THE NATURAL HISTORY OF CORONARY ARTERY DISEASE: AN UPDATE ON SURGICAL AND MEDICAL MANAGEMENT ROBERT E. WHALEN, M.D., ANDREW G. WALLACE, M.D., AND (BY INVITATION) J. FRED McNEER, M.D., ROBERT A. ROSATI, M.D. AND KERRY L. LEE, PH.D. DURHAM
"Figures often beguile me, particularly when I have the arranging of them myself: In which case the remark attributed to Disraeli would often apply with justice and force: 'There are three kinds of lies: Lies, damn lies and statistics."' MARK TWAIN Autobiography. Volume I, Page 246. INTRODUCTION Although the wisdom of Mark Twain's observation above cannot be denied, I hope that my discussion of the natural history of coronary artery disease, which relies heavily on statistics, will help to clarify one of the more vexing issues in medicine today. If nothing else, it is hoped that the data and the discussion will demonstrate the extraordinary complexity involved in trying to assess the role of surgery in effecting survival in this and other series. The natural history of coronary artery disease has been of great interest to members of this Association and, indeed, both past and present members have made landmark contributions to the subject.1' 2.3 FrQm 1926 until the early 1960's, such studies were almost of academic interest since there did not appear to be a great deal that could be done to alter the course of coronary artery disease. In the 1960's, a host of new therapeutic approaches appeared and served as a stimulus to look even more carefully at the natural history of the disease. These new factors include the development of coronary care units, the introduction of new antiarrhythmic and beta adrenergic blocking agents, a growing From the Cardiovascular Division of the Department of Medicine, Duke University Medical Center, Durham, North Carolina. This study was made possible by support from Grant HL17670 from the National Heart, Lung and Blood Institution; a contract from Health Resources Administration, HEW, #HRA 230-76-0300; a training grant from the National Library of Medicine LM 07003; and grants from the Prudential Foundation and Jefferson-Pilot Corporation. 19
20
WHALEN ET AL.
awareness of the importance of controlling certain risk factors and the development of coronary artery bypass graft surgery (CABG). The purpose of this discussion is to focus on the natural history of patients with arteriographically proven coronary artery disease who have been treated by standard medical means and those treated by coronary artery bypass graft procedures. Early studies attempted to determine the efficacy of surgery in altering the natural history of coronary artery disease by comparing results in surgical patients with the natural history of patients treated medically years before the development of various surgical series.4' Subsequently, efforts were made to document the course of coronary artery disease in surgically and medically treated groups within the same institution by attempting to match patients treated with the two modalities. Rosati has analyzed these early series and pointed out the discrepancies in the characteristics of these series which make it difficult to arrive at sound conclusions. 6 More recently there have been three randomized series published.7' 8,9 The importance of understanding the natural history of medically treated patients and the appropriateness of surgical intervention is emphasized when it is realized that probably more than 70,000 operative procedures will be performed in 1977 in this country and that the total cost of these endeavors will approach the billion dollar mark.10 The question of the role of surgery in altering the natural history of the disease has become not only of great medical concern, but also has become a matter of national economic concern since it threatens to further escalate the cost of medical care and perhaps challenge the viability of our current medical care system. DUKE SERIES In 1969, when Duke undertook an active surgical approach to the treatment of coronary artery disease, it became readily apparent that it was imperative to have a system designed to rapidly recall our clinical experience with patients treated medically and surgically. It was therefore elected to enter all the pertinent descriptors of every patient demonstrated by arteriography to have significant coronary artery disease (70% or greater obstruction in any major coronary artery) in a computerized data bank.11 These descriptors included the history, physical examination, chest x-rays, blood chemistries, EKG observations, and data from cardiac catheterization including coronary artery anatomy as well as measures of left ventricular function. A follow-up system was instituted which has enabled us to know the clinical status of over 99% of all patients studied. Each patient has been contacted by telephone at six months after arteriography or surgery and thereafter
THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
21
at yearly intervals. The majority of patients have been examined at one two year intervals by a cardiologist at Duke. From the outset of the study, no policy decisions concerning the type of management for a particular type of patient were instituted. It was left to the decision of the individual cardiologist caring for the patient to recommend medical or surgical management. After several years, the series was examined to determine if there was any consistent pattern of decision making concerning surgical versus medical management. 12 Somewhat to our surprise, no consistent pattern of decision making could be detected among individual cardiologists or in the group as a whole. This inconsistency provided the opportunity to match patients receiving medical and surgical therapy or
with similar clinical and laboratory features. Since then larger amounts of outcome data have become almost immediately available from the data bank and there has been more modification in decision making dependent upon our past experience. This has led to the introduction of some inhomogeneity between surgical and medical groups over the past eight years. However, this is easily detected by analysis of various descriptors in the data bank and the data you are to see today have been chosen with every effort to recognize major discrepancies between medically and surgically treated patients. The series has the virtue of being a large one, both in terms of surgically and medically treated patients, it has a relatively long follow-up, and it comes from an institution with a relatively stable staff and philosophy concerning the treatment of coronary artery disease. The general composition of the series is shown in Table I which dates from 10/1/69 and includes all patients with arteriographically proven coronary artery disease from then until 2/1/77. It consists of 1992 patients who have been demonstrated to have greater than a 70% lesion in any of the three major coronary arteries. It consists of 1252 medically treated patients and 740 surgically treated patients. A group of 233 patients with a 50% or greater lesion in the left main coronary artery will be discussed separately. The data have been analyzed using the life table method.13 Time 0 for the medical group is considered to be the date of cardiac catheterization and time 0 for the surgical group is the TABLE I Duke Experience from 10/1169 to 2/1/77 Anatomy
Single Vessel Two Vessel Three Vessel TOTALS
Patients
Medical
445 553 994 1992
308 323 621 1252
Surgical 137 230 373 740
22
WHALEN ET AL.
date of surgery. These two dates seldom differ by more than 4-6 weeks in patients undergoing surgery. The data are graphed in terns of percent survival, pain relief, or subsequent myocardial infarction from time 0 for each group of patients as a defined period of time after time 0. Statistical significance has been calculated by using the categorical linear model.14 The survival data have also been further analyzed using the Cox survival model'5 which allows analysis of the statistical significance of survival differences after accounting for the effects of prognostic descriptors, some of which may be unequally distributed between treatment groups. RESULTS In general, it has been thought that there are three major reasons to treat patients with coronary artery disease surgically rather than medically. It has been hoped that surgery would increase survival, increase pain relief, and decrease subsequent myocardial infarction. Figure 1 summarizes our total experience in the 1992 patients. In the TOTAL DUKE GROUP- 1992 PATIENTS (10/1/69- 2/1/77)
100 e
,
90
%
52 **ME D ~~~~~~12 740 o---o SURG
\ S
80
---- * -
70 100 e
_.
