Risk factors in coronary artery bypass surgery

Coronary artery bypass grafting: Part 1--the evolution over the first 50 years

Surgical treatment for angina pectoris was first proposed in 1899. Decades of experimental surgery for coronary artery disease finally led to the introduction of coronary artery bypass grafting (CABG) in 1964. Now that we are approaching 50 years of CABG experience, it is appropriate to summarize the advancement of CABG into a procedure that is safe and efficient. This review provides a historical recapitulation of experimental surgery, the evolution of the surgical techniques and the utilization of CABG. Furthermore, data on contemporary clinical outcomes are discussed.

Coronary by-pass for bad ventricle; adoption of "hybrid-pump" bypass

BACKGROUND

The outcomes of on-pump and hybrid-pump bypass surgery in patients with depressed left ventricular function (EF<30%) were analyzed.

METHODS

109 patients with preoperative left ventricular ejection fraction of <30% and bypassable circumflex coronary disease were randomized in a double blind fashion to undergo hybrid-pump (combination of off-pump and on-pump) procedure (54 patients), or on-pump coronary bypass (55 patients). In patients who underwent hybrid-pump procedure only circumflex system was bypassed on-pump to shorten CPB and myocardial ischemic time. Pre- peri and postoperative variables were analyzed.

RESULTS

Mean LVEF 24.4 +/- 4.8%. The patients in hybrid-pump group received less graft than others, but difference was not significant. Duration of the surgery was not different statistically between hybrid-pump and on-pump groups. A longer intraoperative duration of ischemia and extra corporeal circulation was found in on-pump group. Significant improvement in the postoperative course such as shorter mechanical ventilation, less catecholamines and IABP usage, less ICU and hospital stay, less stroke, less need for hemodyalisis and most importantly less hospital mortality was observed in hybrid-pump group.

CONCLUSION

Shortening the CPB and myocardial ischemic time and avoiding related problems, adoption of hybrid-pump strategy, in patients with severely impaired LVEF and bypassable circumflex coronary disease results in better outcome than conventional on-pump bypass.

Current trends and technique in OPCAB surgery

BACKGROUND AND AIM OF THE STUDY

Aging of the population, increased surgical risk, and technical improvement have contributed to the recent revival of off pump coronary artery bypass surgery (OPCAB). We present our experience with the systematic use of this technique.

METHODS

Between September 1996 and June 2000, 500 OPCAB procedures were performed at the Montreal Heart Institute (95% of all procedures during time frame, single surgeon). Contraindications were unstable hemodynamics, intramyocardial left anterior descending artery, and reoperation with extensive adhesions. Stabilization was achieved with pericardial sutures and mechanical compression. Surgical strategy was to first bypass the culprit lesion. Anesthetic management consisted of adequate fluid loading and minimal use of alpha-agonist. This cohort was compared to a contemporary cohort of 1,444 patients operated with cardiopulmonary bypass (CPB).

RESULTS

Demographics and risk factors were comparable for all. OPCAB patients received more grafts (3.1 +/- 0.9 vs 2.9 +/- 0.7, p = 0.006), conversion rate was low (0.4%), and complete revascularization was achieved in 93%. Operative mortality and perioperative myocardial infarction were comparable in both groups. Transfusion need, CK-MB count, postoperative use of intra-aortic balloon pump, and creatinine increase were less significant in OPCAB. Postoperative hemorrhage, atrial fibrillation, prevalence of cerebrovascular accident, and hospital stay were comparable for both groups. These results are comparable to those currently reported in the literature.

CONCLUSION

OPCAB surgery in the current era has established its safety and short-term efficacy although long-term clinical results are still warranted. Considering the changing pattern in surgical practice, OPCAB surgery should remain a therapeutic option in modern cardiac surgery.

