Outcomes of direct coronary angioplasty for acute myocardial infarction in candidates and non-candidates for thrombolytic therapy

Outcomes of Direct Coronary Angioplasty for Acute Myocardial Infarction in Candidates and Non-Candidates for Thrombolytic Therapy Bruce R. Brodie, MD, Richard A. Weintraub, MD, Thomas D. Stuckey, MD, E. Joseph LeBauer, MD, Jeffrey D. Katz, MD, Thomas A. Kelly, MD, and Charles J. Hansen, MA

Coronary angioplasty without prior thromboiytii therapy was performed in 383 patients with acute myocardial infarction (AMI). Patients wem divided into 2 groups depending on whether they were candidates or non-candidates for thromboiytic therapy. Patients were not considered thrombofytii candidates if they: (1) presented in cardiogenk shoch, (2) were 175 years of age, (3) had had coronary artery bypass surgery or, (4) had a reperfusion time of >6 hours. Thrombotytk and nonthrombotytic candidates had similar rates of reperfusion (92 vs 88%), nonfatal reintarction (6.0 vs 5.9%) and recurrent myocardial ischemia (1.8 vs 0%). Thromboiytk candidates had a tower mortality rate (3.9 vs 24% p 6 hours (143%). These outcomes suggest that direct coronary angkpfasty is a vtabk alternative method of reperfuskn in patients with AMI who are candidates for thrombotytic therapy. Nonthromboiytk candidates are a high-risk group of patfents. DIM coronary angioptasty may be benefkiai in certain subgroups, especiagy for patients in cardtogenic shock and for patients presenting >6 hours after the onset of chest pain with evidence of ongdng ischemia. (Am J Cardid lSS1;67:7-12)

I

t is now well established that coronary artery reperfusion is beneficial in the early treatment of acute myocardial infarction (AMI).1-3 Intravenous thrombolytic therapy is the most widely used method of reperfusion, but is limited by modest reperfusion rates, significant residual stenosis of the infarct vessel and contraindications to its usein many patients. Percutaneous transluminal coronary angioplasty has been used in an attempt to overcometheselimitations, but the results of several large multicenter trials suggest that routine angioplasty after thrombolytic therapy may have limited value.4-7 Direct coronary angioplasty without prior thrombolytic therapy has been used to establish reperfusion in patients with AMI, but its role has remained controversial.8-*0 Most published studies have been small and have not allowed analysis of subsetsof patients, and this has made comparisonswith other reperfusion strategies diffkult.8~gJ-14 This study evaluates the role of direct angioplasty in the treatment of AM1 in 2 major subgroups of patients-patients who are consideredcandidates and patients who are considerednot to be candidates for thrombolytic therapy. METHODS Study patients: The study population comprised383

consecutivepatients with transmural AM1 treated with primary coronary angioplasty, without prior thrombolytic therapy, at The Moses Cone Memorial Hospital from 1984 through 1988. An electrocardiographic STsegment elevation of 11 mm in >2 contiguous leads was required. Patients presentingwith chest pain after 4 to 6 hours were selectedonly if they had evidence of ongoing ischemia or hemodynamic compromise.During the study period, 636 patients with AM1 were treated by our cardiology group. Of thesepatients, 201 were not treated with reperfusion therapy becausethey did not meet electrocardiographiccriteria for transmural AMI, presentedlate after the onset of chest pain, or had severe diseaseof other organ systems.Twenty-seven patients were treated with primary thrombolytic therapy, From the Department of Medicine, The Moses H. Cone Memorial which was often given before referral to our institution, Hospital, Greensboro,North Carolina. This work was supported by a grant from the Education Committee, The Moses H. Cone Memorial Twenty-five patients had emergency catheterization, Hospital, Greensboro,North Carolina, and by a grant from United but did not have coronary angioplasty becausethe inStates Catheters and Instruments division of CR Bard, Inc., Billerica, farct vesselwas small or becausethe anatomy was unfaMassachusetts.Manuscript received July 2, 1990;revised manuscript vorable for angioplasty. The remaining 383 patients receivedand acceptedAugust 28,199O. Addressfor reprints: Bruce R. Brcdie, MD, 520 North Elam Ave- treated with direct angioplasty comprised our study group. nue, Greensboro,North Carolina 27403. THE AMERICAN JOURNAL OF CARDIOLOGY JANUARY 1, 1991

