Detection, prediction, and significance of perioperative myocardial infarction following aorta-coronary bypass

Twenty-year follow-up of patients with new perioperative Q waves after coronary artery bypass grafting

It is unclear whether the development of new Q waves on the electrocardiogram after coronary artery bypass grafting (CABG) is associated with an adverse prognosis. We analyzed the 20-year survival of 227 patients who underwent CABG, and found that new perioperative Q waves had no impact on long-term survival; therefore, conservative management may be appropriate for uncomplicated patients with new Q waves after CABG.

Predictors and outcomes of cardiac complications following elective coronary bypass grafting

Our objective was to determine the predictors of cardiac complications among a cohort of elective coronary artery bypass graft (CABG) surgery patients and to determine the relationship of such complications to subsequent quality of life and symptoms. A total of 248 patients were enrolled and 237 completed 6 month follow-up. The combined rate of both major and minor cardiac complications was 9.7% (n = 24). Patients in this study were evaluated preoperatively, monitored intraoperatively, followed immediately postoperatively and at 6 months. Major cardiac complications accounted for 3.6% (n = 9) and minor complications for 6% (n = 15). Using multivariable logistic regression analysis, the predictors of major cardiac complications were receiving diuretics preoperatively (p = .01) and increased time during cross-clamping (p = .006). At 6 months after surgery, 19% of the patients with postoperative cardiac complications experienced worsening of symptoms, in contrast to only 8% of those without cardiac complications (p = .03). We concluded that patients who were on preoperative diuretics and those who had longer cross-clamp times were at higher risk of cardiac complications. The majority of patients who had acute cardiac complications had improved function and symptoms at 6 months postoperatively.

Indium-111 antimyosin scintigraphy before and after coronary bypass surgery: unexpected preoperative myocardial uptakes

The present study was designed to evaluate 111In-antimyosin scintigraphy in detecting pre- and post-operative myocardial infarction in patients undergoing coronary artery bypass surgery. Fab antimyosin scintigraphy has been shown to be sensitive and specific in detecting myocardial necrosis and to be potentially valuable in situations where other criteria are not reliable. In a previous study, postoperative antimyosin uptakes occurred in 82% of the studied patients. Sixteen consecutive patients with an indication of coronary artery surgery were assessed by preoperative coronary angiography, serial electrocardiograms, and myocardial scanning with 111Indium-labeled antimyosin antibodies performed before and after operation. In four patients, a recent myocardial infarction (1 to 3 months) was detected with an accurate localization when compared to the classic criteria of myocardial infarction. One more patient with a 21-year old myocardial infarction showed an intense uptake whereas there was no recent acute coronary event. Four other patients had an unexpected preoperative uptake, since there were no acute coronary events in their medical history. All preoperative scintigraphic uptakes were still present on the second scan performed postoperatively in these nine patients. Only one patient showed a new postoperative uptake when compared to the preoperative scan which was normal; this postoperative septal infarct was confirmed by a postoperative coronary angiography. Extracardiac uptakes (sternum and ribs) were frequently observed after operation and might hamper the interpretation of postoperative scintigrams. Unexpected preoperative uptakes may be related to non diagnosed small necrosis. A preoperative reference scan is required for an accurate interpretation of a postoperative 111In-antimyosin uptake. Moreover, extracardiac uptakes may limit the interpretation of perioperative cardiac damage.

Cardiac troponin T and troponin I release during coronary artery surgery using cold crystalloid and cold blood cardioplegia

OBJECTIVE

To evaluate and compare myocardial protection using cold crystalloid and blood cardioplegia by measuring release of cardiac Troponin T and Troponin I during coronary artery surgery.

METHODS

Forty two patients undergoing myocardial revascularization were prospectively randomised into two groups in whom myocardial protection was achieved with either antegrade cold (4 degrees C) crystalloid (CCP) (n = 21) St. Thomas' I cardioplegic solution. Serial venous blood samples were collected for measurement of cardiac Troponin T and Troponin I, prior to induction of anesthesia and at 4, 12, 24 and 48 h after removal of the aortic cross clamp.

