Shigeyuki Nishimura

Quantitative thallium-201 single-photon emission computed tomography during maximal pharmacologic coronary vasodilation with adenosine for assessing coronary artery disease

The diagnostic value of maximal pharmacologic coronary vasodilation with intravenously administered adenosine in conjunction with thallium-201 single-photon emission computed tomography (SPECT) for detection of coronary artery disease was investigated in 101 consecutive patients who had concomitant coronary arteriography. Tomographic images were assessed visually and from computer-quantified polar maps of the thallium-201 distribution. Significant coronary artery disease, defined as greater than 50% luminal diameter stenosis, was present in 70 patients. The sensitivity for detecting patients with coronary artery disease using quantitative analysis was 87% in the total group, 82% in patients without myocardial infarction and 96% in those with prior myocardial infarction; the specificity was 90%. The sensitivity for diagnosing coronary artery disease in patients without infarction with single-, double-and triple-vessel disease was 76%, 86% and 90%, respectively. All individual stenoses were identified in 68% of patients with double-vessel disease and in 65% of those with triple-vessel disease. The extent of the perfusion defects, as quantified by polar maps, was directly related to the extent of coronary artery disease. In conclusion, quantitative thallium-201 SPECT during adenosine infusion has high sensitivity and specificity for diagnosing the presence of coronary artery disease, localizing the anatomic site of coronary stenosis and identifying the majority of affected vascular regions in patients with multivessel involvement.

Equivalence between adenosine and exercise thallium-201 myocardial tomography: A multicentre, prospective, crossover trial

OBJECTIVES The study was designed to compare pharmacologic and exercise stress during thallium-201 single-photon tomography in a multicenter prospective crossover trial. BACKGROUND Both exercise and adenosine myocardial perfusion imaging have high sensitivity and specificity for detection of coronary artery disease. However, few data are available comparing these two stress tests in the same patients. METHODS The study group consisted of 175 subjects: 55 healthy volunteers and 120 patients with suspected coronary artery disease. All subjects underwent two thallium tomographic tests performed 30 days apart, one during intravenous administration of adenosine (140 micrograms/kg per min for 6 min) and one during exercise stress. All images were computer quantified and interpreted without knowledge of the stress test performed. Interpretation agreement was assessed by kappa and Z statistics. RESULTS Agreement on the presence of normal or abnormal tomograms by adenosine and exercise scintigraphy was 82.8% by visual analysis with kappa and Z statistics of 0.65 (p less than 0.0001) and 11.1 (p less than 0.00001), respectively. The agreement by computer quantification was 86% with kappa and Z statistics of 0.709 (p less than 0.0001) and 12.2 (p less than 0.00001), respectively. Agreement on localization of the perfusion defect to a specific coronary vascular territory varied from 82.7% to 91.4% with highly significant kappa and Z statistics (p less than 0.0001). There was a good correlation between quantified perfusion defect size by adenosine and exercise (r = 0.80, p less than 0.0001), but the values for defect size were significantly greater by adenosine scintigraphy (p = 0.0073). Adenosine side effects were frequent but transient and ceased spontaneously in most subjects within 1 to 2 min after the infusion was discontinued. CONCLUSIONS Adenosine thallium-201 scintigraphy provides diagnostic information similar to that of exercise scintigraphy, although values for defect sizes are greater with adenosine.

Tolerance and safety of pharmacologic coronary vasodilation with adenosine in association with thallium-201 scintigraphy in patients with suspected coronary artery disease.

Adenosine thallium-201 myocardial scintigraphy is a promising test for coronary artery disease detection, but its safety has not been reported in large patient cohorts. Accordingly, the tolerance and safety profile of adenosine infusion were analyzed in 607 patients (351 men, 256 women, mean age 63 +/- 11 years) undergoing this test either because of suspected coronary artery disease (Group I, n = 482) or for risk stratification early (5.2 +/- 2.8 days) after myocardial infarction (Group II, n = 125). Adenosine increased the heart rate from 74.5 +/- 14.0 to 91.8 +/- 15.9 beats/min (p less than 0.001) and decreased systolic blood pressure from 137.8 +/- 26.8 to 120.7 +/- 26.1 mm Hg (p less than 0.001). Side effects were frequent and similar in both groups. Flushing occurred in 35%, chest pain in 34%, headache in 21% and dyspnea in 19% of patients. Only 35.6% of Group I patients with chest pain during adenosine infusion had concomitant transient perfusion abnormalities, compared with 60.7% of Group II patients (p less than 0.05). First- and second-degree AV block occurred in 9.6% and 3.6% of patients, respectively, and ischemic ST changes in 12.5% of cases. Concomitance of chest pain and ischemic ST depression was uncommon (6%) but, when present, predicted perfusion abnormalities in 73% of patients. Most side effects ceased rapidly after stopping the adenosine infusion. The side effects were severe in only 1.6% of patients and in only six patients (1%) was it necessary to discontinue the infusion. No serious adverse reactions such as acute myocardial infarction or death occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative adenosine 201Tl single-photon emission computed tomography for the early assessment of patients surviving acute myocardial infarction.

