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Delayed semielective coronary bypass surgery for unstable angina pectoris
Delayed semielective coronary bypass surgery for unstable angina pectoris C finical follow-up and results of postoperative treadmill exercise Eighty patients with continued or repeated episodes of chest pain at rest and transitory ischemic electrocardiographic (ECG) changes were classified as having unstable angina pectoris. Following 10 days of intensive medical therapy, including beta blockade, all underwent coronary arteriography. Medical treatment completely relieved the chest pain in 43 patients (Group I, 54 percent). In 37 patients (Group II, 46 percent) angina recurred within a week of admission (12 patients) or later (25 patients). Seventeen patients were not operated upon (nine were inoperable, four refused operation, and in four operation was not recommended). Sixty-three underwent saphenous vein bypass grafting either following a month of medical therapy (Group I) or within 24 to 48 hours of recurrent angina (Group II). The over-all operative mortality rate was 1.6 percent (1 patient) and the incidence of peroperative infarction was 11 percent. Of the 62 operative survivors, 71 percent were asymptomatic (mean follow-up period 22 months). The incidence of late operative myocardial infarction was 5 percent. Of 44 operative survivors tested by treadmill ECG, 66 percent had a negative response. Thirteen patients underwent postoperative angiographic evaluation (mean, 19.5 months). The over-all patency rate was 84 percent, and in 92 percent of patients at least one graft was patent. Thus, after stabilization by medical treatment, bypass operation could be performed with a low operative mortality rate and the long-term results compare favorably with those achieved in patients with chronic stable angina.
J. F. Huret, M.D., B. Agier, M.D., S. P. Rosier, M.D., P. Gueret, M.D., J. C. Kahn, M.D., M. Ben Farhat, M.D., J. Bardet, M.D., and J. P. Bourdarias, M.D., Boulogne, France
With the availability of direct saphenous vein coronary bypass in recent years, enthusiasm for surgical intervention in a variety of clinical syndromes considered to represent a preinfarction state has resulted in widespread use of this therapeutic modality.v '! However, the lack of general agreement about the criteria to be used made objective assessment of surgical therapy quite difficult. Although some authors have stated that emergency revascularization carries little additional operative risk over that of elective bypass, 10, 12, 13 the surgical mortality rate was higher in most reports, ranging from 8 4 , 7, 9 to 10 or 12 percent" 14 or even more." From Hopital Ambroise-Pare, 9, Avenue Ch de Gaulle 92100, Boulogne, France. Received for publication July 5, 1977. Accepted for publication Sept. 13, 1977. Address for reprints: J. P. Bourdarias, M.D., Hopital AmbroisePare, 9, Avenue Ch de Gaulle 92100, Boulogne, France.
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Furthermore, the immediate and remote natural history of the syndrome remains controversial. Recently, good results, at least on a short-term basis, have been described with medical treatment.J"?" Whereas several well-controlled comparative studies are currently in progress.P- 19 only a few systematic studies of delayed semiemergent surgery have been reported. 20. 21 This study concerns (I) the feasibility of revascularization surgery after an attempt of stabilization on intensive medical therapy and (2) the late postoperative results for an average follow-up interval of 22 months, in regard to symptomatic relief and electrocardiographic (ECG) responses to treadmill exercise.
Patients and methods Between January, 1971, and December, 1975, 80 patients were classified as having unstable angina if they met the following criteria: (I) severe, prolonged
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(> 15 minutes) episodes of anginal pain at rest, (2)
documentation of transient ST-segment and/or T-wave changes, recorded during at least one episode of chest pain, (3) absence of new pathological (;;.:0.04 second) Q waves or permanent loss of R-wave amplitude in the precordial leads, (4) absence of changes (or less than 50 percent above normal) in serum enzymes (glutamic oxaloacetic transaminase, lactic dehydrogenase, creatine phosphokinase), and (5) presence on the coronary arteriogram of a significant stenosis of one (or more) of the three major coronary arteries. Patients with crescendo patterns of pain on exertion and patients with exertional angina of recent onset were not included unless they also had pain at rest. Precipitating extracardiac factors such as anemia, arrhythmias, congestive heart failure, or severe hypertensive disease of recent onset were excluded in each patient. All patients were treated with bed rest and shortand/or long-acting nitrates; 74 underwent anticoagulation with intravenously administered heparin to maintain clotting time at three times control level. Seventyone patients were given propranolol. The drug was usually started at 20 mg. orally every 4 or 6 hours and the dose was gradually increased until the heart rate was below 60 per minute. The average daily dose was 120 mg. (range, 80 to 240 mg.). Twelve-lead ECG's were recorded daily and in most cases additional recordings were obtained during episodes of chest pain. Serial determinations of serum enzymes made it possible to exclude evolving myocardial infarction. Selective coronary arteriography was performed usually following 10 days of intensive medical therapy, according to the Judkins technique. A coronary artery was considered to be significantly obstructed if the diameter narrowing was ;;.:75 percent. Criteria for the presence of coronary collateral circulation were those suggested by Helfant, Vokonas, and Gorlin.P None of the patients had left main coronary artery stenosis. All patients underwent a left ventriculography in the right anterior oblique projection. An outline of the left ventricular cavity was traced at end diastole and end systole, and silhouettes were superimposed according to the technique suggested by Leighton, Wilk, and Lewis.f" Left ventricular volumes were estimated with the area-length method.>' Four patients were supported during coronary angiography by intra-aortic balloon pumping as described previously. 25 The criteria for institution of balloon assist were (I) severe and prolonged chest pain, not relieved by nitroglycerin at the time of ventriculography (two patients), or (2) continued
Table I. Preoperative clinical profile (a total of 80 patients) No. ofpatients Previous stable angina pectoris Angina of recent onset Age < 50 yr. 50 to 60 yr. >60 yr. Previous myocardial infarction Inverted T wave Isolated With ST-segment depression With ST-segment elevation ST-segment depression ST-segment elevation Mean risk factors per patient*
58 22 19 38
23 21
35} 16
59
8 14 7
1.6 ± 0.8
'Hypertension, lipid abnormalities, smoking.
episodes of angina despite propranolol administration in doses of 240 mg. per day (two patients). Seventeen patients were not operated upon: four refused surgery although they were deemed operable; nine were considered inoperable due to distal disease in obstructed vessels; one had a myocardial infarction immediately after coronary angiography; in the remaining three patients surgery was not recommended because of single vessel disease involving the right coronary artery. Sixty-three patients were operated upon, but the time of surgery depended on whether anginal pain recurred or not: In patients in whom chest pain was controlled, surgery was postponed usually after a month (32 ± 23 days), whereas patients in whom medical therapy had failed to prevent recurrence of ischemic attacks were operated on within 24 to 48 hours of recurrent angina. All patients were personally seen in follow-up by one of us (1. F. H.). Treadmill ECG's were obtained in 44 patients 6 months or more after the coronary artery grafting by means of the multistage maximal exercise protocol of Bruce and Hornsten.t" In 18 patients of the surgically treated group this study was not performed because of late death (one patient), being maintained on digitalis (four patients), disabling noncardiac symptoms (seven patients), abnormalities (bundle branch block) of the resting ECG (three cases), and inability to visit our department (three patients). Four patients of the medically treated group also underwent an ECG stress test. A response was considered positive if during or after the exercise there was greater than I mm. horizontal (or downsloping) ST -T-segment depression or greater than I
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Table II. Extent of coronary occlusive disease assessed by arteriography Collateral circulation Coronary artery disease
(%)
Single vessel disease (29%) RCA* 3 LAD 20 LCF 0
9
Double vessel disease (37%) LAD + RCA 16 11 LAD + LCF 3 RCA + LCF
13
Triple vessel disease (34%) LAD + RCA + LCF:27
52
'LAD, Left anterior descending artery. RCA, Right coronary artery. LCF, Left circumflex artery.
mm. upsloping ST-segment depression 0.08 second after the J poinr" in any of the twelve monitored leads. Thirteen patients underwent postoperative angiographic evaluation with visualization of saphenous grafts and native coronary arterial circulation.
