Immediate coronary artery bypass for acute evolving myocardial infarction

J THORAC CARDIOVASC

SVRG

81:493-497, 1981

Immediate coronary artery bypass for acute evolving myocardial infarction Two hundred twenty-seven consecutive patients had chest pain and electrocardiographic, coronary angiographic, ventriculographic, and retrospective enzyme changes consistent with acute evolving myocardial infarction (AEMI). These patients underwent coronary artery bypass grafting an average of less than 6 hours after the start of chest pain. The mean age was 55.8 years (range 28 to 79 years). Sex, coronary artery involvement, and preoperative and postoperative enzymes and electrocardiograms are presented. Follow-up angiocardiograms done an average of 12.7 months postoperatively revealed 99 patent primary grafts in 102 patients (94.3%). Ejection fractions were normal, unchanged, or improved in 86.3% of the patients. Two ventricular aneurysms measuring less than 2.5 em in diameter were noted. Surgical in-hospital mortality was 1.76% and first-year mortality was 1.44%. Conventional therapy in 200 AEMI patients treated at the same hospitals resulted in an in-hospital mortality of 11.5%. Follow-up of 213 patients having coronary artery bypass grafting revealed that 14% had mild angina. AEMI interrupted by coronary artery bypass grafting early in the syndrome yields results which are superior to conventional management.

Ralph Berg, Jr., M.D., Samuel L. Selinger, M.D. (by invitation), Jack J. Leonard, M.D. (by invitation), Ronald P. Grunwald, M.D. (by invitation), and William P. O'Grady, M.D. (by invitation), Spokane, Wash.

Infarction is defined as "an area of tissue in an organ or part which undergoes necrosis following cessation of the blood supply. "\ The term acute myocardial infarction is commonly used for the clinical entity with which we are dealing. We believe acute evolving myocardial infarction (AEMI) should be used to designate patients who are early in the syndrome and have reversibly damaged myocardium. Established myocardial infarction indicates necrotic myocardium. Revascu1arization by prompt coronary artery bypass salvages cardiac muscle and life when performed early. In this study, we treated 227 consecutive patients from March, 1971, through April, 1979, with coronary artery bypass grafts for AEMI. From Sacred Heart Medical Center and Deaconess Hospital, Spokane, Wash. Supported by the Spokane Eagles Lodge and the Max Baer Heart Fund. Read at the Sixtieth Annual Meeting of The American Association for Thoracic Surgery, San Francisco, Calif., April 28 to 30, 1980. Address for reprints: Ralph Berg, Jr., M.D., South Center Medical Building, Spokane, Wash. 99204.

Patients and methods From March, 1971, through April, 1979, 227 patients underwent immediate coronary artery bypass grafting for AEMI at Sacred Heart Medical Center or Deaconess Hospital in Spokane, Washington. All 227 patients were initially evaluated by cardiologists and fulfilled the following criteria for AEMI2: (1) chest pain typical of acute infarction, (2) Q waves and ST injury patterns on the electrocardiogram, (3) major lesion in coronary artery cineangiography, (4) ventriculographic abnormality, (5) Nos. 2, 3, and 4-all consistent, (6) elevation of serum glutamic oxaloacetic transaminase (SOOT) and creatinine kinase (CPK) (retrospective). The decision to treat the patient medically or surgically was shared by the cardiologist and surgeon. Those not afforded emergency coronary artery bypass were (1) patients who were too far into the infarction syndrome, (2) patients with evolving infarctions resulting from small coronary artery branch occlusions, and (3) patients whose evolving infarctions were small because of obstructions to nondominant right or nondominant circumflex arteries. No patients were refused operation because of age, arrhythmia, pulmonary edema, or cardiogenic shock. No catheterization laboratory accidents

0022-5223/81/040493+05$00.50/0 © 1981 The C. V. Mosby Co.

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1--

Table I. Age and sex distribution

Age (yr)

Sex Male (81.9%) Female (18.1%)

Average

Range

54.9 56.8

28-75 33-79

Table II. Coronary artery primarily involved Coronary artery LAD RCA Circumflex Combined Uncertain

I

No.

1---%---

104 85 26 8 4

46 37 II 4

2

Legend: LAD, Left anterior descending. RCA, Right coronary artery.

Table III. Average preoperative and postoperative enzyme values in AEMI patients _ _ _ _ _1

SGOT

CPK

Preop.

'--A-Vg-.-n-o-rm-.--

Pos/op.

