 81%, 72% and 79%, respectively. Cardiac cinefluoroscopy correctly classified 74% of the 297 subjects as to their disease status (more than 50% coronary narrowing), compared to 69% for stress electrocardiography and 76% for thallium imaging. There was no significant difference between the sensitivity or specificity of the test combination of stress electrocardiography and cinefluoroscopy and the combination of stress electrocardiography and thallium imaging. Cardiac cinefluoroscopy, a relatively cost-effective diagnostic test, is similar in accuracy to other, more expensive noninvasive diagnostic examinations for CAD.     

"Left main equivalent" coronary artery disease: its clinical presentation and prognostic significance with nonsurgical therapy

The clinical characteristics and nonsurgical prognosis of 55 patients with "left main (LM) equivalent" coronary artery disease (CAD) were evaluated and defined as: (1) greater than or equal to 75% diameter reduction of the left anterior descending coronary artery (LAD) before the takeoff of any large septal perforator or anterolateral (diagonal) branches; (2) greater than or equal to 75% diameter reduction of the left circumflex artery (LC) before the takeoff of any large marginal branch; and (3) absence of greater than or equal to 50% stenosis of the LM coronary artery. Compared with nonsurgically treated patients with greater than or equal to 75% stenosis of the LM artery, patients with LM equivalent CAD had a shorter duration of symptoms (median of 51 months vs 66 months) and more often had a Q wave on the electrocardiogram (60 vs 39%). Survival in patients with LM equivalent CAD (78% at 1 year and 55% at 5 years) was better than that in patients with LM disease with nonsurgical therapy (65% at 1 year and 40% at 5 years) (p = 0.02), although the rate of freedom from cardiovascular events was not significantly different. Compared with other nonsurgically treated patients with 2- or 3-vessel CAD involving the LAD and LC (28 and 42%, respectively, with progressive angina), patients with LM equivalent CAD had more severe anginal symptoms (55% with progressive angina) and a longer duration of symptoms (medians of 20 months in 2-vessel CAD, 36 months in 3-vessel CAD and 51 months in LM equivalent CAD).(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased thallium lung uptake after exercise in isolated left anterior descending coronary artery disease

Increased thallium lung uptake during exercise correlates with an exercise-induced elevation In left ventricular filling pressure. This finding was analyzed in 48 patients with 1-vessel left anterior descending (LAD) coronary artery disease (CAD) before and after percutaneous transiuminal coronary angioplasty. Patients were separated into 2 groups: 13 (27%) patients with Increased (group 1) and 35 patients with normal thallium lung uptake (group 2). Compared with group 2, group 1 patients had more severe LAD luminal diameter narrowing (90 ± 6% vs 81 ± 11 % [mean ± standard deviation], p <0.003); slower clearance of thallium from the LAD territory segments (half-life 13.5 ± 8.0 vs 6.5 ± 5.0 hours, p <0.007); and more abnormal thallium segments per patient by quantitative criteria (p <0.02). After angioplasty, thallium lung uptake became normal in 12 of 13 patients in whom it was previously elevated. Increased thallium lung uptake after exercise occurs in 1-vessel LAD disease, and is related to the severity of ischemia by thallium scan and the severity of stenosis by angiography. Therefore, increased thallium lung uptake identifies a subset of patients with 1-vessel CAD with a greater amount of myocardium at risk.     

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.     

Usefulness of exercise electrocardiography and thallium scintigraphy in unstable angina pectoris in predicting the extent and severity of coronary artery disease

The safety and efficacy of exercise electrocardiography and thallium scintigraphy early in the course of unstable angina pectoris were assessed 4.6 +/- 1.6 days after admission in 67 patients with unstable angina that stabilized after medical therapy. Coronary arteriography was performed in all patients 5.4 +/- 2.4 days after admission. There was no difference in clinical, exercise or scintigraphic variables between patients with stenoses less than 50% and patients with 1-vessel coronary artery disease (CAD) defined as a diameter stenosis greater than or equal to 50%. Patients with 3-vessel CAD had a significantly shorter exercise duration than patients with less than 50%-diameter narrowing (5.5 +/- 2.2 vs 8.3 +/- 3.3 minutes, respectively), lower exercise heart rate (119 +/- 20 vs 149 +/- 22 beats/min) and systolic blood pressure (156 +/- 29 vs 166 +/- 33 mm Hg), more frequent chest pain (76 vs 20%) and more pronounced ST depression (-1.48 +/- 1.37 vs -0.33 +/- 0.72 mm). In addition, thallium defect size on exercise was greater in the patients with 2-vessel CAD (159 +/- 132 degrees) and 3-vessel CAD (255 +/- 132 degrees) than in patients with no CAD (28 +/- 319 degrees) or 1-vessel CAD (73 +/- 78 degrees), p greater than or equal to 0.05. Multiple regression analysis demonstrated that thallium defect size was the best predictor of extent of CAD, with exercise heart rate and presence of chest pain during exercise also predictive of extent of CAD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of exercise electrocardiography and thallium tomographic imaging in detecting asymptomatic coronary artery disease in diabetic patients