Results Clinical findings. The clinical profile of the 80 patients is depicted in Table I. The mean age was 55 years, with a range of 38 to 69 years. Sixty-five patients had experienced more than two anginal pain episodes at rest; in 25 patients the ischemic attack was unique but markedly prolonged (mean duration, 113 minutes) and usually necessitated control by narcotics. Fifty-eight patients (74 percent) had a history of stable exertional angina. In the 22 remaining patients (26 percent) spontaneous angina was of recent onset. Twenty-one patients either had a history of infarction or showed changes of a previous myocardial infarction. Thirty patients showed transitory ST-segment depression either isolated (14 patients) or associated with T-wave inversion (16 patients). Forty-three showed T -wave inversion either isolated (35 patients) or associated with ST elevation (eight patients). Seven patients demonstrated transitory ST-segment elevation during pain. Angiography. The results of the preoperative coronary arteriograms and left ventricular angiograms are given in Table II. The mean number of diseased vessels was 2.1 per patient. Twenty-three patients had single vessel disease, 30 had double vessel disease, and 27 had triple vessel disease. The left descending artery was most often involved (74 patients). The right coronary artery had significant obstruction in 49 patients
and the circumflex artery in 41. Visible collateral circulation was found in only 24 percent of the patients. Collateral circulation was noted in 9 and 13 percent of patients with single or double vessel disease, respectively, a significantly lower incidence compared to 52 percent of patients with three vessel disease (p < 0.01). None of the patients with isolated left descending artery stenosis exhibited collaterals. Arteriographically, 86 percent of patients were considered to have at least one operable vessel. Forty-five patients had a normal left ventricular cineangiogram. Fourteen patients showed areas of hypokinesia usually involving (one) or (two) myocardial segments (10 patients) but it was rather diffuse (three to five segments) in four patients. Akinesia of one or two segments was noted in 21 patients. The left ventricular end-diastolic pressure was greater than 12 mm. Hg in 21 patients (average, 10 ± 3) and ejection fraction was lower than 0.50 in seven patients (average, 0.64 ± 0.14). Medical therapy. Anginal pain episodes did not recur in 43 patients; in 37 patients ischemic attacks reappeared within 17 ± 10 days of admission (3 to 8 days in 12 patients, 9 to 30 days in 25 patients). For the entire group the mean heart rate decreased from 76 ± 14 to 59 ± 8 beats per minute (p < 0.001) and the systolic blood pressure dropped from 147 ± 24 to 131 ± 17 mm. Hg (p < 0.001) (Table III). Decreases in heart rate and systolic blood pressure were not significantly different in patients in whom pain was controlled (Group I) and in those in whom it was not (Group II). In the latter group the heart rate increased slightly from 58 ± 18 beats per minute before pain to 63 ± 10 (p < 0.05) during pain. Analysis of clinical, ECG, and arteriographic data showed the two groups to be similar. The only difference to reach statistical significance was the incidence of collaterals, which was higher in Group I (52 percent) than in Group II (26 percent, p < 0.01). Clinical signs of left ventricular failure developed in two patients, and in both the propranolol daily dose required was 240 mg. In each case the dosage was lowered but chest pain reappeared within 24 hours of the decrease in dosage. Surgical therapy. Aorta-coronary saphenous vein bypass grafting was performed in 63 patients. Propranolol was usually progressively discontinued so that the patients were completely withdrawn from the drug 24 to 36 hours before operation. Revascularization was carried out 32 ± 23 days after admission in 30 patients of Group I. In the 33 Group II patients with recurrent
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Table III. Management and effects of medical therapy in patients with (Group II) and without (Group l) recurrent angina Time between admission and Patients (No.)
Coronary arteriography (days)
Group 1(43) Group II (37)
10 ± 9 9 ± 8 N.S.
I
Recurrent angina idays) 17 ± 10
I
Surgery (days) 32 ± 23 19 ± 13
p < 0.01
Heart rate*
Propranolol daily dose (mg.)
Before (b.p.m.)
124 ± 40 127 ± 36 N.S.
77 ± 13 75 ± 16 N.S.
I
Systolic blood pressure*
After (b.p.m.)
Before (mm. Hg)
60 ± 9 58 ± 8 N.S.
142 ± 19 152 ± 20 N.S.
I
After (mm. Hg) 132 ± 18 130 ± 17 N.S.
*Hean rate and systolic blood pressure were measured out of episodes of chest pain (mean ± standard deviation).
angina, surgery was performed on the nineteenth day after admission (mean, 19 ± 13). Forty patients had single, 20 patients had double, and 3 patients had triple vessel bypass, for an average of 104. vessels bypassed per patient. The left descending artery was bypassed in 84 percent of the patients. Among the 63 patients operated upon, there was one surgical death (1.6 percent). Seven patients (II percent) had a postoperative myocardial infarction; none was fatal (Table IV). By contrast, Q waves compatible with an old myocardial infarction disappeared in 3 patients. Table IV shows the long-term clinical results in the 62 operative survivors. The duration of follow-up ranged from 7 to 50 months, with a mean of 22 months. There were three late myocardial infarctions as documented by subsequent ECG's. In the surviving patients, 44 01 percent) were completely asymptomatic and another three have had marked improvement of their angina pectoris. One patient is symptomatically worse and in seven patients there has been no significant change in the angina pectoris pattern. Patients with residual symptoms were older (58 ± 7 years) than asymptomatic patients (54 ± 7, P < 0.05), had previous stable angina of longer duration (42 as against 14 months, p < 0.05) and a greater incidence of postoperative myocardial infarction (28 versus 4 percent; p < 0.05). Table V shows the results of the postoperative treadmill ECG. Of the 44 patients studied, 29 (66 percent) had a negative response. The maximal heart rate achieved during the stress test was 85 to 99 percent (eight patients) and 100 percent or more (21 patients) of the maximal heart rate predicted for normal subjects. Fifteen patients (34 percent) had positive treadmill ECG results. Of note, however, is the fact that seven patients without postoperative angina had a positive response. Thirteen patients underwent postoperative hemodynamic evaluation (mean, 19.5 months; range, 9 to 33). Of these 13 restudied patients, ten were pain
Table IV. Follow-up in 62 postoperative survivors (22 ± 10 months) Status
I
Percent 71 29
Asymptomatic Symptomatic Angina Heart failure Isolated With angina Late postoperative Myocardial infarction Fatal Nonfatal
No. 44 18
II
4 I 3
I 2
Table V. Postoperative relationships of persisting angina and results of treadmill electrocardiogram Treadmill electrocardiogram Patients
No. negative
No. positive
Without angina pectoris With angina pectoris
27 2
7 8
free, two had angina pectoris, and one had heart failure. The over-all graft patency rate was 84 percent, and in 92 percent of the patients at least one graft was patent. Follow-up studies in nonsurgical cases (17 patients). Follow-up data for an average of 18 months were available for the 14 survivors of the medically treated group. Of the nine inoperable patients, two died from a myocardial infarction, six have severe angina pectoris despite continuing propranolol therapy, and one is asymptomatic. All three patients with single vessel disease of the right coronary artery, in whom surgery was not advised, are asymptomatic. Of the four patients who refused surgery, one died suddenly within a month after discharge from hospital, two sustained nonfatal myocardial infarction, and one has severe angina pectoris and heart failure.