RESULTS

There were no hospital deaths in the two groups and one patient in each group suffered a perioperative myocardial infarction. Rising levels of Troponin T and Troponin I were found in all patients. Serum concentrations increased as early as 4 h after removal of the aortic cross clamp, and reached a peak at 12 h postoperatively in both groups. These levels subsequently declined, but remained higher than preoperative values at 48 h. There were no differences between the two groups with respect to serum Troponin T and I release at 4, 12, 24 and 48 h, area under the respective curves, and peak Troponin T and I release. Serum Troponin levels were significantly higher in patients with unstable angina and in two patients who suffered a perioperative myocardial infarction.

CONCLUSION

Serum release of cardiac Troponin T and Troponin I is significantly raised in low risk patients undergoing myocardial revascularization. This release is similar when either cold crystalloid or cold blood cardioplegia are used. This may imply that both methods offer identical protection to the myocardium in a low risk group of patients.

Acadesine: a new drug that may improve myocardial protection in coronary artery bypass grafting. Results of the first international multicenter study. Multinational Acadesine Study Group

The effect of acadesine, an adenosine-regulating agent, on the incidence of myocardial infarction, all adverse cardiovascular outcomes (myocardial infarction, cardiac death, left ventricular dysfunction, life-threatening arrhythmia, or cerebrovascular accident) and mortality was assessed in 821 patients undergoing coronary artery bypass grafting. Patients were prospectively stratified to a high-risk group (age > 70 years, unstable angina, previous coronary bypass, unsuccessful angioplasty, or ejection fraction < 30%) or a non-high-risk group. They were randomized in a double-blind manner to placebo (n = 418) or acadesine (n = 403) by intravenous infusion over 7 hours (0.1 mg/kg per minute) and in the cardioplegic solution (placebo or acadesine; 5 micrograms/ml). Acadesine did not significantly affect the incidence of myocardial infarction in the overall study population, but it significantly reduced the incidence of Q-wave myocardial infarction in high-risk patients (placebo, 19.7%; acadesine, 10.0%; p = 0.032). The incidences of all adverse cardiovascular outcomes (placebo, 19.4%; acadesine, 18.4%) and overall mortality (placebo, 3.4%; acadesine, 2.7%) were similar between the two treatment groups. However, acadesine reduced the incidence of cardiac related events that contributed to deaths occurring during the first 3 postoperative days so that the incidence of death in this period was lower (placebo, 1.9%; acadesine, 0.2%; p = 0.038). No adverse events were related to acadesine treatment. Although overall there were no statistically significant between-group differences for the primary study end points, a secondary analysis in a prospectively defined high-risk subgroup suggests that acadesine may be beneficial in some patients.

Long-term prognosis after peri-operative cardiac complications

The objective was to document the 5 year prognosis of patients who had cardiac complications after non-cardiac surgery.

DESIGN

5-year follow-up of 218 patients originally enrolled in a prospective study to identify risks factors for peri-operative complications.

SETTING

an academic medical center. Participants were hypertensives and diabetics who underwent elective surgery between 1982 and 1985. In the original study, patients were evaluated pre-operatively, monitored intra-operatively by an independent observer, and followed daily for 7 days post-operatively according to a standard surveillance protocol. Outcomes were judged by assessors blinded to the pre-operative status and intra-operative course. Patients were interviewed at 3 and 5 years post-operatively. Patients with post-operative cardiac complications had significantly higher rates of overall mortality, mortality attributable to cardiac causes (MI, CHF, arrest), and mortality attributable to other cardiovascular causes (stroke, renal failure) than patients without cardiac complications. For example, at 5 years 11% of those patients without post-operative cardiac complications had cardiac deaths, in contrast to 45% of those patients with post-operative cardiac complications. Proportional hazards analysis demonstrated that post-operative cardiac complications remained a significant predictor of cardiac (p < 0.001) and cardiovascular (p < 0.0001) mortality controlling for pre-operative cardiac disease, other non-cardiovascular comorbid diseases, age, sex, diabetes, and pre-operative renal insufficiency or stroke. Similarly, patients with post-operative non-fatal cardiac complications had higher rates of cardiac or cardiovascular events during the 5 year follow-up period. We conclude that post-operative cardiac complications have a significant adverse long-term prognostic impact comparable to the prognostic impact of myocardial infarction, ischemia or congestive failure in the non-operative setting. Understanding these events could be an important factor in identifying patients at high risk for subsequent peri-operative complications.