Coronary artery bypass grafting in patients with poor left ventricular function

Coronary artery bypass grafting (CABG) in patients with poor left ventricular function remains a surgical challenge and is still controversial. The purposes of this study were to evaluate the effectiveness of CABG in such patients when performed without case selection on the basis of preoperative viability tests and to determine the predictors of postperative outcome. The preoperative, perioperative, and postoperative early and mid-term follow-up data of 273 patients with < or = 30% left ventricular ejection fraction (LVEF) who underwent isolated CABG between January 1995 and November 2000 were evaluated. Preoperative echocardiography and cardiac catheterization, and postoperative control echocardiography were performed in all patients. Follow-up was achieved via monthly periodical examinations in the first 6 months, and thereafter by either regular visits or phone contact. Preoperatively, 242 (88.65%) patients were in NYHA class III or IV, and the mean LVEF was 26.51 +/- 3.64%. The overall hospital mortality total was 14 (5.13%) patients. There were 44 (16.12%) late mortalities. Postoperative morbidities were observed in 74 (27.1%) patients. Two-hundred and two (93.95%) of the surviving 215 (78.75%) patients were in NYHA class I or II at 49.55 +/- 14.84 months of follow-up. Postoperative follow-up echocardiographic examinations revealed a mean LVEF of 39.66% +/- 5.43%. The improvements in functional capacity and LVEF were significant. Advanced age, diabetes, hypertension, cross-clamp time >60 min, bypass time>120 min, and severity of functional class (class III-IV of NYHA) were found to be the determinants of mortality. However, multivariate analyses revealed only older age and class III-IV of NYHA and CCS were predictors of mortality. The low mortality and morbidity rates as well as satisfactory postoperative improvements in functional capacity and LVEF measurements support the use of CABG without the need for any viability assessment in patients with left ventricular dysfunction.

OPCAB surgery: a critical review of two different categories of pre-operative ejection fraction

OBJECTIVE

Literature review found little information on off-pump coronary artery bypass (OPCAB) procedure in patients with poor left ventricular function and there was no information comparing the low EF and normal EF patients undergoing OPCAB procedure.

METHODS

Between 1/1/1998 and 6/30/1999, 387patients had surgery performed utilizing the off-pump technique and 45 of these patients had pre-operative left ventricular function of equal to or less than 30% (LVEF < or =30). The two groups (LVEF < or =30 and LVEF>30) were compared using univariate analysis. Patients in LVEF < or =30 were older and more female gender. LVEF< 30 had more NYHA class IV patients (64 vs. 50%) and more symptoms related to depressed left ventricular function. The mean pre-operative left ventricular function was 25% in LVEF < or =30 and 56% in LVEF>30. Pre-operative predicted risk was 6.4+/-5.5% in LVEF < or =30 and 2.7+/-4.5% in LVEF>30 (P< 0.001). Most (> 95%) of the patients in both groups were elective status, and LVEF < or =30 patients had increased incidence of redo (11 vs. 6%, P=0.2). In LVEF>30, 84% of the patients had stable angina while only 69% in LVEF < or =30 (P=0.009).

RESULTS

Intra-operatively no significant differences were measured in number of grafts per patient (2.7 vs. 2.8), amount of blood loss, peak CK-MB, skin-to-skin time, or OR time. Patients with LVEF < or =30 have more frequent utilization IABP during pre, intra and post-operative period. The statistical analysis yields no significance in post-operative major neurological deficit between these two groups; and are comparative to the nationally reported incidence of neurological deficit for on-pump patients. The operative mortality in the low EF group was 4.4 and 1.8% in LVEF>30 group (P=0.23).

CONCLUSIONS

Given the clinical presentation of the low EF group, higher prediction risk, longer pre-operative stay, and length of ventilation (24 vs. 8 h P=0.12) a longer surgery to discharge stay (8 vs. 6 days, P=0.02) is anticipated. Short-term clinical outcomes for both groups of OPCAB patients encouraged us to continue to offer this approach to this broad base of patient population.

Clinical importance of stunned and hibernating myocardium

Myocardial stunning and hibernation are states of potentially reversible myocardial dysfunction, which were first described more than 20 years ago (c.1980). Important advances have now been made in the ability to detect stunned and hibernating myocardium, as well as in the understanding of the impact of these conditions on patient outcomes. We discuss here the clinical importance of stunned and hibernating myocardium for patients with several common cardiac conditions.

