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Late graft patency and symptom relief after aorta-coronary bypass
J
THORAC CARDIOVASC SURG
79:288-293, 1980
Late graft patency and symptom relief after aorta-coronary bypass One hundred six consecutive patients underwent elective or emergency coronary artery bypass grafting (CABG) between January. 1974. and November. 1975. There were 90 men of an average age of 54 years and 16 women an average of 64 years. Unstable angina (preinfarction angina. angina decubitus. and crescendo angina) was present in 54 patients of this group and eight were in congestive heart failure. Sixty-two of the 106 had previously had myocardial infarctions and four had evolving infarctions. There were four operative deaths (3 .8%) and one early hospital death (less than 30 days' hospitalization). Perioperative infarction occurred in five of the survivors. Of the 197 grafts placed in the 101 survivors. 94% were patent by angiography at 1 to 2 weeks (175 of 187 vein grafts and 10 of 10 left internal mammary grafts). At 1 to 2 years after CABG. 62% of the survivors consented to repeat angiography at which time 94% of the grafts were patent (101 of lOB vein grafts and seven of seven left internal mammary grafts). Clinical follow-up of 81 of the 101 survivors at 1 year found 99% of them to be asymptomatic or improved. Repeat clinical follow-up of all survivors (99 of 101) at 3 to 4 years found 93.9% asymptomatic or improved. Overall survival. including operative deaths. was 92.4% at 4 years.
Burt N. Fowler, M.D., Marshall L. Jacobs, M.D., Leonard Zir, M.D., Robert E. Dinsmore, M.D., Michael P. Vezeridis, M.D., and Willard M. Daggett, M.D., Boston, Mass.
Controversy still exists as to the long-term benefits of aorta-coronary bypass grafting for persons with coronary artery occlusive disease. As more experience has been gained, operative mortality as well as late mortality rates have decreased, as expected. Nevertheless, reports of patients followed for several years postoperatively have contained mixed information in terms of recurrent symptoms and graft patency. 1-3 The following is a report of 106 consecutive patients who underwent aorta-coronary bypass grafting by one surgeon at Massachusetts General Hospital between January, 1974, and November, 1975. The study was planned prospectively to examine early and late graft patency and to assess the effects of aorta-coronary bypass grafting on left ventricular function." All survivors underwent selective angiography 1 to 2 weeks From the Surgical Cardiovascular Unit, Cardiac Unit, and Radiology Department of the Massachusetts General Hospital. and the Departments of Surgery. Medicine. and Radiology of Harvard Medical School, Boston Mass. Supported in part by U. S. Public Health Service Grant HL-17665. Received for publication May 18, 1979. Accepted for publication July 13, 1979. Address for reprints: Willard M. Daggett, M.D., Massachusetts General Hospital, Boston, Mass. 02114.
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postoperatively, and 63 patients consented to follow-up angiography at 1 to 2 years after operation. Analysis of postoperative left ventricular segmental wall motion in this group of patients showed significant improvement, the results having been the subject of another report. 5 Acute and long-term graft patency, progression of disease, recurrent symptoms, and postoperative rehabilitation are herein analyzed. Follow-up was done in the office by one of the authors, as well as through questionnaires or telephone conversations with the patients and/or their physicians.
Patients and methods One hundred six consecutive patients, referred to one surgeon, underwent elective or emergency coronary artery bypass operation at Massachusetts General Hospital between January, 1974, and November, 1975.* There were 90 men and 16 women; the men ranged in age from 34 to 73 years (mean age, 54 years) and the women from 36 to 66 years (mean age, 64 years). Unstable angina (preinfarction angina, crescendo an*One hundred six patients were included in the protocol in order to ensure that at least 100 survivors would be available for follow-up angiography. Consecutive patient No. 107 and subsequent patients did well, but were not subjected to the protocol.
0022-5223/80/020288+06$00.60/0 © 1980 The C. V. Mosby Co.
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Aorta-coronary bypass
Number 2 February, 1980
gina, or angina decubitus) was present in 54 patients, and eight had congestive heart failure. Fifteen patients had a decrease in luminal diameter of the left main coronary artery exceeding 70%. Sixty-two of the 106 had previously had myocardial infarctions, and there were four patients with evolving acute myocardial infarction at the time of operation. Of the latter four, two were in cardiogenic shock and were supported preoperatively with the intra-aortic balloon pump. In addition, the intra-aortic balloon pump was used preoperatively for control of symptoms in seven patients. In seven additional patients intra-aortic balloon pumps were inserted for hemodynamic support either at the beginning of or immediately following the bypass phase of operation. In addition to aorta-coronary bypass grafting, three patients underwent concomitant mitral valve replacement, one patient underwent aortic valve replacement, and one closure of a postinfarct ventricular septal defect. Indications for operation were the presence of symptoms of myocardial ischemia or insufficiency unrelieved by medical management, and significant narrowing (2=70% decrease in luminal diameter) of one or more major coronary arteries. Techniques of operation employed during the study were as follows. The saphenous vein was harvested in such a manner as to leave it in its bed until time for use. It was then removed from the leg and distended with Hanks solution. Proximal anastomoses were performed prior to cardiopulmonary bypass using a side-biting clamp on the aorta. Cardiopulmonary bypass was accomplished with a bubble oxygenator (Bentley Temptrol). Systemic hypothermia to 28° C was induced with a heat exchanger, and topical myocardial cooling was also used. Most distal graft-ta-coronary artery anastomoses were performed with local vessel occlusion technique, aortic cross-clamping being reserved for anastomoses on the posterior surface of the heart. Distal anastomoses were performed in end-to-side fashion using nonabsorbable (7-0 Prolene) sutures. One mattress suture was placed at each end of the longitudinal arteriotomy and then run to the middle on each side, where they were tied. After separation of the patient from cardiopulmonary bypass, flow was measured in each graft using a Statham electromagnetic probe and meter. Postoperatively, all survivors had selective angiography at I to 2 weeks. Between I and 2 years after operation, all survivors were contacted for repeat catherization; 63 gave consent and were catheterized either at this institution or at the hospital where the patient's cardiologist practiced. All angiograms and