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Discussion There is still a great deal of uncertainty in the literature as to the prognosis of unstable angina in terms of morbidity and mortality rates. The incidence of myocardial infarction for patients treated medically ranged from 5 to 91 percent and the mortality rate from o to 46 percent. 10. 14. 15. 28. 29 The marked disparity of these figures is obviously due to the variability in definitions, and particularly to the fact that patients were included without arteriographic confirmation. In order to select a group of patients with definite and severe myocardial ischemia, we have used rigorous clinical and ECG criteria. The requirement of ischemic changes on the ECG recorded during pain added an objective criterion and might explain the absence of false-positive results, as opposed to other reports where 4 to 19 percent of patients were found to have normal coronary arteries. 3. 6. 14. 30 In this study, the extent of occlusive coronary disease was not different from that found in chronic stable angina" and was strictly similar to that reported in the randomized Veterans Administration cooperative study. 19 However, two angiographic findings are noteworthy: (1) the high incidence (92.5 percent) of involvement of the left descending artery, which is not dissimilar from that reported in other series," 10. 14. 19 and (2) the paucity of collateral circulation, in contrast to stable angina, a finding confirmed in other reports. 6, 11. 14, 16. 32 Intensive medical therapy, including beta blockade, dramatically relieved the chest pain, at least for the first week following admission, in 85 percent of patients. Fishl, Herman, and Gorlin'" reported that 20 of their 23 patients treated by propranolol had prompt relief of pain. Papazoglov'" also obtained a favorable result in six of seven patients. The beneficial effects of propranolol in angina pectoris are thought to be secondary to a decrease in myocardial oxygen consumption.P' This is most probably the same mechanism of action of propranolol in unstable angina. Recent studies indicate that spontaneous angina is preceded by changes which increase myocardial oxygen demand. Since heart rate, systolic arterial pressure, and left ventricular enddiastolic pressure increase steadily before most episodes of angina pectoris, it may be postulated that myocardial oxygen requirements progressively increase before and during the ischemic attack.P"?" In the present study systolic blood pressure decreased by 11 percent and heart rate by 22 percent. Although propranolol therapy was continued at the same dosage, in 31 percent of the patients pain recurred 8 to 30 days following admission. Thus in 46 percent of the patients angina
Thoracic and Cardiovascular Surgery
pectoris could not be controlled medically either within the first week (15 percent) or later (31 percent). The need for surgery in patients whose angina persisted on intensive medical therapy is obvious. These nonresponders represent a subgroup of patients who are at high risk of death or myocardial infarction. In the 54 patients with frequent and prolonged attacks of angina continuing after 48 hours of bed rest, Gazes and associates'" reported a 35 percent incidence of acute myocardial infarction within 3 months and a 12 month survival of only 57 percent. In the series of Krauss, Hutter, and De Sanctis " of the 36 patients who continued to experience ischemic pain after 12 hours of bed rest, six progressed to infarction. Matloff and associates.!" in 35 patients with continuing or repeated episodes of pain while at bed rest, most of them being treated by beta-blocking drugs, reported a 40 percent mortality rate within a month after admission. In patients who have been stabilized on intensive medical regimen, the rationale for surgical management becomes more difficult to justify. Despite the relatively benign in-hospital course in the available medical series (1 percent mortality rate and 6 percent incidence of myocardial infarction), the mortality rate in the first year of follow-up is 12 percent, and the myocardial infarction rate is approximatively twice that.": 38 Preliminary results of two well-controlled studies reveal a similar incidence rate of nonfatal myocardial infarctions (2 percent per month) but a lower I year mortality rate (8 percent). The latter difference may be explained by the fact that in these studies patients who were not suitable for surgery were excluded, as were those who died within the first 4 days'" and those with left main coronary artery disease. 19 In our surgical group, if we combine the operative (1.6 percent) and late cardiac mortality rates (1.6 percent), 3 percent of patients have died after a mean follow-up period of 22 months. This would suggest that the I year mortality rate might be reduced by surgery. Recent evaluation of five controlled studies by Hultgren'" indicate a 13.8 percent mortality rate in 280 patients treated medically, with a mean follow-up time of 18 months. Furthermore, our data, like those of others, 16, 20. 21 appear to indicate that surgical intervention is less hazardous when it is preceded by I to 4 weeks of intensive medical therapy. Although it might be expected that early emergency surgery will prevent death in some patients, this potential advantage is probably small, since only 2.5 percent of patients die within 4 days of admission. 18. 38 The 11 percent incidence of postoperative myocardial infarctions is similar to that reported by others in
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unstable'": 14. 21. 29. 39 and stable angina pectoris. 18 In addition, 5 percent of the patients sustained a late myocardial infarction, for a total incidence of 16 percent for the 63 patients. Previous studies have shown that in similar groups of patients treated medically a myocardial infarction develops in 21 to 37.5 percent of patients over a follow-up period of 8 to 30 months. 14-16. 38 In two recent controlled studies, the incidence of nonfatal myocardial infarcts was 24 percent at 18 months and 15 percent at 1 year. 18. 19 However, longer follow-up studies are needed to determine if surgery can prevent late infarction. More than 70 percent of operative survivors have been totally relieved of their angina pectoris. This symptomatic improvement compares favorably with that obtained in patients with stable angina pectoris-?41. 42 and is significantly better than in patients with unstable angina treated medically. 10. 29. 43 Objective evidence of the effectiveness of bypass graft was provided by the fact that 81 percent of asymptomatic patients had a negative ECG test. However, seven patients were pain free, and their stress test showed a definite ischemic response. This is similar to the 28 to 30 percent incidence of positive stress tests in patients treated surgically for stable angina pectorisw 45 but somewhat less than the 49 percent incidence reported by Berndt and associates" in unstable angina. The relatively high incidence of positive treadmill ECG's might be explained by the presence of significant coronary occlusive lesions which were not bypassed. Of the 15 patients with a postoperative ischemic stress test, 12 had incomplete revascularization (ratio of number of stenosed arteries to number of grafts, > 1) as against 11 of the 29 patients with a negative stress test. The graft patency rate (84 percent) was the same as that previously reported for patients receiving bypass grafts for chronic stable angina" and for unstable angina,"- 29. 39. 47 Because only a relatively small fraction and presumably nonrepresentative fraction of our patients was restudied, these figures are difficult to interpret. REFERENCES Flemma RJ, Johnson WD, Tector AJ, Lepley D Jr, Blitz 1: Surgical treatment of preinfarction angina. Arch Intern Med 129:828, 1972 2 Spencer, FC: Bypass grafting for preinfarction angina. Circulation 45:1314, 1972 3 Conti CR, Brawley RK, Griffith LSC, Pitt B, Humphries JO, Gott VL, Ross RS: Unstable angina pectoris. Morbility and mortality in 57 consecutive patients evaluated angiographically. Am J Cardiol 32:745, 1973