Is low ejection fraction safe for off-pump coronary bypass operation?

BACKGROUND

Does the manipulation of the heart during off-pump coronary artery bypass (OPCAB) procedure further compromise the hemodynamic stability of a patient with depressed left ventricular function compared with the conventional coronary artery bypass (CCAB) approach? Does this manipulation induce a more dramatic hypoperfused state that may contribute to an increase in the incidence of related complications or mortality? This retrospective review of data attempted to answer the above concern.

METHODS

Between January 1, 1998, and June 30, 1999, 177 patients with ejection fractions of 30% or less underwent full sternotomy coronary artery bypass grafting at our institution. Of these patients, 45 underwent OPCAB procedures and 132 patients underwent CCAB. Pre-, intra-, and postoperative variables as identified by The Society of Thoracic Surgeons National Cardiac Surgery Database were compared using univariate and logistical regression analysis.

RESULTS

Despite recognized hemodynamic derangement during cardiac displacement, these groups of OPCAB patients appeared to tolerate the procedure well. Univariate analysis of cardiac enzyme leak and blood loss was statistically significant in the OPCAB patients. Utilizing regression analysis, cardiopulmonary bypass was the only predictor for all postoperative complications.

CONCLUSIONS

Multivessel coronary artery bypass utilizing the OPCAB approach in patients with depressed left ventricular function of equal to or less than 30% is appropriate and applicable. Analysis of CCAB and OPCAB variables was nonsignificant except for operative and postoperative blood loss and peak cardiac enzyme leak. Attention to intraoperative detail and hemodynamic management could be credited for the success with OPCAB.

Results of revascularization in patients with severe left ventricular dysfunction

OBJECTIVE

In patients with coronary disease and poor left ventricular function, bypass grafting remains a surgical challenge. This study evaluates experience in 125 consecutive patients with ejection fraction less than 20% (study group).

METHODS

Preoperative viability studies were not used for patient selection. Clinical data were prospectively collected. The average age of the study subjects was 59 +/- 9 years, and 112 (90%) were male. Most patients (108 [86%]) were in symptom class III or IV. Main indications for surgery included angina in 62 (50%), heart failure and angina in 36 (29%), heart failure in 9 (7%), ventricular arrhythmia in 2 (2%), and critical anatomy in 16 (13%). Significant mitral regurgitation was present in 48 (38%), and distal vessels were poorly visualized in 67 (54%). At surgery, temperature mapping guided an integrated approach to cold cardioplegia. Results in this group were compared with those obtained in case-matched control subjects receiving cardioplegia without temperature mapping (matched for age, sex, functional class, and urgency of operation).

RESULTS

Hospital morbidity (intra-aortic balloon pump support) and mortality rates were significantly lower in the study group versus those of control subjects (15% vs 30%, P =. 004; and 4% vs 11%, P =.03, respectively). In study patients the 5-year actuarial survival was 72%. Among survivors, both anginal class and heart failure class improved significantly. By means of multivariate analysis, survival was adversely affected by older age, class IV symptoms, and poorly visualized distal vessels.

CONCLUSIONS

These results support the use of coronary artery bypass grafting in patients with severe left ventricular dysfunction without case selection on the basis of viability studies or visibility of distal vessels. Low hospital morbidity and mortality rates have been achieved when temperature mapping guides cardioplegia. Symptoms are improved in most patients, and long-term survival is encouraging.

Results of revascularization in patients with severe left ventricular dysfunction

BACKGROUND

In patients with coronary artery disease and poor ventricular function (ejection fraction, < 20%), bypass grafting remains a surgical challenge. This study evaluates experience with isolated revascularization in such patients.

