Prognostic value of intravenous dipyridamole thallium scintigraphy after an acute myocardial ischemic event

Seventy-seven patients recovering from an acute coronary event were studied by intravenous dipyridamole thallium scintigraphy to evaluate the prognostic value and safety of the test in this patient subset. Forty-four patients (58%) had unstable angina and 33 (42%) had an acute myocardial infarction. One death occurred within 24 hours of testing. Sixty-eight patients were followed for an average of 12 months; 25, 31 and 23% had a fixed, reversible or combined thallium defect on their predischarge thallium scan. During follow-up, 10 patients died or had a nonfatal myocardial infarction; in each case, a reversible or combined myocardial thallium defect was present. Univariate analysis of 17 clinical, scintigraphic and angiographic variables showed that a reversible thallium defect and the angiographically determined extent of coronary artery disease were predictors of future cardiac events. The extent of coronary disease and global left ventricular ejection fraction were predictors of subsequent reinfarction or death. Logistic regression analyses revealed that a reversible thallium defect (p less than 0.001) and the extent of coronary disease (p less than 0.009) were the only significant predictors of a cardiac event. When death or reinfarction were the outcome variables, the extent of coronary disease (p less than 0.02) and left ventricular ejection fraction (p less than 0.06) were the only variables selected. Thus, intravenous dipyridamole thallium scintigraphy after an acute coronary ischemic syndrome is a useful and relatively safe noninvasive test to predict subsequent cardiac events.     

Prognostic importance of silent myocardial ischemia detected by intravenous dipyridamole thallium myocardial imaging in asymptomatic patients with coronary artery disease

One hundred seven asymptomatic patients who underwent intravenous dipyridamole thallium imaging were evaluated to determine prognostic indicators of subsequent cardiac events over an average follow-up period of 14 +/- 10 months. Univariate analysis of 18 clinical, scintigraphic and angiographic variables revealed that a reversible thallium defect, a combined fixed and reversible thallium defect, number of segmental thallium defects and extent of coronary artery disease were significant predictors of subsequent cardiac events. Of the 13 patients who died or had a nonfatal infarction, 12 had a reversible thallium defect. Stepwise logistic regression analysis selected a reversible thallium defect as the only significant predictor of cardiac events. When death or myocardial infarction was the outcome variable, a combined fixed and reversible thallium defect was the only predictor of outcome. In patients without previous myocardial infarction, the cardiac event rate was significantly greater in those with an abnormal versus normal thallium scan (55% versus 12%, p less than 0.001). Thus, intravenous dipyridamole thallium scintigraphy is a useful noninvasive test to risk stratify asymptomatic patients with coronary artery disease. A reversible thallium defect most likely indicates silent myocardial ischemia in a sizable fraction of patients in this clinical subset and is associated with an unfavorable prognosis.     

Perioperative and long-term prognostic value of intravenous dipyridamole thallium scintigraphy in patients with peripheral vascular disease

The prognostic value of long-term risk stratification of patients with peripheral vascular disease who undergo intravenous dipyridamole thallium scintigraphy has not been well studied. We screened 131 patients with peripheral vascular disease who underwent intravenous dipyridamole thallium testing to determine cardiac event rates over an average follow-up of 18 +/- 10 months. Of the 131 patients, 111 subsequently had peripheral vascular surgery. The patients with abnormal thallium scans after dipyridamole had a significantly higher risk of death or myocardial infarction, both in the perioperative phase (7% versus 0%; p less than 0.001) and at late follow-up (17% versus 6%; p less than 0.01). The risk of a cardiac event was two-fold greater when a reversible as compared to a fixed thallium defect was present. Multivariate analysis selected the number of thallium segments with perfusion defects, prior history of angina pectoris, and chest pain during dipyridamole testing as perioperative predictors of a cardiac event. A reversible thallium defect was the only predictor of death or nonfatal myocardial infarction during late follow-up. Thus intravenous dipyridamole thallium scintigraphy is a useful noninvasive test for risk stratification of patients before peripheral vascular surgery and provides prognostic information as to the risk of a cardiac event in the 2-year period after the test. A reversible thallium defect is associated with a significant increased risk and would indicate that coronary angiography should be considered and preoperative coronary revascularization.     