30.78 134.46

12.5 35.0

162.87 1221.92

Legend: SOOT, Serum glutamic oxaloacetic transaminase. CPK, Creatinine phosphokinase.

are included. All of our patients with AEMI who underwent coronary artery bypass grafting have been included.

Features of clinical management Sacred Heart Medical Center and Deaconess Hospital in Spokane, Washington, have cardiac catheterization and operating room facilities and personnel available on an emergency basis at all times. Patients with AEMI are taken directly to the operating room from the cardiac catheterization laboratory. Cardiopulmonary bypass is achieved by cannulation of the ascending aorta and a single-stage, right atrial venous siphon. Hypothermia is established by core cooling to 25° to 28° C. Topical, cold (4° C) Ringer's solution is applied immediately to the heart as it lies in the pericardial sac. Following aortic cross-clamping, cardioplegic solution at 4° C is injected into the aortic root, completing the hypothermic protection of the myocardium. Vessels with proximal stenoses of 50% or more are grafted, the first one grafted always being the vessel to the dyskinetic area of myocardium. (Only three primary vessels were less than 90% obstructed.) A side-biting aortic clamp affords a short cross-clamp time by allowing

coronary perfusion with blood through the aortic root while the aortic anastomoses are made. Probing of the coronary arteries is minimized. Clots in the coronary arteries are removed only if encountered at the coronary arteriotomy site.

Results Age and sex. Age and sex distributions are shown in Table I. The oldest patient was a 79-year-old woman and the youngest was a 28-year-old man. Women, on the average, were approximately 2 years older than men. Men predominated in the group, comprising 82% of the patients. Coronary artery primarily involved. Table II summarizes the coronary artery that was primarily involved in the AEMI. The left anterior descending (LAD) coronary artery was the most frequently involved, followed by the right coronary artery and then the circumflex. In 4% of the cases more than one vessel contributed to the infarction, and in 2% of the cases the primary vessel could not be labeled with any certainty. Enzymes. The average preoperative and postoperative SGOT and CPK values are presented in Table III. SGOT and CPK values were elevated preoperatively in 76% of the patients and rose further in the postoperative period. A typical rise in CPK values is presented in Table IV. A 56-year-old man experienced the onset of AEMI at 12:00 midnight on Feb. 10, 1977, and the operation was begun at 7:10 A.M. The CPK value peaked shortly after operation with the MB fraction returning to normal within 72 hours. Catheterization and operation time. The average time required to complete the cardiac catheterization and cineangiographic studies on these patients was 34.10 minutes. The average time to complete the operation was 3 hours, 14 minutes. The number of grafts ranged from one to five, with an average of 2.2 grafts per patient. The average time from the onset of pain to the beginning of operation was 5 hours, 22 minutes. The primary graft was placed within 1 hour. The shortest time from the onset of pain to the beginning of operation was I hour, 20 minutes in a patient who had been previously studied, was in the hospital, and exhibited the AEMI syndrome in the postcatheterization period. The longest time from the onset of pain to the beginning of operation was 13 hours, 40 minutes in a patient who had a "stuttering" infarction syndrome. Preoperative complications. In 93 of the 227 patients (41%), preoperative complications of significance occurred. Forty-eight patients (21.2%) had arrhythmias, and five had temporary pacemakers placed. Twenty-five patients had major arrhythmias (11%), eight requiring

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one or more defibrillations by external shock. Seventeen patients required defibrillation and cardiopulmonary resuscitative efforts including external cardiac compression. Nineteen patients (8.4%) had all of the clinical criteria for cardiogenic shock. Only one ofthese patients died. Radiographic and clinical findings of pulmonary edema were present in seven patients (3.1 %). Only one patient (0.4%) was supported by intra-aortic balloon counterpulsation preoperatively. Mortality. There were four postoperative deaths in this series, yielding an operative mortality of 1.76%. The clinical course of these four patients is summarized below.