4 Goodin RR, Ingleby TV, Lansing AM, Wheat MW: Preinfarction angina pectoris. A surgical emergency. J THORAC CARDIOVASC SURG 66:934, 1973 5 Miller DG, Cannom DS, Fogarty 11, Schroeder JS, Daily PO, Harrison DC: Saphenous vein coronary artery bypass in patients with preinfarction angina. Circulation 47:234, 1973 6 Scanlon PJ, Nemickas R, Moran JF, Talano JV, Amirparviz F, Pifarre R: Accelerated angina pectoris. Clinical, hemodynamic, arteriographic, and therapeutic experience in 85 patients. Circulation 47:19, 1973 7 Wisoff BG, Kolker P, Hartstein ML, Hamby RI: Surgical approach to impending myocardial infarction. J THORAC CARDIOVASC SURG 65:535, 1973 8 Berndt TB, Miller DC, Silverman JF, Stinson EB, Harrison DC, and Schroeder JS: Coronary bypass surgery for unstable angina pectoris. Clinical follow-up and results of postoperative treadmill electrocardiograms. Am J Med 58:171, 1975 9 Hammond GL, Poirier RA: Surgical management for acute coronary insufficiency with three years' follow-up. J THORAC CARDIOVASC SURG 69:625, 1975 10 Matloff JM, Sustaita H, Chatterjee K, Chaux A, Marcus HS, Swan HJC: The rationale for surgery in preinfarction angina. J THORAC CARDIOVASC SURG 69:73, 1975 11 Vogel R, Pappas G, Levitt P, Battock D, Steele P: Results of medical and surgical management of high-risk unstable angina (abst). Am J Cardiol 35: 175, 1975 12 Auer JE, Johnson WD, Flemma RJ, Tector AJ, Lepley D, Jr: Direct coronary artery surgery for impending myocardial infarction (abst). Circulation 44:Suppl 2:102, 1971 13 Lambert CJ, Mitchel BF, Adam M: Emergency myocardial revascularization for impending myocardial infarctions. Chest 61:479, 1972 14 Bertolasi CA, Tronge JE, Riccitelli MA, Villamayor RM, Zuffardi E: Natural history of unstable angina with medicalor surgical therapy. Chest 70:596, 1976 15 Krauss KR, Hutter AM, De Sanctis RW: Acute coronary insufficiency: course and follow-up. Circulation 45:Suppl 1:66, 1972 16 Fischl SJ, Herman MV, Gorlin R: The intermediate coronary syndrome. Clinical, angiographic and therapeutic aspects. N Engl J Med 288: 1193, 1973 17 Master AM, Jaffe HL: Propranolol vs. saphenous vein graft bypass for impending infarction (preinfarction angina). Am Heart J 87:321, 1974 18 Hultgren HN: Medical versus surgical treatment of unstable angina. Am J Cardiol 38:479, 1976 19 Russel RO, Moraski RE, Kouchoukos N, Karp R, Mantle JA, Rackley CE, Resnekov L, Falicov RE, AI-Sadir J, et al: Unstable angina pectoris: National cooperative study group to compare medical and surgical therapy. I. Report of protocol and patient population. Am J Cardiol 37:896, 1976 20 Theroux P, Campeau L: The influence of timing of surgery on mortality and incidence of myocardial infarc-
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tion following aorto-coronary vein graft surgery in crescendo angina (abst). Am J Cardiol 31:162, 1973 Kouchoukos NT, Russel RO, Jr, Moraski RE, Karp RB, Oberman A, Rackley CE: Surgical treatment of unstable angina pectoris: Results in 65 patients (abst). Am J Cardiol 35:149, 1975 Helfant RH, Vokonas PS, Gorlin R: Functional importance of the human coronary collateral circulation. N Engl J Med 284: 1277, 1971 Leighton RF, Wilt SM, Lewis RP: Detection of hypokinesis by a quantitative analysis of left ventricular cineangiograms. Circulation 50: 121, 1974 Dodge DT: Determination of left ventricular volume in man. Radiol Clin North Am 9:459, 1971 Bardet J, Masquet C, Kahn JC, Gourgon R, Bourdarias JP, Mathivat A, Bouvrain Y: Clinical and hemodynamic results of intra-aortic balloon counterpulsation and surgery for cardiogenic shock. Am Heart J 93:280, 1977 Bruce RA, Homsten TR: Exercise stress testing in evaluation of patients with ischemic heart disease. Prog Cardiovasc, Dis 11:371,1969 Stuart RJ, Jr, Ellestad MH: Upsloping ST segments in exercise stress testing. Six years follow-up study of 438 patients and correlation with 248 angiograms. Am J Cardiol 37:19, 1976 Skjaeggestad 0: The natural history of intermediate coronary syndrome Acta Med Scand 193:533, 1973 Selden R, Neill WA, Ritzmann LW, Okies JE, Anderson RP: Medical versus surgical therapy for acute coronary insufficiency. A randomized study. N Engl J Med: 293:1329, 1975 Alison HA, Moraski RE, Mantle JA: Coronary anatomy and arteriography in patients with unstable angina pectoris (abst). Am J Cardiol 35:118, 1975 Becker J, Lichtlen P, Baumann PC, Preter B, Albert H, Kaltenbach M, Kober G, Kollath J, Spitz P: History and clinical findings related to selective coronary angiography. In Kaltenbach M and Lichtlen P, editors: Coronary Artery Disease. Stuttgart, 1971, Georg Thieme Verlag, p.56 Lawson RM, Chapman R, Wood J, Starr A: Acute coronary insufficiency. An urgent surgical condition Br Heart J 37:1053, 1975 Papazoglov NM: Use of propranolol in pre-infarction angina. Circulation 44:303, 1971 Aronow WS: The medical treatment of angina pectoris. Propranolol as an antianginal drug. Am Heart J 84:706, 1972
35 Roughgarden JW: Circulatory changes associated with spontaneous angina pectoris. Am J Med 41:947, 1966 36 Amsterdam EA, Manchester JH, Kemp HG, Gorlin R: Spontaneous angina pectoris: Hemodynamic and metabolic changes (abst). Clin Res 17:225, 1969 37 Cannom DA, Harrison DC, Schroeder JS: Hemodynamic observation in patients with unstable angina pectoris. Am J Cardiol 33:17, 1974 38 Gazes PC, Mobley EM, Faris HM, Duncan RC, Humphries GB: Pre infarctional (unstable) angina. A prospective study. Ten years follow-up. Prognostic significance of ECG changes. Circulation 48:Suppl 2:331, 1973 39 Bonchek LI, Rahimtoola SH, Anderson RP, McAnulty JA, Rosch J, Bristow JD, Starr A: Late results following emergency saphenous vein bypass grafting for unstable angina. Circulation 50:972, 1974 40 Manley JC, Johnson WD: Effects of surgery on angina (pre and post infarction) and myocardial function (failure). Circulation 46:1208, 1972 41 Najmi M, Ushijama K, Blanco G: Results of aortocoronary artery saphenous vein bypass surgery for ischemic heart disease. Am J Cardiol 33:42, 1974 42 Hartman CW, Kong Y, Margolis JR, Warren SG, Peter RH, Behar VS, Oldham HN: Aortocoronary bypass surgery. Correlation of angiographic, symptomatic and functional improvement at I year. Am J Cardiol 37:352, 1976 43 Berk G, Kaplitt M, Padmanabhan V, Frantz S, Morrison J, Gulotta SJ: Management of pre-infarction angina. Evaluation and comparison of medical versus surgical therapy in 43 patients J THoRAc CARDtOVASC SURG 71: 110, 1976 44 Lapin ES, Murray JA, Bruce RA, Winterscheid L: Changes in maximal exercise performance in the evaluation of saphenous vein bypass surgery. Circulation 47:1164,1973 45 Bartel AG, Behar VS, Peter RH, Orgain ES, Kong Y: Exercise stress testing in evaluation of aorto-coronary bypass surgery. Report of 123 patients Circulation 48: 141, 1973 46 Mundth ED, Austen WG: Surgical measures for coronary heart disease. N Engl J Med 293:13,75, 124, 1975 47 Segal BL, Likoff W, Van Den Broek H, Kimbiris D, Najmi M, Linhart JW: Saphenous vein bypass surgery for impending myocardial infarction. Critical evaluation and current concepts. JAMA 223:767, 1973
J. F. Huret, M.D., B. Agier, M.D., S. P. Rosier, M.D., P. Gueret, M.D., J. C. Kahn, M.D., M. Ben Farhat, M.D., J. Bardet, M.D., and J. P. Bourdarias, M.D., Boulogne, France
With the availability of direct saphenous vein coronary bypass in recent years, enthusiasm for surgical intervention in a variety of clinical syndromes considered to represent a preinfarction state has resulted in widespread use of this therapeutic modality.v '! However, the lack of general agreement about the criteria to be used made objective assessment of surgical therapy quite difficult. Although some authors have stated that emergency revascularization carries little additional operative risk over that of elective bypass, 10, 12, 13 the surgical mortality rate was higher in most reports, ranging from 8 4 , 7, 9 to 10 or 12 percent" 14 or even more." From Hopital Ambroise-Pare, 9, Avenue Ch de Gaulle 92100, Boulogne, France. Received for publication July 5, 1977. Accepted for publication Sept. 13, 1977. Address for reprints: J. P. Bourdarias, M.D., Hopital AmbroisePare, 9, Avenue Ch de Gaulle 92100, Boulogne, France.