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hemodynamic records were obtained and analyzed. One to 2 years following operation, a questionnaire was sent to all survivors asking for information regarding current symptoms and employment. Eighty-one patients responded. At 2 to 4 years (average, 3.32) postoperatively, patients or their physicians were again contacted by phone or letter to determine their New York Heart Association (N.Y.H.A.) functional classifications and any changes in health or work status. At that time, information from all 99 late survivors was obtained. Results There were four operative deaths among the 106 patients, for a mortality rate of 3.8%. All were men; three had had angina decubitus (two with left main coronary artery stenosis and severe left ventricular dysfunction and the third with an evolving acute anterior infarct) and one had had Prinzmetal's variant angina. Also, there was an additional hospital death (woman) which occurred 3 weeks after operation. This patient's complicated postoperative course followed an intraoperative myocardial infarct due to subplaque hemorrhage in a vessel which had not appeared to be significantly narrowed on the preoperative angiogram. Postmortem examination was performed on four of the five patients who died and all grafts examined were patent. Thus the overall hospital mortality rate (operative and early deaths) was 4.7% for the patient population studied. The hospital mortality rates for patients with stable and unstable angina were 1.9% and 7.4%, respectively. Among the survivors there were five patients (4.9%) in whom a diagnosis of peri operative infarction was made on the basis of new Q waves or loss of R wave on follow-up electrocardiograms. One hundred ninety-seven grafts were placed in the 101 survivors (1.95 per patient): 29 patients (28.7%) received one graft; 49 patients (48.5%) received two grafts; 22 patients (21.7%) received three grafts; and one patient received four aorta-coronary bypass grafts. The left internal mammary artery was used in 10 patients for a graft to the left anterior descending coronary artery. Sequential grafts (two distal anastomoses-one side to side and one end to side) were used in seven patients and "Y" grafts in two patients. At cardiac catheterization I to 2 weeks postoperatively, 92% of the vein grafts and all of the left internal mammary grafts were patent. Of the occluded vein grafts, there were five (in 80) left anterior descending grafts, one (in 10) left anterior descending diagonal graft, four (in 42) left circumflex grafts, and five (in 55) right coronary or posterior descending artery grafts. Six of the seven se-
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quential grafts were patent (13 of 14 vessels) and both "Y" grafts were patent. Of vein grafts with flows of 60 ccl min or more, measured at the time of operation ( 160 grafts), II grafts (6.9%) were closed when studied angiographically at I to 2 weeks. Of the 27 vein grafts with flows less than 60 cc/min at the time of operation, four grafts (14.8%) were closed when studied angiographically at I to 2 weeks. There were no deaths during the first year of followup, and of the 101 survivors, 63 (62%) consented to repeat catheterization I to 2 years after operation. There were 115 grafts available for study. One hundred eight grafts were patent, including 101 of 108 vein grafts (93.5%) and seven of seven internal mammary grafts ( 100%). Four patients with sequential grafts were restudied. All grafts were patent, as was the single "Y" graft that was restudied. Operative flow data were available on all but three grafts restudied. Of vein grafts with flows of 60 cc/min or more (91 grafts), five (5.5%) were closed when studied angiographically at I to 2 years. Of the 14 vein grafts with flows less than 60 cc/min, one (7.1%) was closed. In addition to office follow-up, a questionnaire was filled out by 81 patients between I and 2 years postoperatively. At that time, 99% were asymptomatic or improved in terms of angina, and one patient reported a worsened condition. Forty-seven percent of those who responded were working full-time and 5% were working part-time. Reasons for unemployment included: (I) disability associated with coronary artery disease (13.5% ), (2) retirement by the company that had employed the patient preoperatively (8.6%), (3) retirement by personal choice (6.1%), (4) age (4.9%), (5) retirement at physician's request (3.7%), (6) medical disability other than coronary artery disease (2.4%), and (7) other, including family-related health problems (3.7%). At 3 to 4 years (average, 3.32 years) postoperatively it was possible to contact 99 patients through questionnaire and telephone conversations. This represented 100% of those surviving to that date. At that time, 65.3% were entirely asymptomatic, and 28.6% complained of rare to occasional chest pain but felt improved over their preoperative conditions; 6.1% felt that chest pain was the same or worse than the preoperative symptom pattern. Thus 93.9% remained asymptomatic or improved. At this second follow-up, 43.8% were working full-time and 4% were working part-time. Of those not working, 16% had retired postoperatively because of coronary artery disease; 8% had retired as a result of disability related to other medical problems; 4% had
been retired by the company after operation; 5% had retired because of age; 2% had retired at a doctor's request; and I% had retired for medical problems related to other members of their families. There had been two deaths by the time of latest follow-up. One death occurred in a 66-year-old woman 15 months after she had undergone three-vessel bypass and mitral valve replacement for congestive heart failure and mitral regurgitation of ischemic origin. A 54year-old man also died 3 1/ 2 years after he had undergone a two-vessel bypass. The first patient had been doing well but subsequently died in bed, and the second patient had reportedly developed symptoms of congestive heart failure prior to his death. Postmortem examination was not performed on either patient, and neither had undergone angiography I year after operation. All grafts in both patients had been shown to be patent at the time of early angiography, 2 weeks postoperatively. Approximately 2 months subsequent to the second follow-up, one other patient died-a 44-year-old dentist who had undergone a two-vessel bypass 2 years prior to his death. At the time of follow-up, he was reported to be asymptomatic and employed. The cause of death was a cerebrovascular accident. Total postoperative mortality rate to date is 3%, or about I% per year of follow-up. At the time of this report, none of the patients in this study group had undergone reoperation for symptoms of coronary artery disease. However, one patient had undergone cholecystectomy, one total knee replacement, one removal of a thromboembolus from the leg, and one resection of an abdominal aortic aneurysm. None of these patients had either intraoperative or postoperative cardiac complications. Discussion That aorta-coronary bypass grafting provides early symptomatic relief for patients with angina is well recognized. What remains to be answered, however, is how long these patients will remain without symptoms, and whether long-term survival is altered by revascularization of previously ischemic myocardium. This prospective study of a consecutive series of patients with both stable and unstable angina was planned to determine early and late graft patency. This subject has not been addressed previously at this institution in any systematic way. Considerably more information, beyond the subject of graft patency, was ultimately derived from the study. Survival. Mortality rate for patients during aorta-coronary bypass grafting for chronic, stable angina has decreased from as high as 12% in early series to 1%