7

Patient subgroups: Patients were classified into 2 major subgroupsdependingon whether they met generally acceptedcriteria for inclusion in thrombolytic trials.4y7Patients were considerednonthrombolytic candidates if they: (1) presented in cardiogenic shock, (2) were 175 years of age, (3) had undergonecoronary artery bypassgraft surgery, or (4) had a reperfusion time of >6 hours. All other patients were consideredthrombolytic candidates. These criteria are those used in the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) trial and are similar to criteria used in the Thrombolysis in Myocardial Infarction (TIMI) II-B trial, although the TIM&II-B trial included a small number of patients with cardiogenic shock.4,7J5 Treatment protocol: Patients with AM1 were given sublingual and intravenous nitroglycerin, intravenous heparin (5,000 U) and lidocaine in the emergencyroom and were transported promptly to the cardiovascular laboratory. An experienced cardiac catheterization team consisting of 3 technicians and 1 or 2 invasive cardiologists was on call 24 hours a day and the procedure generally could be started within 30 to 60 minutes of notification. Coronary angiography and left ventriculography were performed by the femoral approach. The infarct vesselwas identified, reperfusion was established mechanically with a guidewire, and coronary angioplasty was performed using standard techniques.In patients in cardiogenic shock, an intraaortic balloon was frequently inserted. All patients received 12,000 to 20,000 U heparin during the procedure and a heparin infusion for 4 to 6 days to keep the partial thromboplastin time 2 to 3 times the control. Unless contraindicated, all patients received enteric-coated aspirin, intravenous nitroglycerin, calcium channel blockers and p blockers after the procedure.Aspirin was not given routinely before the procedureuntil the last few months of the study period. Definitions: Cardiogenic shock was defined as hypotension (systolic blood pressure <85 mm Hg) not responsiveto volume expansionand associatedwith severe left ventricular dysfunction or severe right ventricular infarction. Reperfusion time was the time from the onset of chest pain until mechanical reperfusion was estab lished with the angioplasty wire. Successfulangioplasty was defined as successfulreperfusion with reduction in the luminal diameter stenosis to 160%. Reinfarction was defined as recurrent ischemic chest pain associated with new or worse ST-segmentelevation, or a new rise in creatine kinase and the MB fraction, or both. Recurrent ischemia was defined as recurrent ischemic chest pain, without criteria for infarction, requiring intervention with either repeat coronary angioplasty or coronary bypassgraft surgery. Follow-up catheterization and anglography: Followup angiography was performed routinely at 6 months in consenting patients during the first 3 years of the study but was performed only when clinically indicated during the last 2 years. Follow-up studies were obtained in 81% of survivors during the first 3 years and in 63% of survivors during the entire study period. Left ventricular ejection fractions were calculated from tracing contours 8

