REPORTS ON THERAPY
Coronary Artery Bypass Surgery for Left Main Coronary Artery Disease
DAVID R. McCONAHAY, MD, DUNCAN A. KILLEN, MD
FACC
BEN D. McCALLISTER, MD, FACC MALCOLM ARNOLD, MD WILLIAM A. REED, MD, FACC JAMES E. CROCKETT, MD, FACC HUBERT H. BELL, MD, FACC
Kansas City, Missouri
The course of 146 consecutive patients with significant occlusive disease of the left main coronary artery who underwent coronary artery bypass surgery during a 4 year period is reviewed. Preoperatively, 11 patients were in New York Heart Association functional class II, 57 in class Ill and 76 in class IV. Seventy patients had progressive angina and 12 unstable angina. There were two operative deaths (surgical mortality rate 1.4 percent). Seven patients (4.6 percent) had a perioperative acute myocardial infarction. Complete follow-up has been achieved in the surgical survivors over an average period of 16.1 months; 77 percent of the surviving patients are completely asymptomatic and 19 percent are in functional class ii. Four patients (2.6 percent) had a nonfatal late postoperative myocardiai infarction and five (3.5 percent) died during the late postoperative period (3.3 percent annual mortality rate during a 2 to 47 month follow-up period). Postoperative cardiac catheterization studies performed in 35 patients an average of 12.1 months postoperatively revealed 76 percent of 60 grafts and patency of at least 1 graft in 93 percent of patients. Results of 42 (69 percent) of 47 near maximal treadmill stress tests were abnormal preoperativeiy compared with results of 14 (26 percent) of 54 postoperatively; in 74 percent of patients having both a preoperative and postoperative stress test, abnormal preoperative test results converted to normal after surgery. This study suggests that direct myocardiai revascuiarization may offer an effective means of improving both the quality and duration of life in a patient with significant occlusive disease of the left main coronary artery.
To advise a patient about the indications and benefits of coronary artery bypass surgery, one should understand the natural history of ischemic heart disease from that patient’s standpoint and be able to evaluate the possible influence of surgical intervention on the natural history.le6 Many excellent studies have indicated that coronary arteriography may provide the most precise definition of the natural history of patients with ischemic heart disease and that occlusive lesions involving the left main coronary artery are associated with the most adverse prognosis.6-15 This report describes in detail the course of 146 consecutive patients with significant occlusive disease of the left main coronary artery (greater than 50 percent occlusion) who underwent coronary artery bypass surgery during the 4 year period ending December 31,1974. Methods From the Department of Cardiology and Cardiovascular Surgery, St. Luke’s Hospital, Kansas City, MO. Manuscript accepted October 1, 1975. Address for reprints: David R. McConahay, MD, 410 Medical Plaza, 4320 Wornall Rd., Kansas City, MO. 64111.
The coronary arteriograms of all patients undergoing cardiac catheterization from January 1971 to January 1975 and reported to have any narrowing of the left main coronary artery were reviewed independently by at least two of us without knowledge of the patient’s clinical status. Only patients with greater than 50 percent luminal narrowing of the left main coronary artery were included in the study. Patients with stenosis involving the origins of
May 1976
The American
Journal
of CARDIOLOGY
Volume
37
085
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
ET AL.
both the left anterior descending and left circumflex coronary arteries were not included unless the stenosis significantly compromised the left main coronary artery. The clinical records, catheterization data, operative procedure, postoperative course and follow-up of each patient were then reviewed in detail. The severity of the angina noted immediately before operation was classified on a symptomatic basis as defined by the New York Heart Association. The quality of the preoperative angina (that is, stable, progressive or unstable [preinfarctional]) was also assessed. Patients were considered to have unstable angina if they were experiencing episodes of angina lasting more than 15 minutes with transient or incomplete relief with nitroglycerin, normal or nondiagnostic serial serum enzyme levels and no electrocardiographic evidence of a new transmural myocardial infarction. They were considered to have progressive angina if its evolutionary pattern had changed, increasing in intensity, duration and frequency but without fulfilling the requirements for unstable angina. Each coronary arteriogram and left ventriculogram was interpreted independently by at least two of us and, in each instance, the major coronary arteries and their branches were evaluated and the most severe luminal narrowing in each vessel was measured. Lesions compromising the luminal diameter by more than 50 percent were considered “significant.” The right anterior oblique projection of each left ventriculogram was qualitatively evaluated for localized and generalized disorders of myocardial contraction by analysis of the internal contour of the left ventricular chamber in end-systole and end-diastole. Near maximal treadmill exercise electrocardiographic stress tests were performed using a modified Balke protocol with the patient exercising to a point of intolerable symptoms or to a heart rate in excess of 85 percent of the maximal heart rate for his age. Patients taking digitalis or having electrocardiographic evidence of left bundle branch block were excluded. A treadmill test was considered abnormal if there was a 1.0 mm or greater “horizontal” S-T segment depression in one of the three monitored leads during or after exercise. Follow-up of all patients was completed through December 1974. The patients were evaluated personally by one of us or information regarding their current status was obtained from the referring physician, The survival curve was constructed by actuarial method.16 Clinical
citated from cardiac arrest, and another had ventricular tachycardia that was controlled medically. Both complications were without sequelae, and both patients subsequently underwent successful revascularization surgery. The third patient had an acute myocardial infarction after the catheterization. No deaths were related to the catheterization procedure. Nonsurgically
Surgically
There were 176 patients with significant occlusive disease of the left main coronary artery who underwent coronary arteriography during the 4 year study period. Three patients experienced complications attributable to the cardiac catheterization procedure. One was successfully resus-
TABLE I Angina Status:Number of Patients With Left Main Coronary Artery Disease Undergoing Coronary Bypass Surgery
Ii
III
IV
Stable
Progressive
Unstable
2
11
57
76
62
70
12
086
May 1976
Operative
The American
Journal
of CARDIOLOGY
Volume
Treated
Patients
Techniques
All operative procedures were performed using hemodilution prime and mild hypothermia (30’ C). Ventricular fibrillation was routinely induced before exposure of the coronary arteries. After the artery was opened, ischemic arrest was used during performance of the distal anastomosis. The aorta was temporarily declamped after each distal anastomosis when multiple bypasses were performed.