Volume 79 Number 2 February, 1980
to 2% in most recently published series.P: 7 Concomitant with this has been a decrease in deaths of patients with unstable angina who have undergone surgical treatment for the disease. Patient selection has probably played a role in this decrease, but more importantly there have been improvements in preoperative medical management including pharmacologic interventions, improvement in surgical technique including myocardial protection, and improvement in postoperative care, the latter being the result of the creation of special postoperative cardiac surgical units. The operative mortality rate in this group of patients was 3.8%. This compares favorably with the results of other series in the same time period, as does the early mortality rate of 4.7%.8-10 Comparing the hospital deaths for stable versus unstable angina, the rates are 1.9% and 7.4%, respectively, again highlighting the added but not prohibitive risk of operating for unstable angina. The operative mortality rate in this and other recent series is considerably lower than that cited in the Veterans' Administration Cooperative Group for the study of the results of surgical and medical management of patients with chronic stable angina. I I In this series, 92.5% of all patients were alive at the time of most recent follow-up (average, 3.5 years). If the patients are divided into stable and unstable angina groups, then the survival rates are 96.3% and 88.5%, respectively. Even though surgical mortality rate imposes a bias on survival statistics, cumulative annual attrition remains low, with an average of 1.0% per year for patients with stable angina and 3.3% per year for those with unstable angina. Both of these figures are comparable to other surgical series.I'': 13. 14 and the survival for patients with unstable angina is better than the results among patients with unstable angina treated nonoperatively as reported by Hultgren and associates.I"
Several authors": 16. 17 have emphasized the differences in survival based on the extent of disease. From preoperative angiograms in this series, 23 patients had single-vessel, 35 patients had double-vessel, and 48 patients had triple-vessel involvement. Of the early and late deaths, there were no patients with single-vessel involvement, three patients with double-vessel involvement, and five patients with triple-vessel involvement. Graft patency. Although the group restudied at I to 2 years comprised only 64% of the population, restudy was performed without bias. This group of patients did not differ from those who did not undergo late study in terms of symptoms, number of vessels involved, or number of grafts.
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Early and I to 2 year graft patency rates in this series are comparable to rates in other reported series. 18. 19 The fact that the patency rates did not differ at the late study compared to the early study confirms the findings of Grondin and co-workers'? and those of Seides and colleagues- who reported that most graft failures in their series occurred early within the first year after operation; following that period, few grafts were lost. In some series.F" graft closure has been related to low flow. In this series, the attrition rate at both early and late angiographic follow-up was greater for grafts with less than 60 cc/min flow (measured at the time of operation). This, however, was not statistically significant (p = 0.15 and p = 0.59, respectively). Symptom relief. The relief of symptoms following aorta-coronary bypass grafting has been thought to be related to completeness of revascularization, perioperative infarction, and patency of aorta-coronary grafts. Analysis of this population, which preoperatively contained patients with stable and unstable angina, revealed that I year after operation, 76% were entirely symptom free, and of the 24% who claimed some chest pain, all but one felt significantly improved over preoperative status. As has been the case in other long-term series, follow-up after 2 to 4 years has revealed increases in the numbers of patients experiencing angina. The incidence of anginal symptoms increased from 24% to 35% during the follow-up interval of 2 to 3 1h years. However, a total of 94% of all survivors remained asymptomatic or improved as compared to preoperative status. Of the seven patients who had one graft closed at the time of late follow-up (no patient had more than one graft occluded), two had anginal symptoms, in one of whom they were less severe than preoperative symptoms. Of the 56 patients (out of 63 patients studied), 16 had patent grafts at I to 2 years and some persistent anginal symptoms. In 14 instances, however, symptoms were less severe than those existing preoperatively. Employment. Improvement in "quality of life" is a phrase frequently used when discussing symptoms following aorta-coronary bypass grafting. This can be extended to the ability to return to work after operation. In this series, 55% of those queried at I to 2 years claimed to have been out of work preoperatively because of symptoms related to coronary artery disease. At the time of follow-up, 52% of the group responding were employed, and of those not employed, only II (13.5%) were unemployed because of heart disease. At 3 to 4 years, the number of patients working decreased to
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47.8%, paralleling advancing age and, in a few patients, recurrence of symptoms. There was a small increase (to 17%) in the number unemployed because of coronary artery disease. The number working postoperatively is somewhat less than that reported by Symmes and associates" They pointed out, however, that while the increase in employment is small compared to the number of patients with symptomatic relief, the potential for job rehabilitation is greater. This is particularly true in light of the fact that many are unemployed for reasons not related to heart disease. As yet, there has been no long-term study with strict randomization of a large series of patients with angina into either a purely nonoperative course of treatment or an operative course of treatment. The relatively early long-term study of nonoperatively treated patients reported by Bruschke and his group" revealed a 5 year survival of 64.4% in a large group with angiographically proved coronary artery disease, and the primary cause of death was cardiac related. Several smaller but more recent studies revealed little difference in survival between medically and surgically treated groups, but the surgical groups were less symptomatic during the period of follow-up.t"?" Recent large surgical series have revealed overall 5 year survival of about 88%, with better survival rate in patients with good left ventricular function and single-or double-vessel disease and somewhat worse survival rate in patients with poor left ventricular function and multiple-vessel disease. 