80
--
a
60
L
40
20 a
I
I
I
I
IL l
10
3 4 5 Years FIG. 1. Summary of total group survival, pain relief, and myocardial infarction rate over a 5 year period. The asterisks in the top panel indicate statistically significant survival data when the categorical linear model is used. This statistical significance is not noted when the Cox survival model is used (see text). 1
2
23 upper portion of the panel, it can be seen that there is a greater five year survival rate among surgically treated patients and this increased survival (indicated by an asterisk) is statistically significant at three, four and five years utilizing the categorical linear model.'4 However, no conclusion should be drawn from this in terms of the individual patient since, as will be shown later, there are subsets of patients who do not show this beneficial effect and much of the beneficial effect depends upon improvement in subsets of patients. Furthermore, discrepancies in left ventricular function between the medically and surgically treated groups as shown by the Cox model15 may account for some if not all the difference in survival between medical and surgical groups. The middle panel of Figure 1 demonstrates that there is, indeed, a striking early improvement in terms of pain relief as defined by either complete relief of pain or improvement by two classes of pain utilizing the New York Heart Association classification. There is a fall in the improvement rate at approximately two years, but surgical patients still have a better chance of having less pain than medical patients at five years. The third panel in Figure 1 illustrates that the hoped for reduction in myocardial infarction rate after surgery has really not been obtained. These observations about pain relief and prevention of infarction conform with conclusions of other series and therefore we would like to concentrate our efforts on an analysis of survival data for the remainder of the discussion. Table II has been provided in order to present all of the survival data in this series. The p values in Table II and III have been calculated using the categorical linear model. However, these data cannot be used in an indiscriminate fashion since there are many subgroups which may act quite differently from the entire group. Figure 2 emphasizes the importance of severe left ventricular dysfunction in determining the natural history of coronary artery disease, both in the surgical as well as the medical group. It is clear from looking at this figure that an ejection fraction of less than 30%, which, in essence, represents a generalized diffusely abnormal left ventricular contraction pattern, has a dismal five year survival rate whether the patient is treated medically or surgically. The surgical and medical survival curves are almost superimposable in 200 patients. Because of early disappointing surgical experience with these patients and also because of the poor long-term survival of patients who did live through surgery, this group is seldom considered for operation at the present time. Thus, many of these patients end up being placed in the medical group by default. This tends to make indiscriminate comparisons ofmore recent surgical and medical groups inappropriate because the medical group is burdened by patients who are destined for higher mortalities because of severe left ventricular dysfunction whether they are operated on or not. THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
24
WHALEN ET AL.
TABLE II
Medical and Surgical Survival Total Duke Group (1011/69-211/77) One Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
243 209 167 119 76 44
Medicine (308) Dead NRA* Survival
8 2 1 1 2 2
57 32 41 47 41 30
96.8% 95.9% 95.3% 94.5% 92.1% 88.1%
Alive
132 120 111 92 77 61 49
Surgery (137) Dead NRA* Survival 5 0 96.4% 1 11 95.6% 0 9 95.6%
1 1 0 0
18 14 16 12
94.5% 93.3% 93.3% 93.3%
p
.475 .774 .664 .600 .787 .257
Two Vessel Disease
Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
261 221 165 119 78 46
Medicine (323) Dead NRA* Survival
11 5 13 6 4 0
51 35 43 40 37 32
96.0% 93.8% 87.0% 82.8% 78.8% 78.8%
Alive
214 188 169 155 130 107 82
Surgery (230) Dead NRA* Survival 16 0 93.0% 4 22 91.1% 2 17 90.0% 14 0 90.0% 1 24 89.4%
2 2
21 23
87.7% 85.6%
p
.020 .089 .456 .102 .048 .155
Three Vessel Disease Medicine (621)
Surgery (373) Survival Dead NRA* Survival p Surgical 42 331 0 88.7% Six-Month 469 61 91 41 88.5% 280 10 85.7% .090 One-Year 391 21 57 84.0% 236 6 38 .518 83.6% Two-Year 282 31 78 75.7% 199 5 32 81.5% .132 Three-Year 194 23 65 24 7 67.6% 168 78.2% .007 Four-Year 137 15 42 61.0% 134 3 31 76.5% .000 Five-Year 60 3 74 58.1% 77 6 51 71.0% .008 * NRA = Not yet reached anniversary date (i.e., number of patients that have not reached specific follow-up duration after catheterization or surgery). Alive
Dead NRA*
Alive
In an effort to eliminate this bias, we have deleted patients with ejection fractions of less than 30% or severe generalized diffusely abnormal left ventricular contraction patterns from the following considerations. We have chosen to use the term "selected" patients to indicate all of those patients who have ejection fractions greater than 30%, thus eliminating the high mortality group from both the surgical and medical series. In addition to that, in order to be certain that our series is comparable to other series, we have eliminated in our "selected" group, patients who have undergone emergency surgery, left ventricular surgery or valvular surgery.