Noninvasive Coronary Risk Stratification of Elderly Patients

The prognostic value of stress thallium-201 myocardial perfusion imaging has not been defined in an elderly (at or above 70 years) population. To this end, we studied 468 consecutive elderly patients undergoing either Bruce protocol exercise stress (n equals 120) or intravenous dipyridamole stress (n equals 348) with quantitative planar thallium-201 imaging. These patients were followed for at least 2 years after testing to determine their rates of cardiac events (cardiac death, myocardial infarction, coronary revascularization). There were no stress-related complications in either subgroup. A 10% cardiac event rate (6 deaths and 6 myocardial infarctions) was observed in the exercise subgroup. Survival without cardiac events was associated with greater exercise duration (5.6?+/-2.4 vs 3.1?+/-2.4 min; P is less than 0.001) and peak exercise heart rate (131?+/-18 vs 120?+/-19 bpm; P is less than 0.05). Multivariate analysis identified the combination of peak exercise at or below Stage 1 and thallium-201 perfusion defects as significant predictors of cardiac events (relative risk equals 5.3 at 1 year). Sixty-four percent of elderly patients were successfully stratified into very low and high risk subgroups, with annual cardiac event rates of less than 1% and greater than 15%, respectively. The cardiac event rate in dipyridamole stress patients was 22% (24 myocardial infarction, 52 death, 42 revascularization). The cardiac event rate was significantly lower (5%) in 150 patients with a normal dipyridamole thallium-201 study (P is less than 0.001). Clinical univariate predictors of cardiac events were previous myocardial infarction, congestive heart failure symptoms, hypercholesterolemia and diabetes (all P equals 0.05). A fixed, reversible, or combined thallium defect pattern was correlated with cardiac death or myocardial infarction (P is less than 0.05). Multivariate analysis demonstrated that the presence of an abnormal dipyridamole thallium study was the single-best predictor of cardiac events (relative risk equals 7.2; P is less than 0.01) We conclude that exercise and dipyridamole thallium-201 myocardial imaging are powerful independent noninvasive techniques for prognostication in the elderly patient population, a group with the potential for advanced coronary artery disease and a high risk of cardiac events.     

Limited usefulness of exercise testing and thallium scintigraphy in evaluation of ambulator patients several months after recovery from an acute coronary event: Implications for management of stable coronary heart disease

Objectives. This study evaluated the value of noninvasive testing to predict cardiac events in patients with stable coronary disease after hospital admission (and risk stratification) for an acute coronary event.Background. Exercise testing with thallium perfusion imaging identifies patients with obstructive coronary artery disease and has been used to stratify patients after myocardial infarction. Its usefulness for predicting cardiac events in patients with stable coronary disease after recovery from an acute coronary event was explored.Methods. Nine hundred thirty-six patients were enrolled 1 to 6 months after hospital admission for a coronary event Patients underwent exercise treadmill testing with planar thallium-201 scintigraphy and were followed up for an average of 23 months (range 6 to 43). End points were 1) unstable angina requiring hospital admission, nonfatal myocardial infarction or cardiac death; 2) nonfatal infarction or cardiac death; or 3) cardiac death alone.Results. Twelve patients died of cardiac causes (1.2%); 32 had a nonfatal myocardial infarction (3.4%); and 79 patients (8.4%) developed unstable angina in the first year. Exercise testing improved proportional hazards models constructed from clinical variables for all three end points (p < 0.05). The perfusion scan further improved models for the end points (nonfatal infarction or cardiac death and cardiac death alone, p < 0.05). However, the exercise test with or without thallium added little to the overall prediction of primary events (area under the receiver operating curve increased from 0.649 to 0,663), and only 2% to 13% of patients with abnormal results either had a nonfatal infarction or died.Conclusions. Thallium-201 scintigraphy and exercise testing variables identify patients at risk for subsequent cardiac events. However, the poor predictive performance of these tests in this group of patients with stable coronary disease severely limits their usefulness. These results suggest a limited role for exercise and thallium testing in predicting cardiac events in patients with known coronary disease.     

