Relation of Technetiuni-99m Pyrophosphate Accumulation to Time Interval After Onset of Acute Myocardial Infarction as Assessed by a

Tomographic Acquisition Technique Thomas Krause, MD, Wolfgang Kasper, MD, Andreas Zeiher, MD,

Carl Schuemichen, MD, and Ernst Moser, MD, PhD

Technetium99m pyrophosphate (Tc-99m PYP) myocardial scintigraphy was performed in 110 clinically stable patients with acute or healed acute myocardial infarction (AMI). Tomography was performed 12 hours to 7 days (group A), 7 to 30 days (Group B), 1 to 6 months (Group C) and after >6 months (group D) after AMI. All 40 patients in group A, 9 of 31 in group B, 1 of 22 in group C, and no patient (0 of 17) in group D had a pathologic Tc-99m PYP tomogram. Rela- tive Tc-99m PYP accumulation within the area of infarction was measured as infarct zone to blood pool ratio, which decreased significantly (p <O.OOl) from group A (1.54 f 0.39) to group B (6.89 f 0.24), group C (0.8 f 0.19) and group D (0.76 f 0.13). These data were confirmed by se- quential scintigraphy in 17 patients. It is con- cluded that a persisting Tc-99m PYP uptake is rarely found >1 month after AMI using tomo- graphic imaging techniques in clinically stable patients with coronary artery disease. Positive results on Tc-99m PYP tomography are a reli- able indicator of AMI. Thus, Tc-99m PYP to- mography is not only a sensitive but also a spe- cific imaging technique for AMI, which might be especially useful for diagnosis of reinfarction.

(Am J Cardiol1991;68:1575-1579)

From Albert-Ludwigs-University, Freiburg, Federal Republic of Ger- many. Manuscript received May 8, 1991; revised manuscript received and accepted August 12,199 1.

Address for reprints: Thomas Krause, MD, Radiologische Univer- sitltsklinik, Abteilung Nuldearmedizin, Hugstetter Strasse 55, 7800 Freiburg, Federal Republic of Germany.

T echnetium-99m pyrophosphate (Tc-99m PYP) has been demonstrated to be a sensitive marker of acute myocardial infarction (AMI).lm3 Tc-

99m PYP scintigraphy, however, remaining persistently positive for at least up to 8 months, was reported to be frequently found with planar imaging technique.4-6 The low specificity of the planar acquisition of Tc-99m PYP infarction scintigraphy, approximately 50 to 80% re- duces its value in the diagnosis of reinfarction.5,7m9 Clin- ical studies have demonstrated tomographic acquisition to be superior to planar imaging in many respects. lo91 l However, whether persistent Tc-99m PYP accumula- tion after AM1 is due to artifacts resulting from the planar acquisition technique or due to ongoing myocar- dial necrosis has not been solved. This study evaluates whether persistently positive Tc-99m PYP scintigrams may also occur in clinically stable patients using a tomographic imaging technique. A dual tracer myocar- dial scintigraphic imaging technique was used, combin- ing Tc-99m PYP as a tracer for AM1 and thallium (Tl)-201 as an anatomic marker for the myocardium.

METHODS Myocardial scintigraphy was performed in 110 pa-

tients (mean age 54 f 12 years, range 20 to 80) at various time points after AMI. Sequential myocardial scintigrams were recorded in a subset of 17 patients (Figure 1). Scintigraphy was performed in 40 patients 12 hours to 7 days after AM1 (group A), in 31 patients after 7 to 30 days (group B), in 22 patients 1 to 6 months after infarction (group C), and in 17 patients after >6 months (group D). None of these patients had clinical evidence of subsequent AM1 or persistent angi- na (symptoms, electrocardiography, creatine kinase).

The diagnosis of myocardial infarction was made when at least 2 of the following 3 criteria were fulfilled: (1) severe substernal chest pain unresponsive to nitrates during AMI, (2) elevation of total serum creatine ki- nase >70 U/liter with MB-isoenzyme fraction exceed- ing 7%, and (3) standard electrocardiographic criteria consistent with the diagnosis of AMI.12

Myocardial imaging: All patients were examined during a stable phase of their disease. Imaging was be-

TECHNETIUM-99m PYROPHOSPHATE ACCUMULATION 1575

TABLE I Clinical Status and Scintigraphic Findings in the Four Groups Depending on the Time After Acute Myocardial Infarction