Thallium tomographic imaging and exercise electrocardiography were performed on 136 diabetic patients without symptoms of heart disease. Thirty three patients had post-exercise thallium defects and 19 had ST 1 mm greater than or equal to segment depression during exercise electrocardiography. Both tests were positive in 13 patients. Coronary angiography was subsequently performed on 33 patients with either scintigraphic and/or electrocardiographic evidence of myocardial ischaemia. Angiographically significant coronary artery disease (greater than or equal to 50% narrowing of the coronary artery lumen) was detected in 13 patients. Six patients had minimal coronary artery stenosis (less than 50%), and 14 had normal coronary arteries. Six patients refused cardiac catheterisation. In 14 out of 27 patients with post-exercise thallium defects coronary angiography did not show any coronary artery stenoses (positive predictive accuracy 48%). Exercise electrocardiography showed only one false positive result (positive predictive accuracy 94%) but failed to detect coronary artery disease in three patients with a positive scintigraphic result. The accuracy of a positive exercise electrocardiographic test seems to be better than that of a positive thallium tomographic scan for detecting asymptomatic coronary artery disease in diabetic patients. The high number of false positive thallium defects may be the result of technical features inherent in thallium tomography and/or the possible disease of the small intramyocardial arteries in diabetic patients.     

Evaluation of exercise electrocardiography and thallium tomographic imaging in detecting asymptomatic coronary artery disease in diabetic patients.

Thallium tomographic imaging and exercise electrocardiography were performed on 136 diabetic patients without symptoms of heart disease. Thirty three patients had post-exercise thallium defects and 19 had ST 1 mm greater than or equal to segment depression during exercise electrocardiography. Both tests were positive in 13 patients. Coronary angiography was subsequently performed on 33 patients with either scintigraphic and/or electrocardiographic evidence of myocardial ischaemia. Angiographically significant coronary artery disease (greater than or equal to 50% narrowing of the coronary artery lumen) was detected in 13 patients. Six patients had minimal coronary artery stenosis (less than 50%), and 14 had normal coronary arteries. Six patients refused cardiac catheterisation. In 14 out of 27 patients with post-exercise thallium defects coronary angiography did not show any coronary artery stenoses (positive predictive accuracy 48%). Exercise electrocardiography showed only one false positive result (positive predictive accuracy 94%) but failed to detect coronary artery disease in three patients with a positive scintigraphic result. The accuracy of a positive exercise electrocardiographic test seems to be better than that of a positive thallium tomographic scan for detecting asymptomatic coronary artery disease in diabetic patients. The high number of false positive thallium defects may be the result of technical features inherent in thallium tomography and/or the possible disease of the small intramyocardial arteries in diabetic patients.     

Atrial pacing and thallium 201 scintigraphy: combined use for diagnosis of coronary artery disease

To evaluate the presence of coronary artery disease (CAD), atrial pacing and thallium 201 scintigraphy were performed in 36 patients with stable angina pectoris who were unable to perform an adequate exercise stress test. All patients underwent cardiac catheterization. Nine patients had previously undergone coronary artery bypass surgery. Significant CAD (one or more lesions greater than or equal to 50%) was present in 33 patients. Atrial pacing produced ischemic ST segment depression (greater than or equal to 1 mm) in 18 (55%) patients with CAD, and angina in 20 patients (61%). As the number of vessels with CAD increased, there was no significant change in the sensitivities of pacing-induced angina or ST segment depression for detecting CAD. In the 3 patients without CAD, ST segment depression occurred in 1 patient and angina in none. Thallium 201 scintigraphy demonstrated perfusion defects in 27 (82%) patients with CAD, with fixed defects seen in 13 studies (39%) and reversible defects in 15 (45%). In the 3 patients without CAD, no perfusion defects were seen. The thallium 201 scan successfully predicted the presence of CAD in patients with single-vessel disease but usually underestimated the number of vessels involved in patients with multivessel disease. Combined sensitivity of pacing-induced ST segment depression and an abnormal thallium 201 scan finding for detecting CAD was 91%. The authors conclude that combined atrial pacing and thallium 201 scintigraphy is a useful test for detecting CAD in patients unable to perform an adequate exercise stress test.     

