- Email: [email protected]
Identification of viable myocardium by echocardiography during dobutamine infusion in patients with myocardial infarction after thrombolytic therapy: Comparison with positron emission tomography
~o~~~iyti~ therapy of acute y~ca~~ia~ i~~~cti~m with Qt~~(i~ase reduces the i~-~osQ~tal mortality rate and ram left ventr~~~~ar function (1,2), However, intravetokiaase bds lo reQe~~si0~ of the i~~fct~~e~~te~
From the Department of Medicine, Division of Cardiology and Cyclotron ch Ccntsr. University of Li&ge, LiQe, elgium. The sludy was prein part at the 60tb Annual Scientific S sion of the American Heart Association, Anaheim, California, November 1987 and the 38th Annual Meeting of the American College of Cardiology, Anabc~~~. California. March 1989. Manuscript received July IO. 1980: revised manuscript received Novemvember 23. 1989. ber , Luc A. Pikrard. MD. Service de Cardiologie. CHU du Saet-Tilman. B-4000 L&e. Belgium. 61990 by the American
College of Cardiology
coronary I.?e!ayed
artery
in only
50% to 6Qoii
1022
Pll%ARD ET AL. VIABLE MYOCARDIUM
JACC Vol. 15. No. 5 A :1021-31
1N ACUTE lNFARCTlON
glucose utilization aims at identifying compromised but viable myocardium (8)at a time when wall motion is equally impaired in necrotic and stunned tissue (9). positron imaging of myocardial glucose utilization is timeconsuming, requires an on-site cyclotron and a positron camera and is not yet widely available because of the cost. Experimental studies (10-13) have suggested that postischemic myocardial dysfunction may be reversed by moderate inotropic stimulationwithout deleterious effects and that this ed by ultrasonic measurement of was to determine whether myocac
For this purpose, a compar-
consisted of 17 patients 2 + 12 years) who were submitted to intravenous thrombolysis within the first 3 h of a first acute anterior rny~~i~~ infection, Fifteen Q~tie~ts received str~~tokin~se(1.5 million U) infused over 30 min,
uration was 20 to
min. There was no
t-coated vessel in
A ventricular segmentation was use left ventricle was divided into thirds: basal, middle and apical. At basal and middle kvels, the circle was divided into six segments: posteros lateral, ~st~~~ater~ a
tients included in this study had received a )ockiingdrug or an inotropic agent before
teroseptal, apical anterior and apical septai (Fig. 1). The anterior segments were identified on the apical two chamber view and on short-axis views from the anterior interventric-
-am
VICWS.
e left ventricle. For
a bvere ~o~~~~ize~
lo the peak
~~~e~e~~~.
Therewas calculated in each region of the left ventricle. To ~ete~~~~ereference intervals, a ~o~~a~group of 10young subjects was studied.
1024
m case
YACC Vol. 15. No. 5 April 1 :1021-31
Pi&WtD ET AL. VlARLE MYDCARDl9JM IN ACUTE INFARCTlDN
Interval Pain-Th
PET Viability
Coronary Anatomy
Proximsl
identified in the correspondin positronemissiontom
20 0
I I
+P
90
2
20
Echo Viability
-
-
-
-
=+
-
-
2
w-
,
Y
c _
_ + c
_ -
ment examined with
smn was withinnor
tientswerestudied9 2 n 9 ?: 7 monthslater.