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 67

of right anterior oblique ventriculograms using the arealength method with correction for the 30° right anterior oblique projection.16Only sinus beats were analyzed, and ventriculograms were omitted if opacification was inadequate. Observerswere blinded as to whether the ventriculograms were from acute or follow-up studies and whether the infarct vesselwas patent or occluded. Data analysis: Chi-square with Yates’ correction for continuity was usedas a test of the homogeneityof proportions for analyses involving pairs of dichotomous variables. Fisher’s 2-tailed exact probabilities were calculated for all fourfold tables when I1 of the expected cell frequencieswas <5. Student’s t test for independent sampleswas used to analyze the difference in meansof continuous variables. Values are expressedas mean f 1 standard deviation. Multiple logistic regressionwas used to assessthe relations between baseline variables and hospital mortality. RESULTS Bardim characteristics (Table I): As expectedfrom the selection criteria, nonthrombolytic candidates were older and had longer reperfusion times than thrombolytic candidates. Nonthrombolytic candidates also included a greater number of female patients, had a greater incidence of previous myocardial infarction and multivesselcoronary disease,and had a lower initial left ventricular ejection fraction than thrombolytic candidates. Horpital outcomes (Table II): Successfulangioplasty was performed in 92% of thrombolytic and in 88% of nonthrombolytic candidates.Hospital mortality was significantly lower in thrombolytic than in nonthrombolytic candidates(3.9 vs 24%,p 6 hours and multivessel coronary disease.All 4 criteria used to define nonthrombolytic candidates had high mortality and 3 were positive independentpredictors of mortality. outcomes In subgroups of nonthrombolytlc candidates (Table IV): Patients presenting with cardiogenic

TABLE

I Baseline

Characteristics

of 383 Patients

Characteristic Age Ws) Gender (male) Prior myocardial infarction Infarct-related coronary artery Left anterior descending Right Left circumflex Vein graft Multivessel CAD+ Patent infarct vessel on initial angiogram (TIMI flowgrade Initial ejection fraction Reperfusion time (hrs)

Treated

with Direct

Angioplasty

Thrombolytic Candidates (n = 282) No. (%)

Nonthrombolytic Candidates (n = 101) No. (%)

p Value

57flO 215 (76) 50(18)

65413 62 (61) 35 (35)

NA 0.005 0.0008

119 (42) 129 (46) 34(12) 0 (0) 141(50) 61(22)

53 (53) 27 (27) 13 (13) 63 (62) 25 (25)

0.04 NS

53.5 f 12.6 3.2f 1.2

48.4zk 15.6 6.4 f 5.3

0.008 NA

8 (8)

2 or 3)

* Compares l&l anterior descending artery with all other vessels; t >70% stenosis in 2 or 3 major epicardlal vessels: z includes all patients with adequate = 248for thrombolyticcandidates. n = 82for nonthrombolytic candidates. CAD = coronary artery disease; NA = not applicable (variable was used to define nonthrombolytic candidates); NS = not significant; TIMI = Thrombolysis trial.

shock had a lower reperfusion rate and a higher mortality rate than thrombolytic candidates. There were no patients with reinfarction or recurrent ischemia, but coronary bypass surgery was required more frequently than in thrombolytic candidates. Patients 175 years of age had a high reperfusion rate. However, mortality rate, incidence of nonfatal reinfarction and incidence of bleeding were significantly higher than for thrombolytic candidates. Patients with prior coronary artery bypass graft surgery had a lower reperfusion rate and a higher mortality rate than thrombolytic candidates. Angioplasty was successfulin 5 of 8 patients whose infarct vesselwas an occluded vein graft, but 2 developedreinfarction and 2 required repeat bypasssurgery. Patients with reperfusion times >6 hours had a high reperfusion rate, a low incidence of reinfarction and no recurrent ischemia. The hospital mortality rate was high compared with that of thrombolytic candidates, but these patients were selected partly becauseof hemodynamic compromise. The mortality rate in nonthrombolytic candidates,excluding patients in cardiogenic shock,was 13 of 79 (16%). Cardiac catheterization

laboratory

complications:

Laboratory death occurred in 7 (6.9%) nonthrombolytic and in 3 (1.1%) thrombolytic candidates (p <0.004). Most of the deaths in the nonthrombolytic group (6 of 7) occurred in patients in cardiogenic shock or 175 years of age. Ventricular fibrillation occurred in 16 (15.8%) nonthrombolytic and in 24 (8.5%) thrombolytic candidates (p = 0.06). Prolonged cardiopulmonary resuscitation was required in 13 (12.9%) nonthrombolytic and in 9 (3.2%) thrombolytic candidates (p
63% of survivors at a mean follow-up time of 8 months.

