Dipyridamole-induced increased glucose uptake in patients with single-vessel coronary artery disease assessed with PET.

BACKGROUND: The aim of this study was to determine the relationship between vasodilatation-induced ischemia and poststress glucose uptake. Coronary vasodilators may induce myocardial ischemia due to coronary steal through collateral circulation or transmural blood flow redistribution with diminished subendocardial perfusion. Myocardial ischemia can be demonstrated by increased glucose uptake as previously shown in patients with exercise-induced ischemia. METHODS AND RESULTS: We studied 11 patients with single-vessel disease and no history of myocardial infarction. Five patients had no collateral circulation, and 6 had angiographic evidence of collateral vessels. We measured myocardial blood flow (MBF) and glucose uptake at baseline and after the administration of dipyridamole (0.56 mg/kg) with positron emission tomography, using O-15 water and fluorine 18 deoxyglucose (FDG) as perfusion and glucose tracers. MBF at baseline was 0.82 +/- 0.13 mL/g/min in normal areas and 0.80 +/- 0.15 mL/g/min in areas supplied by stenotic arteries. MBF during dipyridamole was 2.05 +/- 0.66 and 1.19 +/- 0.66 mL/g/min in normal areas and areas with stenotic arteries, respectively (P < or = .001). FDG uptake at baseline was 1.36 +/- 0.55 in normal areas and 1.57 +/- 0.62 in areas supplied by stenotic arteries. FDG uptake after dipyridamole infusion was 1.79 +/- 1.1 and 4.04 +/- 0.84 in normal areas and areas with stenotic arteries, respectively (P < or =.001). MBF and FDG uptake were not different between patients with collateral circulation and those without collateral circulation. CONCLUSIONS: Increased myocardial glucose uptake was consistently observed after dipyridamole administration in those areas with diminished coronary vasodilatory capacity. The similar MBF and FDG findings in patients with and without collateral circulation may indicate that transmural blood flow redistribution appears to be a possible mechanism of dipyridamole-induced myocardial ischemia.

Utility of positron emission tomography in predicting improved left ventricular ejection fraction after coronary artery bypass grafting among patients with ischemic cardiomyopathy.

The objective of this study was to determine whether preoperative estimates of regional myocardial uptake of (18)-F-fluorodeoxyglucose (FDG) could predict postoperative improvement in ejection fraction in patients undergoing coronary artery bypass grafting (CABG) for ischemic cardiomyopathy. 20 consecutive patients [left ventricular ejection fraction (LVEF) /=5% change noted in 7 patients (group 1) and <5% noted in 10 patients (group 2). No preoperative or perioperative clinical variable could predict those with improved ventricular function. The relative amount of FDG uptake in the anterior wall was higher in group 1 compared with group 2 (93 +/- 9 vs. 81 +/- 13%; p < 0.05) and correlated with the change in LVEF post-CABG (r = 0.50; p < 0.05). >88% of FDG uptake in the LAD region had a positive predictive accuracy of 67% and negative predictive accuracy of 88% for improved LVEF postbypass. Late follow-up estimates of LVEF (median of 10 months) showed that early changes in function were sustained. In summary, among patients with severe coronary artery disease and depressed LVEF, ventricular function may improve early postrevascularization. PET estimates of relative FDG uptake in the anterior wall help predict those individuals who are likely to have the greatest increment in LVEF.

Glucose uptake increases relative to oxygen consumption during short-term hibernation.

BACKGROUND: Although glucose uptake is increased in chronically hypoperfused, viable myocardium, the dynamic changes in glucose uptake relative to oxygen consumption in "short-term" models of hibernation have not been fully explored. METHODS: 14 anesthetized swine were instrumented with an hydraulic occluder and flow probe on the proximal LAD artery. Blood flow was reduced approximately 30% for 1 hour. Myocardial blood flow and uptake of oxygen, free fatty acids, glucose and lactate were determined in the LAD region at baseline and at 10, 30, and 60 minutes of ischemia. Transmural biopsies for ATP and creatine phosphate (CP) were obtained in the LAD region prior to and at 15 and 45 minutes of ischemia. In 5 animals, glycogen was assayed at baseline and at the end of 60 minutes of ischemia. RESULTS: In the LAD region, myocardial oxygen consumption was reduced from 2.06 +/- 0.16 micromol/min/gram to 1.46 +/- 0.13 micromol/min/gram (P < 0.05). By 15 minutes of ischemia, transmural creatine phosphate fell from 7.48 +/- 0.76 micromol/g-wet weight at baseline to 6.19 +/- 0.32 micromol/g-wet weight (P < 0.05) but normalized by 45 minutes of ischemia (7.39 +/- 0.56 micromol/g-wet weight; NS). Between 10 and 60 minutes of constant flow reduction, glucose uptake as a percentage of MVO2 increased from 3 +/- 2% to 10 +/- 2% (P < 0.05) while lactate uptake increased from -9 +/- 9% to -1 +/- 2% (P < 0.05). Glycogen decreased from 27.8 +/- 3.7 at baseline to 16.9 +/- 1.2 micromol/g-wet weight at end-ischemia. CONCLUSIONS: In this model of short-term hibernation, glucose and lactate uptake increase relative to oxygen consumption during sustained ischemia, and temporally coincide with the recovery of bioenergetics. The findings are consistent with the notion that glycolytically derived ATP is important for the maintainance of energy supply during sustained ischemia.