Non-invasive assessment of perioperative myocardial cell damage by circulating cardiac troponin T

Troponin T is a unique cardiac antigen which is continuously released from infarcting myocardium. Its cardiospecificity as a marker protein might be particularly useful in assessing myocardial cell damage in patients undergoing cardiac surgery. Therefore, circulating troponin T was measured in serial blood samples from 56 patients undergoing cardiac surgery and in two control groups--22 patients undergoing minor orthopaedic surgery and 12 patients undergoing lung surgery by median sternotomy. In both control groups no troponin T could be detected, whereas activities of creatine kinase were raised in all 12 lung surgery controls and activities of the MB isoenzyme were raised in five of the 12 patients in the lung surgery group and in four of the 22 patients in the orthopaedic surgery group, respectively. All the patients undergoing coronary artery bypass grafting (n = 47) and cardiac surgery for other reasons (n = 9) had detectable concentrations of troponin T. Five patients had perioperative myocardial infarction detected as new Q waves and R wave reductions. In these five patients troponin T release persisted and serum concentrations (5.5-23 micrograms/l) reached a peak on the fourth postoperative day. In the 51 patients without perioperative myocardial infarction serum concentrations and the release kinetics of troponin T depended on the duration of cardiac arrest. In patients in whom aortic cross clamping was short troponin T increased slightly on the first postoperative days; in patients with longer periods of aortic cross clamping troponin T concentrations were higher and remained so beyond the fifth postoperative day. In patients with non-specific changes on the electrocardiogram troponin T concentrations were significantly higher on days 1 and 4 after operation than in patients with normal postoperative electrocardiograms(11.2 (5) and 4.5 (2.6) v 8.2 (3.4) and 2.9 (1.6) 1microg/l). Serum concentrations of troponin T showed some myocardial cell damage in every patient undergoing cardiac surgery. The persistent increases that were more common in patients with longer periods of cardiac arrest must have been caused by damage to the contractile apparatus. These results suggest that perioperative myocardial cell necrosis may be more common than indicated by changes of the QRS complex on the electrocardiogram.

Nifedipine reduces the incidence of myocardial infarction and transient ischemia in patients undergoing coronary bypass grafting

A randomized study was performed on 104 patients undergoing elective coronary artery bypass grafting to examine whether the infusion of nifedipine (n = 53) reduces the incidence of perioperative myocardial ischemia and necrosis in the early postoperative period. Continuous hemodynamic and three-channel Holter monitoring was performed for 24 hours and serial assessment of serum enzymes and 12-lead electrocardiography were performed for 36 hours postoperatively. Nifedipine (minimum dose, 10 micrograms/kg/hr for 24 hours) was applied from the onset of extracorporal circulation. The control group (n = 51) received nitroglycerin (minimum dose, 1 micrograms/kg/min for 24 hours). Using the combined analyses of electrocardiography and Holter recordings, myocardial ischemia was defined as being either a transient ischemic event (TIE), transient coronary spasm (TCS), or myocardial infarction (MI). The two groups did not differ with respect to preoperative New York Heart Association classification, age, history of myocardial infarction, extracorporal circulation and aortic cross-clamp time, number of distal anastomoses, or systemic and pulmonary hemodynamics. The incidence of perioperative myocardial ischemia was substantially lower in the nifedipine than in the nitroglycerin group [TIE: three of 53 patients (6%) versus nine of 50 patients (18%), p less than 0.001; MI: two of 53 patients (4%) versus six of 50 patients (12%), p less than 0.001; and TCS: none of 53 patients (0%) versus two of 50 patients (4%), p = NS].(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative myocardial infarction after coronary artery bypass surgery. Clinical significance and approach to risk stratification

