Quality of life after aortic valve replacement at the age of >80 years.

BACKGROUND: The optimal management of aortic valve disease in patients >80 years old depends on functional outcome as well as operative risks and late survival. METHODS AND RESULTS: We retrospectively identified 133 patients (62 men, 71 women) aged 80 to 91 years (mean 84+/-3 years) who underwent aortic valve replacement alone or in combination with another procedure between January 1, 1993, and April 31, 1998. Demographics included hypertension 68%, diabetes mellitus 17%, and history of stroke 11%. Operative (30 day) mortality rate was 11%. Urgent or emergent surgery, aortic insufficiency, and perioperative stroke or renal dysfunction were risk factors for operative death by multivariable analysis. Intensive care unit and total hospital length of stay were prolonged at 6.2 and 14.7 days, respectively. Late follow-up between July 1, 1998, and November 1, 1999, was 98% complete. Actuarial survival at 1 and 5 years was 80% and 55%, respectively. Predictors of late mortality were preoperative or perioperative stroke, chronic obstructive pulmonary disease, aortic stenosis, and postoperative renal dysfunction. The mean New York Heart Association functional class for 65 long-term survivors improved from 3.1 to 1.7. Quality of life assessed with the Medical Outcomes Study Short Form-36 was comparable to that predicted for the general population >75 years old. CONCLUSIONS: Functional outcome after aortic valve replacement in patients >80 years old is excellent, the operative risk is acceptable, and the late survival rate is good. Surgery should not be withheld from the elderly on the basis of age alone.

Capillary basal laminar thichness in diabetic human myocardium.

Biopsied myocardial tissue was obtained from 24 patients electing coronary arterial bypass surgery who were divided into three groups: chemical diabetics (CD) with normal fasting blood sugar levels and incidentally encountered elevated glucose levels after sugar loading; overt diabetics (OD) requiring insulin treatment; and euglycemic, nondiabetic patients (ND) serving as a control group. Specimens from the left anterior apical segment of the heart were processed for ultrastructural examination, with special emphasis on determining capillary basal laminar thickness with the aid of morphometric techniques. Results of this study indicate that (1) a statistically significant increase in basal laminar thickness is evident in myocardial tissue of OD patients; (2) incipient alterations in laminar width are demonstrable in the CD group; (3) the predominant morphologic abnormalities, which we have examined in the parenchymal tissue of the biopsied hearts, namely myocardial hypertrophy and interstitial fibrosis, are present to a comparable degree in all three groups of patients; and (4) the average thickness of basal laminae around myocardial capillaries tends to be narrower compared with measurements reported in other tissue compartments.

The changing profile of the patient undergoing coronary artery bypass surgery.

The first 100 consecutive patients undergoing isolated coronary artery bypass surgery in 1975 were evaluated with respect to the incidence of operative risk factors and outcome. When compared with an identically selected group from 1985, there was significant worsening of the preoperative condition over the decade with regard to mean age (p less than 0.0005), presence of congestive heart failure (p less than 0.05), left ventricular dysfunction (p less than 0.05), severity of coronary artery disease (p less than 0.001) and incidence of emergency operation (p less than 0.05). More patients in 1985 had associated medical diseases such as diabetes (p less than 0.01) and chronic lung disease (p less than 0.005). There was an increase in the occurrence of vascular diseases (hypertension, renal dysfunction, peripheral vascular and cerebrovascular disease) (p less than 0.05). Overall operative mortality increased from 1 to 8% (p less than 0.05) over the decade. Despite the deterioration in the clinical profile of the patient undergoing coronary bypass surgery, elective procedures were still performed with low mortality. The significant increase in overall mortality was chiefly in patients undergoing emergency operation (p less than 0.05). There were also increases in operative morbidity including low output syndrome (p less than 0.01) and respiratory (p less than 0.005) and neurologic (p = 0.06) complications.

Coronary revascularization under age 40 years. Risk factors and results of surgery.