25
THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
Table III and Figure 3 illustrate the survival data for patients with "selected" one, two and three vessel disease. Analysis of the table demonstrates that patients with one and two vessel disease have little differences in prognosis for survival, whether treated medically or surgically. Patients with three vessel disease in this "selected" group (Figure 3) have a statistically greater survival rate at three, four and five years when the categorical linear model is used."4 However, this conclusion cannot be accepted with absolute certainty. There are differences TABLE III Medical and Surgical Survival "Selected"* Duke Group (10/1/69-211/77) One Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
233 203 164 117 74 42
Medicine (294) Dead NRAt Survival
6 2 1 1 2 2
55 28 38 46 41 30
Surgery (130) Alive
126 117 109 91 76 61 49
97.5% 96.5% 96.0% 95.1% 92.6% 88.4%
Dead NRA*
4 0 0 0 1 0 0
0 9 8 18 14 15 12
Survival
p
96.9% 96.9% 96.9% 96.9% 95.7% 95.7% 95.7%
.678 .999 .724 .907 .363 .100
Two Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
237 208 156 112 73 41
Medicine (291) Dead NRAt Survival
5 3 10 5 2 0
49 26 42 39 37 32
Surgery (204) Alive
197 170 153 141 118 98 77
97.9% 96.5% 90.7% 86.8% 84.5% 84.5%
Dead NRA*
7 3 2 0 1 1 1
0 24 15 12 22 19 20
Survival
p
96.6% 94.9% 93.7% 93.7% 92.9% 91.9% 90.8%
.075 .142 .379 .096 .067 .142
Three Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year
Medicine (493) Dead NRAt Survival
Surgery (330) Alive
Dead NRA*
299 31 93.3% 254 6 90.0% 212 6 81.1% 179 3 72.9% 151 5 65.3% 118 2 63.9% 66 5 ejection fraction >30%, No
387 28 78 327 12 48 238 26 63 161 18 59 111 13 37 Five-Year 46 1 64 * "Selected" = Left ventricular ular surgery. t NRA = Not yet reached anniversary date.
Survival
p
0 90.6% 39 88.5% .011 36 86.1% .055 30 84.7% .441 23 81.9% .031 31 80.6% .001 47 74.9% .038 LV, valvular, or ventric-
26
WHALEN ET AL.
SURVIVAL-(EJECTION FRACTION
"Figures often beguile me, particularly when I have the arranging of them myself: In which case the remark attributed to Disraeli would often apply with justice and force: 'There are three kinds of lies: Lies, damn lies and statistics."' MARK TWAIN Autobiography. Volume I, Page 246. INTRODUCTION Although the wisdom of Mark Twain's observation above cannot be denied, I hope that my discussion of the natural history of coronary artery disease, which relies heavily on statistics, will help to clarify one of the more vexing issues in medicine today. If nothing else, it is hoped that the data and the discussion will demonstrate the extraordinary complexity involved in trying to assess the role of surgery in effecting survival in this and other series. The natural history of coronary artery disease has been of great interest to members of this Association and, indeed, both past and present members have made landmark contributions to the subject.1' 2.3 FrQm 1926 until the early 1960's, such studies were almost of academic interest since there did not appear to be a great deal that could be done to alter the course of coronary artery disease. In the 1960's, a host of new therapeutic approaches appeared and served as a stimulus to look even more carefully at the natural history of the disease. These new factors include the development of coronary care units, the introduction of new antiarrhythmic and beta adrenergic blocking agents, a growing From the Cardiovascular Division of the Department of Medicine, Duke University Medical Center, Durham, North Carolina. This study was made possible by support from Grant HL17670 from the National Heart, Lung and Blood Institution; a contract from Health Resources Administration, HEW, #HRA 230-76-0300; a training grant from the National Library of Medicine LM 07003; and grants from the Prudential Foundation and Jefferson-Pilot Corporation. 19
20
WHALEN ET AL.