8, 9, 26 Despite the bias that operative death rate places on cumulative long-term survival statistics, these results and the increasing number of individuals with long-term relief of symptoms point to definite advantages afforded by operative treatment. The positive difference in more recent survival statistics as compared to earlier reports is undoubtedly the result of better operative techniques, higher graft patency rates, plus more complete revascularization. We thank Lois M. Sturm for her assistance in preparing the manuscript. REFERENCES Itscoitz SB, Redwood DR, Stinson EB, Reis RL, Epstein SE: Saphenous vein bypass grafts. Long-term patency and effect on the native coronary circulation. Am 1 Cardiol 36:739-743, 1975 2 Seides SF, Borer is. Kent KM, Rosing DR, McIntosh CL, Epstein SE: Long-term anatomic fate of coronaryartery bypass grafts and functional status of patients five years after operation. N EnglJ Med 298: 1213-1217, 1978 3 Tecklenberg PL, Alderman EL, Miller DC, Shumway
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NE, Harrison DC: Changes in survival and symptom relief in a longitudinal study of patients after bypass surgery. Circulation 51-52:(Suppl 1):98- 104, 1975 4 Dinsmore RE, Daggett WM, Miller SW, Vezeridis MP, Harthome lW, Zir LM: Left ventricular contraction following coronary artery bypass surgery. Circulation 5556:Suppl 3: 194, 1977 5 Zir LM, Dinsmore R, Vezeridis M, Singh lB, Harthorne lW, Daggett WM: Effects of coronary artery bypass surgery on resting left ventricular function in patients studied one to two years following surgery. Am 1 Cardiol 44: 601-606, 1979 6 Schmitt EH, Sharp EH: A comparative study: Operative mortality of coronary bypass surgery. III Med 1 152:99104, 1977 7 Isorn OW, Spencer FC, Glassman E, Cunningham lN, Teiko P, Reed GE, Boyd AD: Does coronary bypass increase longevity? 1 THoRAc CARDIOVASC SURG 75:28-37, 1978 8 Lawrie GM, Morris GC lr, Howell lF, Tredici TD, Chapman DW: Improved survival after 5 years in 1,144 patients after coronary bypass surgery. Am 1 Cardiol 42:709-715, 1978 9 Kaiser GC, Barner HB, Tyras DH, Codd lE, Mudd lG, Willman VL: Myocardial revascularization. A rebuttal of the cooperative study. Ann Surg 188:331-340, 1978 10 Reul GJ lr, Cooley DA, Wukasch DC, Kyger ER III, Sandiford FM, Hallman GL, Norman lC: Long-term survival following coronary artery bypass, Analysis of 4,522 consecutive patients. Arch Surg 110:1419-1424, 1975 11 Murphy ML, Hultgren HN, Detre K, Thomsen 1, Takaro T, Participants of the Veterans' Administration Cooperative Study: Treatment of chronic stable angina. A preliminary report of survival data of the randomized Veterans Administration Cooperative Study. N Engl 1 Med 297:621-627, 1977 12 Lawrie GM, Morris GC Jr, Howell lF, Ogura lW, Spencer WH III, Cashion GR, Winters WL, Beazley HL, Chapman DW, Peterson PK, Lie IT: Results of coronary bypass more than 5 years after operation in 434 patients. Clinical, treadmill exercise and angiographic correlations. Am 1 Cardiol 40:665-672, 1977 13 Schroeder lS, Lamb I, Hu M, Stinson EB: Coronary bypass surgery for unstable angina pectoris. Long-term survival and function. lAMA 237:2609-2612, 1977 14 Bourassa MG, Lesperance 1, Campeau L, Saltiel 1: Long-term results of coronary artery surgery. The Montreal experience, International Symposium on Cardiac Surgery (The Henry Ford Hospital, Detroit), lC Davila, ed., New York, 1975, Appleton-Century-Crofts, pp, 610-614 15 Hultgren HN, Pfeifer lF, Angell WW, Lipton Ml, Bilisoly 1: Unstable angina. Comparison of medical and surgical management. Am 1 Cardiol 39:734-740, 1977 16 Sheldon WC, Rincon G, Pichard AD, Razavi M, Cheanvechai C, Loop FD: Surgical treatment of coronary artery
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disease. Pure graft operations, with a study of 741 patients followed 3-7 yr. Prog Cardiovasc Dis 18:237-253, 1975 Stiles QR, Lindesmith GG, Tucker BL, Hughes RK, Meyer BW: Long-term follow-up of patients with coronary artery bypass grafts. Circulation 54:Suppl 3:32-34, 1976 Lawrie GM, Morris GC Jr, Chapman DW, Winters WL, Lie JT: Patterns of patency of 596 vein grafts up to seven years after aorta-coronary bypass. J THoRAcCARDIOVASC SURG 73:443-448, 1977 Grondin CM, Castonguay YR, Lesperance J, Bourassa MG, Campeau L, Grondin P: Attrition rate of aorta-tocoronary artery saphenous vein grafts after one year. A study in a consecutive series of 96 patients. Ann Thorac Surg 14:223-231, 1972 Campeau L, Crochet D, Lesperance J, Bourassa MG, Grondin CM: Postoperative changes in aortocoronary saphenous vein grafts revisited. Angiographic studies at two weeks and at one year in two series of consecutive patients. Circulation 52:369-377, 1975
21 Symmes JC, Lenkei SCM, Berman ND: Influence of aortocoronary bypass surgery on employment. Can Med Assoc J 118:268-270, 1978 22 Bruschke A VG, Proudfit WL, Sones FM Jr: Progress study of 590 consecutive nonsurgical cases of coronary disease followed 5-9 years. I. Arteriographic correlations. Circulation. 47: 1147-1153, 1973 23 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 293:1329-1333, 1975 24 Aronow WS, Stemmer EA: Two-year follow-up of angina pectoris. Medical or surgical therapy. Ann Intern Med 82:208-212, 1975 25 Guinn GA, Mathur VS: Surgical versus medical treatment for stable angina pectoris. Prospective randomized study with 1- to 4-year follow-up. Ann Thorac Surg 22:524527, 1976 26 Hall RJ, Garcia E, Mathur VS, Busch U, Cooley DA, Gold KA, Gray AG: Long-term follow-up after coronary artery bypass. Cleve Clin 45: 162-165, 1978
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Late graft patency and symptom relief after aorta-coronary bypass One hundred six consecutive patients underwent elective or emergency coronary artery bypass grafting (CABG) between January. 1974. and November. 1975. There were 90 men of an average age of 54 years and 16 women an average of 64 years. Unstable angina (preinfarction angina. angina decubitus. and crescendo angina) was present in 54 patients of this group and eight were in congestive heart failure. Sixty-two of the 106 had previously had myocardial infarctions and four had evolving infarctions. There were four operative deaths (3 .8%) and one early hospital death (less than 30 days' hospitalization). Perioperative infarction occurred in five of the survivors. Of the 197 grafts placed in the 101 survivors. 94% were patent by angiography at 1 to 2 weeks (175 of 187 vein grafts and 10 of 10 left internal mammary grafts). At 1 to 2 years after CABG. 62% of the survivors consented to repeat angiography at which time 94% of the grafts were patent (101 of lOB vein grafts and seven of seven left internal mammary grafts). Clinical follow-up of 81 of the 101 survivors at 1 year found 99% of them to be asymptomatic or improved. Repeat clinical follow-up of all survivors (99 of 101) at 3 to 4 years found 93.9% asymptomatic or improved. Overall survival. including operative deaths. was 92.4% at 4 years.