Effect of regional hyperemia on myocardial uptake of 2-deoxy-2-[(18)F]fluoro-D-glucose.

2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) may be used to predict glucose kinetics when the factor relating differences in transport and phosphorylation between compounds remains constant ("lumped constant"). It is not clear whether hyperemia alters that factor. In anesthetized swine, myocardial FDG uptake was estimated by positron emission tomography, during an intracoronary infusion of either adenosine, ATP, or bradykinin (40 microg x kg(-1) x min(-1), 40 microg x kg(-1) x min(-1), and 2 nmol x kg(-1) x min(-1), respectively; n = 6 for all groups). In controls during normal perfusion (n = 6), FDG uptake was 0.78 +/- 0.32 micromol x g(-1) x min(-1), whereas glucose uptake by Fick was 0.71 +/- 0.25 micromol x g(-1) x min(-1) (r = 0.73; P < 0.05). Adenosine increased blood flow from 1.29 +/- 0.43 to 4.80 +/- 2.19 ml x g(-1) x min(-1) (P < 0.05) and glucose uptake from 1.16 +/- 1.10 to 3.35 +/- 2.12 micromol x g(-1) x min(-1) (P < 0.05), whereas FDG uptake in the hyperemic region was lower than remote regions (0.46 +/- 0.29 and 0.95 +/- 0.55 micromol x g(-1) x min(-1), respectively; P < 0.05). In the ATP and bradykinin groups, blood flow increased four- and twofold, respectively, with no net change in glucose uptake. FDG uptake in the hyperemic region was also significantly lower than remote regions. For all animals, the ratio of blood flow in the hyperemic region relative to remote region was inversely proportional to the ratio of FDG uptake in the same regions (r(2)=0.73; P < 0.001). Because nitric oxide elaboration during hyperemia could potentially alter substrate preference and FDG kinetics, six additional swine were studied during maximal adenosine before and after intracoronary N(G)-monomethyl-L-arginine (1.5 mg/kg). Inhibition of nitric oxide had no effect on either regional myocardial substrate uptake or FDG accumulation. In conclusion, hyperemia decreased regional myocardial FDG uptake relative to normally perfused regions and this effect on the lumped constant was independent of nitric oxide.

Prophylactic coronary artery revascularization for elective vascular surgery: study design. Veterans Affairs Cooperative Study Group on Coronary Artery Revascularization Prophylaxis for Elective Vascular Surgery.

This article describes the design of an ongoing randomized trial intended to test whether patients who require elective vascular surgery would benefit from preoperative coronary artery revascularization prior to the vascular procedure. The primary objective is to determine whether coronary artery revascularization reduces long-term mortality (mean 3.5 years) in patients undergoing vascular surgery. The study design calls for 620 patients to be randomized and followed for a mean of 3.5 years following vascular surgery. Secondary endpoints include measures of quality of life and cost-effectiveness. Patients with coronary artery disease in need of an elective vascular operation are considered candidates for the study. Anatomic exclusion criteria include ejection fraction <20%, severe aortic stenosis (valve area <1.0 cm2), left main stenosis > or =50%, nonobstructive coronary artery disease (stenosis <70%), and coronary arteries that are not amenable to revascularization. Prior to the vascular surgery, the trial randomizes eligible patients to coronary artery revascularization (either bypass surgery or angioplasty) versus medical therapy. The trial stratifies the randomization by hospital and type of vascular surgery (intraabdominal versus infrainguinal) because of differences in long-term prognosis in those patients. A 1-year feasibility trial involving five Veterans Affairs (VA) medical centers of variable vascular surgical loads has been completed. The results showed that over 90% of expected patients could be randomized. As a result, a larger VA Cooperative Study involving 18 centers will begin recruitment of patients. The findings should help determine the best strategy for managing patients with coronary artery disease in need of elective vascular surgery.