awareness of the importance of controlling certain risk factors and the development of coronary artery bypass graft surgery (CABG). The purpose of this discussion is to focus on the natural history of patients with arteriographically proven coronary artery disease who have been treated by standard medical means and those treated by coronary artery bypass graft procedures. Early studies attempted to determine the efficacy of surgery in altering the natural history of coronary artery disease by comparing results in surgical patients with the natural history of patients treated medically years before the development of various surgical series.4' Subsequently, efforts were made to document the course of coronary artery disease in surgically and medically treated groups within the same institution by attempting to match patients treated with the two modalities. Rosati has analyzed these early series and pointed out the discrepancies in the characteristics of these series which make it difficult to arrive at sound conclusions. 6 More recently there have been three randomized series published.7' 8,9 The importance of understanding the natural history of medically treated patients and the appropriateness of surgical intervention is emphasized when it is realized that probably more than 70,000 operative procedures will be performed in 1977 in this country and that the total cost of these endeavors will approach the billion dollar mark.10 The question of the role of surgery in altering the natural history of the disease has become not only of great medical concern, but also has become a matter of national economic concern since it threatens to further escalate the cost of medical care and perhaps challenge the viability of our current medical care system. DUKE SERIES In 1969, when Duke undertook an active surgical approach to the treatment of coronary artery disease, it became readily apparent that it was imperative to have a system designed to rapidly recall our clinical experience with patients treated medically and surgically. It was therefore elected to enter all the pertinent descriptors of every patient demonstrated by arteriography to have significant coronary artery disease (70% or greater obstruction in any major coronary artery) in a computerized data bank.11 These descriptors included the history, physical examination, chest x-rays, blood chemistries, EKG observations, and data from cardiac catheterization including coronary artery anatomy as well as measures of left ventricular function. A follow-up system was instituted which has enabled us to know the clinical status of over 99% of all patients studied. Each patient has been contacted by telephone at six months after arteriography or surgery and thereafter
THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
21
at yearly intervals. The majority of patients have been examined at one two year intervals by a cardiologist at Duke. From the outset of the study, no policy decisions concerning the type of management for a particular type of patient were instituted. It was left to the decision of the individual cardiologist caring for the patient to recommend medical or surgical management. After several years, the series was examined to determine if there was any consistent pattern of decision making concerning surgical versus medical management. 12 Somewhat to our surprise, no consistent pattern of decision making could be detected among individual cardiologists or in the group as a whole. This inconsistency provided the opportunity to match patients receiving medical and surgical therapy or
with similar clinical and laboratory features. Since then larger amounts of outcome data have become almost immediately available from the data bank and there has been more modification in decision making dependent upon our past experience. This has led to the introduction of some inhomogeneity between surgical and medical groups over the past eight years. However, this is easily detected by analysis of various descriptors in the data bank and the data you are to see today have been chosen with every effort to recognize major discrepancies between medically and surgically treated patients. The series has the virtue of being a large one, both in terms of surgically and medically treated patients, it has a relatively long follow-up, and it comes from an institution with a relatively stable staff and philosophy concerning the treatment of coronary artery disease. The general composition of the series is shown in Table I which dates from 10/1/69 and includes all patients with arteriographically proven coronary artery disease from then until 2/1/77. It consists of 1992 patients who have been demonstrated to have greater than a 70% lesion in any of the three major coronary arteries. It consists of 1252 medically treated patients and 740 surgically treated patients. A group of 233 patients with a 50% or greater lesion in the left main coronary artery will be discussed separately. The data have been analyzed using the life table method.13 Time 0 for the medical group is considered to be the date of cardiac catheterization and time 0 for the surgical group is the TABLE I Duke Experience from 10/1169 to 2/1/77 Anatomy
Single Vessel Two Vessel Three Vessel TOTALS
Patients
Medical
445 553 994 1992
308 323 621 1252
Surgical 137 230 373 740
22
WHALEN ET AL.
date of surgery. These two dates seldom differ by more than 4-6 weeks in patients undergoing surgery. The data are graphed in terns of percent survival, pain relief, or subsequent myocardial infarction from time 0 for each group of patients as a defined period of time after time 0. Statistical significance has been calculated by using the categorical linear model.14 The survival data have also been further analyzed using the Cox survival model'5 which allows analysis of the statistical significance of survival differences after accounting for the effects of prognostic descriptors, some of which may be unequally distributed between treatment groups. RESULTS In general, it has been thought that there are three major reasons to treat patients with coronary artery disease surgically rather than medically. It has been hoped that surgery would increase survival, increase pain relief, and decrease subsequent myocardial infarction. Figure 1 summarizes our total experience in the 1992 patients. In the TOTAL DUKE GROUP- 1992 PATIENTS (10/1/69- 2/1/77)
100 e
,
90
%
52 **ME D ~~~~~~12 740 o---o SURG
\ S
80
---- * -
70 100 e
_.