Quality
I
Patients
One hundred forty-six patients with left main coronary occlusive disease underwent coronary artery bypass surgery. There were 126 men and 21 women ranging in age from 35 to 75 years (average 56.5 years); 7 patients were older than 70 years. Sixty patients (41 percent) had had previous transmural myocardial infarctions, as evidenced by the presence of “diagnostic” Q waves in the electrocardiogram, Nineteen additional patients (13 percent) had a history of congestive heart failure. Results of preoperative near maximal treadmill exercise stress tests were abnormal in 42 of 47 patients (89 percent). None of the five patients with normal preoperative stress test results had more than 75 percent luminal narrowing of the left main coronary artery. Angina: Angina was the dominant symptom in the immediate preoperative period of all but two surgically treated patients. The preoperative angina class (New York Heart Association criteria) was II in 11 patients (8 percent), III in 57 (39 percent) and IV in 76 (52 percent) (Table I). The angina was considered stable in 62 patients (42 percent), progressive in 70 (48 percent) and unstable or preinfarctional in 12 (8 percent). Left ventricular function: Left ventricular function was judged angiographically to be moderately abnormal or severely abnormal in 40 percent of patients, and the resting left ventricular end-diastolic pressure exceeded 12 mm Hg preoperatively in 51 percent (Table II). Coronary arteriographic findings: None of the 146 patients had complete occlusion of the left main coronary artery (Table III). In 106 patients, occlusion of this artery exceeded 70 percent of the luminal diameter, and in 30 it exceeded 90 percent of the luminal diameter. It was the only vessel involved in six patients. In 20 additional patients, there was also significant occlusive disease of one of the other three major coronary arteries (left anterior descending, left circumflex, right coronary arteries); 45 patients had significant occlusion of two of these major coronary arteries, and 75 had significant occlusion of all three.
Material
SeverityfNew York Heart Association Functional Class)
Treated
Thirty of the 176 patients with left main coronary artery disease undergoing cardiac catheterization did not undergo surgery. In 13, the distal involvement of the coronary occlusive disease precluded adequate bypass surgery; severe left ventricular dysfunction dictated a medical approach in 8 others. Nine patients whose coronary anatomy was considered operable did not undergo surgery; five of the nine died within 1 to 4 months after catheterization.
37
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
TABLE II Left Ventricular
Function:Percent
Left Ventricular
Left Main Coronary
Artery
Disease Undergoing
Left Ventricular Moderate Abnormality
60
25
TABLE III Coronary Arteriographic
Occlusion
10
Severe Abnormality 15
of Left Main Colonary
Two vessel disease LMCA only LMCA & LAD LMCA & LCf LMCA, LAD & LCf Three vessel disease LMCA & RCA LMCA, RCA 81 LAD LMCA. RCA & LCf LMCA, RCA. LAD 81
End-Diastolic
30
10
5
80-89
190
1
2
3
41
30
20
45
75
TABLE V Early Postoperative Complications Coronary Artery Bypass
Bypasses Related to Distribution of (Greater Than 50 Percent) Lesions
1
Bypasses Performed 2
3
5 2 1 2 4
8”
.
. .
1
Complication Low cardiac output syndrome Acute renal failure Bleeding, upper gastrointestinal Ventricular fibrillation Pulmonary embolism Cerebral vascular accident Acute myocardial infarction Death
..
3 11
:::
3;
3;
“.6
16
74
50
6
LMCA = left artery; RCA =
Results A single bypass was used in 16 patients (11 percent) and without exception it was to the left anterior descending coronary artery (Table IV). Two bypasses were used in 74 patients (51 percent), three in 50 patients (34 percent) and four in 6 patients (4 percent). A left internal mammary artery-left anterior descending artery anastomosis was utilized in 18 instances; the cephalic vein was used for a right coronary bypass in one case and saphenous vein grafts were used for all other bypass grafts. Associated right coronary endarterectomy was performed in five instances. A total of 338 coronary artery bypasses were performed (2.3 grafts per patient). Four patients underwent another procedure in conjunction with coronary bypass, including left ventricular aneurysmectomy in two patients, mitral valve replacement in one, and mitral commissurotomy in one. Significant postoperative complications (Table V): Perioperative acute myocardial infarction with the appearance of pathologic Q waves occurred in
Left Main
Patients
.. . .