No. Anterior/ Relative Size Relative Size Q/Non-Q-Wave of Time After Inferior Positive Uptake Ratio Tc-99m PYP* TI-201 Myocardial

Group Pts. AMI Infarction Studies Tc-99m PYP* (segments) (segments) Infarction

A 40 3 * 2 days 20/20 40 1.54 ” 0.39 2.73 zk 1.28 2.65 tc 1.55 3317 B 31 17 f 6 days 17/14 9 0.89 f 0.24 0.90 r 0.74 2.58 +- 1.11 2516 C 22 3 f 1 mos. 10/12 1 0.80 f 0.19 0.84 + 0.65 3.03 f 1.72 21/l D 17 3 2 2 yrs. 1017 0 0.76 f 0.13 0.72 k 0.50 2.51 e 1.70 17/o

*Significant difference in group A compared with groups B, C and D (p < 0.001). AMI = acute myocardial infarction: PYP = pyrophosphate; Tc = technetium; TI = thallium.

gun 2.5 to 3 hours after intravenous injection of 90 MBq of Tl-201 and 200 to 370 MBq of Tc-99m PYP (Tecephos, Behringwerke Marburg). Scintigrams were recorded using a 38 cm large field-of-view camera (Dyna 4, Picker) with 2 impulse height analyzers. A commercial 7-pinhole collimator focused at 13.5 cm with 7 5.3 mm pinholes was fitted to the camera. Ener- gy discrimination was provided by a 15% window cen- tered on the 75 keV peak for Tl-201 and a 5% window centered on 140 keV for Tc-99m. This adjustment yields optimal results as shown in a previous study.‘l Seven-pinhole tomography was acquired as recently re- ported. ‘3

Scatter corrections: The raw data were corrected for down-scattered Tc-99m counts and for radioactivity from Tl-201 gamma rays ( 135 and 167 keV) according to the following formulasl: a = A - Ba, b = B - A@ where a = corrected Tl-201 counts, A = total sample counts at 75 keV, (Y = Tc-99m standard at 75 keV/Tc- 99m standard at 140 keV, b = corrected Tc-99m

counts, B = total sample counts at 140 keV, and fi = Tl-201 standard at 140 keV/Tl-201 standard at 75 keV.

Data pwcessing and Bvsrlay technique: ‘II-201 and Tc-99m tomograms were separately reconstructed ac- cording to the method used by Vogel et a1.14 Sixteen sections of nominal 0.8 cm intervals were generated. After reconstruction, images were viewed using a 15- step color scale. For dual isotope display, the Tc-99m images were background-subtracted to ensure that re- sidual blood pool activity was just below the display limit. Then the images were inversely colored and over- laid on the normally colored Tl-201 images.

For sizing the infarction, each short-axis slice was subdivided into 8 segments. Relative size of the Tl-201 defects and the Tc-99m PYP accumulation was ex- pressed as the number of segments involved. The results of 6 slices were averaged. Tc-99m PYP uptake ratio was assessed by calculating Tc-99m PYP target to blood pool ratios for the area of infarction and for myo-

EiecrosWBlood Pool Ratio EiecrosWBlood Pool Ratio 3 3

&5 - &5 -

2- 2-

1.5 - 1.5 -

l- l-

).5-. ” I.5 - ”

0,“’ ““““’ ““““““” “I ‘I~““““” 0,“’ ““““’ ““““““” “I ‘I~““““” ld ld 7d 7d 14d 14d 21d 21d 30d 30d 6m 6m ,6n ,6n

Time of Examination after AMI Time of Examination after AMI

FIGURE 1. Time ceuree of tedmetium-BBm pyrephwphete accumulation in 17 patients with early imaging (within 7 days after acute myecerdial infarction [AM]) and follow-up examination (13 days to 4 years). Infarct to blood pool ratio in ths btter scinti- grams decreased in all cases.

1576 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68 DECEMBER 15, 1991

FlGURE 2. Positive rate (infarct to bkd pool ratio > 1.0) of technetium-9Sm pyro- pho@ate scintigraphy depending on the the of examlnatlon after acute myocardi- al infarctktn (AMI).

Rate of Positive Findings (%)

12h-7d 8d-30d lm-8m >8m

Time of Examination after AMI

n n 40 n = 31 l-l * 22 n = 17

cardium with normal Tl-201 uptake, respectively. Tc- 99m PYP uptake ratio >l.O was considered abnormal if measured on 12 contiguous short-axis slices. Tl-201 defects had to be present on at least 2 contiguous short- axis slices as well.