METHODS AND RESULTS

In 79 consecutive patients (69 men, 10 women; average age, 59 +/- 9 years), preoperative ejection fraction was 18 +/- 5%. Indications for surgery were congestive heart failure (CHF) in 5 of 79 patients (6%), CHF and angina in 19 (24%), angina in 41 (52%), ventricular arrhythmias (VAs) in 8 (10%), and critical anatomy in 6 (8%). Some patients had prior VAs (23 of 79; 29%) or mitral regurgitation (18; 23%) and required emergent surgery (25; 32%). At surgery, temperature mapping ensured adequate distribution of antegrade cold cardioplegia, with 3.6 +/- 0.7 grafts per patient, including left internal mammary artery graft in 60 of 79 (76%) and endarterectomy in 14 (18%). Hospital mortality was 3.8%. Perioperative support included intra-aortic balloon pump in 18 of 79 (23%) and drugs for VAs in 28 (35%). Morbidity included myocardial infarction in 2 of 79 (2.5%) and stroke in 2 (2.5%). During follow-up, there were 19 late deaths. Actuarial survival was 94%, 82%, and 68% at 1, 2, and 5 years, respectively, and was similar in patients with severe angina, CHF, mitral regurgitation, or VAs. Freedom from sudden death was 100%, 98%, and 91% at 1, 2, and 5 years, respectively. Among survivors, angina improved in 84% and heart failure improved in 26%.

CONCLUSIONS

These data support bypass graft surgery in patients with severe LV dysfunction. With careful cardioplegic techniques, hospital mortality was low (3.8%). Long-term survival is encouraging, with good relief of symptoms in most patients. Perioperative VAs are frequent but respond to medical treatment, with only 23% of patients discharged on antiarrhythmic drugs. Five-year freedom from sudden death is 91%, with only 3 late sudden deaths in this series.

Difficulties in predicting outcome in cardiac surgery patients

OBJECTIVE

To evaluate a novel combination of preoperative, intraoperative, and postoperative variables (including the Parsonnet, and the Acute Physiology and Chronic Health Evaluation II and III [APACHE II and III] scores) in cardiac surgery patients in order to predict hospital outcome, complications, and length of stay.

DESIGN

Prospective survey.

SETTING

Adult intensive care unit (ICU) at a tertiary care cardiothoracic surgery center.

PATIENTS

All cardiac surgery patients admitted to the ICU over a 1-yr period.

INTERVENTIONS

Medical history, Parsonnet score, intraoperative data (including bypass and ischemic times), APACHE II and III scores, complications, and outcome were collected for each patient.

MEASUREMENTS AND MAIN RESULTS

One thousand eight patients were entered into the study. The mean Parsonnet score was 7.8 (range 0 to 33), mean APACHE II score 11.8 (range 2 to 33), and mean APACHE III score 42.5 (range 9 to 132). ICU mortality rate was 2.7% and hospital mortality rate was 3.8%. The mean APACHE II predicted risk of dying was 5.31%, which gave a standardized mortality ratio of 0.71. The above scores were all statistically well correlated with hospital mortality. Further, a logistic regression model was developed for the probability of hospital death. This model (which included bypass time, need for inotropes, mean arterial pressure, urea, and Glasgow Coma Scale) had an area under the receiver operating characteristic curve of 0.87, while the Parsonnet score had an area of 0.82 and the APACHE II risk of dying had an area of 0.84.

CONCLUSIONS

Cardiac surgery remains a difficult area for outcome prediction. A combination of intraoperative and postoperative variables can improve predictive ability.