.;
LAD = left anterior descending coronary artery; main coronary artery; LCf = left circumflex coronary right coronary artery.
in 146 With
(no.) 4
. : 2 14
Associated Major Coronary Arteries Significantly Involved (no.)
(% luminal diameter)
35
Coronary Arteries
Artery
70-79
30
TABLE IV Number of Coronary Coronary Obstructive
Coronary
Data
60-69
51-59
LCf Totals
With
Angiogram
Normal to Mild Abnormality
Obstructed
of Patients
ET AL.
no.
no.
6 1 2
4.1 0.7 1.4 0.7 2.0 0.7 4.8 1.4
: 1 3
seven patients (incidence rate 4.8 percent). Only two of these seven patients were “incompletely revascularked,” that is, had at least one major coronary artery with a significant occlusion that was not suitable for bypass. Two patients died within the first 30 days postoperatively (operative mortality 1.4 percent). One was a 71 year old man with progressive class IV angina who had undergone a right pneumonectomy for bronchogenic carcinoma; he could not be removed from cardiopulmonary support because of low cardiac output. The other was a 69 year old woman who was doing well several hours postoperatively when bradycardia suddenly developed and progressed rapidly to asystole. External cardiac massage was unsuccessful and open cardiac resuscitation was required. This was initially successful but the patient had irreparable neurologic damage and died on the 3rd postoperative day. Another patient had ventricular fibrillation shortly after transfer from the operating room but responded to prompt defibrillation without sequelae. Postoperative complications resulted in seven transmural myocardial infarctions, two deaths and one instance of persistent hemiparesis. Follow-up results: One hundred forty surgical survivors were followed up 2 to 47 months (average
May 1976
The American Journal of CARDIOLOGY
Volume 37
667
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
TABLE VI Postoperative
ET AL.
larized.” In contrast, only I2 (30 percent) of 40 patients with a normal postoperative stress test were “incompletely revascularized.” Postoperative cardiac catheterization with bypass graft visualization was accomplished in 35 patients an average of 12.1 months postoperatively. Sixty-two (78 percent) of the 80 grafts in these patients were patent, and 93 percent of the patients had at least 1 patent graft. Seventeen patients undergoing postoperative catheterization were judged to be “completely revascularized” with all significant disease bypassed and all bypass grafts patent. Sixteen (94 percent) of these 17 patients had symptomatic improvement, and treadmill stress test results were normal postoperatively in each of the 10 “completely revascularized” patients so tested. No patient with all grafts occluded had symptomatic improvement or a normal postoperative stress test result.
Status* Patients f%)
Status Asymptomatic Angina pectoris? class II class III class IV Acute myocardial Perioperative Late Death Early Late
77 19 4 0 infarction 4.8 2.8 1.4 3.5
Follow-up 2 to 47 months, average 18.1 months. ? New York Heart Association functional class. l
18.1 months) (Table VI). Ninety-nine patients have been followed up for 1 or more years, 53 for 2 or more years, and 19 for 3 or more years. Seventy-seven percent of the surviving patients are now free of angina and 19 percent have class II symptoms. Four patients (2.8 percent of the surgically treated patients) had a nonfatal myocardial infarction at 3, 4, 7 and 13 months, respectively, after operation. Five patients (3.5 percent) died during the late postoperative period at 4, 5, 6, 19 and 24 months, respectively, after operation. All patients with a late postoperative infarction or death had been “incompletely revascularized.” Treadmill exercise stress tests were performed in 54 patients postoperatively; results in 26 percent (14 of 54) were abnormal postoperatively compared with 89 percent preoperatively. Furthermore, in 74 percent of patients having both a preoperative and postoperative exercise stress test, an abnormal preoperative treadmill test result converted to normal postoperatively; in no instance did the reverse occur. Twelve (86 percent) of the 14 patients with an abnormal postoperative stress test were “incompletely revascu-
Discussion The efficacy of any therapeutic intervention in ischemic heart disease must be judged on how well it ameliorates the patient’s angina, improves left ventricular function, reduces the risk of subsequent myocardial infarction and prolongs life expectancy. As has been reported, coronary artery bypass surgery does improve the symptomatic status in a significant proportion of patients. In this study, 88 percent of our patients had symptomatic improvement postoperatively, and 77 percent of the surgical survivors were completely asymptomatic at their last follow-up examination. A sufficient percentage of patients have not undergone recatheterization after left main coronary artery bypass surgery to permit assessment of the frequency of improvement of left ventricular function, but abnormal preoperative treadmill stress test results converted to normal in 74 percent of our patients so tested postoperatively. Furthermore, we cannot establish that bypass surgery has decreased the risk of myocar-
0 Surg.
6
12
24
36
Months Followup
888
May 1976
The American
Journal
of CARDIOLOGY
Volume
37
FIGURE 1. Actuarial survival curves comparing medical with surgical management of patients with left main coronary occlusive disease.