Statistical analysis: Values reported are mean f 1 standard deviation. Comparisons between groups were made with the Fisher’s exact test. For multiple-compar- ison Scheffe’s method was applied.

RESULTS Scintigraphic findings in the four different groups:

Table I summarizes the clinical and scintigraphic pa- rameters. A perfusion defect on the Tl-201 tomograms was seen in all patients studied. The relative size of the

FIGURE 3. Acute tramimural w infarctktn. short- axis cut of combined thallll-2ol/technetllml-88m pyrophos- phate tomography 3 days after acute myocardial infarction showing marked tedndknn-99m p- uptake (ye!- fowandgreen)inthe anteroseptal wag. Normal thallium-201 accumulation is red.

perfusion defect did not differ between the 4 groups (groups A to D: 2.65 f 1.55, 2.58 f 1.11, 3.03 f 1.72 and 2.51 f 1.7 segments). Moreover, Tl-201 defect size was comparable in patients in group B with and without positive Tc-99m PYP accumulation (Tc-99m PYP+, 2.6 f 1.8 segments; Tc-99m PYP-, 2.2 f 1.6 segments). Tc-99m PYP uptake (Figure 2) was present in all 40 patients in group A (AM1 within 7 days) (Fig- ure 3) 9 of 31 patients in group B (7 to 30 days after AMI), 1 of 22 patients in group C (1 to 6 months after AMI), and no (0 of 17) patient in group D (>6

FIGURE 4. Anteroseptal infarction 8 months before scintigra- phy. Sort-axis cut of combined thallium-2Ol/technetium- 88m p-hate tomography showing an evklent region of reduced (bhte) or even abseni actMy at the anterosepM wall (silhuettes indiited by doffed lines). Furthermore, increased thallium-201 uptake was noted at right vent&ular wall (arc row). No pathokbgll technetium-99m pyrophosphate accumu- lation in the anteroseptal wall is seen. Remaining activity of left ventrlcuiar blood pool is yeUow.

TECHNETIUM-99m PYROPHOSPHATE ACCUMULATION 1577

months after AMI) (Figure 4). Compared with group A, patients in Groups B, C and D had significantly lower Tc-99m PYP uptake ratio (1.54 f 0.39 vs 0.89 f 0.24, 0.80 f 0.19, 0.76 f 0.13; p <O.OOl). How- ever, despite a Tc-99m PYP uptake ratio <l in the zone of the Tl-201 defect, this ratio was still higher in 47 of 70 studies of groups B, C and D compared with the Tc-99m PYP uptake ratio of myocardium with normal Tl-201 accumulation versus blood pool (0.81 f 0.18 vs 0.53 f 0.05; p <O.OOl). In the same way, the size of areas with increased uptake of Tc-99m PYP above that of myocardium with normal Tl-201 accu- mulation also decreased (groups A to D: 2.73 f 1.28, 0.90 f 0.74, 0.84 f 0.65 and 0.72 f 0.50 segments). These findings were independent of the location of in- farction in either the anterior or posterior wall.

Scintigraphic findings of the 17 patients with se- quential examinations: In 17 patients, acute examina- tion 2.8 f 2.0 days after AM1 was followed by an ad- ditional examination 1 week to 4 years later. All initial tomograms during the acute phase of AM1 demon- strated a Tc-99m PYP uptake ratio >l. The Tc-99m PYP uptake ratio decreased in all patients at the fol- low-up examinations from 1.79 f 0.4 to 0.84 f 0.23 (p <O.Ol ) (Figure 1). Only 4 of these 17 patients exhib- ited a Tc-99m PYP uptake ratio of >l on days 2, 13, 16 and 17, respectively, and 1 patient had it 4 months after AMI.

DISCUSSION The present study demonstrates that in clinically

stable patients without any evidence of persistent isch- emia, (1) persistently positive Tc-99m PYP tomogra- phy is rarely seen > 1 month after AM1 (1 of 39; 3%), and (2) relative intensity as well as extension of Tc- 99m PYP uptake decreases after 1 week post-AMI. Other investigators using the planar technique have also observed fading Tc-99m PYP accumulation on fol- low-up scintigrams. 5,6 In particular, low-grade diffuse uptake has been described in persistently positive scinti- grams.4A&l5-17 In agreement with these reports com- paring myocardium with normal and decreased Tl-201 accumulation, we identified slightly increased Tc-99m PYP uptake (uptake ratio 0.5 to 1.0) compared with normal myocardium in 69% of the patients in groups B, C and D. Nevertheless, the tomographic technique classified 97% of these studies as normal.