initial ventriculograms: in Myocardial

n

Infarction

Long-term patency of the infarct-related artery was 85%. Adequate paired ventriculograms for measurement of ejection fractions were achievedin 53% of survivors. Nonthrombolytic candidates had lower initial ejection fractions and a greater improvement in ejection fraction than thrombolytic candidates. The final ejection fraction was well preservedin both groups. Patients with anterior infarctions had lower initial ejection fractions and greater improvement in ejection fraction than patients with inferior and posterior infarctions. In patients with adequate paired ventriculograms, the mean improvement in ejection fraction was 7.9 f 8.1% in 7 patients in cardiogenic shock, 7.3 f 11.2%in 6 patients 175 years of age and 14.2 f 9.4% in 20 patients with reperfusion times >6 hours. This study evaluatesthe role of direct angioplasty in the treatment of AMI. By separatingour patients into 2 major subgroups,dependingon whether they were considered candidates or non-candidates for thrombolytic therapy, we were able to obtain a study population of

TABLE Direct

II Hospital Angioplasty

Outcomes

of 383 Patients

Treated

with

Outcome

Thrombolytic Candidates (n = 282) No. (%)

Nonthrombolytic Candidates (n = 101) No. (%)

p Value

Successful PTCA Hospital mortality Nonfatal reinfarction Recurrent ischemia CABG Bleeding*

258(91.5) 11 (3.9) 17 (6.0) 5(1.8) 18 (6.4) 13 (4.6)

89 (88.1) 24 (23.7) 6 (5.9) 0 (0.0) 8 (7.9) 11 (10.9)

NS o.ccQ1 NS NS NS 0.05

l Requiring transfusion of L2 units of blood, excluding patients who had coronary bypass surgery. CABG - coronary artery bypass grafting: NS = not significant (p >O.lO); PTCA percutaneous transluminal coronary angioplasty

THE AMERICAN

JOURNAL

OF CARDIOLOGY

JANUARY

1, 1991

9

TABLE III Variables Related to Hospital Mortality in All 383 Patients Treated with Direct Angioplasty Mortality Rate

Multivariate Analysis

Variable

No. of Pts.

No. (%)

Odds Ratio

95% Cl

Unsuccessful PTCA Cardiogenic shock Age 275 years Reperfusion time >6 hours Multivessel CAD Prior CABG Anterior wall infarction Female gender Prior myocardial infarction

36 22 30 48 204 12 172 106 85

14 (39) ll(50) 9 (30) 8(17) 29 (14)

3.38 3.23 3.10 2.15 1.89 1.40 1.37 1.25 1.21

2.00-5.72 1.77-5.89 1.73-5.54 1.26-3.68 1.12-3.19 0.58-3.40 0.88-2.16 0.78-2.00 0.74-l .96

CABG = coronary

artery bypass grafting;

CAD = coronary

3 (25) 21(12) 13 (12) 14(17)

artery disease; Cl = confidence

Interval; PTCA = percutaneous

transluminal

coronary

angioplasty.

