Angiographic and scintigraphic (perfusion and electrocardiogram-gated SPECT) correlates of clinical presentation in unstable angina.

BACKGROUND: Braunwald classification can be used as a measure of the acuteness or severity of clinical presentation of unstable angina. Gating perfusion images might provide additional information to that obtained from angiography, allowing correlations between the coronary anatomy and extent of myocardium at risk via simultaneous perfusion/function assessment. HYPOTHESIS: The aim of this study was to determine the relation between the highest levels of the Braunwald classification (class III = rest angina within 48 h of presentation; class C = postinfarction angina; class c = refractory angina) and the angiographic findings, and the extent ofperfusion and segmental wall motion abnormalities using technetium-99m ((99m)Tc) sestamibi-gated single-photon emission computed tomography (SPECT) imaging. METHODS: The study group consisted of 86 patients with unstable angina who underwent rest gated (99m)Tc sestamibi SPECT imaging and coronary angiography. Perfusion was graded on a 5-point scale (0 = normal; 4 = absent uptake) and wall motion on a 4-point scale (0 = akinesia/dyskinesia; 3 = normal) using the 20 segment model. Perfusion (PI) and wall motion indices (WMI) were calculated by adding the score of all segments and dividing this by 20. The localization, the degree of stenosis, and the morphology of the culprit lesion were assessed. Multivariate analysis was performed to identify the independent predictors of class III, C, and c angina. RESULTS: Perfusion index was higher and WMI was lower in classes III, C, and c than in classes < III, < C, and < c, respectively (all p < 0.001). Class III angina was associated with PI (p <0.0001), WMI (p< 0.0001), complex morphology (p = 0.01), and decreased Thrombolysis in Myocardial Infarction (TIMI) flow (p = 0.002); class C angina with PI (p < 0.0001), WMI (p< 0.0001), intracoronary thrombus (p = 0.007), and decreased TIMI flow (p = 0.003); and class c angina with PI (p = 0.005) and WMI (p = 0.006). CONCLUSION: The highest levels of the Braunwald classification are associated with a greater size and intensity of myocardial perfusion and wall motion abnormalities and with the angiographic findings of complex morphology, intracoronary thrombus, and decreased TIMI flow.

Usefulness of pulse-wave Doppler tissue sampling and dobutamine stress echocardiography for identification of false positive inferior wall defects in SPECT.

False positive inferior wall perfusion defects restrict the accuracy of SPECT in diagnosis of coronary artery disease (CAD). Pulse-Wave Tissue Doppler (PWTD) has been recently proposed to assess regional wall motion velocities. The objectives of this study were to evaluate the presence of CAD by using PWTD during dobutamine stress echocardiography (DSE) in patients with an inferior perfusion defect detected by SPECT and compare PWTD parameters of normal cases with patients who had inferior perfusion defect and CAD. Sixty-five patients (mean age 58 +/- 8 years, 30 men) with a normal LV systolic function at rest according to echocardiographic evaluation with an inferior ischemia determined by SPECT and a control group (CG) of 34 normal cases (mean age 56 +/- 7 years, 16 men) were included in this study. All patients underwent a standard DSE (up to 40 microg / kg / min with additional atropine during sub-maximum heart rate responses). Pulse-wave Doppler tissue sampling of inferior wall was performed in the apical 2-chamber view at rest and stress. The coronary angiography was performed within 24 hours. The results were evaluated for the prediction of significant right coronary artery (RCA) and / or left circumflex coronary artery (CX) with narrowing (> or = 50% diameter stenosis, assessed by quantitative coronary angiography). It was observed that the peak stress mean E / A ratio was lower in patients with CAD when compared to patients without CAD (0.78 +/- 0.2 versus 1.29 +/- 0.11 p < 0.0001). Also the peak stress E / A ratio of normal cases was significantly higher than patients who had CAD (1.19 +/- 0.3 versus 0.78 +/- 0.2 p < 0.0001). When the cut off point for the E / A ratio was determined as 1, the sensitivity and specificity of dobutamine stress PWTD E / A were 89% and 86 %, respectively. The peak stress E / A ratio was higher than 1 in all patients with a false positive perfusion defect. Systolic S velocity increase during DSE was significantly lower in patients with CAD (54 % +/- 17 versus 99 % +/- 24 p = 0.01). The analysis of S velocity increase yielded 81% sensitivity and 76 % specificity for prediction of CAD when a 70 % increase was accepted as a cut-off value. Pulse-wave Doppler tissue sampling during DSE may help to identify false positive inferior wall defects detected by SPECT.

Myocardial perfusion and angiographic findings in patients with paradoxical sinus deceleration during dobutamine technetium-99m sestamibi-gated SPECT imaging.

AIMS: Dobutamine-gated SPECT imaging allows simultaneous perfusion and function assessment and is an alternative stress method for evaluating coronary artery disease in patients unable to perform treadmill exercise. In some patients, a paradoxical decrease in heart rate has been observed during high dose dobutamine infusion. The purpose of this study was to describe the paradoxical decrease in heart rate observed during dobutamine perfusion scintigraphy and determine its relation to inducible ischemia and angiographic coronary artery disease. METHODS AND RESULTS: We studied 52 patients who underwent dobutamine-gated (99m)Tc sestamibi SPECT imaging and coronary angiography within 30 days. Paradoxical deceleration was defined as a decrease in heart rate >/=5 beats/min lasting at least 3 min during dobutamine infusion. Perfusion was graded on a five-point scale (0 = normal; 4 = absent uptake) and wall motion on a four-point scale (0 = akinesia/dyskinesia; 3 = normal) using the 20-segment model. Significant coronary artery disease was defined as >/=50% narrowing of lumen diameter of a major epicardial artery. Paradoxical deceleration occurred in 10 patients (19%, 95% CI 8-30%). A decrease in systolic blood pressure [8 patients (80%), 95% CI 56-92%] with angina [5 patients (50%), 95% CI 23-71%] often accompanied the decrease in heart rate. All 10 patients with sinus deceleration had an inferior wall perfusion defect and 8 of them had a corresponding wall motion abnormality on gated images. Significant coronary artery disease was present in all 10 patients with sinus deceleration, with an increased incidence of right coronary artery stenosis (p = 0.007). CONCLUSIONS: Paradoxical deceleration observed during dobutamine perfusion scintigraphy is associated with inducible ischemia and angiographic coronary artery disease and the underlying mechanism for this phenomenon may be the activation of the Bezold-Jarisch reflex.