Groups of patients such as the elderly, the diabetic and women have been studied to evaluate the effectiveness of coronary revascularization. In this report 77 patients under age 40 years undergoing coronary revascularization were studied. There was a high prevalence rate of predisposing factors. Sixty-eight percent reported a family history of heart disease and 27 percent a history of diabetes; 57 percent were hypertensive, 43 percent were overweight, 91 percent smoked, 5 percent were diabetic and 16 percent had abnormal glucose tolerance curves. Sixty-four percent had hypercholesterolemia (cholesterol 250 mg/100 ml) and 56 percent hyperlipidemia. Forty-four percent had had a previous myocardial infarction; 95 percent had angina pectoris, 12 percent preinfarction angina and 9 percent congestive cardiac failure. There were no operative deaths. The incidence rate of perioperative myocardial infarction (new Q waves in the electrocardiogram) was 4 percent. The mean length of of follow-up was 26 months (range 6 months to 5 years). The late mortality rate was 4 percent. Eight percent had a late myocardial infarction. Overall graft patency was 85 percent. Sixty-seven percent of patients were free of angina, and 17 percent were in improved condition. Seventy-one percent returned to work, while 29 percent remained unemployed. This study shows that in young patients, coronary revascularization is associated with low mortality and morbidity rates and that, despite the wide prevalence of predisposing factors, the prognosis and graft patency rate of these patients are similar to those of other groups.

Revascularization of the right coronary artery.

This study was undertaken to evaluate revascularization of the right coronary artery with regard to factors that enter into the decision to graft less significant lesions, such as graft flow, graft patency and progression of proximal disease. The results of grafting the right coronary artery were studied in 23 patients with lesions reducing luminal diameter by less than 50 percent (Group 1), 35 patients with luminal narrowing of 50 to 70 percent (Group 2) and 112 patients with greater than 70 percent luminal narrowing (Group 3). At operation there was no significant difference in saphenous vein graft flows among the three groups. Postoperatively the mean follow-up period was 20, 27 and 26 months, respectively. Graft patency was not significantly different among the three groups. Progression of the proximal lesion was studied and compared with that in 71 ungrafted right coronary arteries, 60 with less than 50 percent stenosis and 11 with more than 50 percent stenosis. Among vessels with less than 50 percent narrowing, the proximal lesion showed progression in 26 percent of the ungrafted vessels and in 83 percent of the grafted vessels (P less than 0.005); progression to total occlusion occurred in 3 percent of the former and in 28 percent of the latter (P less than 0.005). Progression to total occlusion was more frequently associated with a patent than with an occluded graft (P less than 0.05). The occurrence of significant progression in ungrafted vessels and the lack of effect on graft patency of the severity of the proximal disease suggest that revascularization of less significant lesions may be of value. However, the resultant increase in progression of proximal disease makes the patient dependent on the long-term patency of the vein graft.

Long-term results of myocardial revascularization.

During 1970 to 1977, among 1,733 patients who underwent isolated coronary bypass grafting, the operative mortality was 2.5 percent. Actuarial 5 year survival is 88.1 percent. At an average follow-up of 46 months (range 13 to 108), 90 percent of patients remain angina-free or with symptomatic improvement. The 5 year survival rate of patients with single vessel coronary artery disease is 97.9 percent. In patients with multivessel disease, operative survival appears to be favorably influenced by the presence of normal preoperative ventricular function. Late survival is significantly better in patients with multivessel disease with normal preoperative ventricular function or with complete revascularization. Risk of perioperative myocardial infarction has been appreciably reduced by the introduction of cold potassium chloride cardioplegia. Late myocardial infarction has occurred at an average annual risk of 1.46 percent. These data show that long-term survival and a small incidence of late myocardial infarction after myocardial revascularization are more likely in patients who undergo complete revascularization before significant left ventricular myocardial damage has occurred.

Relation of silent myocardial ischemia after coronary artery bypass grafting to angiographic completeness of revascularization and long-term prognosis.

The prevalence and characteristics of silent myocardial ischemia as detected by 24-hour ambulatory electrocardiography ST-segment depression were prospectively assessed in 94 patients examined early (1 to 3 months) and 184 patients examined late (12 months) after coronary artery bypass grafting (CABG), and followed for a mean of 48 +/- 11 (range 4 to 62) months. The relation of ambulatory electrocardiographic silent ischemia to evidence of completeness of revascularization as defined by cardiac angiography performed 1 and 12 months after CABG, and to prognosis by follow-up of adverse clinical events was analyzed. Silent ischemia was detected early in 20% (19 of 94) and late in 27% (50 of 184) of patients, and showed a mean frequency of episodes ranging from 6 to 10 episodes/24 hours with a mean duration ranging from 15 to 23 minutes. The circadian distribution of episodes disclosed a significant peak of ischemic activity during the period of 6 A.M. to noon and a secondary peak between 6 P.M. and midnight (p less than 0.01 and p less than 0.001, respectively). Silent ischemia was not found by univariate analysis to be associated with graft or anastomotic site occlusions, low graft flow rates, grafted arteries with significant distal residual stenoses or ungrafted stenotic native coronary arteries. Kaplan-Meier analysis of time to cardiac event showed that silent ischemia was not predictive of an adverse clinical event in the early years after CABG. Cox regression analysis of 30 covariates only disclosed age (relative risk 1.06 [95% confidence interval, 1.01 to 2.94]) as having an effect on time to adverse clinical event.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary artery bypass surgery in patients aged 80 years or older.