thrombolytic therapy or a combination of intravenous thrombolytic therapy and angioplasty. Hospital outcomes in thrombolytii candidaer: Our Reperfusion patency rate of 92% with direct angioplasty is higher Prior Time >6 Cardiogenic Age 275 than patency rates with intravenous streptokinase(41 to Hours CABG Years Shock 55%) or standard dosesof intravenous tissue plasmino(n = 30) (n = 22) (n = 48) High patency rates have regen activator (75%).17~18v4 No. (%) No. (%) No. (“7) Outcome cently been reported with rapid- or high-dose tissue Successful 15 (68)* 27 w9 9 (75) 46 (96) plasminogenactivator infusion protocols, but thesemay PTCA be associatedwith an increasedrisk of bleeding.19~20 Hospital 11(50)§ 9 (30)5 3 (25)+ 8(17)* mortality The hospital mortality rate in our thrombolytic canNonfatal 0 (0) 6 (20)+ l(8) 2 (4) didates of 3.9%comparesfavorably with the 7% mortalreinfarction ity rate in the TAM1 trial and with the 4.7% mortality Recurrent 0 (0) 0 (0) 0 (0) 0 (0) rate in the TIMI-II-B tria1.4v7O’Keefe et allo also re ischemia ported a very low hospital mortality rate in thrombolytCABG 3 (14) 2 (7) 207) 3 (6) Bleeding* 3 (13) 5 (17)+ 2(17) 2 (4) ic candidatestreated with direct angioplasty. Requiring transfusion of >2 units of blood, excluding patients who had coronary The incidence of nonfatal reinfarction in our thrombypass surgery; + p <0.05 (compares each subgroup of nonthrombolytic candidates bolytic candidatesis similar to the 5.6%incidencein the with thrombolytic candidates); * p
TABLE IV Outcomes After Direct Angioplasty in Subgroups of Nonthrombolytic Candidates

l

TABLE V Improvement in Left Ventricular Ejection Fraction in Survivors After Direct Angioplasty Ejection Fraction Initial (%)

Final (%)

Improvement (%)

Thrombolytic candidates (n = 149) Nonthrombolytic candidates (n = 36) p Value

53.3 f 12.6 47.8& 13.1 0.03

57.7 f 13.1 58.3f11.6 NS

4.4 h 10.4 10.5 f 9.9 0.002

Thrombolytic candidates Anterior wall infarction (n = 69) Inferior and posterior infarction (n = 80) p Value

47.1 f 12.5 58.7 f 10.0 0.001

54.8& 15.1 60.3f 10.4 0.02

7.7 & 10.9 1.6i9.2 0.0003

Nonthrombolytic candidates Anterior wall infarction (n = 22) Inferior and posterior infarction (n = 12) p Value

41.8f7.7 57.4 f 13.3 0.002

56.9 f 9.2 61.9f 12.1 NS

n - number

10

of patients with adequate

paired ventriculograms;

NS - not significant.