of potassium-38and “F-
segmentsshowed concordant decreases in perfusionand ghtcoseuptake. In contrast,only 3 of the 21 segmentswith high glucose to perfusi ratio and decreased ion were normal at follow study. Three other glucoseuptake, and ainingsegmentsrevealedconcordantdecreasesin lucose uptake, indicatingnecrosis. R~gionQipe~usion was higher in group 1 ~Qeie~ts tern in group i patients: 7 I .2% f 22.4% versus54.6% +- 16.0% (p = 0.001)in the early studiesand 73.6%f 19.9%versus58.8% f 15.5%(p = 0.001)in the follow-upstudies.The glucoseto
these SLX patvmts. At the baseline exa
1026
P&RARD ET AL. VIABLE MYOCARDIUM
JACC Vol. 15. No. 5 :!021-31 April I
IN ACUTE INFARCTION
Table 2. Echocardiographic Score index in Groups lA, IB and 2 Rest
12.0 + 2.0 p = 0.003
Bobutamine
7.8 f 1.3 NS
Follow-up
Group 2 (n = 6)
Group 1B (n = 6)
Group IA (n = 5)
r p = 0.005
1.4 L 1.7
IS.0 t 0.9 NS
:.s r 2.2 0.055
12.0 + 2.1 p = 0.025
NS
14.7 2 0.8
NS
p = 0.04 15.5 s 1.0
16.0 2 1.7
tation of the reco
results in another ties wereresolvedby consensusbetweenthe two observers on reevaluationof the studies. F&V 6 presents end-diastolic and end-systolic stop frame images of illustrative echocardiograms obtained in the same group IA patient as in Figure 2, show improve-
ment in contractilityof viable stunned myoc ium with dobutamineduringthe acute phase of infarctionand func-
t
rest, but indicatingakincsia
UP ‘IA
re 5. individual chances in the cardio~raphic score index between the dally study at rest and dur dobutamine (DOW) infusion and follow-up (F-UP) study in five patie from group IA (normal perfus ~tients from group 1B (high perfusion ratio) and six patie group 2 fmyocardial necrosis by positron emission tomography). Viable was ide~ti~ed in all paonly in patients
EARLY REST
EARLY OOW
F-UP
EARLY REST
EARLY OOBU
F-UP
Figure 7. End-diastolic (ED) and end-systolic 03) stop frame images of illustrative echocardiograms obtained in the same patient from group IB as in Figure
parent with do~utamiue. In the follow-up shdy. affected segments are akinetic brrowsh
ED
I028
PItiRARD ET AL. VIABLE MYOCARDlUM
IN ACUTE
JACC Vol. 15. No. 5 April I! :IOZ1-31
LNFARCTION
Figure 8, End-diastolic (ED) and endsystolic (ES) stap frame images of illustrative ech~ardio~~ms obtai~~ed in the same ~at~e~t from ~r~~~ 2 as in Parasternal lon~axis views a The septum is akinetic at rest (ar change is i~~~s~o~~~I turn remains akinetic ~~~~0~s~.
ED
myocardial salvage of functional significance. Assessment of lobal left ventricular function by the ejection fraction may not reliably reflect myocardial salvage because it is largely influenced by changes in the compensatory hyperkinesia of the uninvolved regions (IS). Assessment of regional wall motion appears to be more accurate than global ejection fraction for detecting improvement in function produced by thrombolysis (19,201. However. early reperfusion of the occluded coronary artery is usually not accompanied by immediate recovery of contractile function (6.21). The true effectiveness of reperfusion cannot be clearly established for as several weeks (22). The results of ~x~erirncnt~~~ cst that an earlier assessment of myocar-
mntian may be ~lini~~~ly implant
in de~~di~
that the ~ont~~ti~e dobutamine infusio and iufar~t~~~ ~~~i~~s. In dyskincti~ during dobota return of ~ont~~tile functton was 0 co0troI e~bo~ard~~gra
Concordsnscbetween Ike two techniques for early and its. Concordant results are found in a majority of number of viable segmentsdecreasesfrom the early up studies, and the number of necrotic segments tiirqgly. Abbreviations as in Figure I.
between viable and ir~versibl~ dama number of segments that were viable by the two techniques
Tatale 3. Follow-Up Findings in the 16 Myocardial Segments With Discor~nt Results in the Early Studies Follow-Up Early Studies Viable
PET
Studies ~choca~io~~aphy
Necrotic
Normal
Necrotic
Viable on ccb~a~io~~phy: necrotic on PET
1
5
2
5
2
Necl-oiic on echocardiography; viable on PET
9
3
6
0
9
Abbreviations
as in Table
I.
al study (26) by comparing rest stressed ejection fraction in patients wi ssels with use of radio~ucl~de ventriculog2 weeks after ~~yoc~rdia~ ~~f~~rc~ion. Satler
tomography is considetzd to be oninvasive ide~~i~cation of isc ium (27). In our study, positron deformed after a carbohydrate-cent better visualization of normal myoca creasing the ratio of nor al myocardial glucose Is free fatty acid utilization (16). This procedure contrasts with t previous study (9) in which patients fasted overnight; viable but jeopardized tissue was identified by maintained I&Fdeoxyglucose uptake in segments with reduced blood WOW.