Coronary artery bypass in patients with severely depressed ventricular function

This study evaluates whether patients with coronary artery disease and severely depressed left ventricular ejection fraction benefit from coronary artery bypass grafting. From 1981 to 1991, 118 consecutive patients with ejection fraction less than or equal to 0.25 underwent isolated coronary artery bypass grafting at Duke University Medical Center. Operative mortality was 11%. Ventricular arrhythmia requiring treatment was the most common postoperative complication (27%), followed by low cardiac output state (22%). Median length of postoperative hospitalization was 9 days. Kaplan-Meier estimate of survival at 1 year and 5 years was 77.2% and 57.5%, and was better than estimated survival with medical therapy alone. Survivors experienced significant improvement in angina class (p < 0.0001), congestive failure class (p < 0.0001), and follow-up ejection fraction (p < 0.005). Of 22 preoperative factors evaluated by univariate survival analysis, five were associated with significantly greater mortality: other vascular disease (p < 0.005), female sex (p < 0.005), hypertension (p < 0.005), elevated left ventricular end-diastolic pressure (p < 0.05), and depressed cardiac index (p < 0.05). Considering length of hospitalization, three factors showed significant adverse effect in a multivariate Cox model: time on cardiopulmonary bypass (p < 0.005), acute presentation (p < 0.005), and female sex (p < 0.01). These data and review of the literature suggest that patients with coronary artery disease and severely depressed ejection fraction benefit from coronary artery bypass grafting, and specific preoperative factors may help determine optimal treatment.

Equilibrium radionuclide angiocardiography prior to elective abdominal aortic surgery

Equilibrium radionuclide angiocardiography (ERNA) was employed preoperatively in 183 patients undergoing elective abdominal aortic reconstruction to measure left ventricular ejection fraction (LVEF) and to detect abnormal regional wall movement. Abnormal ejection fractions were virtually confined to the 97 patients who had clinical, electrocardiographic or radiographic evidence of heart disease. An operative mortality of 8.7% was recorded. Major cardiac events (defined as myocardial infarction, cardiac failure or malignant ventricular arrhythmia) occurred in 15 of 86 abdominal aortic aneurysm patients (17.4%) and six of 96 (6.25%) patients with aorto-iliac occlusive disease. Patients with an abdominal aortic aneurysm and abnormal LVEF or regional wall motion abnormality were more likely to suffer a cardiac event (p less than 0.001), the event rate exceeding 60% in patients whose LVEF was less than 35%. An abnormal LVEF failed to predict a cardiac event in patients with aorto-iliac occlusive disease. While not indicated in patients lacking clinical evidence of heart disease, ERNA can refine the assessment of cardiac risk, particularly in patients with previous myocardial infarction and define a high risk group in whom aortic reconstruction should be avoided except for the most compelling of indications.

Surgical revascularization of left main coronary artery stenosis: determinants of perioperative and long-term outcome in the 1980s

The postoperative courses of 176 patients who underwent coronary artery bypass surgery for significant left main coronary artery stenosis were analyzed to determine which preoperative clinical and angiographic factors correlated best with outcome. Clinical variables included age, sex, New York Heart Association (NYHA) anginal class, presence of unstable angina, and surgical class. The angiographic variables included percentage of left main stenosis, presence of right coronary artery stenosis, coronary dominance, number of vessels diseased, myocardial jeopardy score, and ejection fraction. The overall perioperative mortality rate was 9.1%. There was a significant increase in perioperative mortality among female patients (p less than 0.05) and patients undergoing emergency surgery (p less than 0.05). Patients with left main stenosis of 80% or more or with balanced or left dominant circulation showed trends toward increased perioperative mortality. Life-table analysis showed that emergency surgery and left main stenosis of 80% or more correlated with increased long-term mortality (p less than 0.05). No other variable tested showed a significant correlation with either perioperative or long-term mortality. A comparison of these results with studies performed in the 1970s shows that there has been considerable change in those factors which place a patient at increased risk for mortality during surgical treatment of left main coronary artery stenosis.

Monitoring the diffusion of a technology: coronary artery bypass surgery in Ontario

Technology assessment involves not only examining technologies before they are released but also their diffusion into practice once they have been released. In this study we show how basic analysis of a large administrative data set, combined with a review of evidence on effectiveness, can be used as the first step in technology assessment. We analyze the use of coronary artery bypass surgery (CABS) in the province of Ontario, Canada. The annual number of procedures increased 52 per cent over a seven-year period between 1979 and 1985. Large increases in CABS rates in the over-65 population accounted for more than half of this increase in procedures. Increased rates of surgery in the over-65 population are unlikely to be caused by increased prevalence of coronary artery disease and may be the result of a change in clinical attitude toward the use of CABS. This change is discussed in the context of the evidence on the effectiveness and cost-effectiveness of CABS. We conclude that there is a need to carefully monitor and evaluate the use of technologies especially in the elderly.