BACKGROUND We prospectively investigated whether adenosine 201Tl tomography (SPECT) could determine the extent of coronary artery disease, the presence of jeopardized myocardium, and the risk for in-hospital cardiac events in 120 clinically stable patients early (5 +/- 3 days) after myocardial infarction. METHODS AND RESULTS All patients had coronary angiography and SPECT in close proximity. Adenosine SPECT identified 99% of infarct-related arteries and 82% of severely stenosed (> or = 70%) noninfarct arteries. Multivessel disease was accurately predicted in 69% of patients. Sixty-five percent of stenosed noninfarct arteries had matching thallium perfusion defects, and 92% of these were reversible. The specificity of adenosine SPECT was > 90%. Thallium redistribution occurred often within infarct (59%) and noninfarct (92%) zones. The patency status of the arteries, however, did not predict the presence or extent of jeopardized myocardium. The perfusion defect size was larger (p = 0.0001) in patients with (45 +/- 18%) than in those without (22 +/- 15%) in-hospital cardiac events. Furthermore, 90% of patients with events had a > or = 20% perfusion defect compared with only 38% of those without events (p = 0.0001). The positive-predictive accuracy for developing a cardiac event was 70% when the perfusion defect size was > 30%. The ischemic defect also was larger in patients with (19 +/- 14%) than in those without (10 +/- 10%) events (p = 0.001). The positive- and negative-predictive values for developing early postinfarction angina were 43% and 91%, respectively, when the ischemic defect was > 12%. CONCLUSIONS In selected low-risk survivors of myocardial infarction, early quantitative adenosine SPECT is safe and accurate in detecting and localizing coronary stenoses, assessing the extent of jeopardized myocardium, and determining subsequent risk for in-hospital cardiac events.

Angiographic and hemodynamic determinants of myocardial ischemia during adenosine thallium-201 scintigraphy in coronary artery disease.

Background. Myocardial ischemia attributed to coronary steal may occur in some patients receiving pharmacological coronary vasodilation. ECG ST‐segment depression is a marker of myocardial ischemia in these patients, but the factors determining the presence or absence of ischemia are not well known. Methods and Results. To examine the angiographic, hemodynamic, and scintigraphic determinants of adenosine‐induced ischemic ST‐segment depression in patients with coronary artery disease, we studied 65 consecutive patients (45 men and 20 women; mean age, 65 ± 12 years) who showed reversible perfusion defects during adenosine (140 &mgr;g · kg‐1 · min‐1 for 6 minutes) 201TI single‐photon emission computed tomography. Patients with prior myocardial infarction were excluded. Ischemic ST depression occurred in one third of the whole cohort (22 of 65 patients). The presence of coronary collateral vessels (p =0.001), systolic blood pressure at baseline (p =0.006), and adenosine‐induced anginal chest pain (p =0.011) were the only significant independent predictors of ischemic ST‐segment depression by stepwise logistic regression analysis. Rate‐pressure product at baseline, systolic blood pressure, heart rate, rate‐pressure product, increase in heart rate, and rate‐pressure product during adenosine infusion and maximal percent stenosis were variables also significantly related to ischemic ST depression by univariate analysis but were not predictive after the three primary variables were included in the regression model. Perfusion defect size, number of diseased vessels, and age did not correlate with ST‐segment depression. Conclusions. The presence of collaterals, which may predispose to coronary collateral steal, is the most significant correlate of ischemic ST‐segment depression during adenosine infusion. Systolic blood pressure at baseline, which may affect the myocardial oxygen supply/demand ratio and anginal chest pain induced by adenosine, are additional variables related to ischemic ST‐segment depression during adenosine infusion. (Circulation 1993;87:1211‐1219)

Quantification of left ventricular performance during transient coronary occlusion at various anatomic sites in humans: A study using tantalum-178 and a multiwire gamma camera☆