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Furthermore, the immediate and remote natural history of the syndrome remains controversial. Recently, good results, at least on a short-term basis, have been described with medical treatment.J"?" Whereas several well-controlled comparative studies are currently in progress.P- 19 only a few systematic studies of delayed semiemergent surgery have been reported. 20. 21 This study concerns (I) the feasibility of revascularization surgery after an attempt of stabilization on intensive medical therapy and (2) the late postoperative results for an average follow-up interval of 22 months, in regard to symptomatic relief and electrocardiographic (ECG) responses to treadmill exercise.
Patients and methods Between January, 1971, and December, 1975, 80 patients were classified as having unstable angina if they met the following criteria: (I) severe, prolonged
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(> 15 minutes) episodes of anginal pain at rest, (2)
documentation of transient ST-segment and/or T-wave changes, recorded during at least one episode of chest pain, (3) absence of new pathological (;;.:0.04 second) Q waves or permanent loss of R-wave amplitude in the precordial leads, (4) absence of changes (or less than 50 percent above normal) in serum enzymes (glutamic oxaloacetic transaminase, lactic dehydrogenase, creatine phosphokinase), and (5) presence on the coronary arteriogram of a significant stenosis of one (or more) of the three major coronary arteries. Patients with crescendo patterns of pain on exertion and patients with exertional angina of recent onset were not included unless they also had pain at rest. Precipitating extracardiac factors such as anemia, arrhythmias, congestive heart failure, or severe hypertensive disease of recent onset were excluded in each patient. All patients were treated with bed rest and shortand/or long-acting nitrates; 74 underwent anticoagulation with intravenously administered heparin to maintain clotting time at three times control level. Seventyone patients were given propranolol. The drug was usually started at 20 mg. orally every 4 or 6 hours and the dose was gradually increased until the heart rate was below 60 per minute. The average daily dose was 120 mg. (range, 80 to 240 mg.). Twelve-lead ECG's were recorded daily and in most cases additional recordings were obtained during episodes of chest pain. Serial determinations of serum enzymes made it possible to exclude evolving myocardial infarction. Selective coronary arteriography was performed usually following 10 days of intensive medical therapy, according to the Judkins technique. A coronary artery was considered to be significantly obstructed if the diameter narrowing was ;;.:75 percent. Criteria for the presence of coronary collateral circulation were those suggested by Helfant, Vokonas, and Gorlin.P None of the patients had left main coronary artery stenosis. All patients underwent a left ventriculography in the right anterior oblique projection. An outline of the left ventricular cavity was traced at end diastole and end systole, and silhouettes were superimposed according to the technique suggested by Leighton, Wilk, and Lewis.f" Left ventricular volumes were estimated with the area-length method.>' Four patients were supported during coronary angiography by intra-aortic balloon pumping as described previously. 25 The criteria for institution of balloon assist were (I) severe and prolonged chest pain, not relieved by nitroglycerin at the time of ventriculography (two patients), or (2) continued
Table I. Preoperative clinical profile (a total of 80 patients) No. ofpatients Previous stable angina pectoris Angina of recent onset Age < 50 yr. 50 to 60 yr. >60 yr. Previous myocardial infarction Inverted T wave Isolated With ST-segment depression With ST-segment elevation ST-segment depression ST-segment elevation Mean risk factors per patient*
58 22 19 38
23 21
35} 16
59
8 14 7
1.6 ± 0.8
'Hypertension, lipid abnormalities, smoking.
episodes of angina despite propranolol administration in doses of 240 mg. per day (two patients). Seventeen patients were not operated upon: four refused surgery although they were deemed operable; nine were considered inoperable due to distal disease in obstructed vessels; one had a myocardial infarction immediately after coronary angiography; in the remaining three patients surgery was not recommended because of single vessel disease involving the right coronary artery. Sixty-three patients were operated upon, but the time of surgery depended on whether anginal pain recurred or not: In patients in whom chest pain was controlled, surgery was postponed usually after a month (32 ± 23 days), whereas patients in whom medical therapy had failed to prevent recurrence of ischemic attacks were operated on within 24 to 48 hours of recurrent angina. All patients were personally seen in follow-up by one of us (1. F. H.). Treadmill ECG's were obtained in 44 patients 6 months or more after the coronary artery grafting by means of the multistage maximal exercise protocol of Bruce and Hornsten.t" In 18 patients of the surgically treated group this study was not performed because of late death (one patient), being maintained on digitalis (four patients), disabling noncardiac symptoms (seven patients), abnormalities (bundle branch block) of the resting ECG (three cases), and inability to visit our department (three patients). Four patients of the medically treated group also underwent an ECG stress test. A response was considered positive if during or after the exercise there was greater than I mm. horizontal (or downsloping) ST -T-segment depression or greater than I
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Table II. Extent of coronary occlusive disease assessed by arteriography Collateral circulation Coronary artery disease
(%)
Single vessel disease (29%) RCA* 3 LAD 20 LCF 0
9
Double vessel disease (37%) LAD + RCA 16 11 LAD + LCF 3 RCA + LCF
13
Triple vessel disease (34%) LAD + RCA + LCF:27
52
'LAD, Left anterior descending artery. RCA, Right coronary artery. LCF, Left circumflex artery.
mm. upsloping ST-segment depression 0.08 second after the J poinr" in any of the twelve monitored leads. Thirteen patients underwent postoperative angiographic evaluation with visualization of saphenous grafts and native coronary arterial circulation.