THE AMERICANJOURNALOF CARDIOLOGYVOLUME67

15.1 *8.5 4.5 f 7.3 0.0009

patients may benefit.3 It is not clear from our data which is the best therapeutic approach in thesepatients. In our patients with prior coronary artery bypass grafting, the reperfusion rate with direct angioplasty was lower than it was for thrombolytic candidates because of a lower rate of reperfusion in occluded vein grafts. Occluded vein grafts also have an increased chance of reocclusion after successfulangioplasty. Despite theselimitations, others have suggestedthat angioplasty may be preferential to intravenous thrombolytic therapy in this group of patients.25,26 The number of patients with prior bypasssurgery in our seriesis small, and we cannot draw any conclusionsregarding the potential benefit of direct angioplasty. Patients with reperfusion times >6 hours treated with direct angioplasty had a high reperfusion rate and substantial improvement in left ventricular ejection fraction. The marked improvement in ejection fraction is unexpectedwith late reperfusion and may be related to the selection criteria. These patients were selectedin part becauseof persistent chest pain and evidence of ongoing ischemia, which may be an indication of continued myocardial viability. The relatively high mortality rate in this group of patients also may be related to the selection criteria. Patients were selected for intervention after 6 hours of chest pain partly becauseof evidence of hemodynamic compromise. If patients in cardiogenic shock and with pulmonary edema, and patients 175 years are excluded, the hospital mortality rate is 2.5%in this group of patients. Thesedata suggest that in patients who present late after the onset of chest pain, but who have evidenceof ongoing ischemia, direct Hospital outcomes in nonthrombolytic candidates: The baseline characteristics and hospital outcomes of angioplasty may offer substantial benefit. Limitations of direct angioplarty: Direct angioplasty our nonthrombolytic candidates suggestthat they are a high-risk subgroup compared to thrombolytic candi- has several limitations as a reperfusion strategy. Only dates. Nonthrombolytic candidateswere older, included about 12%of hospitals in the United States have angioa greater number of women, had a greater incidence of plasty facilities and not all of theseare equippedto perprevious myocardial infarction and multivesselcoronary form emergency angioplasty.27There is time-delay in disease,and had a lower initial ejection fraction than mobilizing the catheterization laboratory team and in establishing coronary reperfusion with direct angiothrombolytic candidates. Patients presenting in cardiogenic shock comprise plasty, although in our institution this delay is small. the subgroup at highest risk. Hospital mortality rates Direct angioplasty is also associatedwith risks as demwith conventional therapy have been 73 to 83%.22,23 onstrated by our laboratory complications. Most of With thrombolytic therapy, reperfusion rates have been these complications occurred early in our series, suglow (43%) and mortality rates have remained relatively gesting that experienceis important in minimizing comhigh (67 to 70%).2J4Our reperfusion rate of 68% and plications with this approach. Fortunately, the risk of our hospital mortality rate of 50% compare very favor- complications appearssmall, especially in thrombolytic ably with this. Other investigators have reported similar candidates, and our overall results suggest that the reperfusion and mortality rates with direct angioplasty benefits outweigh the risks. and have advocated this approach in the treatment of Study limitations: Our study is limited by the lack of AM1 complicated by cardiogenic shock.1ov23 a concurrent randomly selected control group of paPatients 275 years of age also are a very high-risk tients treated by another reperfusion strategy. We cansubgroup. In these patients, direct angioplasty resulted not exclude the possibility that the outcomesobservedin in a high patency rate and good improvement in ejec- our patients were produced by selectionbias. The obsertion fraction, but was associatedwith a high incidence vations made by others-that direct angioplasty is assoof bleeding and reinfarction and a high mortality rate. ciated with favorable hospital outcomesin thrombolytic Thrombolytic therapy has frequently beenavoidedin el- candidates-support the hypothesis that these results derly patients becauseof the increasedrisk of bleeding occurred becauseof therapeutic benefitlo complications, but data from the second International Our data regarding the improvement in left ventricStudy of Infarct Survival (ISIS) trial suggestthat these ular ejection fraction after direct angioplasty are based to study design and definitions. The TAM1 study included nonfatal reinfarction in the recurrent ischemia group and the TIM&II-B study provoked ischemia with stresstesting before hospital discharge and at 6 weeks. Despite these differences, the incidence of recurrent ischemia with direct angioplasty is very low compared with that of other strategies. Our incidence of bleeding (4.6%) is similar to the incidence of bleeding from intravenous thrombolytic therapy alone (4.3%) and is substantially lower than the incidence of bleeding when intravenous thrombolytic therapy is combined with invasive procedures (21%).4,7 The major catastrophic complication of intravenous thrombolytic therapy-intracerebral hemorrhage, which occurs in approximately 0.5% of patients treated with intravenous tissue plasminogen activato#,7did not occur in our study and has not been reported in other series of patients treated with direct angioplasty.*-lo We were able to document a 4.4% improvement in left ventricular ejection fraction at follow-up angiography in thrombolytic candidates and a 7.7% improvement in patients with anterior infarctions. This contrasts with 1.2% improvement in ejection fraction in the TAM1 study.4Other studies with direct angioplasty, including 1 controlled study comparing direct angioplasty with intracoronary streptokinase, have shown substantial improvement in ejection fraction at follow-up angiography.8,21This suggeststhat direct angioplasty may have an advantage over other reperfusion strategies in the preservation of left ventricular function.

THE AMERICAN JOURNAL OF CARDIOLOGY JANUARY 1, 1991

i 1

on follow-up studies in 53% of survivors. Extrapolation to the entire population is subject to possible error. However, our results in the first 3 years of the study, when follow-up angiography was available in 81% of survivors, were similar to the entire group, and suggest that the improvement in ejection fraction is representative of the entire population. Acknowledgment: We thank the technical staff of the cardiovascular laboratory at The Moses H. Cone Memorial Hospital for their invaluable help with these patients, Mike Duran, PAC, Michelle Mullaney, PAC, and Ken Hampton for their help in processingthe data, and Susan Welborn for secretarial assistance.