Relation of plasma lipoprotein(a) with myocardial viability and left ventricular performance in survivors of myocardial infarction.

Previous studies have reported that high serum lipoprotein(a) levels may be responsible for total occlusion of the infarct-related artery via inhibition of intrinsic fibrinolysis during acute myocardial infarction. We evaluated whether this would result in a greater extent of myocardial necrosis and impaired left ventricular function in patients with high lipoprotein(a) levels. Sixty-eight patients with prior myocardial infarction, who were not receiving thrombolytic therapy underwent coronary angiography and stress-redistribution-reinjection Tl-201 scintigraphy. Antegrade TIMI flow in the infarct-related artery was lower (1.54 +/- 1.14 vs 2.15 +/- 1.05; p = 0.03) and the collateral index was higher (1.3 +/- 1.0 vs 0.8 +/- 0.9; p = 0.07) in patients with high lipoprotein(a) levels (> 30 mg/dl) compared to those with low lipoprotein(a) levels (< or = 30 mg/dl). Regional wall motion score index was lower (0.8 +/- 0.8 vs 1.4 +/- 0.5; p = 0.008) and global ejection fraction was higher (46 +/- 10% vs 40 +/- 11%; p = 0.03) in patients with low lipoprotein(a) levels. On SPECT images, the number of non-viable defects was higher in patients with high lipoprotein(a) levels (4.0 +/- 2.5 vs 1.9 +/- 1.3; p = 0.0002), whereas the number of viable defects was higher in those with low lipoprotein(a) levels (2.5 +/- 1.8 vs 1.5 +/- 1.3; p = 0.02). We conclude that high lipoprotein(a) levels may prolong the occlusion of infarct-related artery during acute myocardial infarction and lead to a greater extent of myocardial necrosis and impaired left ventricular function.

Assessment of Graft Patency Rate After Coronary Artery Bypass Surgery by Exercise TL-201 Single Photon Emission Computed Tomography.

Noninvasive assessment of graft function requires detection of myocardial ischemia. Although T1-201 scintigraphy was primarily used to demonstrate improved perfusion soon after bypass surgery, it may be important in detecting graft stenosis late after surgery, identifying patients with symptoms due to graft occlusion. To investigate this, 38 symptomatic patients aged 58 +/- 10 years who had undergone bypass surgery 3-7 years previously (mean 4.0 +/- 1.2 years) in our center were studied by exercise T1-201 single photon emission computed tomography (SPECT) and coronary angiography. Patients with previous myocardial infarction were not included in the study. Of the 88 coronary bypass grafts examined 42 had significant luminal narrowing (>50%) T1-201 SPECT detected 36 of 42 (86%) stenosed grafts with perfusion defects corresponding to the proper vascular territory. T1-201 SPECT had a higher sensitivity (83% vs 50%, p < 0.01) and predictive accuracy (84% vs 58%, p < 0.02) compared with exercise stress testing in detecting graft stenosis. Sensitivity, specificity, and predictive accuracy of T1-201 SPECT for detection of stenosis were 87%, 93%, and 89% for the left anterior descending coronary artery; 90%, 89%, and 89% for the right coronary artery; and 78%, 76%, and 76% for the circumflex artery, respectively. These results indicate that T1-201 SPECT is a highly sensitive and specific noninvasive technique for detecting and localizing graft stenosis long after coronary bypass surgery.

Assessment of viable myocardium and prediction of postoperative improvement in left ventricular function in patients with severe left ventricular dysfunction by quantitative planar stress-redistribution-reinjection 201-T1 imaging.

A noninvasive approach to determine viable but asynergic myocardium will be clinically significant in identifying patients with coronary artery disease and severe left ventricular dysfunction who will benefit most from coronary bypass surgery. Accordingly, 12 patients (mean ejection fraction 0.32 +/- 0.03) underwent quantitative planar stress-redistribution-reinjection thallium scintigraphy and radionuclide ventriculography before and 8 weeks after revascularization for viability and segmental and global left ventricular function assessment, respectively. Reinjection scan showed new fill-in in 63% of segments without redistribution. Postoperative improvement in perfusion and function of asynergic segments were significantly better in viable compared to nonviable segments (P < 0.001, P < 0.01, respectively) with a strong correlation between improvement in 201-T1 uptake and function (P < 0.001). When adequacy of revascularization was considered, the predictive value of a positive preoperative viability test for functional improvement was 83%. Finally, mean ejection fraction and global wall motion score increased significantly after revascularization for the group as a whole (0.32 +/- 0.03 to 0.44 +/- 0.04, P < 0.001 and 24.08 +/- 2.90 to 33.16 +/- 3.32, P < 0.001, respectively). Thus, preoperative quantitative planar stress-redistribution-reinjection thallium imaging detects viable but asynergic segments which improve function postoperatively and may be valuable in selection of patients with severe left ventricular dysfunction for revascularization.