Prognostic value of dipyridamole thallium-201 scintigraphy in patients with stable chest pain.

The usefulness of dipyridamole testing with planar thallium-201 scintigraphy for assessing risk of subsequent cardiac events was evaluated in 373 patients with stable chest pain. Follow-up information was complete in 362 patients (mean age 64 +/- 9 years). During an average follow-up period of 18 months, cardiac events occurred in 59 patients--unstable angina in 27, nonfatal acute myocardial infarction in 11, and death from cardiac causes in 21. A history of previous myocardial infarction, congestive heart failure, or coronary bypass surgery before the study, or the presence of an abnormal scan or one with a fixed perfusion defect was associated with a significantly increased frequency of subsequent cardiac events (p less than 0.05). However, the presence of a reversible perfusion defect was not associated with increased risk (p = 0.1872). Stepwise logistic regression showed that a history of coronary artery bypass surgery before the study and the presence of a fixed perfusion defect were the only variables with independent predictive value for occurrence of a subsequent cardiac event (p less than 0.05). Survival analysis revealed a significantly increased cardiac event rate in patients with abnormal scans compared with those with normal scans over a 30-month follow-up period (p less than 0.01). We conclude that dipyridamole testing with thallium-201 scintigraphy can provide prognostic information concerning risk of future cardiac events in patients with stable chest pain. The presence of a fixed perfusion defect in particular identifies patients at increased risk.     

Dipyridamole thallium imaging

Dipyridamole cardiac imaging is a useful alternative to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole has been approved recently for clinical use. Oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow in excess of the increase in myocardial oxygen consumption and cardiac output. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg and the optimal oral dose is 300-375 mg, although higher doses may be necessary in some patients. The sensitivity and specificity of dipyridamole-thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole-thallium imaging has also been useful in identifying high-risk patients undergoing major elective vascular surgery. The relative merits of dipyridamole imaging versus exercise testing after acute myocardial infarction require further studies.     

Prediction of late cardiac events by dipyridamole thallium imaging in patients undergoing elective vascular surgery.

Dipyridamole thallium scintigraphy has previously been shown to have prognostic value in the preoperative assessment of patients scheduled to undergo vascular surgery, but its effect on the long-term outcome is less well-defined. In the largest series to date, dipyridamole thallium scanning was performed in 360 patients before elective vascular surgery and survivors were followed for a mean of 31 months. In the 327 patients who underwent vascular surgery, operative death and nonfatal myocardial infarction occurred in 4.9 and 6.7%, respectively. A cardiac event (nonfatal myocardial infarction or cardiac death) occurred in 14.4% of patients with a transient thallium defect, as opposed to 1% with a normal scan (p < 0.001). Logistic regression analysis revealed that the best predictor of a perioperative event was the presence of a reversible thallium defect, elevating the risk by 4.3-fold. Late cardiac events occurred in 53 (15.2%) surgical survivors or nonsurgically treated patients. Patients with a fixed perfusion abnormality had a 24% late event rate, compared with 4.9% in those with a normal dipyridamole thallium study (p < 0.01). Cox analysis demonstrated that a fixed thallium defect was the strongest factor for predicting a late event and increased the relative risk by almost fivefold. A history of congestive heart failure was the only significant variable that contributed additional value to that of a fixed defect alone. Life-table analysis confirmed the strong relation of a fixed defect to cardiac event free survival (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

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)     

Additional prognostic value of exercise testing and thallium-201 scintigraphy in catheterized patients without previous myocardial infarction

To determine whether exercise testing and thallium scintigraphy provide additional prognostic information in symptomatic patients undergoing catheterization, we studied 432 consecutive male patients without a previous myocardial infarction by means of an exercise test, thallium scintigraphy and catheterization. The follow-up period was 46 +/- 24 months (from 12 to 96). Events were defined as death (27 patients), nonfatal myocardial infarction (occurring in 27 patients) or late (greater than 60 days after test) surgery or dilatation (needed in 45 patients). The 5 year survival rate was 89% and the event-free rate was 72%. History, noninvasive and invasive variables were submitted to a stepwise Cox regression analysis. By multivariate analysis, the significant variables related to death were the number of diseased vessels and exercise workload; the selected variables for all cardiac events were the number of diseased vessels; the score at thallium exercise testing and exercise workload. Among the subgroups of 337 coronary patients, the predictive variables for death were exercise workload and the number of diseased vessels. For all cardiac events, the selected variables were the number of diseased vessels, the score of defects during thallium exercise and exercise workload. Thus, in patients without a previous myocardial infarction, noninvasive variables do provide prognostic information which is not available either from the history or from catheterization.     