Between August 1980 and January 1986, 23 patients aged 80 years or older underwent coronary artery bypass grafting (CABG) operations. These patients had a higher incidence of severe left main coronary artery narrowing (p less than 0.0001), 3-vessel coronary artery disease (p less than 0.05) and moderate to severe left ventricular dysfunction (p less than 0.05) than patients in the Coronary Artery Surgery Study registry older than 65 years. Of 14 patients undergoing elective simple CABG procedures, none died; of 19 elective cases overall, 2 patients died (11%). Three of 4 patients undergoing emergency procedures (75%) and 4 of 6 patients (67%) requiring intraaortic balloon counterpulsation died. Significant complications occurred in 9 of 18 survivors (50%). All operative survivors improved at least 1 New York Heart Association class, with a mean classification improvement of 3.7 to 1.6 (p less than 0.0001); 13 of 16 long-term survivors were in class I or II. Actuarial survival at 1 and 2 years is 94% and 82%, respectively. CABG can be performed electively in octogenarian patients with increased but acceptable mortality and morbidity risks. Functional improvement and long-term survival are excellent.

Pathomorphologic aspects of muscular tissue in diabetes mellitus.

Biopsy specimens from the myocardium were examined in a series of 145 patients who had elected coronary arterial bypass grafting. The patients were divided into three groups; 1) overtly diabetic (OD) patients; 2) chemically diabetic (CD) patients, who demonstrated impaired glucose tolerance only when stressed with a sugar load; and 3) normoglycemic, nondiabetic (ND) patients, who served as a control group. Tissue plugs from the left anterior apical segment of the heart and from the quadriceps femoris in 71 patients, for comparative evaluation, were prepared for ultrastructural examination. Findings were as follows: 1) Myocardial hypertrophy and interstitial fibrosis were twin characteristic abnormalities, seen in all but two of the biopsy specimens; capillary endothelial changes, the third most common abnormality, were present in approximately half of these specimens, regardless of the patients' metabolic status. 2) In patients matched by sex, age, weight, blood pressure, preoperative myocardial ventricular function, and coronary arterial integrity, capillary basal laminar thickening represented a pathomorphologic hallmark, distinguishing structural alterations in the diabetic from those in the normoglycemic patient. 3) Although clear-cut and statistically significant thickening of basal laminae was noticeable in OD patients, a) in the quadriceps markedly increased laminar thickening was present in a number of ND patients, rendering interpretation of this change in skeletal muscle as pathognomonic for diabetes doubtful; and b) within cardiac muscle this increase in laminar width was less than that seen in skeletal muscle, leaving the functional implications of this alteration in doubt. 4) Early but statistically significant increases in capillary basal laminar thickening were observed in the myocardium of CD patients; these patients demonstrated impaired glucose tolerance only when stressed with a sugar load, without exhibiting overt diabetic manifestations. 5) In this group of highly selected patients with epicardial coronary arterial disease, the histopathologic profile of the diabetic myocardium did not include distinctive abnormalities sufficient to warrant the designation of "diabetic cardiomyopathy," indicating that coronary arterial bypass grafting can be recommended for the diabetic patient who requires this procedure.

A noncannulating coronary perfusion cannula.

A noncannulating cannula was devised to avoid trauma to the coronary ostia and secondary ostial stenosis. The cannula achieves a seal with the aortic wall through the use of bulbous silicone gel-filled tip. The same cannula has effectively perfused the right and left ostia and previously placed aorta-coronary bypass grafts with one exception, in which calcification of the aortic wall prevented a satisfactory seal.

Aortic venting. Comparison of vent effectiveness.