in
was made our study by semi tive analysis. ~om~uterized q~a~~itative measure myocardial thicke~~~~ re used in en~crimenta~ studies nrdial and (10-12). but require co ly, this is epicardial outlines on difficult to obtain. Q are frcque~~~y the coronary artery disease. docardial motion may be there is no consensus on h
1030
PlfiRARP ET AL. VIABLE MYWARDIUM
JAW Vol. 15, No. 5 April t990:1OY!t-31
IN ACUTE INFARCTION
mic myocardium may influence the function Of normal adjacent tissue (31-33). Recent experimentat studies (14,)5,34) indicate that dysfunction extends <30” or 1 cm outside of the ischemic area. In experimental conditions (35). dobutamine increases myocardial thickening of nonischemic myocardium adjacent to necrotic tissue. prOdUCin6 a decrease in the size of the functional border zone. TO avoid such mi&,terpretation, we ignored improvement in COnti%tility extending ~30” or 1 cm at the boundary of the involved myocafdium. In all patients in whom dobutamine infusion resulted in a decrease in the echocardiographic score index, the improvem~t~t in contractility was seen in the csntral ischcmic arca Patients underwent positron emisan average of 9 * 5 days after admission. This delay was rcquircd because the cyclotron and the positron camera are located outside the hospital, in an arca without an intensive care unit. Therefore. patients were not studied until the infarction was considered stable as assessed by cardiac rhythm and hemodynamic status. To minimize potential errors in the correlation between positron emission tomographic and echocardiographic findings, the two techniques were not performed ~48 h apart. Echocardiography during dobutamine infusion was never performed just before positron emission tomography. This could have been a drawback because suppression of myocardial glucose uptake during dopamine infusion has since been shown (36) to be mediated by changes in substrate availability in dogs. The little bcn& 9bscrved in patients in whom perfusion metabolic mismatch was identified su sts that carlicr use of these methods would be more ;~pp~~ri~tc to identify vinbility at a time when there is potentially greater myoc~~rdial p~i~a~~~~. 0ur findings indicate that the idcn-
yocardiwl salvqp after thr~mbol~sis in the utc myoca~ial infarction may ssible hefore :ioa of functional recovery b Dimensions ~h~~io~raphy during infusion of a small dose of dobutamim. Improvement in myocardial thickening in the involved area that is not limited to the border zone correlates ~11 with the presence of viable myocardium by positron emission tomography and with long-term functional recovery. Such information may be important for clinical decision m&it@ and can be obtained at the bedside with a safe, widely available, noninvasive and ~ontime-consuming method. e’iinical use of ~ch~~io~~~ph~ during dobusion is not limited to the setting of acute myocar0n treated by thrombolysis. but may be indicated cted stunned myocardium independent anism, such as incomplete obstruction of the inbt-related coronary artery. spontaneous reperfusion equate collateral circulation.
I. Gruppo Italian0 per lo Studiodella Streptochinasi nell’lnfmto ~io~~~~co (ClSSl). Effectiveness of intravenous thrombolytic treatment in acute. myocardial infarction. Lancet 1986:1:397-401. 2. White HD. Norris KM. Brown MA. et al. Effect ofinlr~venous streptokinase on left ventricular function and early sthvid after xi&e myocurdial infarction. N Engl J Med I987:317:85U-5. 3. Schrtier R. Systemic versus intrxoronary strentokinase infusion in the treatment ofacute myocardinl infarction. J Am l’oll Catdiol 1983:1:1?5461. 4, The TlMl Study Group. The Thrombolysis in Myocardial (TIMI) Trial: phase I findings. N Eagl J Med 1~~~:31~~3~-6.
Infarction
Fetpuson DW, Collinb SM. et al. ~et~r~~l~os~s irfter th streptokinase: importance of geometry of residual lee sions. Circulation 1~~4;6~~l~~. 6. Rraunwuld E. Klonrr RA. The stunned nty~~ilrdiM~1: pr(~~~~~~e~, portischemic ventricular dyalhnction. Circ~l~ltio~ 19X2;66z Il46=9. 7. Murshall KC. Tillinch JH, Phelps ME, et al. ldet~ti~c~ltiot~ am! d atian of resting myocardud ihcbfmia ;md in~Irctiot~ in rllnn wirlt computed tomography, l~~~lilbe~ed thlar(~dcu.uyfilucusc and N= 13 ~11tt1t~~~~ nis. Circulation ll~~3:67:7~~7~. tl. Geltman EM. Riello 1). Welch MJ. ‘l’er-Pogossiart BE, CRaraclerisation of n~~atr~lnsmur~ll r~y~~~lrd~~~ emission tontoSmphy. Circulution lY~~:6~:747~~~.