Adenosine receptor blockade enhances myocardial stunning without a sustained effect on fluorine-18-FDG uptake postreperfusion.

UNLABELLED: The aim of this study was to determine whether adenosine receptor blockade before ischemia would enhance the degree of stunning and induce a sustained decrease in glucose uptake after reperfusion. METHODS: Stunning was induced in 14 anesthetized swine by partially occluding the left anterior descending artery (LAD) for 20 min (> 80% flow reduction). Seven animals were pretreated with the nonspecific adenosine receptor blocker 8-phenyltheophylline (8-PT; 5 mg/kg), which decreased reactive hyperemia by an average of 38%. Myocardial glucose uptake was assessed 1 hr following reperfusion with PET and the glucose analog 18F-fluorodeoxyglucose (FDG). RESULTS: Before ischemia, systolic shortening in the LAD region was 15% +/- 6% in the control group and 16% +/- 4% in the 8-PT group and in both groups was reduced to - 1% +/- 2% during ischemia. After reperfusion, systolic shortening was 7% +/- 3% in the control group and 2% +/- 3% in the 8-PT group (p < 0.05). Myocardial oxygen consumption before ischemia was 4.58 +/- 3.03 micromol/min/g in the control group and 4.44 +/- 1.83 micromol/min/g in the 8-PT group (ns) and neither were different after reperfusion. In the postischemic LAD region, myocardial glucose uptake was 0.18 +/- 0.15 micromol/min/g in the control group and was similar to that of the 8-PT group (0.17 +/- 0.08 micromol/min/g; ns). CONCLUSION: The nonspecific adenosine blocker 8-PT enhanced the degree of stunning when given before ischemia but did not induce a sustained effect on myocardial glucose uptake after reperfusion.

The influence of perioperative myocardial infarction on long-term prognosis following elective vascular surgery.

STUDY OBJECTIVE: The present study was performed to determine the influence of a perioperative myocardial infarction on long-term mortality in patients who have undergone elective vascular surgery. STUDY DESIGN: This was a 4-year follow-up of patients who had undergone elective vascular procedures at a Veterans Affairs Medical Center. Between January 1989 and December 1990, 115 consecutive patients underwent surgery for either an expanding abdominal aortic aneurysm (AAA) (38%) or for pain in the lower extremities (62%). RESULTS: Vital status at 4 years postsurgery was determined for all patients. Thirty-day postoperative mortality was 3%, while estimates at 1, 2, 3, and 4 years were 19%, 26%, 35%, and 39%, respectively. Of the 45 patients who died within 4 years following surgery, the major causes of death were cardiac (40%), cancer (18%), cerebrovascular (13%), and peripheral vascular disease (11%). Univariate predictors of 1-year mortality on preoperative evaluation were an abnormal ECG, moderate or greater sized exercise thallium defect and left ventricular ejection fraction < or =40%, and a perioperative myocardial infarction. Univariate predictors of 4-year mortality were non-AAA surgery and diabetes mellitus. Perioperative myocardial infarction was a marginally significant independent predictor of 1-year mortality (p=0.06), while the need for non-AAA surgery was a strong independent predictor at 4 years. CONCLUSIONS: Cardiac mortality is the major cause of late death among patients undergoing elective vascular surgery. Although preoperative indicators of symptomatic coronary artery disease and nonfatal perioperative myocardial infarction identified those individuals at increased mortality in the first postoperative year, the extent of vascular disease at presentation may be a more important determinant of long-term survival. A randomized trial in such patients is needed to assess the best strategy for treating patients with coexistent coronary artery and vascular diseases.

Regional glucose uptake within hypoperfused swine myocardium as measured by positron emission tomography.