Association of exercise-induced ventricular ectopic activity with thallium myocardial perfusion and angiographic coronary artery disease in stable, low-risk populations

This study sought to determine the association of exercise-induced ventricular ectopic activity with thallium perfusion defects and severity of angiographic coronary artery disease (CAD). Two cohorts consisting of adults without heart failure or known severe ventricular ectopic activity at rest were studied. The first cohort consisted of adults (n = 2,743) who underwent maximum exercise thallium stress testing. The second cohort consisted of adults (n = 423) who underwent coronary angiography within 90 days of treadmill testing. Significant exercise-induced ventricular ectopic activity was defined as frequent ventricular premature complexes or nonsustained ventricular tachycardia. Severe CAD was defined as left main CAD (> or = 50% stenosis), 3-vessel CAD (> or = 70% stenosis), or 2-vessel CAD with > or = 70% stenosis of the proximal left anterior descending artery. In the thallium cohort, exercise-induced ventricular ectopic activity was associated with a greater frequency of thallium defects (35.2% vs 18.7%, odds ratio [OR] 2.35, 95% confidence intervals [CI] 1.62 to 3.42, p <0.001); after adjusting for possible confounders, this association persisted (for any defect adjusted OR 1.66, 95% CI 1.09 to 2.53, p = 0.02; for septal defect adjusted OR 2.77, 95% CI 1.51 to 5.07, p <0.001). There was no association between exercise-induced ventricular ectopic activity and mortality during 2 years of follow-up. In the angiographic cohort, there was no association of exercise-induced ventricular ectopy with severe CAD (19% vs 20%, OR 0.93, 95% CI 0.41 to 2.09, p = NS). Exercise-induced ventricular ectopic activity was associated with a greater likelihood of thallium perfusion defects, but was not associated with angiographic severity of coronary disease or with short-term mortality.     

Stress myocardial scintigraphy in coronary artery disease: its clinical significance]

To evaluate the clinical significance of asymptomatic ischemic heart disease, exercise electrocardiography and stress myocardial scintigraphy were performed. These were correlated with symptoms during exercise tests and histories of myocardial infarction (MI). The study subjects consisted of 70 patients with coronary artery disease, including 34 with MI, and 36 without MI but with angina pectoris. Stress tests were performed using bicycle ergometer under electrocardiographic monitoring throughout the test. Transient myocardial ischemia was confirmed by perfusion defects on thallium myocardial imaging demonstrated immediately after exercise, but not 3 hours after the stress test. Asymptomatic ST depression was observed in 18 of 34 patients with MI (53%) and in 21 of the 36 patients with angina (58%); however, transient myocardial perfusion defects were confirmed in 61% of the patients with MI (11 of 18 patients), but in only 33% of those with angina (7 of 21 patients). The difference was statistically significant (p less than 0.05). It was suggested that there are some differences in the clinical significance of asymptomatic ST depression between the patients with MI and those without MI but with angina pectoris.     

Value of dipyridamole thallium-201 imaging in noninvasive differentiation of idiopathic dilated cardiomyopathy from coronary artery disease with left ventricular dysfunction.

The purpose of this study was to noninvasively differentiate in patients with reduced global left ventricular function between those with idiopathic dilated cardiomyopathy (IDC) and coronary artery disease (CAD). Clinical features and findings of dipyridamole thallium-201 imaging in 55 consecutive patients with IDC were compared with those in 77 with CAD. Left ventricular ejection fraction was similar between the 2 groups (34 +/- 16% vs 39 +/- 7%). Patients with IDC had lower incidences of ischemic chest pain (11 vs 79%; p less than 0.0001), electrocardiographic evidence of myocardial infarction (24 vs 82%; p less than 0.0001), and reversible defects (4 vs 57%; p less than 0.0001) than did those with CAD. The lowest percent thallium uptake in the initial imaging was less with CAD than IDC (30 +/- 15% vs 59 +/- 10%; p less than 0.001). Patterns of perfusion defects were classified as: no defects, multiple small defects and large defects. Of patients with IDC, 15 had no defects, 19 had multiple small defects, and 21 had large defects, whereas all those with CAD had large defects (p less than 0.0001). Stepwise discriminant analysis, using chest pain and electrocardiography, revealed sensitivity of 89%, specificity of 87%, accuracy of 88%, and positive predictive value of 83% in the identification of patients with IDC.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Value of Exercise Electrocardiography and Exercise Thallium-201 Myocardial Perfusion Scanning in Determining the Presence of Single Vessel Coronary Artery Obstruction