,WukwlsK, S&l rclion by ~~sitl~~n~
9. Schwaiger M. Drunken R. ~I~~ver-McKi~y M. CI al. ~e~io~ul my metabolism in puticnts with acute rny~~r~~~ i~a~~rction asse positron emission torn~~~~a)¶hy, J Am Colt Cnrdiol )~~f~~~:~~~-$. IO. Mercier JC, Lundo V. Kummatsuse K. et al. inotropic stimuhttion on the isckemic and seventy ayocardium. Circulation l~~~~~~:3~7-4~~.
1I. Ellis SC. Wynne J. Mraunwald E. Hens&kc
CL Smtdor T. Kloner RA. Response of repb~fuclion-sulv~~[l. blunned ~~~y~a~~Mt~t to irtol~~~ic ~tiflltt~;lti~~n. Am Heart J I’dXJ: 107: 1.3-!r.
I.?. Rolli R. Zhu WX. Myers ML. Hartley C!, Roberts R. zeta-a~rene~ic sliniulation reverses pastiscbemic myocardi;rl dysfM~ction withoul pro. ducing subsequent functional deterioration. Am J Curdioi 115:56:946-8. 1.X Reeker LC. Levine JH. Di Paula Al-. Guarnieri T. Aversano T. Rrversul of dysfunction in postixhcmic stunned nly~~~~~M~~ by ep~ne~ltr~~~eund ~~ste~t~systolic potentiation. J Am Coil Cmdiol l~~7;~~0-~. 14. PiCard LA. Spry~~er M. Curlier J. ~cb~~r~io~~pbie ~~~~ctio~ of I& site of coronary artery abstruction in acute myoc~~~ial infarction. Em Heart J 1987:8:116-23. 15. Gallagher KP. Gerren RA. Ning X-H, el al. The futtctioaa~ border zone in conscious dogs. Circulation 1987:76%9-42. 16. De Landsheere CM. Raets G, PiCrard LA. et MI. lnvestigrtion of myocardiul viability atIer an acute myocardiul inbrction using positron emission tamogmphy. In: Weiss WD, Pawlik G. Herhohz K. Wienhard K, eds. Clinical Efficacy of Positron Emission Tomqmphy. lhdrecht. The Netherlands: Murtinus Nijhoff. I987:279-90. 17. Stamm RB. Gibson RS. Bishop HL. Carabello RA. Belier GA, Martin RP. Eehocardiographic detection of infarct-localized asynergy and remote rsyncrgy during acute myocardial infarction: correlation with the exteut of angiographic coronary disease. Circulation 19833673233-44. IH. Stack RS. Phihpps HR III. Grierson US. et al. Functional improvement of jeogrdized myocardium following intracotonrry streptokinase infusion in acute myocardinl infarction. J Clin Invest 1%3:72:84-95. ’ 19. Ross 3 Jr. Assessment of ischemic regional myocardial reversibility. Circulation 19X6:74: 1186-90.
dysfunction and its
20. Topol EJ. Weiss JL. Brinker JA. et al. Regional wail motion ~~p~~vc~e~t after COn_XtaQ’thrombolysis with recombinant tissue plasminogen nctivatOr: importance of coronary angioplasty. J Am Coll Cardiol 1985:6:42633.