To study the functional significance of transient coronary occlusion on systolic and diastolic left ventricular function relative to the anatomic site of occlusion, first-pass radionuclide angiography with a mobile multiwire gamma camera using tantalum-178 (dose activity less than or equal to 84 mCi/elution) was performed in 46 patients undergoing balloon coronary angioplasty. First-pass images were acquired immediately before angioplasty and during the last 30 s of a 60-s balloon inflation in 23 left anterior descending arteries, 18 right coronary arteries, 8 circumflex arteries and 3 diagonal coronary arteries. Occlusion of the left anterior descending artery resulted in significant decreases in left ventricular ejection fraction (54.6 +/- 12.7% to 32.3 +/- 10.6%, p = 0.0001) and peak filling rate (2.48 +/- 0.68 to 1.75 +/- 0.64 end-diastolic volumes/s, p = 0.0001), accompanied by severe abnormalities in regional function and left ventricular dilation. Right coronary artery occlusion caused inferior hypokinesia, but did not significantly change left ventricular ejection fraction (48.5 +/- 12.4% vs. 45.8 +/- 12.5%, p = NS) or peak filling rate (2.05 +/- 0.81 vs. 2.09 +/- 0.81 end-diastolic volumes/s, p = NS). Circumflex artery occlusion resulted in mild wall motion deterioration and a borderline decrease in ejection fraction (54.7 +/- 11.4% to 50.5 +/- 12%, p = 0.057). Diagonal artery occlusion did not cause significant changes in left ventricular ejection fraction or filling rate. The decrease in left ventricular ejection fraction during coronary occlusion was 9 +/- 25% and 27 +/- 22%, respectively, in those arteries with and without collateral supply (p = 0.052). These data provide strong evidence for the critical importance of the left anterior descending artery and the secondary role of the other coronary arteries in maintaining global systolic and diastolic left ventricular function and suggest a protective role of collateral vessels during coronary occlusion.

Effects of acute, transient coronary occlusion on global and regional right ventricular function in humans☆

OBJECTIVES The aim of this study was to investigate the changes in right ventricular function during acute coronary occlusion produced by inflating a coronary angioplasty balloon catheter. BACKGROUND Alterations in right ventricular function are well known to occur in patients with acute myocardial infarction or ischemic cardiomyopathy. However, the changes in right ventricular function resulting from acute, transient coronary occlusion of each of the major coronary arteries have been scantily studied, perhaps because of serious limitations of currently available technology. METHODS A newly designed, mobile, multiwire gamma camera, in combination with generator-produced tantalum-178, affords high count rate first-pass radionuclide angiography and is thus ideal for studying right ventricular function at the bedside. Accordingly, 46 patients underwent first-pass radionuclide angiography at baseline and during transient coronary occlusion induced by a coronary angioplasty balloon catheter. RESULTS A significant, albeit modest, decrease in global right ventricular ejection fraction occurred during occlusion of the left anterior descending (from 42.9 +/- 9.3% to 39 +/- 8.7%, p < 0.05) and left circumflex (from 44 +/- 9.1% to 38.8 +/- 7.9%, p = 0.03) coronary arteries, but diagonal artery occlusion caused no significant change in right ventricular ejection fraction. Occlusion of the right coronary artery proximal (but not distal) to the acute marginal branch caused a significant decrease in right ventricular ejection fraction (from 42.6 +/- 4.7% to 35.7 +/- 7.2%, p < 0.01). Although occlusion of the left anterior descending, left circumflex and proximal right coronary arteries all caused significant deterioration in regional right ventricular function, only proximal right coronary occlusion caused right ventricular dilation (p < 0.005). CONCLUSIONS Significant impairment of right ventricular function occurs during transient occlusion of the left anterior descending, left circumflex and proximal right coronary arteries, but only occlusion of the latter causes acute right ventricular dilation, probably as a result of ischemia.

Adenosine-induced ST-segment depression during thallium-201 scintigraphy in coronary artery disease: Angiographic and hemodynamic determinants

To examine the angio raphic and hemodynamic determinants of adenosine a AD)-induced depression (ST-DEP) in patients with corona ST segment artery disease, 65 patients with angiographically documcnte r coronary artery disease who underwent AD infusion (140 pg/kg/mrn for 6 .mn) thallium (II)-201 myocardial scintigraphy were studied. Patients with prior myocardral infarction were excluded. AD-Induced STDEP occurred in 22 patients, 14 of whom had chest pain. The onset of ST-DEP was at 3.9 f 1.1 min after the beginning of AD infusion, Systolic blood pressure was higher in patients with than those without ST-DEP, both at baseline (152 ! 28 and 135 f 23, respectively, p c 0.05). and during AD Infusion (141 f 27 and 126 t 22 mmHg, respectively, p c 0.05). Rate-pres,sure product during AD infusion was significantly higher tn patrents with than in those without ST-DEP (13093 f 3445 and 10228 t 3053, respectively, p c 0.05). The angiographic and scintigraphic results were