Chronic myocardial ischemia and 2-[18F]fluoro-2-deoxy-D-glucose (FDG) uptake were studied with positron emission tomography in 12 swine instrumented with an external constrictor on the left anterior descending coronary artery (LAD). Serial changes in function (by echocardiography), blood flow (with H215O) and FDG were determined weekly. At 1 wk, function was normal and FDG uptake in the LAD and non-LAD regions was 0.43 +/- 0.12 and 0.45 +/- 0.11 mumol. min-1.g-1, respectively (not significant). At approximately 5 wk, LAD wall thickening decreased to 18 +/- 5 from 27 +/- 8% (P < 0.05), whereas LAD and non-LAD blood flows were 0.68 +/- 0.28 and 1.03 +/- 0.25 ml.min-1.g-1, respectively (P < 0.05). At that time, FDG uptake in LAD and non-LAD regions was 0.60 +/- 0.43 and 0.49 +/- 0.30 mumol.min-1.g-1, respectively (P < 0.05). By the use of transmural biopsies (n = 6), ATP and creatine phosphate in the LAD region were 3.62 +/- 0.73 and 5.91 +/- 1.44 mumol/g wet wt, respectively, and neither differed from values in remote regions. In this model of chronic ischemia, hypoperfused dysfunctional regions were characterized by enhanced glucose uptake and preserved bioenergetics. This supports the concept that the myocardium adapts to chronic ischemia.

Temporal changes in function and regional glucose uptake within stunned porcine myocardium.

UNLABELLED: This study compared the effects of porcine myocardial stunning on the uptake of [18F]-fluorodeoxyglucose (FDG) at 24 hr and 7 days after reperfusion. Prior studies in animals subjected to severe myocardial ischemia have shown a sustained increase in FDG uptake relative to perfusion (FDG/MBF). The time course of recovery of FDG/MBF relative to function poststunning, however, has not been well characterized. METHODS: Stunning was induced in eight swine by partially occluding the LAD artery for 20 min. At 1 and 7 days postreperfusion, function was assessed by two-dimensional echocardiography and PET studies were obtained with FDG and either 15O-water or 13N-ammonia. Blood flow by microspheres was determined at baseline, during ischemia and after stunning. Myocardial uptake of FDG relative to blood flow on matching images (FDG/MBF) was calculated for all ROIs and expressed as a ratio of LAD to non-LAD areas. RESULTS: After stunning, left ventricular ejection fraction (LVEF) increased from 42% +/- 10% on Day 1 to 52% +/- 6% on Day 7 (p < 0.05). At Day 1, myocardial blood flow was 0.60 +/- 0.10 ml/min/g in LAD and 0.67 +/- 0.16 in non-LAD regions and neither differed at Day 7. The magnitude of FDG/MBF in the LAD region when normalized to the non-LAD region was 1.29 +/- 0.16 on Day 1 and 1.09 +/- 0.08 on Day 7 (p < 0.05) and was inversely proportional to global measures of LVEF (r2 = 0.61; p < 0.005). CONCLUSION: The severity of postischemic LV dysfunction at 1 and 7 days after stunning correlates with the degree of enhanced regional glucose uptake as estimated by PET. Both normalize within 7 days, suggesting that metabolic and functional abnormalities within completely reperfused myocardium recover in parallel.

Myocardial glucose metabolism and ATP levels are decreased two days after global ischemia.

We hypothesized that following reversible myocardial ischemia recovery of glucose metabolism would be prolonged and would parallel recovery of high energy phosphate levels. Normothermic ischemia was achieved in dogs by aortic cross-clamping for 20 min on cardiopulmonary bypass. Glucose uptake was determined by [18F]fluorodeoxyglucose uptake and positron emission tomography (PET) 1 week pre-ischemia and at 2 and 7 days post-ischemia (n = 8). Oxygen consumption (MVO2) and glucose uptake were also measured by Fick. In a separate group of animals, adenosine triphosphate (ATP) and creatine phosphate (CP) levels were measured by left ventricular/septal biopsies at baseline, 2 days, and 7 days (n = 6). Glucose uptake, as measured by PET, was reduced to 15% of baseline at 2 days post-ischemia and returned to normal by 7 days post-ischemia (P < 0.05). These results were confirmed by Fick measures of glucose uptake. ATP levels were reduced to 49% of pre-ischemic levels at 2 days and returned to baseline by 7 days (P < 0.05). CP and MVO2 levels were normal at 2 and 7 days following ischemia. We conclude that reduced glucose uptake in the presence of intact oxidative metabolism suggests that glucose is not the favored substrate for ATP production following ischemia.

Cardiopulmonary support mitigates the effects of experimental myocardial ischemia.