Tc-99m PYP tomography has been shown to be a sensitive method for detecting AMI.‘- Even non-Q- wave infarction can be reliably detected, especially when performed by overlay technique with an anatomic marker such as either tomographic blood pool or Tl- 201 scintigrams. l”,18 Although the 7-pinhole technique used for this study is apparently restricted by a limited

depth resolution ,i3J9 it has been shown to correctly identify and localize AMI. 11,18 However, the value of Tc-99m PYP infarction imaging has been questioned on several occasions because of persistently positive scintigrams.537-9 Prior studies performed as planar scin- tigrams, reported persistently positive findings in up to 57% of the examinations within the first year after AM1417J5 and prompted the search for more suitable markers for necrosis. Indium-I 11 antimyosin, a mono- clonal antibody highly specific in delineating myocardi- al damage,*O appeared most promising.21-23 However, owing to the slow blood clearance of the tracer, imag- ing can be performed only 24 to 48 hours after injec- tion 2124

In contradistinction to indium- 111 antimyosin scan- ning, Tc-99m PYP tomography of AM1 is possible within the first hours.25-27 Tc-99m PYP scintigraphy is particularly attractive for diagnosing acute myocardial necrosis when specificity is high. All previous studies reporting a low specificity of Tc-99m PYP scintigraphy were performed with the planar imaging technique.5,7-9

Several reasons may explain positive scintigrams not related to AMI. This has been reported for persistent Tc-99m PYP blood pool activity,8Ji,28 left mastecto- my,8l29 extensive AM1 or ventricular aneurysm.4~7~11J6 However, in the present study, infarct size determined by Tl-201 tomograms in group B patients with and without positive Tc-99m PYP uptake was not signiti- cantly different. Several factors may add up to an ap- parently positive planar scintigram, such as faint blood pool activity, slightly increased focal Tc-99m PYP up- take (uptake ratio 0.5 to 1 .O), and physiologic accumu- lation in the bone. Tomographic imaging by dual radio isotope technique as a necessary prerequisite for sup- porting blood pool subtraction enables discrimination of adjacent structures and blood pool activity and there- fore avoids misinterpretation.

Moreover, persistently positive Tc-99m PYP imag- ing can also be true positive, indicating ongoing myo- cardial necrosis.4330 According to clinicopathologic stud- ies, a persistently positive scintigram was frequently correlated with myocytolytic degeneration and fibro- sis,31 acute3,31T32 or recurrent ischemia4J7 and chronic ischemic injury.30,33 Persistent Tc-99m PYP uptake was found to predict cardiac death or impairment of left ventricular function.6*30T33

Study limitation: In this study we did not compare the planar and tomographic imaging techniques. There- fore, no conclusion can be drawn on the frequency of false-positive planar Tc-99m PYP scintigrams.

Conchsions: The present study shows that a positive Tc-99m PYP tomogram reliably indicates an acute myocardial necrosis and thus may be especially useful for detecting reinfarction. Tomographic imaging of Tc-

1578 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68 DECEMBER 15. 1991

99m PYP accumulation may increase the specikity of this technique.