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
dial infarction in this patient population because sufficient data are not available in patients treated medically. However, during the follow-up period (2 to 47 months, average 18 months), there was a 7.6 percent incidence rate of transmural myocardial infarction; 4.8 percent occurred at operation and 2.8 percent during the late follow-period. Effect of surgery on life expectancy: The surgical mortality at our institution has been slightly greater in patients with left main coronary artery disease than in our overall surgical coronary bypass experience (1.4 percent operative mortality in patients with left main coronary artery disease and 0.9 percent in 1,407 coronary bypass procedures performed during the same period). In addition, for patients with left main coronary artery disease undergoing surgery, the mortality rate, including the surgical mortality rate, was 3.8 percent in the 1st year with a 3.3 percent annual mortality rate in an average follow-up period of 18.1 months. This compares with a 15 to 35 percent annual expected mortality rate reported for patients with left main coronary artery disease managed medically over a comparable period.g-11J3-15 Figure 1 compares the surgical survival in our patients with the survival of patients with left main coronary artery disease followed up medically by Bruschke et al. for a similar period.‘O In these actuarial curves,16 the predicted survival rate of the
ET AL.
surgical patients was 92.4 percent at 3 years compared with 53 percent for the medical patients. Although a randomized prospective study would be ideal and perhaps necessary to establish firmly the relative merits of medical and surgical treatment in patients with left main coronary artery disease, at present these data are not available. Of clinical note was a small group of nine patients who underwent coronary arteriography during the study period; although their condition was considered operable and surgery was offered, they refused surgery; five of these nine patients died 1 to 4 months after catheterization. Implications: Further studies will be necessary to compare the results of medical and surgical therapy in patients with severe ischemic heart disease. Control studies with randomized patients undergoing surgery and medical therapy would be ideal, and the present study is imperfect and preliminary in this regard. However, the data presented in this report indicate that patients with left main coronary artery disease can undergo coronary arteriography and coronary bypass surgery at a relatively low and acceptable risk. In addition, the data suggest that patients who have coronary artery bypass may have improved survival time and greater relief of symptoms when compared with similar subsets of medically treated patients.
References 1. Pichard AD, Sheldon WD, Shinji K, et al: Severe arteriosclerotic obstruction of the left main coronary artery: Follow-up results in 176 patients (abstr). Circulation 48:Suppl IV:IV-53, 1973 2. Zeft HJ, Manley JC, Huston JH, et al: Left main coronary artery stenosis. Results of coronary bypass surgery. Circulation 49: 68-76, 1974 3. Alford WC Jr, Shaker IJ, Thomas CS Jr, et al: Aortocoronary bypass in the treatment of left main coronary artery stenosis. Ann Thorac Surg 17:247-253, 1974 4. Demots H, Rosch J, Bonchek LI, et al: Survival in left main coronary artery disease. The role of coronary angiography, coexisting coronary artery disease and revascularization (abstr). Am J Cardiol 33:134, 1974 5. Khaja F, Sharma SD, Easley RM Jr, et al: Left main coronary artery lesions. Risks of catheterization exercise testing and surgery. Circulation 5O:Suppl ll:ll-136-11-140, 1974 6. Demots H, Bonchek LI, Rbsch J, et al: Left main coronary artery disease. Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization. Am J Cardiol 36:136-141, 1975 7. Freisinger GC, Page EE, Ross RS: Prognostic significance of coronary arteriography. Trans Assoc Am Phys 83:78-92, 1970 8. Oberman A, Jones WW, Riley CP, et al: Natural history of coronary artery disease. Bull NY Acad Sci 48:1109-l 125, 1972
9. Cohen MV, Cohn PF, Herman MV, et al: Diagnosis and prognosis of main left coronary artery obstruction. Circulation 45: Suppl 1:1-57-l-65, 1972 IO. Bruschke AVG, 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-l 153, 1973 1 I. Lavine P, Kimbiris D, Segal BL, et al: Left main coronary artery disease. Clinical, arteriographic and hemodynamic appraisal. Am J Cardiol30:791-796. 1972 12. Humphries JO, Kuller L, Ross RS, et al: Natural history of ischemit heart disease in relation to arteriographic findings. Circulation 49:489-497, 1974 13. Burggraf GW, Parker JO: Prognosis in coronary artery disease: angiographic, hemodynamic and clinical factors. Circulation 51:146-156, 1975 14. Cohen MV, Gorlin R: Main left coronary artery disease: clinical experience from 1964-1974. Circulation 52:275-285. 1975 15. Lim JS, Proudfit WL, Sones FM Jr: Left main coronary arterial obstruction: long-term follow-up of 141 nonsurgical cases. Am J Cardiol 36:131-135, 1975 16. Berkson J, Gage RP: Calculation of survival rates for cancer. Proc Mayo Clin 25:270-286, 1950
May 1976
The American
Journal
of CARDIOLOGY
Volume
37
889
Coronary Artery Bypass Surgery for Left Main Coronary Artery Disease
DAVID R. McCONAHAY, MD, DUNCAN A. KILLEN, MD
FACC
BEN D. McCALLISTER, MD, FACC MALCOLM ARNOLD, MD WILLIAM A. REED, MD, FACC JAMES E. CROCKETT, MD, FACC HUBERT H. BELL, MD, FACC
Kansas City, Missouri