Prognostic effect of bundle branch block related to coronary artery bypass grafting

The incidence and prognostic effect of the development of new perioperative ventricular conduction abnormalities were examined in all patients undergoing coronary artery bypass surgery at Duke University Medical Center between 1976 and 1981. Of the 913 patients included, transient (resolved before discharge) ventricular conduction abnormalities developed in 156 (17%) and persistent (until discharge) changes developed in 126 (14%). Complete right bundle branch block (BBB) was the most frequent type of new ventricular conduction abnormality, followed by left anterior hemiblock and incomplete right BBB (found in 60%, 26%, and 9%, respectively, of all patients with transient changes and 29%, 33% and 26% of all patients with persistent changes). Development of new ventricular conduction abnormalities was most strongly related to date of operation (p less than 0.0001, univariate chi 2 = 122), increasing from 2% transient and 7% persistent in 1976 to 36% transient and 22% persistent in 1981. The incidence was also higher in older patients. Preoperative ejection fraction and number of diseased vessels were related to development of perioperative ventricular conduction abnormalities but were not independently related after adjustment for other baseline characteristics. Contrary to findings in other studies, development of new perioperative ventricular conduction abnormalities, including isolated new left BBB, did not worsen the survival rate in patients followed up to 3 years after surgery.

Multivariate discriminant analysis of risk factors for operative mortality following isolated coronary artery bypass graft. Loyola University Medical Center experience, 1970 to 1984

The Loyola Open-Heart Registry is a fully operational database that contains detailed data on approximately 9,000 patients who have undergone coronary bypass or cardiac valve replacement from January 1970 to December 1984. We analyzed the registry data using multivariate discriminant analysis to identify and quantitate those factors that might predict operative mortality (OM) for patients undergoing coronary artery bypass grafts at Loyola University Medical Center: Operative mortality was defined as death within 30 days following surgery. A total of 50 clinical and angiographic variables were analyzed for possible univariate association with operative mortality. Twenty-two variables were found to have significant univariate association with OM, and these 22 variables were subjected to multivariate discriminant analysis. For patients undergoing isolated, elective coronary artery bypass, the factors found to be predictive of OM are age (greater than 70) (F = 11.57), severe (more than six stenoses) coronary artery disease (F = 5.81), diffuse disease (F = 5.54), positive family history (F = 5.17), and number of coronary arteries bypassed (F = 4.78).

Assessment of myocardial function before aortic surgery by radionuclide angiocardiography

A consecutive series of 41 patients undergoing elective aortic surgery had pre-operative assessment of cardiac function by radionuclide angiocardiography. Their subsequent progress was monitored. There were 4 patients whose pre-operative left ventricular ejection fraction was less than 30 per cent and 3 of these patients died of cardiac failure postoperatively. There was only 1 death from cardiac failure amongst the 37 patients whose pre-operative left ventricular ejection fraction was less than 30 per cent. Radionuclide angiocardiography is an accurate indicator of myocardial function of patients before major aortic surgery.

On the relationship between Q waves in leads II and VF and inferior-posterior wall motion abnormalities

Twelve electrocardiographic criteria, based on various combinations of Q wave morphology in leads II and aVF, were tested in 235 cases for their diagnostic value in detecting inferoposterior wall motion abnormality (presumably reflecting infarction in the area) as demonstrated on left ventriculogram. The most reliable indicator of inferoposterior wall motion abnormality was found to to a QR complex with a Q wave width greater than or equal to .03 or greater than or equal to .04 sec associated with a Q/R ratio greater than .25. Using as criterion a QR complex with a Q wave width greater than or equal to .04 sec and a Q/R ratio greater than .25, the sensitivity was 41.9% in the cases with akinetic-dyskinetic wall motion and 3.7% in the cases with hypokinesis with an associated specificity of 100%. By lowering the Q wave duration to greater than or equal to .03 sec, the sensitivity increased to 51.6% and 9.3%, respectively, while retaining a very high specificity (96%). The exclusion of cases with a Q and R of less than 5 mm markedly lowered the sensitivity with a negligible increase in specificity. QS complexes in leads II or aVF were not found to be reliable indicators of inferoposterior wall motion abnormality.