The clinical significance of perioperative myocardial infarction (MI) after coronary artery bypass surgery is not known. Therefore, strategies for the risk stratification of these patients do not exist. This study was undertaken to define the effect of perioperative MI on prognosis after discharge from the hospital and to develop an approach to the risk stratification of these patients. Fifty-nine patients with and 115 patients without perioperative MI were observed for 30 months for the development of cardiac events (death, nonfatal MI, and admission to hospital for unstable angina or congestive heart failure). Patients with perioperative MI were significantly more likely than patients without to have a cardiac event (31% versus 12%, p less than 0.01) and multiple events (19% versus 1%, p less than 0.001). Cox regression analysis identified two independent predictors of cardiac events other than perioperative MI (relative risk, 2.7): inadequate revascularization (relative risk, 3.5) and depressed (less than 40%) postoperative ejection fraction (EF) (relative risk, 2.1). Event-free survival rate of patients with perioperative MI varied markedly depending on the number of other negative prognostic variables present. Patients with perioperative MI who were adequately revascularized and had a postoperative EF greater than 40% had an event-free survival rate similar to patients without a perioperative MI (92% versus 87%, p = NS). Patients with perioperative MI who were inadequately revascularized and had depressed postoperative EF had an event-free survival rate of 13% (p less than 0.001 versus all other subsets). Event-free survival rate was intermediate (68%) in patients with perioperative MI and with only one of the other two variables (p less than 0.001 versus other subsets). In conclusion, perioperative MI adversely affects prognosis. Patients can be stratified into low, high, and intermediate risk subsets based on a simple assessment of the adequacy of revascularization and a determination of residual left ventricular function.

Serum creatine phosphokinase, lactic dehydrogenase, and their isoenzymes in the perioperative period

The purpose of the present investigation was to determine the normal perioperative variations in the serum concentration of creatine phosphokinase (CPK) and its isoenzymes MM, MB, and BB, and of lactic dehydrogenase (LDH) and its isoenzymes LDH1 to LDH5 to distinguish operation-induced changes in these enzymes from those due to acute myocardial infarction or malignant hyperthermia. In 30 patients, 52 to 75 years of age undergoing elective orthopedic operations, 10 serial blood samples were obtained in the perioperative period: two samples before skin incision and eight samples after the incision over a time span of 70 hours. The preinduction mean serum CPK level of 141 U/L increased gradually and significantly and reached a maximum mean concentration of 809 U/L 34 hours after incision (p less than 0.01). The CPK-MM percent increased after incision, whereas that of CPK-MB and CPK-BB decreased, although their absolute values in terms of U/L rose. The preinduction mean serum LDH value of 173 U/L increased gradually after incision and achieved peak levels at 34 hours (203 U/L) and 58 hours (210 U/L) after incision (p less than 0.05). The LDH1:LDH2 ratio did not change. The LDH5 percent increased and peaked 10 hours after incision (p less than 0.05). There was a significant correlation between severity of operation-induced tissue damage and the serum CPK concentration (p less than 0.001). The large increase in total CPK (primarily MM fraction) occurring after surgery may minimize the percentile effects caused by an increase in MB level due to myocardial infarction.