Burt N. Fowler, M.D., Marshall L. Jacobs, M.D., Leonard Zir, M.D., Robert E. Dinsmore, M.D., Michael P. Vezeridis, M.D., and Willard M. Daggett, M.D., Boston, Mass.
Controversy still exists as to the long-term benefits of aorta-coronary bypass grafting for persons with coronary artery occlusive disease. As more experience has been gained, operative mortality as well as late mortality rates have decreased, as expected. Nevertheless, reports of patients followed for several years postoperatively have contained mixed information in terms of recurrent symptoms and graft patency. 1-3 The following is a report of 106 consecutive patients who underwent aorta-coronary bypass grafting by one surgeon at Massachusetts General Hospital between January, 1974, and November, 1975. The study was planned prospectively to examine early and late graft patency and to assess the effects of aorta-coronary bypass grafting on left ventricular function." All survivors underwent selective angiography 1 to 2 weeks From the Surgical Cardiovascular Unit, Cardiac Unit, and Radiology Department of the Massachusetts General Hospital. and the Departments of Surgery. Medicine. and Radiology of Harvard Medical School, Boston Mass. Supported in part by U. S. Public Health Service Grant HL-17665. Received for publication May 18, 1979. Accepted for publication July 13, 1979. Address for reprints: Willard M. Daggett, M.D., Massachusetts General Hospital, Boston, Mass. 02114.
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postoperatively, and 63 patients consented to follow-up angiography at 1 to 2 years after operation. Analysis of postoperative left ventricular segmental wall motion in this group of patients showed significant improvement, the results having been the subject of another report. 5 Acute and long-term graft patency, progression of disease, recurrent symptoms, and postoperative rehabilitation are herein analyzed. Follow-up was done in the office by one of the authors, as well as through questionnaires or telephone conversations with the patients and/or their physicians.
Patients and methods One hundred six consecutive patients, referred to one surgeon, underwent elective or emergency coronary artery bypass operation at Massachusetts General Hospital between January, 1974, and November, 1975.* There were 90 men and 16 women; the men ranged in age from 34 to 73 years (mean age, 54 years) and the women from 36 to 66 years (mean age, 64 years). Unstable angina (preinfarction angina, crescendo an*One hundred six patients were included in the protocol in order to ensure that at least 100 survivors would be available for follow-up angiography. Consecutive patient No. 107 and subsequent patients did well, but were not subjected to the protocol.
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Aorta-coronary bypass
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gina, or angina decubitus) was present in 54 patients, and eight had congestive heart failure. Fifteen patients had a decrease in luminal diameter of the left main coronary artery exceeding 70%. Sixty-two of the 106 had previously had myocardial infarctions, and there were four patients with evolving acute myocardial infarction at the time of operation. Of the latter four, two were in cardiogenic shock and were supported preoperatively with the intra-aortic balloon pump. In addition, the intra-aortic balloon pump was used preoperatively for control of symptoms in seven patients. In seven additional patients intra-aortic balloon pumps were inserted for hemodynamic support either at the beginning of or immediately following the bypass phase of operation. In addition to aorta-coronary bypass grafting, three patients underwent concomitant mitral valve replacement, one patient underwent aortic valve replacement, and one closure of a postinfarct ventricular septal defect. Indications for operation were the presence of symptoms of myocardial ischemia or insufficiency unrelieved by medical management, and significant narrowing (2=70% decrease in luminal diameter) of one or more major coronary arteries. Techniques of operation employed during the study were as follows. The saphenous vein was harvested in such a manner as to leave it in its bed until time for use. It was then removed from the leg and distended with Hanks solution. Proximal anastomoses were performed prior to cardiopulmonary bypass using a side-biting clamp on the aorta. Cardiopulmonary bypass was accomplished with a bubble oxygenator (Bentley Temptrol). Systemic hypothermia to 28° C was induced with a heat exchanger, and topical myocardial cooling was also used. Most distal graft-ta-coronary artery anastomoses were performed with local vessel occlusion technique, aortic cross-clamping being reserved for anastomoses on the posterior surface of the heart. Distal anastomoses were performed in end-to-side fashion using nonabsorbable (7-0 Prolene) sutures. One mattress suture was placed at each end of the longitudinal arteriotomy and then run to the middle on each side, where they were tied. After separation of the patient from cardiopulmonary bypass, flow was measured in each graft using a Statham electromagnetic probe and meter. Postoperatively, all survivors had selective angiography at I to 2 weeks. Between I and 2 years after operation, all survivors were contacted for repeat catherization; 63 gave consent and were catheterized either at this institution or at the hospital where the patient's cardiologist practiced. All angiograms and
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hemodynamic records were obtained and analyzed. One to 2 years following operation, a questionnaire was sent to all survivors asking for information regarding current symptoms and employment. Eighty-one patients responded. At 2 to 4 years (average, 3.32) postoperatively, patients or their physicians were again contacted by phone or letter to determine their New York Heart Association (N.Y.H.A.) functional classifications and any changes in health or work status. At that time, information from all 99 late survivors was obtained. Results There were four operative deaths among the 106 patients, for a mortality rate of 3.8%. All were men; three had had angina decubitus (two with left main coronary artery stenosis and severe left ventricular dysfunction and the third with an evolving acute anterior infarct) and one had had Prinzmetal's variant angina. Also, there was an additional hospital death (woman) which occurred 