Results Clinical findings. The clinical profile of the 80 patients is depicted in Table I. The mean age was 55 years, with a range of 38 to 69 years. Sixty-five patients had experienced more than two anginal pain episodes at rest; in 25 patients the ischemic attack was unique but markedly prolonged (mean duration, 113 minutes) and usually necessitated control by narcotics. Fifty-eight patients (74 percent) had a history of stable exertional angina. In the 22 remaining patients (26 percent) spontaneous angina was of recent onset. Twenty-one patients either had a history of infarction or showed changes of a previous myocardial infarction. Thirty patients showed transitory ST-segment depression either isolated (14 patients) or associated with T-wave inversion (16 patients). Forty-three showed T -wave inversion either isolated (35 patients) or associated with ST elevation (eight patients). Seven patients demonstrated transitory ST-segment elevation during pain. Angiography. The results of the preoperative coronary arteriograms and left ventricular angiograms are given in Table II. The mean number of diseased vessels was 2.1 per patient. Twenty-three patients had single vessel disease, 30 had double vessel disease, and 27 had triple vessel disease. The left descending artery was most often involved (74 patients). The right coronary artery had significant obstruction in 49 patients
and the circumflex artery in 41. Visible collateral circulation was found in only 24 percent of the patients. Collateral circulation was noted in 9 and 13 percent of patients with single or double vessel disease, respectively, a significantly lower incidence compared to 52 percent of patients with three vessel disease (p < 0.01). None of the patients with isolated left descending artery stenosis exhibited collaterals. Arteriographically, 86 percent of patients were considered to have at least one operable vessel. Forty-five patients had a normal left ventricular cineangiogram. Fourteen patients showed areas of hypokinesia usually involving (one) or (two) myocardial segments (10 patients) but it was rather diffuse (three to five segments) in four patients. Akinesia of one or two segments was noted in 21 patients. The left ventricular end-diastolic pressure was greater than 12 mm. Hg in 21 patients (average, 10 ± 3) and ejection fraction was lower than 0.50 in seven patients (average, 0.64 ± 0.14). Medical therapy. Anginal pain episodes did not recur in 43 patients; in 37 patients ischemic attacks reappeared within 17 ± 10 days of admission (3 to 8 days in 12 patients, 9 to 30 days in 25 patients). For the entire group the mean heart rate decreased from 76 ± 14 to 59 ± 8 beats per minute (p < 0.001) and the systolic blood pressure dropped from 147 ± 24 to 131 ± 17 mm. Hg (p < 0.001) (Table III). Decreases in heart rate and systolic blood pressure were not significantly different in patients in whom pain was controlled (Group I) and in those in whom it was not (Group II). In the latter group the heart rate increased slightly from 58 ± 18 beats per minute before pain to 63 ± 10 (p < 0.05) during pain. Analysis of clinical, ECG, and arteriographic data showed the two groups to be similar. The only difference to reach statistical significance was the incidence of collaterals, which was higher in Group I (52 percent) than in Group II (26 percent, p < 0.01). Clinical signs of left ventricular failure developed in two patients, and in both the propranolol daily dose required was 240 mg. In each case the dosage was lowered but chest pain reappeared within 24 hours of the decrease in dosage. Surgical therapy. Aorta-coronary saphenous vein bypass grafting was performed in 63 patients. Propranolol was usually progressively discontinued so that the patients were completely withdrawn from the drug 24 to 36 hours before operation. Revascularization was carried out 32 ± 23 days after admission in 30 patients of Group I. In the 33 Group II patients with recurrent
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Table III. Management and effects of medical therapy in patients with (Group II) and without (Group l) recurrent angina Time between admission and Patients (No.)
Coronary arteriography (days)
Group 1(43) Group II (37)
10 ± 9 9 ± 8 N.S.
I
Recurrent angina idays) 17 ± 10
I
Surgery (days) 32 ± 23 19 ± 13
p < 0.01
Heart rate*
Propranolol daily dose (mg.)
Before (b.p.m.)
124 ± 40 127 ± 36 N.S.
77 ± 13 75 ± 16 N.S.
I
Systolic blood pressure*
After (b.p.m.)
Before (mm. Hg)
60 ± 9 58 ± 8 N.S.
142 ± 19 152 ± 20 N.S.
I
After (mm. Hg) 132 ± 18 130 ± 17 N.S.
*Hean rate and systolic blood pressure were measured out of episodes of chest pain (mean ± standard deviation).
angina, surgery was performed on the nineteenth day after admission (mean, 19 ± 13). Forty patients had single, 20 patients had double, and 3 patients had triple vessel bypass, for an average of 104. vessels bypassed per patient. The left descending artery was bypassed in 84 percent of the patients. Among the 63 patients operated upon, there was one surgical death (1.6 percent). Seven patients (II percent) had a postoperative myocardial infarction; none was fatal (Table IV). By contrast, Q waves compatible with an old myocardial infarction disappeared in 3 patients. Table IV shows the long-term clinical results in the 62 operative survivors. The duration of follow-up ranged from 7 to 50 months, with a mean of 22 months. There were three late myocardial infarctions as documented by subsequent ECG's. In the surviving patients, 44 01 percent) were completely asymptomatic and another three have had marked improvement of their angina pectoris. One patient is symptomatically worse and in seven patients there has been no significant change in the angina pectoris pattern. Patients with residual symptoms were older (58 ± 7 years) than asymptomatic patients (54 ± 7, P < 0.05), had previous stable angina of longer duration (42 as against 14 months, p < 0.05) and a greater incidence of postoperative myocardial infarction (28 versus 4 percent; p < 0.05). Table V shows the results of the postoperative treadmill ECG. Of the 44 patients studied, 29 (66 percent) had a negative response. The maximal heart rate achieved during the stress test was 85 to 99 percent (eight patients) and 100 percent or more (21 patients) of the maximal heart rate predicted for normal subjects. Fifteen patients (34 percent) had positive treadmill ECG results. Of note, however, is the fact that seven patients without postoperative angina had a positive response. Thirteen patients underwent postoperative hemodynamic evaluation (mean, 19.5 months; range, 9 to 33). Of these 13 restudied patients, ten were pain
Table IV. Follow-up in 62 postoperative survivors (22 ± 10 months) Status
I
Percent 71 29
Asymptomatic Symptomatic Angina Heart failure Isolated With angina Late postoperative Myocardial infarction Fatal Nonfatal
No. 44 18
II
4 I 3
I 2
Table V. Postoperative relationships of persisting angina and results of treadmill electrocardiogram Treadmill electrocardiogram Patients
No. negative
No. positive
Without angina pectoris With angina pectoris
27 2
7 8
free, two had angina pectoris, and one had heart failure. The over-all graft patency rate was 84 percent, and in 92 percent of the patients at least one graft was patent. Follow-up studies in nonsurgical cases (17 patients). Follow-up data for an average of 18 months were available for the 14 survivors of the medically treated group. Of the nine inoperable patients, two died from a myocardial infarction, six have severe angina pectoris despite continuing propranolol therapy, and one is asymptomatic. All three patients with single vessel disease of the right coronary artery, in whom surgery was not advised, are asymptomatic. Of the four patients who refused surgery, one died suddenly within a month after discharge from hospital, two sustained nonfatal myocardial infarction, and one has severe angina pectoris and heart failure.