REFERENCES 1. Buja LM, Parkey RW, Stokely EM, Bonte FJ, Willerson JT. Pathophysiology of technetium-99m stannous pyrophosphate and thallium-201 scintigraphy of acute anterior myocardial infarcts in dogs. J C&t Incest 1976;57:1508-1522. 2. Buja LM, Tofe AJ, Kulkarni PV, Mukherjee KA, Parkey RW, Francis MD, Bonte FJ, Willerson JT. Sites and mechanisms of localization of technetium-99m phosphorus radiopharmaceuticals in acute myocardial infarcts and other tissues. J Clin Invest 1977;60:724-740. 3. Willerson JT, Parkey RW, Bonte FJ, Meyer SL, Atkins JM, Stokely EM. Technetium stannous pyrophosphate myocardial scintigrams in patients with cheat pain of varying etiology. Circulation 51:1046-1051. 4. Buja LM, Poliner LR, Parkey RW, Pulido JI, Hutcheson D, Platt MR, Mills LJ, Bonte FJ, Willerson JT. Clinicopathologic study of persistently positive tech- netium-99m stannous pyrophosphate myocardial scintigrams and myocytolytic degeneration after infarction, Circulafion 1977;56:1016-1023. 5. Malin FR, Rollo FD, Gertz EW. Sequential myocardial scintigraphy with technetium-99m stannous pyrophosphate following myocardial infarction. JNucl Med 1978;19:1111-1115. 6. Olson HG, Lyons KP, Aronow WS, Kuperus J, Orlando J, Hughes D. Prognos- tic value of a positive technetium-99m stannous pyrophosphate myocardial scinti- gram after myocardial infarction. Am J Cardiol 1979;43:889-898. 7. Ahmad M, Dubiel JP, Logan KW, Verdon TA, Martin RH. Limited clinical diagnostic specificity of technetium-99m stannous pyrophosphate myocardial im- aging in acute myocardial infarction. Am J Cardiol 1977;39:50-54. 8. Prasquier R, Taradsh M, Botvinick EH, Shames DM, Parmley WW. The specificity of the diffuse pattern of cardiac uptake in myocardial infarction imag- ing with technetium-99m stannous pyrophosphate. Circulation 1977;55:61-66. 9. Turi ZG, Rutherford JD, Roberts R, Muller JE, Jaffe AS, Rude RE, Parker C, Raabe DS, Stone P, Hartwell TD, Lewis SE, Parkey RW, Gould HK, Robertson TL, Sobel B, Willerson JT, Braunwald E. Electrocardiographic, enzymatic and scintigraphic criteria of acute myocardial infarction as determined from study of 726 patients (A MILIS study). Am J Cardiol 1985;55:1463-1468. 10. Corbett JR, Lewis M, Wilierson JT, Nicod PH, Huxley RL, Simon T, Rude RE, Henderson E, Parkey R, Rellas JS, Buja LM, Sokolov JJ, Lewis SE. 99m-Tc- pyrophosphate imaging in patients with acute myocardial infarction: comparison of planar imaging with single-photon tomography with and without blood pool overlay. Circulation 1984;69:1120-1128. 11. Krause T, Kasper W, Schiimichen C, Meinertz T, Joseph A, Just H. Im- proved detection of acute myocardial infarction by means of combined thallium- 201/technetium-99m-PPi-tomography compared to planar infarction imaging. Z Kardiol 1989;78:161-166. 12. Zema MJ. Q wave, ST segment, and T-wave myocardial infarction: useful clinical distinction. Am J Med 1985;78:391-398. 13. Krause T, Schiimichen C, Fischer R, Strauss E, Hoffmann G. Simultaneous 201T1/99mTc-seven-pinhole tomography in acute myccardial infarction, Nucl Med 1986;25:99-105. 14. Vogel RA, Kirch D, LeFree M, Steele P. A new method of multiplanar emission tomography using a seven pinhole collimator and an Anger scintillation camera. J Nucl Med 1978;19:648-654. 15. Olson HG, Kenneth PL, Aronow WS, Brown WT, Greenfield RS. Follow-up technetium-99m stannous pyrophosphate myocardial scintigrams after acute myocardial infarction, Circulation 1977;56:181-187. 16. Botvinick EH, Shames DM, Sharpe DN, Klausner SC, Werner JA, Chatter- jee K, Parmley WW. The specificity of pyrophosphate myocardial scintigrams in patients with prior myocardial infarction: concise communication. J Nucl Med 1978;19:1121-1125.