The course of 146 consecutive patients with significant occlusive disease of the left main coronary artery who underwent coronary artery bypass surgery during a 4 year period is reviewed. Preoperatively, 11 patients were in New York Heart Association functional class II, 57 in class Ill and 76 in class IV. Seventy patients had progressive angina and 12 unstable angina. There were two operative deaths (surgical mortality rate 1.4 percent). Seven patients (4.6 percent) had a perioperative acute myocardial infarction. Complete follow-up has been achieved in the surgical survivors over an average period of 16.1 months; 77 percent of the surviving patients are completely asymptomatic and 19 percent are in functional class ii. Four patients (2.6 percent) had a nonfatal late postoperative myocardiai infarction and five (3.5 percent) died during the late postoperative period (3.3 percent annual mortality rate during a 2 to 47 month follow-up period). Postoperative cardiac catheterization studies performed in 35 patients an average of 12.1 months postoperatively revealed 76 percent of 60 grafts and patency of at least 1 graft in 93 percent of patients. Results of 42 (69 percent) of 47 near maximal treadmill stress tests were abnormal preoperativeiy compared with results of 14 (26 percent) of 54 postoperatively; in 74 percent of patients having both a preoperative and postoperative stress test, abnormal preoperative test results converted to normal after surgery. This study suggests that direct myocardiai revascuiarization may offer an effective means of improving both the quality and duration of life in a patient with significant occlusive disease of the left main coronary artery.
To advise a patient about the indications and benefits of coronary artery bypass surgery, one should understand the natural history of ischemic heart disease from that patient’s standpoint and be able to evaluate the possible influence of surgical intervention on the natural history.le6 Many excellent studies have indicated that coronary arteriography may provide the most precise definition of the natural history of patients with ischemic heart disease and that occlusive lesions involving the left main coronary artery are associated with the most adverse prognosis.6-15 This report describes in detail the course of 146 consecutive patients with significant occlusive disease of the left main coronary artery (greater than 50 percent occlusion) who underwent coronary artery bypass surgery during the 4 year period ending December 31,1974. Methods From the Department of Cardiology and Cardiovascular Surgery, St. Luke’s Hospital, Kansas City, MO. Manuscript accepted October 1, 1975. Address for reprints: David R. McConahay, MD, 410 Medical Plaza, 4320 Wornall Rd., Kansas City, MO. 64111.
The coronary arteriograms of all patients undergoing cardiac catheterization from January 1971 to January 1975 and reported to have any narrowing of the left main coronary artery were reviewed independently by at least two of us without knowledge of the patient’s clinical status. Only patients with greater than 50 percent luminal narrowing of the left main coronary artery were included in the study. Patients with stenosis involving the origins of
May 1976
The American
Journal
of CARDIOLOGY
Volume
37
085
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
ET AL.
both the left anterior descending and left circumflex coronary arteries were not included unless the stenosis significantly compromised the left main coronary artery. The clinical records, catheterization data, operative procedure, postoperative course and follow-up of each patient were then reviewed in detail. The severity of the angina noted immediately before operation was classified on a symptomatic basis as defined by the New York Heart Association. The quality of the preoperative angina (that is, stable, progressive or unstable [preinfarctional]) was also assessed. Patients were considered to have unstable angina if they were experiencing episodes of angina lasting more than 15 minutes with transient or incomplete relief with nitroglycerin, normal or nondiagnostic serial serum enzyme levels and no electrocardiographic evidence of a new transmural myocardial infarction. They were considered to have progressive angina if its evolutionary pattern had changed, increasing in intensity, duration and frequency but without fulfilling the requirements for unstable angina. Each coronary arteriogram and left ventriculogram was interpreted independently by at least two of us and, in each instance, the major coronary arteries and their branches were evaluated and the most severe luminal narrowing in each vessel was measured. Lesions compromising the luminal diameter by more than 50 percent were considered “significant.” The right anterior oblique projection of each left ventriculogram was qualitatively evaluated for localized and generalized disorders of myocardial contraction by analysis of the internal contour of the left ventricular chamber in end-systole and end-diastole. Near maximal treadmill exercise electrocardiographic stress tests were performed using a modified Balke protocol with the patient exercising to a point of intolerable symptoms or to a heart rate in excess of 85 percent of the maximal heart rate for his age. Patients taking digitalis or having electrocardiographic evidence of left bundle branch block were excluded. A treadmill test was considered abnormal if there was a 1.0 mm or greater “horizontal” S-T segment depression in one of the three monitored leads during or after exercise. Follow-up of all patients was completed through December 1974. The patients were evaluated personally by one of us or information regarding their current status was obtained from the referring physician, The survival curve was constructed by actuarial method.16 Clinical
citated from cardiac arrest, and another had ventricular tachycardia that was controlled medically. Both complications were without sequelae, and both patients subsequently underwent successful revascularization surgery. The third patient had an acute myocardial infarction after the catheterization. No deaths were related to the catheterization procedure. Nonsurgically
Surgically
There were 176 patients with significant occlusive disease of the left main coronary artery who underwent coronary arteriography during the 4 year study period. Three patients experienced complications attributable to the cardiac catheterization procedure. One was successfully resus-
TABLE I Angina Status:Number of Patients With Left Main Coronary Artery Disease Undergoing Coronary Bypass Surgery
Ii
III
IV
Stable
Progressive
Unstable
2
11
57
76
62
70
12
086
May 1976
Operative
The American
Journal
of CARDIOLOGY
Volume
Treated
Patients
Techniques
All operative procedures were performed using hemodilution prime and mild hypothermia (30’ C). Ventricular fibrillation was routinely induced before exposure of the coronary arteries. After the artery was opened, ischemic arrest was used during performance of the distal anastomosis. The aorta was temporarily declamped after each distal anastomosis when multiple bypasses were performed.