The effectiveness of cardiopulmonary support (CPS) as a rescue method following failed angioplasty is unknown. The proximal left anterior descending (LAD) was occluded for 20 min in 21 dogs. Group 1 animals (n=15) were given CPS and group 2 animals (n=6) served as controls. During coronary occlusion, animals receiving CPS had increased mean arterial pressure (71+/- 12 vs 58+/-7 mm Hg), decreased left atrial pressure (3+/-3 vs 12+/-3 mm Hg), increased ischemic area blood flow (0.20+/-0.16 vs 0.02+/-0.04 mL/min/g) and myocardial oxygen consumption (0.014+/- 0.008 vs 0.003+/-0.006 mL O2/min/g), decreased remote area myocardial oxygen consumption (0.026+/-0.010 vs 0.091+/-0.047 mL O2/min/g), and an improved myocardial oxygen consumption index (0.60+/-0.33 vs 0.02+/-0.03) when compared with controls (p<0.05). During reperfusion (no CPS), group 1 animals had increased cardiac index (210+/-95 vs 117+/-46 mL/min/kg), renal blood flow (110+/-38% vs 53+/-45%), ischemic area blood flow (1.13+/-0.40 vs 0.58+/-0.27), and myocardial oxygen consumption (0.066+/-0.015 vs 0.032+/-0.018) when compared with controls (p<0.05). CPS improves oxidative metabolism in selective myocardial segments during coronary occlusion, promotes recovery of the postischemic myocardium, and results in improved peripheral circulation.

Impaired endothelium-dependent vasodilation of coronary resistance vessels in severely stunned porcine myocardium.

The effect of stunning on endothelium-dependent responses of resistance vessels in vivo remains of interest. We utilized the coronary pressure-flow relationship during maximal vasodilation in anesthetized swine to identify subtle changes in flow reserve within stunned myocardium. Prior to and following stunning, the coronary pressure-flow relationship during maximal doses of intracoronary adenosine was compared with that of the endothelium-dependent vasodilator ATP. In 11 anesthetized swine, 30 min of partial LAD occlusion and 40 min of reperfusion reduced fractional shortening from 16 +/- 4% to 6 +/- 5% (p < 0.05). This caused a rightward shift of the coronary pressure-flow relationships during infusions of either adenosine or ATP, suggestive of increased extra vascular compressive forces. With adenosine, the slope of the linear portion of the relationship (i.e., coronary pressures > 30 mmHg) was 1.31 +/- 0.54 ml/min-mmHg at baseline and 1.30 +/- 0.55 ml/min-mmHg following stunning (NS). With ATP however, the slope decreased from 1.34 +/- 0.48 ml/min-mmHg at baseline to 1.08 +/- 0.47 ml/min-mmHg following reperfusion (p < 0.05), indicating an attenuation of endothelium-dependent vasodilator capacity. In five of the animals, the slope of the pressure-flow relationship during intracoronary nitroprusside was unchanged post-stunning, which is similar to the adenosine results. In conclusion, the data support the hypothesis that endothelium-dependent vasodilation of resistance vessels in the intact animal is altered within severely stunned myocardium. The rightward shift of the coronary pressure-flow relationships with both classes of vasodilators suggest that extra vascular factors may also play a role in limiting coronary flow reserve.

FDG uptake within regionally stunned myocardium.

Clinical cardiologists are now aware of several conditions in which myocardial function can be depressed in the absence of overt ischemia or infarction. Myocardial stunning refers to a particular situation in which the contractile state of the myocardium remains depressed after a brief period of ischemia and reperfusion. Positron emission tomography has been shown to be an important tool for identifying viability within stunned myocardium on the basis of enhanced fluorine 18-fluorodeoxyglucose (FDG) uptake relative to perfusion. This image pattern has been referred to as a ¿flow-metabolism mismatch¿ and is predictive of patients who would benefit from reperfusion therapies. This review highlights the importance of considering the time course of altered FDG uptake within regionally stunned myocardium.

Myocardial blood flow and FDG retention in acutely stunned porcine myocardium.