Three commercially available aortic vents have been evaluated as to effectiveness in removing small volumes of air introduced into a mock circulatory circuit. Without aspiration, Vent 2 was the most effective and removed 58 per cent of 0.1 ml., 90 per cent of 0.5 ml., and 74 per cent of 1.0 ml. boluses at a cardiac output of 2 L. At a cardiac output of 4 L., Vent 2 removed 42, 76, and 49 per cent, respectively. With aspiration (Vent 2 not designed for aspiration) and a 2 L. cardiac output, Vents 1 and 3 removed 84 to 98 per cent of 0.1 ml., 68 to 92 per cent of 0.5 ml., and 74 to 86 per cent of 1.0 ml. boluses. With aspiration and a 4 L. cardiac output, Vent 3 was significantly more effective than Vent 1 and removed 92 to 94 per cent of 0.1 ml., 82 to 86 per cent of 0.5 ml., and 77 to 80 per cent of 1.0 ml. boluses. One liter of canine blood was aspirated through Vents 1 and 3 and a flow rate of 250 ml. per minute. For Vent 1, serum hemoglobin levels increased from 40 to 249 mg. per 100 ml. and for Vent 3 from 49 to 212 mg. per 100 ml. There are significant differences in the ability of commercially available aortic vents to remove small air bubbles trapped in the heart after initial direct cardiac venting. Vents having the capability of aspiration are more effective and result in acceptable hemolysis.

The left internal mammary artery as a sequential graft to the left anterior descending system.

The left internal mammary artery (IMA) has been used as a sequential graft to the left anterior descending (LAD) system in 39 patients. Seven patients having operation in 1977 were followed up for 2 years, and cardiac catheterization in four revealed no problems related to the anastomoses. After a 2 year hiatus we resumed use of the procedure in 1980. A total of 10 patients have had catheterization from 1 month to 5 years postoperatively with no anastomotic narrowing or restriction of distal IMA flow by the side-to-side anastomosis. The IMA should be equal to or greater in size than the larger of the two vessels to be grafted. We continue to use this procedure in carefully selected patients.

Effects of dilation with a balloon catheter on the endothelium of the internal thoracic artery.

Controlled dilation of the internal thoracic artery with a balloon catheter has been reported to effectively treat intraoperative arterial spasm. It has been shown in laboratory animals that dilation of the internal thoracic artery at prescribed shear force levels will not cause intimal damage. Using scanning electron and light microscopy, we have examined the effects of calibrated balloon dilation on the endothelium of the human internal thoracic artery. In 10 patients with bilateral internal thoracic artery grafting, the artery was dilated with a Fogarty IMAG balloon catheter (Baxter Healthcare Corporation, Edwards Division, Santa Ana, Calif.) that was withdrawn at tensions of 20 or 30 gm. Arterial segments and nondilated control specimens were prepared for scanning electron microscopy. The intimal surface of each internal thoracic artery was evaluated by assigning a score (from 0 to 3) to 10 examined scanning electron microscopy fields; subsequently the arterial tissue was viewed by light microscopy with paraffin-embedded sections stained for elastic tissue. Arteries were obtained from three additional patients so that the microscopic appearance of the arteries could be observed after rough manipulation or removal of the balloon without shearing. The results of this study are as follows: (1) By scanning electron microscopy, dilated internal thoracic arteries yielded consistently higher scores than the control arteries, reflecting severe, tension-dependent alterations of the endothelium, which included marked desquamation of endothelial cells, with extensive areas of complete denudation and pronounced attachment of platelets to these areas; (2) endothelial injury occurred by inflation alone, without shearing by the inflated balloon; (3) by light microscopy, the internal thoracic arteries showed (a) fenestrations of the internal elastic lamina with occasional transmigration of smooth muscle cells through these gaps and (b) foci of intimal thickening without overt atherosclerotic lesions. We conclude that the endothelium of human internal thoracic arteries is highly vulnerable to balloon dilation, which can severely injure the intimal surface. For this reason we prefer not to include this procedure in our protocol for preparing the internal thoracic artery.

Twelve-year experience with internal mammary artery for coronary artery bypass.