From the Department of Medicine, Division of Cardiology and Cyclotron ch Ccntsr. University of Li&ge, LiQe, elgium. The sludy was prein part at the 60tb Annual Scientific S sion of the American Heart Association, Anaheim, California, November 1987 and the 38th Annual Meeting of the American College of Cardiology, Anabc~~~. California. March 1989. Manuscript received July IO. 1980: revised manuscript received Novemvember 23. 1989. ber , Luc A. Pikrard. MD. Service de Cardiologie. CHU du Saet-Tilman. B-4000 L&e. Belgium. 61990 by the American
College of Cardiology
coronary I.?e!ayed
artery
in only
50% to 6Qoii
1022
Pll%ARD ET AL. VIABLE MYOCARDIUM
JACC Vol. 15. No. 5 A :1021-31
1N ACUTE lNFARCTlON
glucose utilization aims at identifying compromised but viable myocardium (8)at a time when wall motion is equally impaired in necrotic and stunned tissue (9). positron imaging of myocardial glucose utilization is timeconsuming, requires an on-site cyclotron and a positron camera and is not yet widely available because of the cost. Experimental studies (10-13) have suggested that postischemic myocardial dysfunction may be reversed by moderate inotropic stimulationwithout deleterious effects and that this ed by ultrasonic measurement of was to determine whether myocac
For this purpose, a compar-
consisted of 17 patients 2 + 12 years) who were submitted to intravenous thrombolysis within the first 3 h of a first acute anterior rny~~i~~ infection, Fifteen Q~tie~ts received str~~tokin~se(1.5 million U) infused over 30 min,
uration was 20 to
min. There was no
t-coated vessel in
A ventricular segmentation was use left ventricle was divided into thirds: basal, middle and apical. At basal and middle kvels, the circle was divided into six segments: posteros lateral, ~st~~~ater~ a
tients included in this study had received a )ockiingdrug or an inotropic agent before
teroseptal, apical anterior and apical septai (Fig. 1). The anterior segments were identified on the apical two chamber view and on short-axis views from the anterior interventric-
-am
VICWS.
e left ventricle. For
a bvere ~o~~~~ize~
lo the peak
~~~e~e~~~.
Therewas calculated in each region of the left ventricle. To ~ete~~~~ereference intervals, a ~o~~a~group of 10young subjects was studied.
1024
m case
YACC Vol. 15. No. 5 April 1 :1021-31
Pi&WtD ET AL. VlARLE MYDCARDl9JM IN ACUTE INFARCTlDN
Interval Pain-Th
PET Viability
Coronary Anatomy
Proximsl
identified in the correspondin positronemissiontom
20 0
I I
+P
90
2
20
Echo Viability
-
-
-
-
=+
-
-
2
w-
,
Y
c _
_ + c
_ -
ment examined with
smn was withinnor
tientswerestudied9 2 n 9 ?: 7 monthslater.
of potassium-38and “F-
segmentsshowed concordant decreases in perfusionand ghtcoseuptake. In contrast,only 3 of the 21 segmentswith high glucose to perfusi ratio and decreased ion were normal at follow study. Three other glucoseuptake, and ainingsegmentsrevealedconcordantdecreasesin lucose uptake, indicatingnecrosis. R~gionQipe~usion was higher in group 1 ~Qeie~ts tern in group i patients: 7 I .2% f 22.4% versus54.6% +- 16.0% (p = 0.001)in the early studiesand 73.6%f 19.9%versus58.8% f 15.5%(p = 0.001)in the follow-upstudies.The glucoseto
these SLX patvmts. At the baseline exa
1026
P&RARD ET AL. VIABLE MYOCARDIUM
JACC Vol. 15. No. 5 :!021-31 April I
IN ACUTE INFARCTION
Table 2. Echocardiographic Score index in Groups lA, IB and 2 Rest
12.0 + 2.0 p = 0.003
Bobutamine
7.8 f 1.3 NS
Follow-up
Group 2 (n = 6)
Group 1B (n = 6)
Group IA (n = 5)
r p = 0.005
1.4 L 1.7
IS.0 t 0.9 NS
:.s r 2.2 0.055
12.0 + 2.1 p = 0.025
NS
14.7 2 0.8
NS
p = 0.04 15.5 s 1.0
16.0 2 1.7
tation of the reco
results in another ties wereresolvedby consensusbetweenthe two observers on reevaluationof the studies. F&V 6 presents end-diastolic and end-systolic stop frame images of illustrative echocardiograms obtained in the same group IA patient as in Figure 2, show improve-
ment in contractilityof viable stunned myoc ium with dobutamineduringthe acute phase of infarctionand func-
t
rest, but indicatingakincsia
UP ‘IA
re 5. individual chances in the cardio~raphic score index between the dally study at rest and dur dobutamine (DOW) infusion and follow-up (F-UP) study in five patie from group IA (normal perfus ~tients from group 1B (high perfusion ratio) and six patie group 2 fmyocardial necrosis by positron emission tomography). Viable was ide~ti~ed in all paonly in patients
EARLY REST
EARLY OOW
F-UP
EARLY REST
EARLY OOBU
F-UP
Figure 7. End-diastolic (ED) and end-systolic 03) stop frame images of illustrative echocardiograms obtained in the same patient from group IB as in Figure
parent with do~utamiue. In the follow-up shdy. affected segments are akinetic brrowsh
ED
I028
PItiRARD ET AL. VIABLE MYOCARDlUM
IN ACUTE
JACC Vol. 15. No. 5 April I! :IOZ1-31
LNFARCTION
Figure 8, End-diastolic (ED) and endsystolic (ES) stap frame images of illustrative ech~ardio~~ms obtai~~ed in the same ~at~e~t from ~r~~~ 2 as in Parasternal lon~axis views a The septum is akinetic at rest (ar change is i~~~s~o~~~I turn remains akinetic ~~~~0~s~.