UNLABELLED: This study assesses regional differences in myocardial blood flow and 18F-fluorodeoxyglucose (FDG) retention in acutely stunned porcine myocardium. METHODS: Two groups of swine were used for these studies. In Group 1, 15 animals underwent stunning induced by 20 min of myocardial ischemia followed by reperfusion. Regional function was measured with ultrasonic crystals and myocardial blood flows were quantitated with radiolabeled microspheres. Within 2 hr postischemia, myocardial blood flow images were obtained with 15O-water, and FDG uptake was estimated with dynamic scanning. In a second group of five animals, PET scanning was performed 2 hr poststunning and repeated 24 hr later. RESULTS: In Group 1 animals, postischemic reductions were noted in both regional shortening and myocardial oxygen consumption. Myocardial blood flows at baseline were 0.72 +/- 0.05 ml/min/g in the LAD region and 0.83 +/- 0.07 ml/min/g in the non-LAD region; following reperfusion they were 0.70 +/- 0.07 ml/min/g and 0.89 +/- 0.08 ml/min/g, respectively. Within 2 hr of reperfusion, FDG retention was significantly lower in the LAD region compared with remote myocardium. As with Group 1, Group 2 also showed a reduction in FDG uptake in acutely reperfused myocardium relative to remote regions. Twenty-four hours later, FDG uptake within reperfused regions increased to 0.31 +/- 0.04 mumole/min/g and did not differ from remote myocardium. CONCLUSION: FDG uptake in acutely stunned swine myocardium is lower than remote regions at a time when regional myocardial blood flows are not dissimilar. This differs from 24 hr following reperfusion in which enhanced FDG uptake may be observed relative to perfusion. Therefore, the time course of metabolic changes following reperfusion needs to be considered in patients undergoing viability studies with PET.

Effects of dobutamine stimulation on regional myocardial glucose uptake poststunning as measured by positron emission tomography.

OBJECTIVES: The aim was to determine whether dobutamine stimulation of energy expenditure within the postischaemic myocardium would affect regional differences in glucose uptake as measured by positron emission tomography (PET). METHODS: The metabolic rate of glucose uptake within the myocardium can be assessed with the glucose analog 18F-fluorodeoxyglucose (FDG). Stunning was induced in 14 anaesthetised pigs by partially occluding the left anterior descending coronary artery (LAD) for 20 min (> 80% flow reduction). The metabolic rate of glucose uptake was determined 2 h after reperfusion in the LAD and non-LAD regions in two groups: without (group 1; n = 7) and during (group 2; n = 7) a constant intravenous infusion of dobutamine (4 micrograms.kg-1.min-1). RESULTS: In all pigs, stunning reduced systolic shortening from 16(SD 4)% to 5(5)% (p < 0.05) and slightly lowered myocardial oxygen consumption, from 3.18(1.21) to 2.67(0.93) mumol.min-1.g-1 (p = 0.08). In the postischaemic LAD region of group 1, the metabolic rate of glucose uptake was significantly lower than the non-LAD region (0.11(0.08) and 0.43(0.33) mumol.min-1.g-1 respectively). In group 2, dobutamine induced a sustained increase in both fractional shortening (7(4)% to 16(5)%; p < 0.05) and oxygen consumption (2.34(0.94) to 4.53(1.52) mumol.min-1.g-1; p < 0.05) within the postischaemic LAD region. Despite recruitment of function and oxygen consumption in group 2, the metabolic rate of glucose uptake was similar to that of group 1 (0.11(0.09) and 0.40(0.28) mumol.min-1.g-1 in LAD and remote regions respectively). CONCLUSIONS: In this pig model of stunning, uptake of FDG was lower in stunned compared with remote myocardium and was independent of postischaemic changes in oxygen consumption and wall thinning. This supports the contention that after stunning, non-glucose substrates play an important part in maintaining energy expenditure during catecholamine stimulation.

Prognostic value of dipyridamole sestamibi single-photon emission computed tomography and dipyridamole stress echocardiography for new cardiac events after an uncomplicated myocardial infarction.

A high-dose dipyridamole stress test (0.84 mg/kg in 6 minutes) with simultaneous sestamibi single-photon emission computed tomographic (SPECT) and echocardiographic imaging was performed in 89 patients before hospital discharge after an uncomplicated myocardial infarction. The aim of this study was to determine the prognostic value of these tests for new cardiac events and to compare the relative values of SPECT and echocardiography in a postinfarction dipyridamole stress test. Two years after infarction, nine patients (10%) had died, five patients (6%) had suffered a nonfatal reinfarction, and 14 patients (16%) had been readmitted to the hospital for a revascularization procedure. Cardiac death had occurred in 5 (10%) of 48 patients with a positive SPECT versus 4 (10%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 3 (5%) of 56 with a negative echocardiogram (p = 0.05). Cardiac death or reinfarction had occurred in 8 (17%) of 48 patients with a positive SPECT versus 6 (15%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 8 (14%) of 56 with a negative echocardiogram (difference not significant). Thus the predictive value of the dipyridamole stress test for new cardiac events after an uncomplicated myocardial infarction was limited, irrespective of the method used to detect ischemia. Reversible perfusion defects were identified more frequently than new wall motion abnormalities but did not predict late events. A positive dipyridamole echocardiogram was associated with a higher late mortality rate but did not predict other cardiac events.