Summary: In 39 patients with single vessel coronary artery disease and no previous myocardial infarction, exercise thallium-207 myocardial perfusion scanning and 12 lead exercise electrocardiography (ECG) were compared to see how reliably each method identified the site of coronary artery obstruction. Significant (≥ 70% diameter) stenosis was present in the left anterior descending (LAD) coronary artery in 21 patients, in the right coronary artery (RCA) in 14 patients and in the left circumflex (LCX) in four patients. Thallium defects on the scan in the septa1 (SEPT), anteroseptal (ANT SEPT) and anterior (ANT) segments correlated (P < 0.0005) with LAD disease and defects in the inferior (INF), posteroinferior (POST INF), and posterior (POST) segments correlated (P < 0.0005) with RCA or LCX disease. Exercise induced ST segment elevation in VI and/or AVL correlated with LAD disease. The site of ischaemic ST depression did not correlate with disease in any vessel. ST segment depression in leads L2, 3, AVF (67%) and in leads V4–6 (67%) was most sensitive for detecting patients with LAD disease and ST depression in leads V4–6 was most sensitive (56%) for detecting patients with RCA or LCX disease but neither differentiated LAD from RCAILCX disease.
During exercise induced ischaemia, the site of ST segment depression on the 12 lead exercise ECG will not identify the area of ischaemia in patients with single vessel disease but thallium defects will. In contrast to ST depression, ST elevation in V1 and/or AVL may identify LAD stenosis.     

Thallium Scintigraphy in Prediction of Occlusion of Bypass Grafts in Asymptomatic and Symptomatic Patients

ABSTRACT To evaluate thallium scintigraphy in predicting coronary artery bypass graft patency, exercise thallium scintigraphy and selective graft and native vessel angiograms were performed in 22 asymptomatic and 29 symptomatic consecutive patients three months after coronary artery bypass grafting (CABG). Twelve out of 22 asymptomatic patients (55%) had reversible thallium defects on postoperative images; in 10 patients the postoperative scans were normal. The graft patency was significantly lower in asymptomatic patients with abnormal thallium perfusion compared to those with normal perfusion after CABG (68% vs. 91%. p<0.05). The rate of graft patency in symptomatic patients was 66/87 (76%). Thallium scintigraphy was 77% sensitive and 78% specific in detecting one or more stenosed or occluded bypass grafts in patients without angina (accuracy 77%). When data from exercise electrocardiography were combined with scintigraphy, all but one patient with incomplete revascularization could be detected (positive predictive accuracy 92%). In symptomatic patients, thallium scintigraphy accurately predicted the presence or absence of graft occlusion in 24/29 (83%) cases. Thus, abnormal myocardial perfusion due to stenosis or occlusion of bypass grafts is common in both asymptomatic and symptomatic patients after CABG. Thallium scintigraphy together with exercise electrocardiography appear to be useful non-invasive methods in detecting painless myocardial ischemia and in predicting bypass graft occlusion after CABG.     

Thallium scintigraphy in patients with angina at rest

Sixty six patients with angina at rest were investigated by exercise electrocardiography, thallium scintigraphy, and coronary arteriography. A positive exercise electrocardiogram was highly predictive (93%) but poorly sensitive (52%) of coronary artery disease (greater than or equal to 50% stenosis). Thallium scintigraphy was as predictive of the presence of coronary artery disease (91%) but was also highly sensitive (91%). The diagnostic contribution of the thallium scan was greatest in those patients with an inconclusive exercise electrocardiogram without Q waves.     

Thallium scintigraphy in patients with angina at rest.

Sixty six patients with angina at rest were investigated by exercise electrocardiography, thallium scintigraphy, and coronary arteriography. A positive exercise electrocardiogram was highly predictive (93%) but poorly sensitive (52%) of coronary artery disease (greater than or equal to 50% stenosis). Thallium scintigraphy was as predictive of the presence of coronary artery disease (91%) but was also highly sensitive (91%). The diagnostic contribution of the thallium scan was greatest in those patients with an inconclusive exercise electrocardiogram without Q waves.     

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.