Quality
I
Patients
One hundred forty-six patients with left main coronary occlusive disease underwent coronary artery bypass surgery. There were 126 men and 21 women ranging in age from 35 to 75 years (average 56.5 years); 7 patients were older than 70 years. Sixty patients (41 percent) had had previous transmural myocardial infarctions, as evidenced by the presence of “diagnostic” Q waves in the electrocardiogram, Nineteen additional patients (13 percent) had a history of congestive heart failure. Results of preoperative near maximal treadmill exercise stress tests were abnormal in 42 of 47 patients (89 percent). None of the five patients with normal preoperative stress test results had more than 75 percent luminal narrowing of the left main coronary artery. Angina: Angina was the dominant symptom in the immediate preoperative period of all but two surgically treated patients. The preoperative angina class (New York Heart Association criteria) was II in 11 patients (8 percent), III in 57 (39 percent) and IV in 76 (52 percent) (Table I). The angina was considered stable in 62 patients (42 percent), progressive in 70 (48 percent) and unstable or preinfarctional in 12 (8 percent). Left ventricular function: Left ventricular function was judged angiographically to be moderately abnormal or severely abnormal in 40 percent of patients, and the resting left ventricular end-diastolic pressure exceeded 12 mm Hg preoperatively in 51 percent (Table II). Coronary arteriographic findings: None of the 146 patients had complete occlusion of the left main coronary artery (Table III). In 106 patients, occlusion of this artery exceeded 70 percent of the luminal diameter, and in 30 it exceeded 90 percent of the luminal diameter. It was the only vessel involved in six patients. In 20 additional patients, there was also significant occlusive disease of one of the other three major coronary arteries (left anterior descending, left circumflex, right coronary arteries); 45 patients had significant occlusion of two of these major coronary arteries, and 75 had significant occlusion of all three.
Material
SeverityfNew York Heart Association Functional Class)
Treated
Thirty of the 176 patients with left main coronary artery disease undergoing cardiac catheterization did not undergo surgery. In 13, the distal involvement of the coronary occlusive disease precluded adequate bypass surgery; severe left ventricular dysfunction dictated a medical approach in 8 others. Nine patients whose coronary anatomy was considered operable did not undergo surgery; five of the nine died within 1 to 4 months after catheterization.
37
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
TABLE II Left Ventricular
Function:Percent
Left Ventricular
Left Main Coronary
Artery
Disease Undergoing
Left Ventricular Moderate Abnormality
60
25
TABLE III Coronary Arteriographic
Occlusion
10
Severe Abnormality 15
of Left Main Colonary
Two vessel disease LMCA only LMCA & LAD LMCA & LCf LMCA, LAD & LCf Three vessel disease LMCA & RCA LMCA, RCA 81 LAD LMCA. RCA & LCf LMCA, RCA. LAD 81
End-Diastolic
30
10
5
80-89
190
1
2
3
41
30
20
45
75
TABLE V Early Postoperative Complications Coronary Artery Bypass
Bypasses Related to Distribution of (Greater Than 50 Percent) Lesions
1
Bypasses Performed 2
3
5 2 1 2 4
8”
.
. .
1
Complication Low cardiac output syndrome Acute renal failure Bleeding, upper gastrointestinal Ventricular fibrillation Pulmonary embolism Cerebral vascular accident Acute myocardial infarction Death
..