Noninvasive evaluation of cardiac risk before elective vascular surgery

The prognostic utility for predicting cardiac events was determined for dipyridamole-thallium scintigraphy, exercise stress testing (when possible; n = 69) and multiple clinical variables in 100 consecutive patients admitted for elective surgical repair of peripheral vascular disease. After initial noninvasive evaluation, 11 patients were referred for coronary angiography and the remaining 89 patients had surgery without further cardiac studies. Fifteen patients (17%) had a postoperative myocardial infarction, one of which was fatal. Of these 15 patients, 14 had thallium redistribution and 3 had positive ST segment depression during stress testing. Among the many variables tested, the presence of redistribution on serial dipyridamole-thallium images was the most significant predictor of serious cardiac events. All 11 patients who had coronary angiography had both redistribution and multivessel coronary artery disease. Four of these 11 patients died during follow-up and 6 had coronary artery bypass surgery. It is concluded that dipyridamole-thallium imaging has significant prognostic utility in predicting postoperative myocardial infarction and death in patients with severe peripheral vascular disease, and is superior to exercise testing or clinical variables in determining cardiac risk. The odds for a serious cardiac event were 23 times greater in a patient with thallium redistribution than in a patient without redistribution, strongly suggesting that myocardial imaging may be used as a primary screening test before elective vascular surgery.     

Long-term prognostic value of a normal dipyridamole thallium-201 perfusion scan.

In a 4-year period, 84 patients who were referred for a dipyridamole thallium-201 stress test to rule out significant coronary artery disease had normal scans. A dipyridamole study was recommended instead of exercise because of arthritis, severe obesity, peripheral vascular disease, pulmonary disease, other chronic illnesses, or combinations of these problems. All patients had three-view (i.e., anterior, shallow left anterior oblique, and steep left anterior oblique) planar thallium-201 imaging 10 minutes and 3.5 hours after administration of 0.6 mg/kg of intravenous dipyridamole. The patients were followed for 42 +/- 13 (range 1-58) months to document the cardiac event rate. Of the 84 patients with normal results, 14 died during the follow-up period from noncardiac causes. Three other patients died 29-51 months after the test due to an acute myocardial infarction, a probable acute myocardial infarction, and sudden cardiac death, respectively. Of the survivors, 5 suffered an acute myocardial infarction 28-50 months after the dipyridamole thallium scan and 1 had coronary artery bypass grafting due to increasing angina pectoris 58 months after the scan (overall cardiac event rate of 0.4% per year). Of the remaining 61 patients, 39 (64%) were asymptomatic, 20 (33%) had the same symptoms they had at the time of testing without significant deterioration, while 2 patients (3%) had deterioration of their chest pains but no cardiac complication. Thus, in this group of patients, a normal dipyridamole thallium-201 perfusion scan predicted a good cardiovascular outcome for at least 24 months following the test.     