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Discussion There is still a great deal of uncertainty in the literature as to the prognosis of unstable angina in terms of morbidity and mortality rates. The incidence of myocardial infarction for patients treated medically ranged from 5 to 91 percent and the mortality rate from o to 46 percent. 10. 14. 15. 28. 29 The marked disparity of these figures is obviously due to the variability in definitions, and particularly to the fact that patients were included without arteriographic confirmation. In order to select a group of patients with definite and severe myocardial ischemia, we have used rigorous clinical and ECG criteria. The requirement of ischemic changes on the ECG recorded during pain added an objective criterion and might explain the absence of false-positive results, as opposed to other reports where 4 to 19 percent of patients were found to have normal coronary arteries. 3. 6. 14. 30 In this study, the extent of occlusive coronary disease was not different from that found in chronic stable angina" and was strictly similar to that reported in the randomized Veterans Administration cooperative study. 19 However, two angiographic findings are noteworthy: (1) the high incidence (92.5 percent) of involvement of the left descending artery, which is not dissimilar from that reported in other series," 10. 14. 19 and (2) the paucity of collateral circulation, in contrast to stable angina, a finding confirmed in other reports. 6, 11. 14, 16. 32 Intensive medical therapy, including beta blockade, dramatically relieved the chest pain, at least for the first week following admission, in 85 percent of patients. Fishl, Herman, and Gorlin'" reported that 20 of their 23 patients treated by propranolol had prompt relief of pain. Papazoglov'" also obtained a favorable result in six of seven patients. The beneficial effects of propranolol in angina pectoris are thought to be secondary to a decrease in myocardial oxygen consumption.P' This is most probably the same mechanism of action of propranolol in unstable angina. Recent studies indicate that spontaneous angina is preceded by changes which increase myocardial oxygen demand. Since heart rate, systolic arterial pressure, and left ventricular enddiastolic pressure increase steadily before most episodes of angina pectoris, it may be postulated that myocardial oxygen requirements progressively increase before and during the ischemic attack.P"?" In the present study systolic blood pressure decreased by 11 percent and heart rate by 22 percent. Although propranolol therapy was continued at the same dosage, in 31 percent of the patients pain recurred 8 to 30 days following admission. Thus in 46 percent of the patients angina
Thoracic and Cardiovascular Surgery
pectoris could not be controlled medically either within the first week (15 percent) or later (31 percent). The need for surgery in patients whose angina persisted on intensive medical therapy is obvious. These nonresponders represent a subgroup of patients who are at high risk of death or myocardial infarction. In the 54 patients with frequent and prolonged attacks of angina continuing after 48 hours of bed rest, Gazes and associates'" reported a 35 percent incidence of acute myocardial infarction within 3 months and a 12 month survival of only 57 percent. In the series of Krauss, Hutter, and De Sanctis " of the 36 patients who continued to experience ischemic pain after 12 hours of bed rest, six progressed to infarction. Matloff and associates.!" in 35 patients with continuing or repeated episodes of pain while at bed rest, most of them being treated by beta-blocking drugs, reported a 40 percent mortality rate within a month after admission. In patients who have been stabilized on intensive medical regimen, the rationale for surgical management becomes more difficult to justify. Despite the relatively benign in-hospital course in the available medical series (1 percent mortality rate and 6 percent incidence of myocardial infarction), the mortality rate in the first year of follow-up is 12 percent, and the myocardial infarction rate is approximatively twice that.": 38 Preliminary results of two well-controlled studies reveal a similar incidence rate of nonfatal myocardial infarctions (2 percent per month) but a lower I year mortality rate (8 percent). The latter difference may be explained by the fact that in these studies patients who were not suitable for surgery were excluded, as were those who died within the first 4 days'" and those with left main coronary artery disease. 19 In our surgical group, if we combine the operative (1.6 percent) and late cardiac mortality rates (1.6 percent), 3 percent of patients have died after a mean follow-up period of 22 months. This would suggest that the I year mortality rate might be reduced by surgery. Recent evaluation of five controlled studies by Hultgren'" indicate a 13.8 percent mortality rate in 280 patients treated medically, with a mean follow-up time of 18 months. Furthermore, our data, like those of others, 16, 20. 21 appear to indicate that surgical intervention is less hazardous when it is preceded by I to 4 weeks of intensive medical therapy. Although it might be expected that early emergency surgery will prevent death in some patients, this potential advantage is probably small, since only 2.5 percent of patients die within 4 days of admission. 18. 38 The 11 percent incidence of postoperative myocardial infarctions is similar to that reported by others in
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unstable'": 14. 21. 29. 39 and stable angina pectoris. 18 In addition, 5 percent of the patients sustained a late myocardial infarction, for a total incidence of 16 percent for the 63 patients. Previous studies have shown that in similar groups of patients treated medically a myocardial infarction develops in 21 to 37.5 percent of patients over a follow-up period of 8 to 30 months. 14-16. 38 In two recent controlled studies, the incidence of nonfatal myocardial infarcts was 24 percent at 18 months and 15 percent at 1 year. 18. 19 However, longer follow-up studies are needed to determine if surgery can prevent late infarction. More than 70 percent of operative survivors have been totally relieved of their angina pectoris. This symptomatic improvement compares favorably with that obtained in patients with stable angina pectoris-?41. 42 and is significantly better than in patients with unstable angina treated medically. 10. 29. 43 Objective evidence of the effectiveness of bypass graft was provided by the fact that 81 percent of asymptomatic patients had a negative ECG test. However, seven patients were pain free, and their stress test showed a definite ischemic response. This is similar to the 28 to 30 percent incidence of positive stress tests in patients treated surgically for stable angina pectorisw 45 but somewhat less than the 49 percent incidence reported by Berndt and associates" in unstable angina. The relatively high incidence of positive treadmill ECG's might be explained by the presence of significant coronary occlusive lesions which were not bypassed. Of the 15 patients with a postoperative ischemic stress test, 12 had incomplete revascularization (ratio of number of stenosed arteries to number of grafts, > 1) as against 11 of the 29 patients with a negative stress test. The graft patency rate (84 percent) was the same as that previously reported for patients receiving bypass grafts for chronic stable angina" and for unstable angina,"- 29. 39. 47 Because only a relatively small fraction and presumably nonrepresentative fraction of our patients was restudied, these figures are difficult to interpret. REFERENCES Flemma RJ, Johnson WD, Tector AJ, Lepley D Jr, Blitz 1: Surgical treatment of preinfarction angina. Arch Intern Med 129:828, 1972 2 Spencer, FC: Bypass grafting for preinfarction angina. Circulation 45:1314, 1972 3 Conti CR, Brawley RK, Griffith LSC, Pitt B, Humphries JO, Gott VL, Ross RS: Unstable angina pectoris. Morbility and mortality in 57 consecutive patients evaluated angiographically. Am J Cardiol 32:745, 1973