Case reports CAS E 1. A 49-year-old man had an acute inferior wall myocardial infarction, diagnosed at an outside hospital. He was brought to Sacred Heart Medical Center in a semicomatose state followingresuscitation from ventricularfibrillation. He underwent coronary artery bypass grafting to the right coronary artery. Postoperatively, he remained in a comatose state and died on the tenth postoperative day. CAS E 2. A 52-year-old man had an acute inferior wall myocardial infarction and underwent coronary artery bypass grafting to the LAD, diagonal, and circumflex coronary arteries. Sixteen hours postoperatively, an exploratory operation was performed for bleeding from a saphenous vein graft, and he had a cardiac arrest at that time. Subsequently, pulmonary edema, renal failure, and upper gastrointestinal tract bleeding developed, and he died of ventricular fibrillation on the fifteenth postoperative day. CASE 3. A 48-year-old woman presented with an anterior wall myocardial infarction and developed hypotension with an aortic systolic pressure of less than 70 mm Hg prior to cardiac catheterization. She was resuscitated with vasopressors and external cardiac massage. She underwent coronary artery bypass grafting for a 90% stenosis of the left main coronary artery and a 100% stenosis of the LAD coronary artery. The LAD coronary artery could not be bypassed at operation. She died of cardiogenic shock on the seventh postoperative day. CASE 4. A 53-year-old man presented with a lateral wall myocardial infarction and underwent coronary artery bypass grafting to the LAD, marginal, and diagonal coronary arteries. The right coronary artery, which was 100% obstructed, could not be bypassed at operation. The patient died on the second postoperative day in cardiogenic shock.

Postoperative complications. Seventy patients had a total of 86 postoperative complications. Hypotension (aortic systolic blood pressure of less than 90 mm Hg) necessitating vasopressor support occurred in 22 patients. Nine of these patients required intra-aortic balloon pumping. Pulmonary edema was present in 10 patients and was treated routinely with digitalis and diuretics. Four patients required reoperation for bleeding, which was primarily graft-related. Pulmonary em-

495

Table IV. Enzyme studies in a 56-year-old man

I

Date/time

I

CPK*

Preop. Feb. 10/4:40 A.M. Postop. Feb. 10/10:00 A.M. Feb. 10/10:55 A.M. Feb. 11/6:00 A.M. Feb. 12/6:00 A.M. Feb. 1317:15 A.M.

MBt

32

0.7

1542 2464 993 365 197

32.7 66.7 9.5 2.9 2.0

"Average normal up to 35.

t Average normal up to 2.0.

Table V. Graft patency rate* Grafts patent

I

Grafts studied

No.

105 140

99 123

Area of infarction Secondary areas

%

94 88

"A total of 102 patients (with 245 grafts) were studied an average of 12.7 months after operation.

Table VI. Enzyme studies in a 43-year-old man Date/time Preop. Jan. 16/midnight Postop. Jan. 16/6:00 Jan. 17/6:00 Jan. 19/6:00 Jan. 21/6:00

A.M.

EJ

El

%MM

E

150

76

1990

97

3

507

308 266 142 89

6820 9550 4475 1009

98 100 100

2

A.M. A.M. A.M.

SGOT

333

Legend: LDH, Lactic dehydrogenase. For other abbreviations see Table Ill.

bolism was demonstrated by pulmonary angiography in seven patients. A typical postpericardiotomy syndrome developed in seven patients, and pneumothorax occurred in seven patients. Two permanent pacemakers were placed for complete heart block. There were six minor leg wound problems and one case of late sternal nonunion. Two patients had gastrointestinal bleeding. No patient in the postoperative period was found to have papillary muscle dysfunction, mitral regurgitation, ventricular rupture, or postinfarction ventricular septal defect. The mean postoperative hospital stay was 9.1 days. Follow-up. Postoperative cineangiographic studies were obtained on 245 vein grafts in 102 patients at an average of 12.7 months postoperatively. The results are shown in Table V. Ninety-nine grafts (94%) to the ischemic areas were patent, and 88.2% of the grafts to

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the nonischemic areas were patent. Eighty-eight patients (86%) studied had normal, unchanged, or improved ejection fractions. There were three late deaths within I year; two occurred 3 months postoperatively and one, 9 months postoperatively. Mild angina was present in 30 patients (14.1 %). Of the 213 patients, 208 felt that the quality of life was the same or improved (97.7%). Four patients (1.9%) felt it was worse-two for noncardiac reasons.