Dipyridamole cardiac imaging

Dipyridamole cardiac imaging is a useful alternative technique to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole is still in the investigational phase, while oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow (due to coronary vasodilation) which is in excess of the increase in myocardial oxygen consumption and cardiac output. The disparity in the increase in coronary blood flow relative to the cardiac output results in an increase in myocardial thallium activity and an increase in the myocardial/background activity ratio. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg, and of the oral dose it is 300 to 400 mg, although higher doses may be necessary in some patients. Analysis of the thallium images has been to a large extent based on visual inspection of the planar images. Delayed images are helpful to establish the nature of the perfusion abnormalities (transient or fixed). The process of redistribution is based on disparate rates of washout from the normal and abnormal zones. The sensitivity and specificity of dipyridamole thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole two-dimensional echocardiography has also been used in the detection of coronary artery disease; transient (new or worsening of preexisting) wall motion abnormalities have been found to be a specific marker of coronary artery disease. Transmural as well as regional coronary steal phenomena have been postulated as the mechanism for dipyridamole-induced regional wall motion abnormalities. Compared to exercise two-dimensional echocardiography, dipyridamole echocardiography provides high-quality studies and in higher proportions of patients. The results of dipyridamole thallium imaging have also been extremely important in identifying high-risk patients after acute myocardial infarction or patients with peripheral vascular disease undergoing elective vascular surgery; the presence of a dipyridamole-induced perfusion abnormality identifies patients at high risk for future cardiac events. Thus, dipyridamole cardiac imaging is helpful in the diagnosis of coronary artery disease and in risk stratification.     

Prognostic value of dipyridamole thallium-201 imaging in elderly patients.

The prognostic value of intravenous dipyridamole myocardial perfusion imaging has not been studied in a large series of elderly patients. Patients greater than or equal to 70 years of age with known or suspected coronary artery disease were evaluated to determine the predictive value of intravenous dipyridamole thallium-201 imaging for subsequent cardiac death or nonfatal myocardial infarction. Of the 348 patients, 207 were symptomatic and 141 were asymptomatic; 52% of the asymptomatic group had documented coronary artery disease. During 23 +/- 15 months of follow-up, there were 52 cardiac deaths, 24 nonfatal myocardial infarctions and 42 revascularization procedures (percutaneous transluminal coronary angioplasty in 20; coronary artery bypass surgery in 22). Clinical univariate predictors of a cardiac event included previous myocardial infarction, congestive heart failure symptoms, hypercholesterolemia and diabetes (all p less than 0.05). The presence of a fixed, reversible or combined thallium-201 defect was significantly associated with the occurrence of cardiac death or myocardial infarction during follow-up (p less than 0.05). Cardiac death or nonfatal myocardial infarction occurred in only 7 (5%) of 150 patients with a normal dipyridamole thallium-201 study (p less than 0.001). Stepwise logistic regression analysis of clinical and radionuclide variables revealed that an abnormal (reversible or fixed) dipyridamole thallium-201 study was the single best predictor of cardiac events (relative risk 7.2, p less than 0.001). As has been demonstrated in younger patients, previous myocardial infarction (relative risk 1.8, p less than 0.001) and symptoms of congestive heart failure at presentation (relative risk 1.6, p = 0.02) were also significant independent clinical predictors of cardiac death or myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise thallium imaging in patients with diabetes mellitus. Prognostic implications

We used exercise thallium 201 imaging in 123 patients with diabetes mellitus (77 men and 46 women, aged 56 +/- 8 years), 75% of whom had angina pectoris (typical or atypical). During exercise testing, 18 patients (15%) had angina pectoris, 28 (23%) had ischemic ST changes, and 69 (56%) had abnormal thallium images. During follow-up (up to 36 months), there were 12 cardiac events; four patients died of cardiac causes and eight had nonfatal acute myocardial infarction. Univariate and multivariate survival analysis identified two independent predictors of cardiac events: the event rate was significantly less in patients with normal images and exercise heart rate over 120 beats per minute than in patients with abnormal images and exercise heart rate of 120 beats per minute or less (0% vs 22%). The patients with abnormal images or exercise heart rate of 120 beats per minute or less had an intermediate event rate (11.5%). Furthermore, two of the 54 patients with normal images and ten of 69 patients with abnormal images had subsequent cardiac events. Thus, exercise thallium imaging is useful in risk stratification in patients with diabetes mellitus.     