From Feb. 1, 1972, to Jan. 30, 1984, 1,000 patients had isolated coronary bypass with at least one internal mammary artery, and 103 of them had bilateral internal mammary artery grafts. There were 1,395 associated vein grafts and 1,158 internal mammary artery anastomoses, for a total of 2,556 grafts (2.5 per patient). Patients were followed up for 1 to 12 years (mean 6.3 years) and 77 patients were lost to follow-up at a mean of 4.0 years. Operative mortality was 1.4%, with 11 of 14 deaths in the first 240 patients (4.6%) and eight of 14 in the 103 patients with bilateral internal mammary artery grafts. There were 93 late deaths, with an actuarial survival rate of 93% at 5 years and 84% at 10 years. Angina occurred at a mean rate of 6.2% +/- 1.2% per year. Perioperative infarction was detected in 37 patients (3.7%). Late infarction occurred in 75 patients, for a mean rate of 1.5% +/- 0.3% per year. Reoperation (or percutaneous transluminal coronary angioplasty) was necessary in 35 patients, for a mean rate of 0.85% +/- 0.28% per year. Graft patency was assessed by 1,029 follow-up catheterizations in 519 patients. The patency rate of the left internal mammary artery was 96.4% at 1 year, 88.1% at 5 years, and 88.1% at 10 years. That of the right internal mammary artery was 92.8% (p = NS) at 1 year, 84.6% (p = NS) at 5 years, and at 10 years the numbers were too small to be meaningful. Comparison of patency rates for all internal mammary artery grafts with vein grafts gave 1 year graft patency rates of 95.7% versus 93.4% (p less than 0.025), 5 year rates of 87.9% versus 74.0% (p less than 0.001), and 10 year rates of 83.0% versus 41.0% (p less than 0.001). Included in these patency data are 20 free internal mammary artery grafts; 16 were studied (mean 2.3 years) and 12 of these 16 (75%) were patent. Of the 58 sequential internal mammary artery grafts, 18 were studied by catheterization (mean interval 2.0 years); 35 of 36 anastomoses were patent and one end-to-side anastomosis was closed. Morbidity and mortality for patients having internal mammary artery grafting are comparable to those of patients having saphenous vein bypass only. The demonstrated superior patency for internal mammary artery grafts supports the routine use of bilateral internal mammary artery grafting.

Cold blood cardioplegia.

The technique of myocardial protection by means of a cardioplegic solution consisting of cold blood (10 degrees C) with potassium (30 mEq. per liter) is described. A disposable cooling coil is used and a separate pump head for coronary perfusion is avoided. The aortic perfusion cannula can be used for venting of the left ventricle and subsequently for venting of air. This method was used in 125 consecutive patients undergoing coronary revascularization and in 73 consecutive pediatric cardiac surgical procedures with excellent results.

Aortic valve replacement in von Willebrand's disease.

A patient with von Willebrand's disease having aortic valve replacement was managed with cryoprecipitate infusions and monitoring of factor VIII levels. This disorder is associated with low factor VIII levels and abnormal platelet function. There may be no history of bleeding, as the severity of the bleeding tendency varies greatly and fluctuates temporally. The partial thromboplastin time is frequently prolonged, but more detailed studies are necessary to establish a diagnosis (bleeding time, platelet adhesiveness to glass beads and ristocetin, von Willebrand's antigen, ristocetin-von Willebrand's factor, and factor VIII clotting activity). Elevation of factor VIII levels to 50 to 100% of normal allows adequate clotting and is best accomplished with cryoprecipitate or fresh frozen plasma rather than commercial concentrates of factor VIII, whose activity is unpredictable.

Afterload reduction with hydralazine following valve replacement.

Impedance reduction with hydralazine was evaluated in 23 patients 1 to 3 hours after aortic or mitral valve replacement. Patients were randomly assigned to Group 1 (0.25 mg/kg) or Group 2 (0.5 mg/kg) and responses at 20, 60, and 120 minutes compared with control (paired t test) and mean values for each group compared (t test). In Group 1 significant responses were the fall in mean arterial pressure (78.3 +/- 3.0 to 66.7 +/- 2.2 mm Hg) and systemic vascular resistance (2,808 +/- 264 to 1,823 +/- 164 dynes-sec/cm5); the increase in cardiac index (2.07 +/- 0.13 to 2.71 +/- 0.21 L/min/m2), stroke volume index (26.9 +/- 2.3 to 34.0 +/- 3.3 ml/beat), and heart rate (80.8 +/- 5.8 to 84.2 +/- 6.6 beats/min). Central venous pressure did not change and left atrial pressure decreased at 120 minutes. Group 2 responses were similar except for higher central venous pressure at 20 minutes, higher left atrial pressures at control, 20, and 60 minutes, and lower left ventricular stroke work at control, 20, and 60 minutes. By selectively dilating the arterial system, hydralazine reduces mean arterial pressure and systemic vascular resistance and increases cardiac output with suble filling pressures.