Case report A 43-year-old man experienced chest pain at 8:00 P.M. and entered the Valley General Hospital Emergency Room at 8:45 P.M. Electrocardiogram was interpreted as normal at 8:54 P.M. He had a cardiac arrest after vomiting at 9:10 P.M. and required external cardiac massage and ten 400 watt-second defibrillations along with morphine, dopamine, lidocaine, and bretylium to stabilize his condition at a blood pressure of 90/60 mm Hg by 10:20 P.M. Electrocardiogram at 9:50 P.M. showed hyperacute changes characteristic of an AEMI in the distribution of the LAD coronary artery. He continuedto have chest pain and was diaphoretic and pale. The patient was transferred to Sacred Heart MedicalCenter where cardiac catheterization and cineangiography, completed by 11:20 P.M., showed 100% occlusion of the LAD vessel, 75% obstruction of the obtuse marginal vessel, and akinesia of the anterolateral wall and septum. The left ventricular pressure before angiography was 81/23/45 mm Hg and after angiography, 71/16/39 mm Hg. Surgical observations included a tense pericardium, akinetic anterolateral wall of the ventricle, and dark blood in the LAD vessel. Cross-clamp time was 27 minutes. Bypass time was I hour, 8 minutes with coronary artery bypass grafting completed at 3:15 A.M. The flow in the LAD graft was 160 cc/min at a blood pressure of 113/64 mm Hg. The flow in the circumflex graft was 50 cc/min at a blood pressure of 111/63 mm Hg. The enzymatic studies were as indicated in Table VI. Postoperatively, mild hypotension was managed with dopamine. He was discharged on the thirteenth postoperative day and is alive and well at the time of this writing.

Discussion The diagnosis of AEMI is made by history, electrocardiogram, cineangiographic, and ventriculographic findings. Time limits preclude waiting for enzyme studies and insertion of an intra-aortic balloon. Every effort is made to place the patient on cardiopulmonary bypass and restore coronary circulation as soon as possible. Delay in operation is associated with a prohibitive surgical mortality. 3 Endotracheal anesthesia relieves the work of ventilation. Operating room facilities provide optimum patient control and physiological monitoring. The cardiac workload is relieved by cardiopulmonary bypass. Hypothermia and cold cardioplegia protect the myocardium until coronary artery bypass grafting has re-

Thoracic and Cardiovascular Surgery

stored the circulation. This provides a return to aerobic metabolism by the return of oxygen and substrate. The washout phenomenon demonstrated in the creatinine kinase table indicates a removal of intracellular products released during the ischemia." 5 DeWood and associates" reported on 228 patients (age range 40 to 65 years) with AEMI who received conventional therapy at Sacred Heart Medical Center and Deaconess Hospital in Spokane, Washington, from 1972 through 1976. The in-hospital mortality for this group of patients was 11.5% (23 patients). Reported hospital mortality ranges from 12% to 24% for acute myocardial infarction. 7- 9 * Kennedy and coworkers'? found a mortality of 27.5% in 655 patients with acute infarction in the distribution of the LAD artery and a 22.5% mortality in 520 patients with inferior wall myocardial infarction. Furthermore, the first-year mortality following acute myocardial infarction has been as high as 14%.10 In contrast, our operated series of 227 patients who received prompt coronary artery bypass for AEMI gave a 1.76% in-hospital mortality and a first-year mortality in the 213 follow-up cases of 1.44%-the sum being 3.2%-roughly a tenfold difference in the two methods of management of an AEMI. This is no longer a unique experience; our results" have been confirmed.'! We have emphasized comparable mortality, since death is a definite end point not subject to argument. However, there are other morbidity items to consider. One would predict a 3% to 20% incidence of ventricular aneurysm. 12. 13 However, there were only two, both less than 2.5 em in diameter, in 102 patients studied postoperatively. Ventricular rupture, ventricular septal perforation, and mitral regurgitation resulting from chordal or papillary muscle rupture all have an incidence of approximately I % in AEMI patients conventionally managed.:" No patient in this group having coronary artery bypass had any of these complications. Persistent angina occurs in 50% of the conventionally managed patients." Less than 14% of the surgically managed patients had persistent angina.

Conclusion This report is the largest published series of AEMI patients treated with coronary artery bypass grafting, dating back to 1971. The cardiovascular surgeon should be involved early in the diagnostic and therapeutic decisions for AEMI patients. AEMI patients *Presentation by Robert O'Rourke, M.D., Cardiology for Consultants, Rancho Santa Fe, April, 1974.