3 11
:::
3;
3;
“.6
16
74
50
6
LMCA = left artery; RCA =
Results A single bypass was used in 16 patients (11 percent) and without exception it was to the left anterior descending coronary artery (Table IV). Two bypasses were used in 74 patients (51 percent), three in 50 patients (34 percent) and four in 6 patients (4 percent). A left internal mammary artery-left anterior descending artery anastomosis was utilized in 18 instances; the cephalic vein was used for a right coronary bypass in one case and saphenous vein grafts were used for all other bypass grafts. Associated right coronary endarterectomy was performed in five instances. A total of 338 coronary artery bypasses were performed (2.3 grafts per patient). Four patients underwent another procedure in conjunction with coronary bypass, including left ventricular aneurysmectomy in two patients, mitral valve replacement in one, and mitral commissurotomy in one. Significant postoperative complications (Table V): Perioperative acute myocardial infarction with the appearance of pathologic Q waves occurred in
Left Main
Patients
.. . .
.;
LAD = left anterior descending coronary artery; main coronary artery; LCf = left circumflex coronary right coronary artery.
in 146 With
(no.) 4
. : 2 14
Associated Major Coronary Arteries Significantly Involved (no.)
(% luminal diameter)
35
Coronary Arteries
Artery
70-79
30
TABLE IV Number of Coronary Coronary Obstructive
Coronary
Data
60-69
51-59
LCf Totals
With
Angiogram
Normal to Mild Abnormality
Obstructed
of Patients
ET AL.
no.
no.
6 1 2
4.1 0.7 1.4 0.7 2.0 0.7 4.8 1.4
: 1 3
seven patients (incidence rate 4.8 percent). Only two of these seven patients were “incompletely revascularked,” that is, had at least one major coronary artery with a significant occlusion that was not suitable for bypass. Two patients died within the first 30 days postoperatively (operative mortality 1.4 percent). One was a 71 year old man with progressive class IV angina who had undergone a right pneumonectomy for bronchogenic carcinoma; he could not be removed from cardiopulmonary support because of low cardiac output. The other was a 69 year old woman who was doing well several hours postoperatively when bradycardia suddenly developed and progressed rapidly to asystole. External cardiac massage was unsuccessful and open cardiac resuscitation was required. This was initially successful but the patient had irreparable neurologic damage and died on the 3rd postoperative day. Another patient had ventricular fibrillation shortly after transfer from the operating room but responded to prompt defibrillation without sequelae. Postoperative complications resulted in seven transmural myocardial infarctions, two deaths and one instance of persistent hemiparesis. Follow-up results: One hundred forty surgical survivors were followed up 2 to 47 months (average
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SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
TABLE VI Postoperative
ET AL.
larized.” In contrast, only I2 (30 percent) of 40 patients with a normal postoperative stress test were “incompletely revascularized.” Postoperative cardiac catheterization with bypass graft visualization was accomplished in 35 patients an average of 12.1 months postoperatively. Sixty-two (78 percent) of the 80 grafts in these patients were patent, and 93 percent of the patients had at least 1 patent graft. Seventeen patients undergoing postoperative catheterization were judged to be “completely revascularized” with all significant disease bypassed and all bypass grafts patent. Sixteen (94 percent) of these 17 patients had symptomatic improvement, and treadmill stress test results were normal postoperatively in each of the 10 “completely revascularized” patients so tested. No patient with all grafts occluded had symptomatic improvement or a normal postoperative stress test result.
Status* Patients f%)
Status Asymptomatic Angina pectoris? class II class III class IV Acute myocardial Perioperative Late Death Early Late
77 19 4 0 infarction 4.8 2.8 1.4 3.5
Follow-up 2 to 47 months, average 18.1 months. ? New York Heart Association functional class. l
18.1 months) (Table VI). Ninety-nine patients have been followed up for 1 or more years, 53 for 2 or more years, and 19 for 3 or more years. Seventy-seven percent of the surviving patients are now free of angina and 19 percent have class II symptoms. Four patients (2.8 percent of the surgically treated patients) had a nonfatal myocardial infarction at 3, 4, 7 and 13 months, respectively, after operation. Five patients (3.5 percent) died during the late postoperative period at 4, 5, 6, 19 and 24 months, respectively, after operation. All patients with a late postoperative infarction or death had been “incompletely revascularized.” Treadmill exercise stress tests were performed in 54 patients postoperatively; results in 26 percent (14 of 54) were abnormal postoperatively compared with 89 percent preoperatively. Furthermore, in 74 percent of patients having both a preoperative and postoperative exercise stress test, an abnormal preoperative treadmill test result converted to normal postoperatively; in no instance did the reverse occur. Twelve (86 percent) of the 14 patients with an abnormal postoperative stress test were “incompletely revascu-
Discussion The efficacy of any therapeutic intervention in ischemic heart disease must be judged on how well it ameliorates the patient’s angina, improves left ventricular function, reduces the risk of subsequent myocardial infarction and prolongs life expectancy. As has been reported, coronary artery bypass surgery does improve the symptomatic status in a significant proportion of patients. In this study, 88 percent of our patients had symptomatic improvement postoperatively, and 77 percent of the surgical survivors were completely asymptomatic at their last follow-up examination. A sufficient percentage of patients have not undergone recatheterization after left main coronary artery bypass surgery to permit assessment of the frequency of improvement of left ventricular function, but abnormal preoperative treadmill stress test results converted to normal in 74 percent of our patients so tested postoperatively. Furthermore, we cannot establish that bypass surgery has decreased the risk of myocar-
0 Surg.
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FIGURE 1. Actuarial survival curves comparing medical with surgical management of patients with left main coronary occlusive disease.