Short-term effect of coronary artery bypass grafting on the signal-averaged electrocardiogram

Ventricular late potentials at the end of the QRS can be detected on the body surface during sinus rhythm by recording a signal-averaged electrocardiogram (SAECG). In patients with coronary artery disease, these late potentials have been shown to be markers for spontaneous or inducible ventricular tachycardia, or both. The short-term (before and 10 +/- 4 days after coronary revascularization) influence of coronary artery bypass grafting (CABG) on the quantitative SAECG variables was studied in 40 patients with chronic coronary artery disease. Twenty-five of these patients had a previous myocardial infarction. In the 15 patients without previous myocardial infarction, no abnormal SAECG indexes were recorded before CABG and no change in the quantitative SAECG variables was observed after surgery. In the patients with a previous myocardial infarction, 7 (28%) had a late potential before CABG. After CABG, 5 (71%) patients remained late potential-positive, whereas the other 2 (29%) lost their late potential. The mean values of their SAECG variables improved after coronary revascularization. In the entire group of postmyocardial infarction patients, the high-frequency QRS duration had shortened (p less than 0.01) after CABG (the other SAECG indexes did not change). The postoperative arrhythmic complications (transient atrial fibrillation, new onset of ventricular couplets) tended to be more frequent in the postmyocardial infarction group and in patients with late potentials. Our findings suggest that the reported increase in ventricular arrhythmias after CABG is probably not related to a change in the arrhythmogenic substrate for ventricular reentry but is associated with changes in the arrhythmogenic milieu.

Preoperative myocardial ischaemia: its relation to perioperative infarction

One hundred consecutive patients undergoing coronary artery bypass surgery were randomly allocated to a preoperative (24 h) intravenous infusion of isosorbide dinitrate (1.5-15 mg/hr) (50 patients) or to placebo (50 patients). The characteristics of the two groups were similar. Evidence of acute myocardial ischaemia was sought by continuous electrocardiographic Holter recordings and acute myocardial infarction by the appearance of new Q waves and increased activity of the creatine kinase MB isoenzyme. Episodes of acute myocardial ischaemia were found in 18% of patients in the control group and in none of those who received isosorbide dinitrate. None the less, the frequency of perioperative myocardial infarction was similar (22% and 18% respectively) in the two groups. Perioperative infarction was significantly more common in women, in patients with unstable angina or poor left ventricular function, in those who had coronary endarterectomy, and in those in whom the aortic clamping time was greater than 50 minutes. These factors may have obscured any effect that prevention of preoperative ischaemia had on perioperative infarction. Preoperative infusion of isosorbide dinitrate eliminated preoperative ischaemia but did not influence the occurrence of perioperative infarction. The probable benefits of prevention of preoperative ischaemia on postoperative left ventricular function, which is a determinant of long term survival, remain to be established.

De novo refractory ventricular tachyarrhythmias after coronary revascularization

Twelve of 1,675 patients who underwent coronary artery bypass grafting during a 2.5-year period had new onset, recurrent, sustained ventricular tachyarrhythmia a mean of 27 days (range 2 to 150) postoperatively. No patient had an intra- or perioperative myocardial infarction and all patients were hemodynamically stable and had normal metabolic and electrolytic indexes at the time of ventricular tachyarrhythmia. Preoperative ejection fraction was 39 +/- 10% (mean +/- standard deviation) and all patients had Lown grade II or less ventricular ectopic activity on ambulatory monitoring. Postoperative angiography demonstrated occluded saphenous vein grafts in 3 of 7 patients studied, none of whom had symptoms suggestive of myocardial ischemia. Treatment with conventional antiarrhythmic therapy was unsuccessful in all but 1 patient, and 10 patients were treated with amiodarone and 1 patient with propafenone. Four of these patients also received an automatic implantable defibrillator. Thus, de novo ventricular tachyarrhythmia can occur unexpectedly after coronary artery bypass grafting and may be the result of several factors related to either subclinical graft occlusion or increased dispersion of repolarization secondary to reperfusion.