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seen in time should have cineangiography. Those found to fit our criteria should be offered prompt coronary artery bypass grafting. We again conclude that prompt coronary artery bypass grafting is the superior method of management for AEMI patients. Preparation of the manuscript as well as research work by Sherri Stockman is gratefully acknowledged. REFERENCES I Taber Cyclopedic Dictionary 2 Berg R Jr, Kendall RW, Duvoisin GE, Ganji JH, Rudy LW, Everhart FJ: Acute myocardial infarction. A surgical emergency. J THORAC CARDIOVASC SURG 70:432-439, 1975 3 Dawson JT, Hall RJ, Hallman GL, Cooley DA: Mortality in patients undergoing coronary artery bypass surgery after myocardial infarction. Am J Cardiol 33:483-486, 1974 4 Vatner SF, Baig H, Manders WT, Maroko PR: Effects of coronary artery reperfusion on myocardial infarct size calculated from creatinine kinase. J Clin Invest 61: 10481056, 1978 5 Roe CR, Starmer CF: A sensitivity analysis of enzymatic estimation of infarct size. Circulation 52:1-5, 1975 6 DeWood M, Spores J, Notske R, Lang H, Shields J, Simpson C, Rudy L, Grunwald R: Medical and surgical management of myocardial infarction. Am J Cardiol 44: 1356-1364, 1979 7 Killip T III, Kimball JT: Treatment of myocardial infarction in a coronary care unit. A two-year experience with 250 patients. Am J Cardiol 20:457-464, 1967 8 Timmis GC: Cardiovascular Review 1980, Baltimore, 1980, The Williams & Wilkins Company, p 53 9 Henning H, Gilpin E, Covel J, Swan E, O'Rourke R, Ross T: Prognosis after acute myocardial infarction. A multivariant analysis of mortality and survival. Circulation 59: 1124-1136, 1979 10 Kennedy HL, Goldberg RM, Szklo M, Tonascia JA: The prognosis of anterior myocardial infarction revisited. A community-wide study. Clin Cardiol 2:455, 1979 11 Phillips SJ, Kongtahwom C, Zeff RH, Benson M, Iannone L, Brown T, Gordon DF: Emergency coronary artery revascularization. A possible therapy for acute myocardial infarction. Circulation 60:241-246, 1979 12 Schlichter J, Hellerstein HK, Katz LN: Aneurysm of the heart. A correlative study of one hundred and two proved cases. Medicine 33:43-86, 1954 13 Dubnow MH, Burchell HB, Titus JL: Postinfarction ventricular aneurysm. A clinicomorphologic and electrocardiographic study of 80 cases. Am Heart J 70:753-760, 1965

14 Fishbein MC: The pathology of myocardial infarction, The Treatment of Acute Myocardial Ischemia, LH Cohen, ed., Mount Kisco, N. Y., 1979, Futura Publishing Co., Inc., pp 11-47 15 Borow KM, Alpert JS: The natural history and treatment of coronary artery disease. Cardiovasc Med 4:87, 1978

Discussion DR. DAVID BREGMAN New York. N. Y.

I rise to compliment Dr. Berg and his associates for this very important presentation. I stand here not to condone or condemn the approach but merely to add another aspect of support to it. If an aggressive approach to these patients is indicated, a technological improvement in intra-aortic balloon pumping has occurred within the last 2 years that might be advantageous, namely, the percutaneous approach to intra-aortic balloon pumping. In brief, the approach uses the standard Seldinger technique and should be employed only by a cardiologist or surgeon experienced with it. The femoral artery is punctured with an angiographic needle and a guide wire is inserted. Initially an 8 Fr. dilator is passed over the guide wire to predilate the subcutaneous tissues and the femoral artery, and this is then replaced by a combination 12 Fr. dilator sheath assembly. Next, the percutaneous balloon is furled for insertion. The difference between this new balloon, which is 40 cc in volume, and the standard balloon is that the catheter segment within the balloon has been replaced by a wire support enabling the operator to wrap the balloon around the wire. This permits passage through the 12 Fr. sheath. Finally, the 12 Fr. dilator and guide wire are removed, and the balloon is inserted through the sheath and is positioned, preferrably fluoroscopically, in the descending thoracic aorta. When the balloon catheter is connected to the pumping console, the balloon unswivels and normal diastolic augmentation commences. The balloon can be removed very simply by pulling out the balloon-sheath combination and exerting external pressure on the artery for 30 minutes. The complications associated with use of this balloon have been fewer in number than our experience with the nonpercutaneous intra-aortic balloon. Therefore, this approach might be a useful complement, especially in the cardiac catheterization laboratory, where patients who are having severe arrhythmias, hypotension, or an evolving massive infarct with cardiogenic shock can be stabilized within 2 or 3 minutes by exchanging the guide wire for the percutaneous intra-aortic balloon.