3 weeks after operation. This patient's complicated postoperative course followed an intraoperative myocardial infarct due to subplaque hemorrhage in a vessel which had not appeared to be significantly narrowed on the preoperative angiogram. Postmortem examination was performed on four of the five patients who died and all grafts examined were patent. Thus the overall hospital mortality rate (operative and early deaths) was 4.7% for the patient population studied. The hospital mortality rates for patients with stable and unstable angina were 1.9% and 7.4%, respectively. Among the survivors there were five patients (4.9%) in whom a diagnosis of peri operative infarction was made on the basis of new Q waves or loss of R wave on follow-up electrocardiograms. One hundred ninety-seven grafts were placed in the 101 survivors (1.95 per patient): 29 patients (28.7%) received one graft; 49 patients (48.5%) received two grafts; 22 patients (21.7%) received three grafts; and one patient received four aorta-coronary bypass grafts. The left internal mammary artery was used in 10 patients for a graft to the left anterior descending coronary artery. Sequential grafts (two distal anastomoses-one side to side and one end to side) were used in seven patients and "Y" grafts in two patients. At cardiac catheterization I to 2 weeks postoperatively, 92% of the vein grafts and all of the left internal mammary grafts were patent. Of the occluded vein grafts, there were five (in 80) left anterior descending grafts, one (in 10) left anterior descending diagonal graft, four (in 42) left circumflex grafts, and five (in 55) right coronary or posterior descending artery grafts. Six of the seven se-
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quential grafts were patent (13 of 14 vessels) and both "Y" grafts were patent. Of vein grafts with flows of 60 ccl min or more, measured at the time of operation ( 160 grafts), II grafts (6.9%) were closed when studied angiographically at I to 2 weeks. Of the 27 vein grafts with flows less than 60 cc/min at the time of operation, four grafts (14.8%) were closed when studied angiographically at I to 2 weeks. There were no deaths during the first year of followup, and of the 101 survivors, 63 (62%) consented to repeat catheterization I to 2 years after operation. There were 115 grafts available for study. One hundred eight grafts were patent, including 101 of 108 vein grafts (93.5%) and seven of seven internal mammary grafts ( 100%). Four patients with sequential grafts were restudied. All grafts were patent, as was the single "Y" graft that was restudied. Operative flow data were available on all but three grafts restudied. Of vein grafts with flows of 60 cc/min or more (91 grafts), five (5.5%) were closed when studied angiographically at I to 2 years. Of the 14 vein grafts with flows less than 60 cc/min, one (7.1%) was closed. In addition to office follow-up, a questionnaire was filled out by 81 patients between I and 2 years postoperatively. At that time, 99% were asymptomatic or improved in terms of angina, and one patient reported a worsened condition. Forty-seven percent of those who responded were working full-time and 5% were working part-time. Reasons for unemployment included: (I) disability associated with coronary artery disease (13.5% ), (2) retirement by the company that had employed the patient preoperatively (8.6%), (3) retirement by personal choice (6.1%), (4) age (4.9%), (5) retirement at physician's request (3.7%), (6) medical disability other than coronary artery disease (2.4%), and (7) other, including family-related health problems (3.7%). At 3 to 4 years (average, 3.32 years) postoperatively it was possible to contact 99 patients through questionnaire and telephone conversations. This represented 100% of those surviving to that date. At that time, 65.3% were entirely asymptomatic, and 28.6% complained of rare to occasional chest pain but felt improved over their preoperative conditions; 6.1% felt that chest pain was the same or worse than the preoperative symptom pattern. Thus 93.9% remained asymptomatic or improved. At this second follow-up, 43.8% were working full-time and 4% were working part-time. Of those not working, 16% had retired postoperatively because of coronary artery disease; 8% had retired as a result of disability related to other medical problems; 4% had
been retired by the company after operation; 5% had retired because of age; 2% had retired at a doctor's request; and I% had retired for medical problems related to other members of their families. There had been two deaths by the time of latest follow-up. One death occurred in a 66-year-old woman 15 months after she had undergone three-vessel bypass and mitral valve replacement for congestive heart failure and mitral regurgitation of ischemic origin. A 54year-old man also died 3 1/ 2 years after he had undergone a two-vessel bypass. The first patient had been doing well but subsequently died in bed, and the second patient had reportedly developed symptoms of congestive heart failure prior to his death. Postmortem examination was not performed on either patient, and neither had undergone angiography I year after operation. All grafts in both patients had been shown to be patent at the time of early angiography, 2 weeks postoperatively. Approximately 2 months subsequent to the second follow-up, one other patient died-a 44-year-old dentist who had undergone a two-vessel bypass 2 years prior to his death. At the time of follow-up, he was reported to be asymptomatic and employed. The cause of death was a cerebrovascular accident. Total postoperative mortality rate to date is 3%, or about I% per year of follow-up. At the time of this report, none of the patients in this study group had undergone reoperation for symptoms of coronary artery disease. However, one patient had undergone cholecystectomy, one total knee replacement, one removal of a thromboembolus from the leg, and one resection of an abdominal aortic aneurysm. None of these patients had either intraoperative or postoperative cardiac complications. Discussion That aorta-coronary bypass grafting provides early symptomatic relief for patients with angina is well recognized. What remains to be answered, however, is how long these patients will remain without symptoms, and whether long-term survival is altered by revascularization of previously ischemic myocardium. This prospective study of a consecutive series of patients with both stable and unstable angina was planned to determine early and late graft patency. This subject has not been addressed previously at this institution in any systematic way. Considerably more information, beyond the subject of graft patency, was ultimately derived from the study. Survival. Mortality rate for patients during aorta-coronary bypass grafting for chronic, stable angina has decreased from as high as 12% in early series to 1%