SURGERY FOR LEFT MAIN CORONARY ARTERY DISEASE-McCONAHAY
dial infarction in this patient population because sufficient data are not available in patients treated medically. However, during the follow-up period (2 to 47 months, average 18 months), there was a 7.6 percent incidence rate of transmural myocardial infarction; 4.8 percent occurred at operation and 2.8 percent during the late follow-period. Effect of surgery on life expectancy: The surgical mortality at our institution has been slightly greater in patients with left main coronary artery disease than in our overall surgical coronary bypass experience (1.4 percent operative mortality in patients with left main coronary artery disease and 0.9 percent in 1,407 coronary bypass procedures performed during the same period). In addition, for patients with left main coronary artery disease undergoing surgery, the mortality rate, including the surgical mortality rate, was 3.8 percent in the 1st year with a 3.3 percent annual mortality rate in an average follow-up period of 18.1 months. This compares with a 15 to 35 percent annual expected mortality rate reported for patients with left main coronary artery disease managed medically over a comparable period.g-11J3-15 Figure 1 compares the surgical survival in our patients with the survival of patients with left main coronary artery disease followed up medically by Bruschke et al. for a similar period.‘O In these actuarial curves,16 the predicted survival rate of the
ET AL.
surgical patients was 92.4 percent at 3 years compared with 53 percent for the medical patients. Although a randomized prospective study would be ideal and perhaps necessary to establish firmly the relative merits of medical and surgical treatment in patients with left main coronary artery disease, at present these data are not available. Of clinical note was a small group of nine patients who underwent coronary arteriography during the study period; although their condition was considered operable and surgery was offered, they refused surgery; five of these nine patients died 1 to 4 months after catheterization. Implications: Further studies will be necessary to compare the results of medical and surgical therapy in patients with severe ischemic heart disease. Control studies with randomized patients undergoing surgery and medical therapy would be ideal, and the present study is imperfect and preliminary in this regard. However, the data presented in this report indicate that patients with left main coronary artery disease can undergo coronary arteriography and coronary bypass surgery at a relatively low and acceptable risk. In addition, the data suggest that patients who have coronary artery bypass may have improved survival time and greater relief of symptoms when compared with similar subsets of medically treated patients.
References 1. Pichard AD, Sheldon WD, Shinji K, et al: Severe arteriosclerotic obstruction of the left main coronary artery: Follow-up results in 176 patients (abstr). Circulation 48:Suppl IV:IV-53, 1973 2. Zeft HJ, Manley JC, Huston JH, et al: Left main coronary artery stenosis. Results of coronary bypass surgery. Circulation 49: 68-76, 1974 3. Alford WC Jr, Shaker IJ, Thomas CS Jr, et al: Aortocoronary bypass in the treatment of left main coronary artery stenosis. Ann Thorac Surg 17:247-253, 1974 4. Demots H, Rosch J, Bonchek LI, et al: Survival in left main coronary artery disease. The role of coronary angiography, coexisting coronary artery disease and revascularization (abstr). Am J Cardiol 33:134, 1974 5. Khaja F, Sharma SD, Easley RM Jr, et al: Left main coronary artery lesions. Risks of catheterization exercise testing and surgery. Circulation 5O:Suppl ll:ll-136-11-140, 1974 6. Demots H, Bonchek LI, Rbsch J, et al: Left main coronary artery disease. Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization. Am J Cardiol 36:136-141, 1975 7. Freisinger GC, Page EE, Ross RS: Prognostic significance of coronary arteriography. Trans Assoc Am Phys 83:78-92, 1970 8. Oberman A, Jones WW, Riley CP, et al: Natural history of coronary artery disease. Bull NY Acad Sci 48:1109-l 125, 1972
9. Cohen MV, Cohn PF, Herman MV, et al: Diagnosis and prognosis of main left coronary artery obstruction. Circulation 45: Suppl 1:1-57-l-65, 1972 IO. Bruschke AVG, 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-l 153, 1973 1 I. Lavine P, Kimbiris D, Segal BL, et al: Left main coronary artery disease. Clinical, arteriographic and hemodynamic appraisal. Am J Cardiol30:791-796. 1972 12. Humphries JO, Kuller L, Ross RS, et al: Natural history of ischemit heart disease in relation to arteriographic findings. Circulation 49:489-497, 1974 13. Burggraf GW, Parker JO: Prognosis in coronary artery disease: angiographic, hemodynamic and clinical factors. Circulation 51:146-156, 1975 14. Cohen MV, Gorlin R: Main left coronary artery disease: clinical experience from 1964-1974. Circulation 52:275-285. 1975 15. Lim JS, Proudfit WL, Sones FM Jr: Left main coronary arterial obstruction: long-term follow-up of 141 nonsurgical cases. Am J Cardiol 36:131-135, 1975 16. Berkson J, Gage RP: Calculation of survival rates for cancer. Proc Mayo Clin 25:270-286, 1950
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