80
--
a
60
L
40
20 a
I
I
I
I
IL l
10
3 4 5 Years FIG. 1. Summary of total group survival, pain relief, and myocardial infarction rate over a 5 year period. The asterisks in the top panel indicate statistically significant survival data when the categorical linear model is used. This statistical significance is not noted when the Cox survival model is used (see text). 1
2
23 upper portion of the panel, it can be seen that there is a greater five year survival rate among surgically treated patients and this increased survival (indicated by an asterisk) is statistically significant at three, four and five years utilizing the categorical linear model.'4 However, no conclusion should be drawn from this in terms of the individual patient since, as will be shown later, there are subsets of patients who do not show this beneficial effect and much of the beneficial effect depends upon improvement in subsets of patients. Furthermore, discrepancies in left ventricular function between the medically and surgically treated groups as shown by the Cox model15 may account for some if not all the difference in survival between medical and surgical groups. The middle panel of Figure 1 demonstrates that there is, indeed, a striking early improvement in terms of pain relief as defined by either complete relief of pain or improvement by two classes of pain utilizing the New York Heart Association classification. There is a fall in the improvement rate at approximately two years, but surgical patients still have a better chance of having less pain than medical patients at five years. The third panel in Figure 1 illustrates that the hoped for reduction in myocardial infarction rate after surgery has really not been obtained. These observations about pain relief and prevention of infarction conform with conclusions of other series and therefore we would like to concentrate our efforts on an analysis of survival data for the remainder of the discussion. Table II has been provided in order to present all of the survival data in this series. The p values in Table II and III have been calculated using the categorical linear model. However, these data cannot be used in an indiscriminate fashion since there are many subgroups which may act quite differently from the entire group. Figure 2 emphasizes the importance of severe left ventricular dysfunction in determining the natural history of coronary artery disease, both in the surgical as well as the medical group. It is clear from looking at this figure that an ejection fraction of less than 30%, which, in essence, represents a generalized diffusely abnormal left ventricular contraction pattern, has a dismal five year survival rate whether the patient is treated medically or surgically. The surgical and medical survival curves are almost superimposable in 200 patients. Because of early disappointing surgical experience with these patients and also because of the poor long-term survival of patients who did live through surgery, this group is seldom considered for operation at the present time. Thus, many of these patients end up being placed in the medical group by default. This tends to make indiscriminate comparisons ofmore recent surgical and medical groups inappropriate because the medical group is burdened by patients who are destined for higher mortalities because of severe left ventricular dysfunction whether they are operated on or not. THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
24
WHALEN ET AL.