Prognostic value of dipyridamole thallium imaging after acute myocardial infarction in older patients

OBJECTIVE: To assess the utility of intravenous dipyridamole thallium testing for predicting major cardiac events following acute myocardial infarction in older patients. DESIGN: Prospective cohort study with a median follow-up of 18 months. SETTING: A university teaching hospital. PARTICIPANTS: 73 patients aged 65 years and older with enzymatically confirmed acute myocardial infarction (mean age 75 years, 56% male, 71% white). MEASUREMENTS: All patients underwent a detailed clinical assessment, an echocardiogram, and an intravenous dipyridamole thallium stress test before hospital discharge. The study endpoint was death or nonfatal reinfarction during the follow-up period. RESULTS: Overall, 24 patients (33%) died or developed recurrent myocardial infarction during follow-up. Among 44 patients with a reversible thallium defect, 19 (43%) reached the study endpoint, compared with only five of 29 patients (17%) without reversible ischemia (P = .04). On multivariate analysis, independent prognostic variables included non-use of aspirin at hospital discharge (P = .002), decreased left ventricular systolic function (P = .009), non-use of a beta-blocker at hospital discharge (P = .013), and reversible ischemia on thallium scintigraphy (P = .025). The relative risks for death or reinfarction associated with non-use of aspirin, non-use of a beta-blocker, left ventricular dysfunction, and reversible ischemia were 2.65, 2.39, 2.01, and 2.51, respectively. Patients with three or four of these risk factors had an 83% probability of death or reinfarction, compared with 41% in patients with two risk factors and 6% in patients with one or no risk factor (P < .001). CONCLUSION: Intravenous dipyridamole thallium imaging provides independent prognostic information in older patients with acute myocardial infarction. Moreover, the combination of clinical, echocardiographic, and dipyridamole thallium variables effectively stratifies older postinfarction patients into high-, intermediate-, and low-risk categories for death or recurrent myocardial infarction.     

Prognostic value of thallium-201 single-photon emission computed tomographic myocardial perfusion imaging according to extent of myocardial defect: Study in 1,926 patients with foilow-up at 33 months

Objectives. This study was designed to assess the prognostic value of thallium-201 single-photon emission computed tomographic (thallium SPECT) perfusion imaging in patients evaluated for stable angina pectoris and to examine the relation, if any, between the preface and extent of myocardial defect and future fatal or nonfatal cardiovascular events (revascularization, secondary myocardial infarction).Background. Compared with planar scintigraphy, thallium SPECT enables better evaluation of the extent of mayocardial perfusion defect. However, its prognostic value has not yet been studied in a large population of patients.Methods. Between 1987 and 1989 we studied 3,193 patients. After exclusion of patients with unstable angina, myocardial infarction during the previous month or earlier revascularization, 1,926 patients were followed up for 33 ± 10 (mean ± SD) months after stress thallium SPECT imaging (performed after exercise in 1,121 patients or during dipyridamole infusion in 805 patients). Thallium SPECT imaging of the left ventricle was divided into six segments.Results. After normal thallium SPECT imaging (715 patients), the annual total and cardiovascular mortality rates were, respectively, 0.42%/year and 0.10%/year and were significantly higher after abnormal thallium SPECT imaging (respectively, 2.1%, relative risk 5, p = 0.012; 1.5%, relative risk 15, p < 0.0001 [log-rank test]). There was a significant relation between the number of abnormal segments and cardiovascular mortality during follow-up (p < 0.02) or the occurrence of nonfatal events (p < 0.001). The extent of defect on the initial scan provided the best SPECT variable for long-term prognosis. Thallium SPECT imaging provided additive prognostic information compared with other clinical variables (gender, previous myocardial infarction) and exercise electrocardiogram.Conclusions. In patients with stable angina, normal thallium SPECT imaging indicates a low risk patient, and the extent of myocardial defect is an important prognostic predictive factor.     

Diagnostic and prognostic value of vasodilator stress echocardiography in asymptomatic Type 2 diabetic patients with positive exercise thallium scintigraphy: a pilot study.