17. Mason JW, Myers RW, Alderman EL, Stinson EB, Gorgis ML, Kriss JP. Technetium-99m pyrophosphate myocardial uptake in patients with stable angina pectoris. Am J Cardiol 1977;40:1-5. 18. Krause T, Joseph A, Kutzner C, Kasper W, Schiimichen C, Just H, Moser E. Acute myccardial infarction delineated by noninvasive thallium 20l/technetium- 99m pyrophosphate tomography. Nucl Med Corn 1990;11:617-629. 19. Williams DL, Ritchie JL, Harp GD, Caldwell JH, Hamilton GW. In viva simulation of thallium-201 myocardial scintigraphy by seven-pinhole emission tomography. J Nucl Med 1980;21:821-X2X. 20. Khaw BA, Fallon JT, Beller GA, Haber E. Specificity of localization of myosin-specific antibody fragments in experimental myocardial infarction: histo- logic, hi&chemical, autoradiographic and scintigraphic studies. Circulation 1979;60:1527-1531. 21. Johnson LL, Seldin DW, Becker LC, LaFrance ND, Liberman HA, James C, Mattis JA, Dean RT, Brown J, Reiter A, Arneson V, Cannon PJ, Berger HJ. Antimyosin imaging in acute transmural myocardial infarctions: results of a multicenter clinical trial. J Am Coil Cardiol 1989;13:27-35. 22. Khaw BA, Strauss HW, Moor R, Fallon JT, Yasuda T, Gold HK, Haber E. Myccardial damage delineated by indium-11 1 antimyosin Fab and tcchnetium- 99m pyrophosphate. J Nucl Med 1987;28:76-82. 23. Volpini M, Giubbiii R, Gei P, Cuccia C, Franzoni P, Riva S, Terzi A, Metra M, Bestagno M, Visioli 0. Diagnosis of acute myocardial infarction by indium- 111 antimyosin antibodies and correlation with the traditional techniques for the evaluation of extent and localization. Am J Cardiol 1989;63:7-13. 24. Khaw BA, Yasuda T, Gold HK, Leinbach RC, Johns JA, Kanke M, Barlai- Kovach M, Strauss HW, Haber E. Acute myocardial infarct imaging with indi- urn-l 1 l-labeled monoclonal antimyosin Fab. J Nucl Med 1987;28:1671-1678. 25. Kondo M, Yuznki Y, Arai H, Shimizu K, Morikawa M, Shimono Y. Com- parison of early myocardial technetium-99m pyrophosphate uptake to early pcak- ing of creatine kinase and creatine kinase-MB as indicators of early reperfusion in acute myocardial infarction. Am J Cardiol 1987;60:762-765. 26. Parkey RW, Kulkarni PV, Lewis SE, Data FL, Dehmer GJ, Gutekunst DP, Buja LM, Bonte FJ, Willerson JT. Effect of coronary blood flow and site of injection on Tc-99m PPi detection of early canine myocardial infarcts. J Nucl Med 1981;22:133-137. 27. Wheelan K, Wolfe C, Corbett J, Rude RE, Winniford M, Parkey RW, Buja LM, Willerson JT. Early positive technetium-99m stannous pyrophosphate im- ages as a marker of reperfusion after thrombolytic therapy for acute myocardial infarction. Am J Cardiol 1985;56:252-256. 28. Berman DS, Amsterdam EA, Hines HH, Sale1 AF, Bailey GJ, DeNardo GL, Mason DT. New approach to interpretation of technetium-99m pyrophosphate scintigraphy in detection of acute myocardial infarction. Am J Cardiol 1977;39: 341-346. 29. Klein MS, Weiss AN, Roberts R, Coleman RE. Technetium-99m pyrophos- phate scintigrams in normal subjects, patients with exercise-induced ischemia and patients with a calcified valve. Am J Cardiol 1977;39:360-363. 30. Croft CH, Rude RE, Lewis SE, Parkey RW, Poole WK, Parker C, Fox N, Roberts R, Strauss W, Thomas LJ, Raabe DS, Sobel BE, Gold HK, Stone PH, Braunwald E, Willerson JT. Comparison of left ventricular function and infarct size in patients with and without persistently positive technetium-99m pyrophos- phate myocardial scintigrams after myocardial infarction: analysis of 357 Pa- tients. Am J Cardiol 19X+53:421-428. 31. Poliner LR, Buja LM, Parkey RW, Bonte FJ, WilIerson JT. Clinicopatholog- ic findings in 52 patients studied by technetium-99m stannous pyrophosphate myocardial scintigraphy. Circhtion 1979;59:257-267. 32. Donsky MS, Curry GC, Parkey RW, Meyer SL, Bonte FJ, Platt MR, Willerson JT. Unstable angina pectoris: clinical, angiographic, and myocardial scintigraphic observations. Br Heart J 1976;38:257-263. 33. Nicod P, Lewis SE, Corbett JC, Buja LM, Henderson G, Raskin P, Rude RE, WilIerson JT. Increased incidence and clinical correlation of persistently abnor- mal technetium pyrophosphate myocardial scintigrams following acute myocardi- al infarction in patients with diabetes mellitus. Am Heart J 1982;103:822-X29.

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