ED
myocardial salvage of functional significance. Assessment of lobal left ventricular function by the ejection fraction may not reliably reflect myocardial salvage because it is largely influenced by changes in the compensatory hyperkinesia of the uninvolved regions (IS). Assessment of regional wall motion appears to be more accurate than global ejection fraction for detecting improvement in function produced by thrombolysis (19,201. However. early reperfusion of the occluded coronary artery is usually not accompanied by immediate recovery of contractile function (6.21). The true effectiveness of reperfusion cannot be clearly established for as several weeks (22). The results of ~x~erirncnt~~~ cst that an earlier assessment of myocar-
mntian may be ~lini~~~ly implant
in de~~di~
that the ~ont~~ti~e dobutamine infusio and iufar~t~~~ ~~~i~~s. In dyskincti~ during dobota return of ~ont~~tile functton was 0 co0troI e~bo~ard~~gra
Concordsnscbetween Ike two techniques for early and its. Concordant results are found in a majority of number of viable segmentsdecreasesfrom the early up studies, and the number of necrotic segments tiirqgly. Abbreviations as in Figure I.
between viable and ir~versibl~ dama number of segments that were viable by the two techniques
Tatale 3. Follow-Up Findings in the 16 Myocardial Segments With Discor~nt Results in the Early Studies Follow-Up Early Studies Viable
PET
Studies ~choca~io~~aphy
Necrotic
Normal
Necrotic
Viable on ccb~a~io~~phy: necrotic on PET
1
5
2
5
2
Necl-oiic on echocardiography; viable on PET
9
3
6
0
9
Abbreviations
as in Table
I.
al study (26) by comparing rest stressed ejection fraction in patients wi ssels with use of radio~ucl~de ventriculog2 weeks after ~~yoc~rdia~ ~~f~~rc~ion. Satler
tomography is considetzd to be oninvasive ide~~i~cation of isc ium (27). In our study, positron deformed after a carbohydrate-cent better visualization of normal myoca creasing the ratio of nor al myocardial glucose Is free fatty acid utilization (16). This procedure contrasts with t previous study (9) in which patients fasted overnight; viable but jeopardized tissue was identified by maintained I&Fdeoxyglucose uptake in segments with reduced blood WOW.