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to 2% in most recently published series.P: 7 Concomitant with this has been a decrease in deaths of patients with unstable angina who have undergone surgical treatment for the disease. Patient selection has probably played a role in this decrease, but more importantly there have been improvements in preoperative medical management including pharmacologic interventions, improvement in surgical technique including myocardial protection, and improvement in postoperative care, the latter being the result of the creation of special postoperative cardiac surgical units. The operative mortality rate in this group of patients was 3.8%. This compares favorably with the results of other series in the same time period, as does the early mortality rate of 4.7%.8-10 Comparing the hospital deaths for stable versus unstable angina, the rates are 1.9% and 7.4%, respectively, again highlighting the added but not prohibitive risk of operating for unstable angina. The operative mortality rate in this and other recent series is considerably lower than that cited in the Veterans' Administration Cooperative Group for the study of the results of surgical and medical management of patients with chronic stable angina. I I In this series, 92.5% of all patients were alive at the time of most recent follow-up (average, 3.5 years). If the patients are divided into stable and unstable angina groups, then the survival rates are 96.3% and 88.5%, respectively. Even though surgical mortality rate imposes a bias on survival statistics, cumulative annual attrition remains low, with an average of 1.0% per year for patients with stable angina and 3.3% per year for those with unstable angina. Both of these figures are comparable to other surgical series.I'': 13. 14 and the survival for patients with unstable angina is better than the results among patients with unstable angina treated nonoperatively as reported by Hultgren and associates.I"
Several authors": 16. 17 have emphasized the differences in survival based on the extent of disease. From preoperative angiograms in this series, 23 patients had single-vessel, 35 patients had double-vessel, and 48 patients had triple-vessel involvement. Of the early and late deaths, there were no patients with single-vessel involvement, three patients with double-vessel involvement, and five patients with triple-vessel involvement. Graft patency. Although the group restudied at I to 2 years comprised only 64% of the population, restudy was performed without bias. This group of patients did not differ from those who did not undergo late study in terms of symptoms, number of vessels involved, or number of grafts.
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Early and I to 2 year graft patency rates in this series are comparable to rates in other reported series. 18. 19 The fact that the patency rates did not differ at the late study compared to the early study confirms the findings of Grondin and co-workers'? and those of Seides and colleagues- who reported that most graft failures in their series occurred early within the first year after operation; following that period, few grafts were lost. In some series.F" graft closure has been related to low flow. In this series, the attrition rate at both early and late angiographic follow-up was greater for grafts with less than 60 cc/min flow (measured at the time of operation). This, however, was not statistically significant (p = 0.15 and p = 0.59, respectively). Symptom relief. The relief of symptoms following aorta-coronary bypass grafting has been thought to be related to completeness of revascularization, perioperative infarction, and patency of aorta-coronary grafts. Analysis of this population, which preoperatively contained patients with stable and unstable angina, revealed that I year after operation, 76% were entirely symptom free, and of the 24% who claimed some chest pain, all but one felt significantly improved over preoperative status. As has been the case in other long-term series, follow-up after 2 to 4 years has revealed increases in the numbers of patients experiencing angina. The incidence of anginal symptoms increased from 24% to 35% during the follow-up interval of 2 to 3 1h years. However, a total of 94% of all survivors remained asymptomatic or improved as compared to preoperative status. Of the seven patients who had one graft closed at the time of late follow-up (no patient had more than one graft occluded), two had anginal symptoms, in one of whom they were less severe than preoperative symptoms. Of the 56 patients (out of 63 patients studied), 16 had patent grafts at I to 2 years and some persistent anginal symptoms. In 14 instances, however, symptoms were less severe than those existing preoperatively. Employment. Improvement in "quality of life" is a phrase frequently used when discussing symptoms following aorta-coronary bypass grafting. This can be extended to the ability to return to work after operation. In this series, 55% of those queried at I to 2 years claimed to have been out of work preoperatively because of symptoms related to coronary artery disease. At the time of follow-up, 52% of the group responding were employed, and of those not employed, only II (13.5%) were unemployed because of heart disease. At 3 to 4 years, the number of patients working decreased to