REFERENCES

1. The I.S.A.M. Study Group. A prospectivetrial of intravenousstreptokinasein acute myocardial infarction (I.S.A.M.): mortality, morbidity, and infarct size at 21 days. N Engl J Med 1986;314:1465-1471. 2. Gruppo Italian0 per lo Studio della Streptochinasi nell’Infarto Miocardico (GISSI). Long-term effects of intravenous thrombolysis in acute myocardial infarction: final report of the GISSI study. Lancer 1987;2:871-874. 3. ISIS-2 Collaborative Group. Randomizedtrial of intravenousstreptokinase, oral aspirin, both, or neither among 17,187caseaof suspectedacute myocardial infarction: ISIS-2. Lmzce~ 1988;2:349-360. 4. Topol EJ, Califf RM, George BS, Kereiakes DJ, Abbottsmith CW, Candela RJ, Lee KL, Pitt B, Stack RS, O’Neill WW. A randomizedtrial of immediate versusdelayedelective angioplastyafter intravenoustissueplasminogenactivator in acute myocardial infarction. N Eng/ J Med 1987;317:581-588. 5. SimoonsML, Arnold AER, Betriu A, deBonoDP, Col J, Dougherty FC, von EssenR, Lambertz H, Lubsen J, Meier B, Michel PL, Raynaud P, Rutsch W, SanzGA, Schmidt W, SerruysPW, Thery C, Uebis R, VahanianA, Van de Werf F, Willems GM, Wood D, Verstraete M. Thrombolysis with tissueplasminogen activator in acute myocardial infarction: no additional benefit from immediate percutaneouscoronary angioplasty. Lancet 1988;1:197-203. 6. TIM1 ResearchGroup. Immediatevs delayedcatheterizationand angioplasty following thrombolytic therapy for acute myocardial infarction. JAMA 1988; 260:2849-2858. 7. TIM1 Study Group. Comparisonof invasive and conservativestrategiesafter treatment with intravenous tissue plasminogenactivator in acute myocardial infarction. N Eng/ J Med 1989;320:618-628. 8. Rothbaum DA, Linnemeier TJ, Landin RJ, SteinmetzEF, Hillis JS, Hallam CC, Noble RJ, SeeMR. Emergencypercutaneoustransluminal coronary angi+ plasty in acute myocardial infarction: a three-year experience. JACC 1987; 10~264-212. 9. Miller PF, Brcdie BR, Weintraub RA, LeBauer EJ, Katz JD, Stuckey TD, Hansen CJ. Emergency coronary angioplasty for acute myocardial infarction: results from a community hospital. Arch Intern Med 1987;147:1565-1570. 10. O’Keefe JH, Rutherford BD, McConahay DR, Ligon RW, JohnsonWL, Giorgi LV, Crockett JE, McCallister BD, Conn RD, Gura GM, Good TH, SteinhausDM, BatemanTM, ShinshakTM, HartzIer GO. Early and late results of coronary angioplastywithout antecedentthrombolytic therapy for acute myo-