in
was made our study by semi tive analysis. ~om~uterized q~a~~itative measure myocardial thicke~~~~ re used in en~crimenta~ studies nrdial and (10-12). but require co ly, this is epicardial outlines on difficult to obtain. Q are frcque~~~y the coronary artery disease. docardial motion may be there is no consensus on h
1030
PlfiRARP ET AL. VIABLE MYWARDIUM
JAW Vol. 15, No. 5 April t990:1OY!t-31
IN ACUTE INFARCTION
mic myocardium may influence the function Of normal adjacent tissue (31-33). Recent experimentat studies (14,)5,34) indicate that dysfunction extends <30” or 1 cm outside of the ischemic area. In experimental conditions (35). dobutamine increases myocardial thickening of nonischemic myocardium adjacent to necrotic tissue. prOdUCin6 a decrease in the size of the functional border zone. TO avoid such mi&,terpretation, we ignored improvement in COnti%tility extending ~30” or 1 cm at the boundary of the involved myocafdium. In all patients in whom dobutamine infusion resulted in a decrease in the echocardiographic score index, the improvem~t~t in contractility was seen in the csntral ischcmic arca Patients underwent positron emisan average of 9 * 5 days after admission. This delay was rcquircd because the cyclotron and the positron camera are located outside the hospital, in an arca without an intensive care unit. Therefore. patients were not studied until the infarction was considered stable as assessed by cardiac rhythm and hemodynamic status. To minimize potential errors in the correlation between positron emission tomographic and echocardiographic findings, the two techniques were not performed ~48 h apart. Echocardiography during dobutamine infusion was never performed just before positron emission tomography. This could have been a drawback because suppression of myocardial glucose uptake during dopamine infusion has since been shown (36) to be mediated by changes in substrate availability in dogs. The little bcn& 9bscrved in patients in whom perfusion metabolic mismatch was identified su sts that carlicr use of these methods would be more ;~pp~~ri~tc to identify vinbility at a time when there is potentially greater myoc~~rdial p~i~a~~~~. 0ur findings indicate that the idcn-
yocardiwl salvqp after thr~mbol~sis in the utc myoca~ial infarction may ssible hefore :ioa of functional recovery b Dimensions ~h~~io~raphy during infusion of a small dose of dobutamim. Improvement in myocardial thickening in the involved area that is not limited to the border zone correlates ~11 with the presence of viable myocardium by positron emission tomography and with long-term functional recovery. Such information may be important for clinical decision m&it@ and can be obtained at the bedside with a safe, widely available, noninvasive and ~ontime-consuming method. e’iinical use of ~ch~~io~~~ph~ during dobusion is not limited to the setting of acute myocar0n treated by thrombolysis. but may be indicated cted stunned myocardium independent anism, such as incomplete obstruction of the inbt-related coronary artery. spontaneous reperfusion equate collateral circulation.
I. Gruppo Italian0 per lo Studiodella Streptochinasi nell’lnfmto ~io~~~~co (ClSSl). Effectiveness of intravenous thrombolytic treatment in acute. myocardial infarction. Lancet 1986:1:397-401. 2. White HD. Norris KM. Brown MA. et al. Effect ofinlr~venous streptokinase on left ventricular function and early sthvid after xi&e myocurdial infarction. N Engl J Med I987:317:85U-5. 3. Schrtier R. Systemic versus intrxoronary strentokinase infusion in the treatment ofacute myocardinl infarction. J Am l’oll Catdiol 1983:1:1?5461. 4, The TlMl Study Group. The Thrombolysis in Myocardial (TIMI) Trial: phase I findings. N Eagl J Med 1~~~:31~~3~-6.
Infarction
Fetpuson DW, Collinb SM. et al. ~et~r~~l~os~s irfter th streptokinase: importance of geometry of residual lee sions. Circulation 1~~4;6~~l~~. 6. Rraunwuld E. Klonrr RA. The stunned nty~~ilrdiM~1: pr(~~~~~~e~, portischemic ventricular dyalhnction. Circ~l~ltio~ 19X2;66z Il46=9. 7. Murshall KC. Tillinch JH, Phelps ME, et al. ldet~ti~c~ltiot~ am! d atian of resting myocardud ihcbfmia ;md in~Irctiot~ in rllnn wirlt computed tomography, l~~~lilbe~ed thlar(~dcu.uyfilucusc and N= 13 ~11tt1t~~~~ nis. Circulation ll~~3:67:7~~7~. tl. Geltman EM. Riello 1). Welch MJ. ‘l’er-Pogossiart BE, CRaraclerisation of n~~atr~lnsmur~ll r~y~~~lrd~~~ emission tontoSmphy. Circulution lY~~:6~:747~~~.
,WukwlsK, S&l rclion by ~~sitl~~n~
9. Schwaiger M. Drunken R. ~I~~ver-McKi~y M. CI al. ~e~io~ul my metabolism in puticnts with acute rny~~r~~~ i~a~~rction asse positron emission torn~~~~a)¶hy, J Am Colt Cnrdiol )~~f~~~:~~~-$. IO. Mercier JC, Lundo V. Kummatsuse K. et al. inotropic stimuhttion on the isckemic and seventy ayocardium. Circulation l~~~~~~:3~7-4~~.
1I. Ellis SC. Wynne J. Mraunwald E. Hens&kc
CL Smtdor T. Kloner RA. Response of repb~fuclion-sulv~~[l. blunned ~~~y~a~~Mt~t to irtol~~~ic ~tiflltt~;lti~~n. Am Heart J I’dXJ: 107: 1.3-!r.
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