Cold-blood potassium cardioplegia: evaluation of glutathione and postischemic cardioplegia.

Potassium (34 mEq/L) cardioplegia was induced with cold blood (CBK) in three groups of six dogs undergoing 60 minutes of myocardial ischemia at a systemic temperature of 27 degrees +/- 2 degrees and a myocardial temperature of 7 degrees +/- 2 degrees C (crushed ice). Group 1 (CBK) animals were reperfused initially with 400 ml cold blood over 8 to 10 minutes at increasing pressures of up to 75 mm Hg. Group II (CBK-K) dogs were reperfused in the same manner as Group I with the addition of potassium chloride, 30 mEq/L. In Group III (CBKG-KG) glutathione, 30 mg/100 ml, was added to both the pre- and postischemic perfusions with CBK. After 30 minutes of reperfusion control studies were repeated. Heart rate, peak systolic pressure, rate of rise of left ventricular pressure, maximum velocity of contractile element, pressure-volume curves, coronary flow distribution, muscle stiffness, and heart water were not significantly different from control values. Total coronary flow and myocardial uptake of oxygen, lactate, and pyruvate did not serve to separate the three groups; the same was true for right ventricular creatine phosphate, adenosine triphosphate, and adenosine diphosphate during ischemia and recovery. Ultrastructural myofibrillar lesions were noted in all groups. thus, postischemic cardioplegia and use of a physiological reducing agent do not enhance CBK cardioplegia with topical and systemic hypothermia.

Topical cardiac hypothermia for myocardial preservation.

We compared moderate (29 degrees C.) and profound (5 degrees C.) (ice chips) cardiac hypothermia for myocardial preservation during aortic cross-clamping for 30 or 60 minutes in a canine right heart bypass preparation. Ventricular function deteriorated significantly at 29 degrees C. but not at 5 degrees C. Maximum dp/dt declined only after 60 minutes of ischemia at 29 degrees C., and Vmax decreased after one hour at either temperature. Lactate and pyruvate washout were greater after 29 degrees C., and pyruvate production persisted after 60 minutes of ischemia at 29 degrees C. Reactive hyperemia was greater after 30 minutes of ischemia at 29 degrees C. Reactive hyperemia was greater after 30 minutes of ischemia at 29 degrees C., and total coronary flow remained elevated after 60 minutes of ischemia at 29 degrees C. Coronary flow distribution was not altered by hypothermia. Ultrastructural changes were primarily time dependent and not temperature dependent. Ice-induced subepicardial injury was not evident in the ultrastructure or by flow distribution. Sixty minutes of profound topical cardiac hypothermia is moderately well tolerated by the canine heart, but functional and structural alterations are evident.

Myocardial injury and bypass grafting. Value of serum enzymes in diagnosis.

To clarify the value of serum enzymes in the detection of intraoperative and postoperative myocardial injury associated with coronary artery bypass grafting, we evaluated 70 consecutive patients (151 grafts). We used electrocardiograms and serial determinations of serum levels: serum glutamic oxaloacetic transaminase (SGOT), creatinine phosphokinase (CPK), lactic dehydrogenase (LDH), and LDH isoenzymes on Days zero, 1, 3, 5, 7, and 10. Patency of all grafts 1 week postoperatively was 92 per cent. Fourteen patients (20 per cent) had ECG evidence of acute myocardial infarction (AMI) or ischemia lasting longer than 48 hours. This incidence of AMI was attendant with no deaths or discernible changes in postoperative ventriculography. LDH-1 (cardiac fraction) was elevated in all patients with myocardial injury. Late elevation of LDH-1 occurred in 2 patients at the time of postoperative catheterization, 1 of whom had negative findings on ECG. Diagnostic correlation was not observed with total LDH, CPK, or SGOT. Predisposing factors to AMI included preinfarction angina (4 of 14 patients), occluded grafts (4 of 14), and a bypass time greater than 120 minutes.