TABLE II
Medical and Surgical Survival Total Duke Group (1011/69-211/77) One Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
243 209 167 119 76 44
Medicine (308) Dead NRA* Survival
8 2 1 1 2 2
57 32 41 47 41 30
96.8% 95.9% 95.3% 94.5% 92.1% 88.1%
Alive
132 120 111 92 77 61 49
Surgery (137) Dead NRA* Survival 5 0 96.4% 1 11 95.6% 0 9 95.6%
1 1 0 0
18 14 16 12
94.5% 93.3% 93.3% 93.3%
p
.475 .774 .664 .600 .787 .257
Two Vessel Disease
Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
261 221 165 119 78 46
Medicine (323) Dead NRA* Survival
11 5 13 6 4 0
51 35 43 40 37 32
96.0% 93.8% 87.0% 82.8% 78.8% 78.8%
Alive
214 188 169 155 130 107 82
Surgery (230) Dead NRA* Survival 16 0 93.0% 4 22 91.1% 2 17 90.0% 14 0 90.0% 1 24 89.4%
2 2
21 23
87.7% 85.6%
p
.020 .089 .456 .102 .048 .155
Three Vessel Disease Medicine (621)
Surgery (373) Survival Dead NRA* Survival p Surgical 42 331 0 88.7% Six-Month 469 61 91 41 88.5% 280 10 85.7% .090 One-Year 391 21 57 84.0% 236 6 38 .518 83.6% Two-Year 282 31 78 75.7% 199 5 32 81.5% .132 Three-Year 194 23 65 24 7 67.6% 168 78.2% .007 Four-Year 137 15 42 61.0% 134 3 31 76.5% .000 Five-Year 60 3 74 58.1% 77 6 51 71.0% .008 * NRA = Not yet reached anniversary date (i.e., number of patients that have not reached specific follow-up duration after catheterization or surgery). Alive
Dead NRA*
Alive
In an effort to eliminate this bias, we have deleted patients with ejection fractions of less than 30% or severe generalized diffusely abnormal left ventricular contraction patterns from the following considerations. We have chosen to use the term "selected" patients to indicate all of those patients who have ejection fractions greater than 30%, thus eliminating the high mortality group from both the surgical and medical series. In addition to that, in order to be certain that our series is comparable to other series, we have eliminated in our "selected" group, patients who have undergone emergency surgery, left ventricular surgery or valvular surgery.
25
THE NATURAL HISTORY OF CORONARY ARTERY DISEASE
Table III and Figure 3 illustrate the survival data for patients with "selected" one, two and three vessel disease. Analysis of the table demonstrates that patients with one and two vessel disease have little differences in prognosis for survival, whether treated medically or surgically. Patients with three vessel disease in this "selected" group (Figure 3) have a statistically greater survival rate at three, four and five years when the categorical linear model is used."4 However, this conclusion cannot be accepted with absolute certainty. There are differences TABLE III Medical and Surgical Survival "Selected"* Duke Group (10/1/69-211/77) One Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
233 203 164 117 74 42
Medicine (294) Dead NRAt Survival
6 2 1 1 2 2
55 28 38 46 41 30
Surgery (130) Alive
126 117 109 91 76 61 49
97.5% 96.5% 96.0% 95.1% 92.6% 88.4%
Dead NRA*
4 0 0 0 1 0 0
0 9 8 18 14 15 12
Survival
p
96.9% 96.9% 96.9% 96.9% 95.7% 95.7% 95.7%
.678 .999 .724 .907 .363 .100
Two Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year Five-Year
237 208 156 112 73 41
Medicine (291) Dead NRAt Survival
5 3 10 5 2 0
49 26 42 39 37 32
Surgery (204) Alive
197 170 153 141 118 98 77
97.9% 96.5% 90.7% 86.8% 84.5% 84.5%
Dead NRA*
7 3 2 0 1 1 1
0 24 15 12 22 19 20
Survival
p
96.6% 94.9% 93.7% 93.7% 92.9% 91.9% 90.8%
.075 .142 .379 .096 .067 .142
Three Vessel Disease Alive
Surgical Six-Month One-Year Two-Year Three-Year Four-Year
Medicine (493) Dead NRAt Survival
Surgery (330) Alive
Dead NRA*
299 31 93.3% 254 6 90.0% 212 6 81.1% 179 3 72.9% 151 5 65.3% 118 2 63.9% 66 5 ejection fraction >30%, No
387 28 78 327 12 48 238 26 63 161 18 59 111 13 37 Five-Year 46 1 64 * "Selected" = Left ventricular ular surgery. t NRA = Not yet reached anniversary date.
Survival
p
0 90.6% 39 88.5% .011 36 86.1% .055 30 84.7% .441 23 81.9% .031 31 80.6% .001 47 74.9% .038 LV, valvular, or ventric-
26
WHALEN ET AL.
SURVIVAL-(EJECTION FRACTION