4 Goodin RR, Ingleby TV, Lansing AM, Wheat MW: Preinfarction angina pectoris. A surgical emergency. J THORAC CARDIOVASC SURG 66:934, 1973 5 Miller DG, Cannom DS, Fogarty 11, Schroeder JS, Daily PO, Harrison DC: Saphenous vein coronary artery bypass in patients with preinfarction angina. Circulation 47:234, 1973 6 Scanlon PJ, Nemickas R, Moran JF, Talano JV, Amirparviz F, Pifarre R: Accelerated angina pectoris. Clinical, hemodynamic, arteriographic, and therapeutic experience in 85 patients. Circulation 47:19, 1973 7 Wisoff BG, Kolker P, Hartstein ML, Hamby RI: Surgical approach to impending myocardial infarction. J THORAC CARDIOVASC SURG 65:535, 1973 8 Berndt TB, Miller DC, Silverman JF, Stinson EB, Harrison DC, and Schroeder JS: Coronary bypass surgery for unstable angina pectoris. Clinical follow-up and results of postoperative treadmill electrocardiograms. Am J Med 58:171, 1975 9 Hammond GL, Poirier RA: Surgical management for acute coronary insufficiency with three years' follow-up. J THORAC CARDIOVASC SURG 69:625, 1975 10 Matloff JM, Sustaita H, Chatterjee K, Chaux A, Marcus HS, Swan HJC: The rationale for surgery in preinfarction angina. J THORAC CARDIOVASC SURG 69:73, 1975 11 Vogel R, Pappas G, Levitt P, Battock D, Steele P: Results of medical and surgical management of high-risk unstable angina (abst). Am J Cardiol 35: 175, 1975 12 Auer JE, Johnson WD, Flemma RJ, Tector AJ, Lepley D, Jr: Direct coronary artery surgery for impending myocardial infarction (abst). Circulation 44:Suppl 2:102, 1971 13 Lambert CJ, Mitchel BF, Adam M: Emergency myocardial revascularization for impending myocardial infarctions. Chest 61:479, 1972 14 Bertolasi CA, Tronge JE, Riccitelli MA, Villamayor RM, Zuffardi E: Natural history of unstable angina with medicalor surgical therapy. Chest 70:596, 1976 15 Krauss KR, Hutter AM, De Sanctis RW: Acute coronary insufficiency: course and follow-up. Circulation 45:Suppl 1:66, 1972 16 Fischl SJ, Herman MV, Gorlin R: The intermediate coronary syndrome. Clinical, angiographic and therapeutic aspects. N Engl J Med 288: 1193, 1973 17 Master AM, Jaffe HL: Propranolol vs. saphenous vein graft bypass for impending infarction (preinfarction angina). Am Heart J 87:321, 1974 18 Hultgren HN: Medical versus surgical treatment of unstable angina. Am J Cardiol 38:479, 1976 19 Russel RO, Moraski RE, Kouchoukos N, Karp R, Mantle JA, Rackley CE, Resnekov L, Falicov RE, AI-Sadir J, et al: Unstable angina pectoris: National cooperative study group to compare medical and surgical therapy. I. Report of protocol and patient population. Am J Cardiol 37:896, 1976 20 Theroux P, Campeau L: The influence of timing of surgery on mortality and incidence of myocardial infarc-
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22
23
24 25
26
27
28 29
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tion following aorto-coronary vein graft surgery in crescendo angina (abst). Am J Cardiol 31:162, 1973 Kouchoukos NT, Russel RO, Jr, Moraski RE, Karp RB, Oberman A, Rackley CE: Surgical treatment of unstable angina pectoris: Results in 65 patients (abst). Am J Cardiol 35:149, 1975 Helfant RH, Vokonas PS, Gorlin R: Functional importance of the human coronary collateral circulation. N Engl J Med 284: 1277, 1971 Leighton RF, Wilt SM, Lewis RP: Detection of hypokinesis by a quantitative analysis of left ventricular cineangiograms. Circulation 50: 121, 1974 Dodge DT: Determination of left ventricular volume in man. Radiol Clin North Am 9:459, 1971 Bardet J, Masquet C, Kahn JC, Gourgon R, Bourdarias JP, Mathivat A, Bouvrain Y: Clinical and hemodynamic results of intra-aortic balloon counterpulsation and surgery for cardiogenic shock. Am Heart J 93:280, 1977 Bruce RA, Homsten TR: Exercise stress testing in evaluation of patients with ischemic heart disease. Prog Cardiovasc, Dis 11:371,1969 Stuart RJ, Jr, Ellestad MH: Upsloping ST segments in exercise stress testing. Six years follow-up study of 438 patients and correlation with 248 angiograms. Am J Cardiol 37:19, 1976 Skjaeggestad 0: The natural history of intermediate coronary syndrome Acta Med Scand 193:533, 1973 Selden R, Neill WA, Ritzmann LW, Okies JE, Anderson RP: Medical versus surgical therapy for acute coronary insufficiency. A randomized study. N Engl J Med: 293:1329, 1975 Alison HA, Moraski RE, Mantle JA: Coronary anatomy and arteriography in patients with unstable angina pectoris (abst). Am J Cardiol 35:118, 1975 Becker J, Lichtlen P, Baumann PC, Preter B, Albert H, Kaltenbach M, Kober G, Kollath J, Spitz P: History and clinical findings related to selective coronary angiography. In Kaltenbach M and Lichtlen P, editors: Coronary Artery Disease. Stuttgart, 1971, Georg Thieme Verlag, p.56 Lawson RM, Chapman R, Wood J, Starr A: Acute coronary insufficiency. An urgent surgical condition Br Heart J 37:1053, 1975 Papazoglov NM: Use of propranolol in pre-infarction angina. Circulation 44:303, 1971 Aronow WS: The medical treatment of angina pectoris. Propranolol as an antianginal drug. Am Heart J 84:706, 1972
35 Roughgarden JW: Circulatory changes associated with spontaneous angina pectoris. Am J Med 41:947, 1966 36 Amsterdam EA, Manchester JH, Kemp HG, Gorlin R: Spontaneous angina pectoris: Hemodynamic and metabolic changes (abst). Clin Res 17:225, 1969 37 Cannom DA, Harrison DC, Schroeder JS: Hemodynamic observation in patients with unstable angina pectoris. Am J Cardiol 33:17, 1974 38 Gazes PC, Mobley EM, Faris HM, Duncan RC, Humphries GB: Pre infarctional (unstable) angina. A prospective study. Ten years follow-up. Prognostic significance of ECG changes. Circulation 48:Suppl 2:331, 1973 39 Bonchek LI, Rahimtoola SH, Anderson RP, McAnulty JA, Rosch J, Bristow JD, Starr A: Late results following emergency saphenous vein bypass grafting for unstable angina. Circulation 50:972, 1974 40 Manley JC, Johnson WD: Effects of surgery on angina (pre and post infarction) and myocardial function (failure). Circulation 46:1208, 1972 41 Najmi M, Ushijama K, Blanco G: Results of aortocoronary artery saphenous vein bypass surgery for ischemic heart disease. Am J Cardiol 33:42, 1974 42 Hartman CW, Kong Y, Margolis JR, Warren SG, Peter RH, Behar VS, Oldham HN: Aortocoronary bypass surgery. Correlation of angiographic, symptomatic and functional improvement at I year. Am J Cardiol 37:352, 1976 43 Berk G, Kaplitt M, Padmanabhan V, Frantz S, Morrison J, Gulotta SJ: Management of pre-infarction angina. Evaluation and comparison of medical versus surgical therapy in 43 patients J THoRAc CARDtOVASC SURG 71: 110, 1976 44 Lapin ES, Murray JA, Bruce RA, Winterscheid L: Changes in maximal exercise performance in the evaluation of saphenous vein bypass surgery. Circulation 47:1164,1973 45 Bartel AG, Behar VS, Peter RH, Orgain ES, Kong Y: Exercise stress testing in evaluation of aorto-coronary bypass surgery. Report of 123 patients Circulation 48: 141, 1973 46 Mundth ED, Austen WG: Surgical measures for coronary heart disease. N Engl J Med 293:13,75, 124, 1975 47 Segal BL, Likoff W, Van Den Broek H, Kimbiris D, Najmi M, Linhart JW: Saphenous vein bypass surgery for impending myocardial infarction. Critical evaluation and current concepts. JAMA 223:767, 1973