12

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 67

cardial infarction. Am J Cardiol 198%64:1221-l230. 11. O’NeiIl W, Timmis GC, Bourdillon PD. Lai P, GanghadarhanV, Walton J Jr, Ramos R, Laufer NS, Gordon S, Schord MA. A prospectiverandomized clinical trial of intracoronary streptokinasevs coronary angioplasty for acute myocardial infarction. N Eng/ J Med 1986;314:812-818. 12. Sriram R, Mullen GM, Foschi A, Bicoff JP. Percutaneoustransluminal coronary angioplasty in acute myocardial infarction without prior thrombolytic therapy. Am J Cardiol 1988;55:842-843. 13. Holmes DR. Smith HC, Vliestra RE, Nishimura RA, ReederGS, BoveAA, BrcsnahamJF, ChesebroJH, Piehler JM. Percutaneoustransluminal coronary angioplasty, alone or in combination with streptokinasetherapy during acute myocardial infarction. Mayo C/in Proc 1985;60:449-456. 14. Ellis SG, Topol El, Gall&n L, Grines CL, Langburd AB, BatesER, Walton JA Jr, O’Neill WW. Predictorsof successfor coronary angioplastyperformed for acute myocardial infarction. JACC 1988;12:1407-1415. 15. Bairn DS, Braunwald E, Feit F, Knatterud GL, PassamaniER, Robertson TL, Rogers WJ, Solomon RE, Williams DO. The thrombolysis in myocardial infarction (TIMI) trial phaseII: additional information and perspectives.JACC 1990;15:1188-1192. 16. KennedyJW, Trenholme SE, Kasser IS. Left ventricular volume and mass from single-planecineangiogram:a comparison of antero-posterior and right anterior oblique methods.Am Heart J 1970;80:343-352. 17. ChesebroJH, Knatterud G, Roberts R, Borer J, Cohen LS, Dalen J, Dodge HT. Francis CK, HiIlis D, Ludbrook P. Thrombolysis in Myocardial Infarction (TIMI) trial. Phase I: a comparison between intravenous tissue plasminogen activator and intravenousstreptokinase.Clinical findings through hospital discharge. Circulation 1987;76:142-154. 18. VerstraeteM, Bernard R, Bory M, Brewer RW, Collen D, deBonoDP, E&l R, Huhmann W, LennaneRJ, LubsenJ. Randomizedtrial of intravenousrecombinant tissue-typeplasminogenactivator versusintravenousstreptokinasein acute myocardial infarction. Report from the European Cooperative Study Group. Lancer 1985;1:842-847. 19. Neuhaus KL, Feuerer W, JeepTebbe S, Niederer W, Vog A, Tebbe U. Improved thrombolysiswith a modified doseregimenof recombinanttissue-type plasminogenactivator. JACC 1989;14:1566-1569. 20. Top01El. Ultrathrombolysis. JACC 1990;15:922-924. 21. Brodie BR, Weintraub RA, Hansen CJ, Miller PF, LeBauer EJ, Katz JD, StuckeyTD. Factorsthat predict improvementin left ventricular ejectionfraction after coronary angioplasty for acute myocardial infarction. Carhel Cardiouasc Diagn 1987;13:372-380. 22. Ratshin RA, Rackley CE, Russell RO. Hemodynamic evaluation of left ventricular function in shock complicating myocardial infarction. Circulakwz 1972;45:127-139. 23. L.eeL, BatesER, Pitt B, Walton JA, Laufer N, O’Neill WW. Percutaneous transluminal coronary angioplastyimprovessurvival in acute myocardial infarction complicated by cardiogenic shock. Circulation 1988;78:1345-135 I. 24. Kennedy JW, Gensini GG, Timmis GC, Maynard C. Acute myocardial infarction treated with intracoronary streptokinase:a report of the society for cardiac angiography.Am J Cardiol 1985;55:871-877. 25. Grinea CL, Booth DC, Nissen SE, Gurley JC, BennettKA, O’Connor WN, DeMaria AN. Mechanismof acute myocardial infarction in patients with prior coronary artery bypass grafting and therapeutic implications. Am J Cardiol 1990;65:1292-1296. 26. Kahn JK, Rutherford BD, McConahay DR. JohnsonW, Giorgi LV, Ligon R, Hartzler GO. Usefulnessof angioplasty during acute myocardial infarction in patientswith prior coronary artery bypassgrafting. Am J Cardiol 1990;65:698702. 27. Top01EJ. Coronary angioplastyfor acute myccardial infarction. Ann Intern Med 1988;109:970-980.