AIM: To assess the diagnostic and prognostic value of vasodilator stress echocardiography in Type 2 diabetic patients with positive exercise perfusion scintigraphy. METHODS: Of an initial cohort of 50 asymptomatic Type 2 diabetic patients undergoing exercise single photon emission computed tomography (SPECT) thallium scintigraphy, 24 had a positive thallium scan, with a reversible perfusion defect. All these 24 underwent high dose (up to 0.84 mg/kg in 10 min) dipyridamole echocardiography and coronary angiography independently of stress echocardiography results. All patients were then followed for 61+/-22 months. RESULTS: Coronary angiography showed normal coronary arteries in 11 patients and significant (> 50% visually assessed diameter reduction in a major vessel) coronary artery disease in 13. Stress echocardiography showed 92% sensitivity and 100% specificity for non-invasive detection of coronary artery disease. During follow-up, five patients experienced cardiac events: heart failure in one, angina with subsequent revascularization in two, and myocardial infarction in two. Event-free survival was 100% in the 12 patients with negative and 58% in the 12 patients with positive stress echocardiography (P = 0.08 by Mantel-Cox test). CONCLUSIONS: In asymptomatic Type 2 diabetic patients with stress-induced perfusion defects, vasodilator stress echocardiography is an excellent diagnostic and prognostic tool proven with long-term follow-up.     

Long-term prognostic value of preoperative dipyridamole thallium imaging and clinical indexes in patients with diabetes mellitus undergoing peripheral vascular surgery

The objective of this study is to assess the prognostic impact of preoperative dipyridamole thallium imaging and clinical variables on the long-term outcome of diabetic patients undergoing peripheral vascular surgery. Complete follow-up was obtained in 101 consecutive patients with diabetes mellitus undergoing routine dipyridamole thallium scintigraphy before vascular surgery (mean 4.2 +/- 3.2 years, range 1 month to 11 years). Low risk was defined by diabetes alone with a normal resting electrocardiogram. High risk was defined as a history of angina, myocardial infarction, congestive heart failure, or resting electrocardiogram abnormalities. There were 71 deaths in 98 patients discharged alive from the hospital (median survival 4.4 years). Age, the presence of resting electrocardiogram abnormalities, and an abnormal thallium scan were independent predictors of late death. After adjusting for age >70 years and thallium abnormalities, high-risk patients had a death rate 4.8 times (95% confidence interval 1.7 to 13.4, p <0.002) greater than low-risk patients. The presence of >2 reversible thallium defects was useful in further risk stratification of both low- and high-risk patients. Low-risk patients with >2 reversible defects had a median survival of 4.0 years compared with 9.4 years in those with < or =2 reversible defects (p <0.001). Similarly, high-risk patients with < or =2 reversible defects had an intermediate median survival rate of 4.7 years compared with 1.8 years in the group with >2 reversible defects (p <0.001). Therefore, advanced age and the presence of resting electrocardiographic or thallium abnormalities identifies a subset of diabetic patients with a poor long-term outcome after vascular surgery. Combined clinical and thallium variables may identify a population in whom intensive medical or surgical interventions may be warranted to reduce both perioperative and late cardiac events.     

Usefulness of exercise myocardial scintigraphy in multivessel coronary disease after incomplete revascularization with coronary stenting

The aim of this prospective study was to evaluate the prognostic value of exercise myocardial scintigraphy in patients who undergo incomplete revascularization with percutaneous coronary stenting. In 322 consecutive patients (mean age 61 +/- 10 years), exercise technetium-99m-tetrofosmin single-photon emission computed tomography scintigraphy was prospectively performed 4 to 6 months after an incomplete revascularization procedure. Follow-up lasted < or = 84 months (median 33). Patients with normal findings were at low risk of cardiac events compared with patients with mildly abnormal and severely abnormal findings (yearly event rate 1.5% vs 5.1% and 8.5%, respectively, p < 0.01). A significant difference was observed in hard, soft, and composite event-free survival among patients with normal, mildly abnormal, and severely abnormal findings (p < 0.01, p < 0.03, and p < 0.01, respectively). Nuclear data provided significant incremental prognostic value for cardiac events compared with the clinical, angiographic, and exercise test findings. In conclusion, in patients with incomplete revascularization procedures, exercise myocardial scintigraphy provides significant independent information concerning the subsequent risk of cardiac events, with an annualized event rate of < 2% for patients with normal scan findings. Myocardial scintigraphy is able to provide incremental prognostic information after adjusting for clinical, angiographic, and exercise variables.