Myocardial infarction related to coronary artery bypass graft surgery

Fifty consecutive patients undergoing coronary artery bypass grafting for chronic stable angina were assessed by serial electrocardiography, preoperative and postoperative myocardial scanning with technetium-99m pyrophosphate, gated radionuclide ventriculography, and serial measurement of creatine kinase, aspartate aminotransferase, urea stable lactic dehydrogenase, and creatine kinase isoenzyme (MB) to assess the incidence of perioperative myocardial infarction and identify the most appropriate diagnostic techniques. The correlation between myocardial scanning and the measurement of peak enzyme and isoenzyme activity was excellent in the diagnosis of perioperative infarction, although electrocardiography proved less helpful. There appeared to be no advantage in measuring creatine kinase MB rather than the more routinely measured enzymes. There were two deaths and evidence of myocardial infarction in five other patients, an incidence of 14%. Perioperative infarction was associated with a significant reduction in resting ejection fraction in two cases. In those patients without evidence of perioperative infarction the mean increase in ejection fraction of 7.8% was statistically significant.

Graft patency in patients with coronary artery bypass operation complicated by perioperative myocardial infarction

Coronary artery bypass graft patency was examined by contrast-enhanced computed tomography in 18 patients with perioperative myocardial infarction soon after surgery to determine the role of graft occlusion. Preoperative coronary angiograms were reviewed to assess native coronary disease and visible collateral channels in the distribution of the myocardial infarction. Perioperative myocardial infarction was diagnosed if creatine kinase-MB was elevated, characteristic electrocardiographic changes occurred and, in the majority of cases, the pyrophosphate scan was positive. Fourteen patients (78%) had patent grafts and perioperative myocardial infarction in the distribution of the grafted vessel. Four patients had an occluded graft with infarction in the distribution of the grafted vessel. Among the 14 patients with patent grafts, there was a significant difference (p less than 0.0005) in the degree of the mean (+/- standard deviation) diameter stenosis of 80 +/- 11% in native coronary vessels supplying the perioperatively infarcted myocardium versus a 55 +/- 12% mean diameter stenosis in the 23 bypassed native coronary vessels supplying noninfarcted myocardium. It is concluded that the majority of perioperative myocardial infarcts associated with coronary artery bypass operations are not caused by graft occlusion. The severity of coronary obstruction in the grafted vessel and the lack of collateral vessels to the region of perioperative infarction in patients with patent grafts suggests that an island of jeopardized myocardium exists that is subject to inadequate intraoperative preservation.

Changes in left ventricular performance related to perioperative myocardial infarction in coronary artery bypass graft surgery

Strict electrocardiographic, enzymatic, scintigraphic, and hemodynamic criteria for perioperative myocardial infarction (MI) were defined and related to serial assessments of left ventricular performance during rest and exercise in patients seen early and late after coronary artery bypass graft operation. Global left ventricular performance was determined by radionuclide ventriculography from which changes in the pattern of serial postoperative ejection fractions (EF) were obtained. Patients were divided into two groups based on the presence or absence of perioperative MI, and were matched in pairs on the basis of preoperative EF and extent as well as location of coronary artery obstructions. The results indicate that neither short- nor long-term depression in resting EF occurred subsequent to perioperative MI. However, an exercise-related increase in EF eight months postoperatively was depressed in patients who had perioperative MI compared with those who did not. Patients with new Q waves and abnormal postoperative elevation in serum levels of the myocardial isoenzyme of creatine kinase (CK-MB) had a greater early decrease in EF compared with patients without evidence of perioperative MI. However, seven days after operation, the EF in both groups returned to preoperative levels. Patients with abnormal technetium 99m-pyrophosphate scintigrams had changes in perioperative EF similar to those in patients without MI. The presence of low cardiac output syndrome immediately after operation was associated with immediate and short-term decreases in EF, which were not seen in any of the other patient subgroups.