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47.8%, paralleling advancing age and, in a few patients, recurrence of symptoms. There was a small increase (to 17%) in the number unemployed because of coronary artery disease. The number working postoperatively is somewhat less than that reported by Symmes and associates" They pointed out, however, that while the increase in employment is small compared to the number of patients with symptomatic relief, the potential for job rehabilitation is greater. This is particularly true in light of the fact that many are unemployed for reasons not related to heart disease. As yet, there has been no long-term study with strict randomization of a large series of patients with angina into either a purely nonoperative course of treatment or an operative course of treatment. The relatively early long-term study of nonoperatively treated patients reported by Bruschke and his group" revealed a 5 year survival of 64.4% in a large group with angiographically proved coronary artery disease, and the primary cause of death was cardiac related. Several smaller but more recent studies revealed little difference in survival between medically and surgically treated groups, but the surgical groups were less symptomatic during the period of follow-up.t"?" Recent large surgical series have revealed overall 5 year survival of about 88%, with better survival rate in patients with good left ventricular function and single-or double-vessel disease and somewhat worse survival rate in patients with poor left ventricular function and multiple-vessel disease. 8, 9, 26 Despite the bias that operative death rate places on cumulative long-term survival statistics, these results and the increasing number of individuals with long-term relief of symptoms point to definite advantages afforded by operative treatment. The positive difference in more recent survival statistics as compared to earlier reports is undoubtedly the result of better operative techniques, higher graft patency rates, plus more complete revascularization. We thank Lois M. Sturm for her assistance in preparing the manuscript. REFERENCES Itscoitz SB, Redwood DR, Stinson EB, Reis RL, Epstein SE: Saphenous vein bypass grafts. Long-term patency and effect on the native coronary circulation. Am 1 Cardiol 36:739-743, 1975 2 Seides SF, Borer is. Kent KM, Rosing DR, McIntosh CL, Epstein SE: Long-term anatomic fate of coronaryartery bypass grafts and functional status of patients five years after operation. N EnglJ Med 298: 1213-1217, 1978 3 Tecklenberg PL, Alderman EL, Miller DC, Shumway
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NE, Harrison DC: Changes in survival and symptom relief in a longitudinal study of patients after bypass surgery. Circulation 51-52:(Suppl 1):98- 104, 1975 4 Dinsmore RE, Daggett WM, Miller SW, Vezeridis MP, Harthome lW, Zir LM: Left ventricular contraction following coronary artery bypass surgery. Circulation 5556:Suppl 3: 194, 1977 5 Zir LM, Dinsmore R, Vezeridis M, Singh lB, Harthorne lW, Daggett WM: Effects of coronary artery bypass surgery on resting left ventricular function in patients studied one to two years following surgery. Am 1 Cardiol 44: 601-606, 1979 6 Schmitt EH, Sharp EH: A comparative study: Operative mortality of coronary bypass surgery. III Med 1 152:99104, 1977 7 Isorn OW, Spencer FC, Glassman E, Cunningham lN, Teiko P, Reed GE, Boyd AD: Does coronary bypass increase longevity? 1 THoRAc CARDIOVASC SURG 75:28-37, 1978 8 Lawrie GM, Morris GC lr, Howell lF, Tredici TD, Chapman DW: Improved survival after 5 years in 1,144 patients after coronary bypass surgery. Am 1 Cardiol 42:709-715, 1978 9 Kaiser GC, Barner HB, Tyras DH, Codd lE, Mudd lG, Willman VL: Myocardial revascularization. A rebuttal of the cooperative study. Ann Surg 188:331-340, 1978 10 Reul GJ lr, Cooley DA, Wukasch DC, Kyger ER III, Sandiford FM, Hallman GL, Norman lC: Long-term survival following coronary artery bypass, Analysis of 4,522 consecutive patients. Arch Surg 110:1419-1424, 1975 11 Murphy ML, Hultgren HN, Detre K, Thomsen 1, Takaro T, Participants of the Veterans' Administration Cooperative Study: Treatment of chronic stable angina. A preliminary report of survival data of the randomized Veterans Administration Cooperative Study. N Engl 1 Med 297:621-627, 1977 12 Lawrie GM, Morris GC Jr, Howell lF, Ogura lW, Spencer WH III, Cashion GR, Winters WL, Beazley HL, Chapman DW, Peterson PK, Lie IT: Results of coronary bypass more than 5 years after operation in 434 patients. Clinical, treadmill exercise and angiographic correlations. Am 1 Cardiol 40:665-672, 1977 13 Schroeder lS, Lamb I, Hu M, Stinson EB: Coronary bypass surgery for unstable angina pectoris. Long-term survival and function. lAMA 237:2609-2612, 1977 14 Bourassa MG, Lesperance 1, Campeau L, Saltiel 1: Long-term results of coronary artery surgery. The Montreal experience, International Symposium on Cardiac Surgery (The Henry Ford Hospital, Detroit), lC Davila, ed., New York, 1975, Appleton-Century-Crofts, pp, 610-614 15 Hultgren HN, Pfeifer lF, Angell WW, Lipton Ml, Bilisoly 1: Unstable angina. Comparison of medical and surgical management. Am 1 Cardiol 39:734-740, 1977 16 Sheldon WC, Rincon G, Pichard AD, Razavi M, Cheanvechai C, Loop FD: Surgical treatment of coronary artery
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disease. Pure graft operations, with a study of 741 patients followed 3-7 yr. Prog Cardiovasc Dis 18:237-253, 1975 Stiles QR, Lindesmith GG, Tucker BL, Hughes RK, Meyer BW: Long-term follow-up of patients with coronary artery bypass grafts. Circulation 54:Suppl 3:32-34, 1976 Lawrie GM, Morris GC Jr, Chapman DW, Winters WL, Lie JT: Patterns of patency of 596 vein grafts up to seven years after aorta-coronary bypass. J THoRAcCARDIOVASC SURG 73:443-448, 1977 Grondin CM, Castonguay YR, Lesperance J, Bourassa MG, Campeau L, Grondin P: Attrition rate of aorta-tocoronary artery saphenous vein grafts after one year. A study in a consecutive series of 96 patients. Ann Thorac Surg 14:223-231, 1972 Campeau L, Crochet D, Lesperance J, Bourassa MG, Grondin CM: Postoperative changes in aortocoronary saphenous vein grafts revisited. Angiographic studies at two weeks and at one year in two series of consecutive patients. Circulation 52:369-377, 1975
21 Symmes JC, Lenkei SCM, Berman ND: Influence of aortocoronary bypass surgery on employment. Can Med Assoc J 118:268-270, 1978 22 Bruschke A VG, Proudfit WL, Sones FM Jr: Progress study of 590 consecutive nonsurgical cases of coronary disease followed 5-9 years. I. Arteriographic correlations. Circulation. 47: 1147-1153, 1973 23 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 293:1329-1333, 1975 24 Aronow WS, Stemmer EA: Two-year follow-up of angina pectoris. Medical or surgical therapy. Ann Intern Med 82:208-212, 1975 25 Guinn GA, Mathur VS: Surgical versus medical treatment for stable angina pectoris. Prospective randomized study with 1- to 4-year follow-up. Ann Thorac Surg 22:524527, 1976 26 Hall RJ, Garcia E, Mathur VS, Busch U, Cooley DA, Gold KA, Gray AG: Long-term follow-up after coronary artery bypass. Cleve Clin 45: 162-165, 1978