Use of survival analysis to determine the clinical significance of new Q waves after coronary bypass surgery

There are few data on the long-term effects of new Q waves on survival and morbidity after coronary bypass graft surgery (CABG). We followed 1340 patients who underwent CABG in 1978 at 10 hospitals participating in the Coronary Artery Surgery Study (CASS). The incidence of perioperative Q-wave infarction was 4.76% (range 0.0-10.3% by hospital). The rate of infarction was higher in patients who had an increased left ventricular end-diastolic pressure or cardiomegaly on the preoperative chest radiograph. Patients who received more grafts or who had longer cardiopulmonary bypass time were also at higher risk of infarction. In a stepwise discriminant analysis of 44 clinical, angiographic and surgical variables, cardiopulmonary bypass time, topical cardiac hypothermia and cardiomegaly entered the stepwise selection of variables. Long-term survival was adversely affected by the appearance of new postoperative Q waves. The hospital mortality was 9.7% in the 62 patients who had new postoperative Q waves and 1.0% in the 1278 patients who did not (p less than 0.001); the 3-year cumulative survival rates were 85% and 95%, respectively (p less than 0.001). In patients who survived to hospital discharge, the presence of new postoperative Q waves did not adversely affect 3-year survival (94% and 96%, respectively). The survival rates were worse in patients who had a history of infarction or who had impaired left ventricular function preoperatively. The number of readmissions to hospital after CABG among the patients who had a transmural perioperative infarction was similar to to that among patients who did not. We conclude that the appearance of new Q waves after CABG adversely affects survival. The major impact on mortality occurs before hospital discharge. Patients who are destined to have a perioperative infarct cannot be predicted from commonly measured preoperative and angiographic variables.

Perioperative myocardial infarction and changes in left ventricular performance related to coronary artery bypass graft surgery

Recent advances in perioperative management and surgical technique have been associated with low operative mortality and a high incidence of symptomatic relief in patients undergoing coronary artery bypass graft (CABG) operations. The frequency and importance of perioperative myocardial infarction (MI) and immediate as well as long-term changes in left ventricular (LV) performance are factors of considerable current interest in any critical analysis of the effectiveness of CABG surgery. The present review describes the effects of patient selection, anesthetic techniques, and newer methods of myocardial protection as they relate to perioperative MI and LV performance. In addition, newer tests useful in the diagnosis of perioperative MI are discussed. The application of noninvasive techniques for the serial determination of LV performance and myocardial perfusion in CABG operations is also described.

Survival in subgroups of patients with left main coronary artery disease. Veterans Administration Cooperative Study of Surgery for Coronary Arterial Occlusive Disease

This report presents the 42-month survival experience of 91 patients with a significant lesion of the left main coronary artery in the Veterans Administration Cooperative Study of Coronary Bypass Surgery. Survival in surgical patients was significantly better than that in the medical group (p = 0.016), even after adjustments were made for two important differences in baseline characteristics--duration of angina and high risk by angiographic criteria--between the two groups (p = 0.019). Subgroups based on severity of left main stenosis and on left ventricular (LV) function showed significant trends in favor of surgery in patients with more than 75% left main stenosis and in those with abnormal LV function. A similar but nonsignificant trend was seen in the two subgroups with 50-75% stenosis or with normal LV function. The surgical benefits were not significantly different between the categories of the subgroups defined separately by stenosis and LV function. Low-, middle- and high-risk subgroups based on four noninvasive clinical predictors also showed significantly improved survival with surgery in the high-risk group. The low-risk groups showed a slight, nonsignificant disadvantage with surgical treatment. These data support the view that patients with left main disease are not a homogeneous group. High- and low-risk subgroups with different outcomes and responses to treatment can be delineated by angiographic or clinical criteria. For most patients with left main disease, coronary artery bypass grafting offers improved longevity.

Effect of perioperative myocardial infarction on late survival in patients undergoing coronary artery bypass surgery

From the Seattle Heart Watch angiography registry, the baseline characteristics and late survival of 77 patients who sustained operative infarction (new Q waves) with myocardial revascularization were compared with 1790 patients who underwent coronary artery bypass without perioperative infarction. With the exception of coronary collateral vessels, which were less frequently seen in the patients with perioperative infarction, no baseline or operative characteristic distinguished between the two groups. Late survival was clearly adversely affected by perioperative infarction. Five-year survival was 76% in patients with perioperative infarction, compared with 90% in those with no perioperative infarction.