Detection of left ventricular dysfunction in ambulatory subjects with the bedside Valsalva maneuver

The bedside sphygmomanometric determination of the arterial pressure response during the Valsalva maneuver was incorporated into the routine physical examination of ambulatory subjects. Four distinct Valsalva responses were noted: ultrasinusoidal, sinusoidal, absent overshoot, and square wave. The absent overshoot response was further divided into positional and constant types--the latter consistently exhibiting this response regardless of body position. Correlation with resting left ventricular ejection fraction was obtained by radionuclide cineangiography in 200 patients, of whom 81 had left ventricular systolic dysfunction (ejection fraction less than 0.50). Significant differences in the mean left ventricular ejection fraction were found in subjects with an ultrasinusoidal response (0.65 +/- 0.11), sinusoidal response (0.55 +/- 0.15), constant absent overshoot response (0.37 +/- 0.18), and square wave response (0.16 +/- 0.04) to Valsalva maneuver. The sensitivity of an abnormal Valsalva response (absent overshoot or square wave responses) for the bedside detection of left ventricular systolic dysfunction was 69 percent, and the predictive value of an ultrasinusoidal Valsalva response for normal ejection fraction was 93 percent. It is concluded that the high predictive accuracy of the Valsalva maneuver makes this simple bedside technique a valuable method for assessing resting left ventricular function.

Coronary artery bypass operation in septuagenarians

Increasing numbers of patients more than 70 years old are at risk from coronary artery disease. The continued success of coronary artery bypass operation in selected patients provides impetus for applying this procedure to older patients as well. Our results indicate coronary artery operation is effective in older patients and has a low mortality (3% in our series). In patients in this age group, coronary artery operation can be combined with other procedures, when indicated, such as cardiac valve replacement or repair, left ventricular aneurysmectomy, carotid endarterectomy, and cholecystectomy.

Clinical and angiographic predictors of operative mortality from the collaborative study in coronary artery surgery (CASS)

Fifteen institutions participating in the Collaborative Study in Coronary Artery Surgery (CASS) have performed isolated coronary artery bypass surgery upon 6630 patients (1061 women and 5569 men) for coronary artery disease. The overall operative mortality (OM) was 2.3% (range 0.3-6.4%). Mortality increased with age, from 0 in the group 20-29 years old to 7.9% in the group 70 years and older. OM was higher for women in each group, ranging from 2.8% for ages 30-39 years to 12.3% for age 70 years and older (0.8% and 5.8% for men). Clinical manifestations of congestive heart failure were associated with increased OM. Mortality was 1.4% in one-vessel, 2.1% in two-vessel and 2.8% in three-vessel disease (diameter narrowing greater than or equal to 70%). Among 1019 patients with left main coronary artery (LMCA) stenosis, OM ranged from 1.6% in patients with mild stenosis and a right-dominant system to 25% in patients with severe (greater than or equal to 90%) stenosis and left dominance. OM varied with ejection fraction (EF) (1.9% for EF greater than or equal to 50% to 6.7% for EF less than 19%) and left ventricular wall motion score (1.7% for least abnormal to 9.1% for most abnormal). For elective surgery, OM was 1.7%, for urgent surgery 3.5%, and for emergency surgery 10.8%. Mortality was 40.0% among 30 patients with severe LMCA stenosis who underwent emergency revascularization. Advanced age, female sex, symptoms of heart failure, LMCA stenosis, impaired left ventricular function and nonelective surgery are associated with a higher OM. These factors should be considered in the selection of patients for coronary artery surgery.

Five-year survival after coronary bypass surgery

The survival and mortality of 128 consecutive patients, who underwent coronary bypass surgery at this clinic between 1970 and 1974, was assessed. All survivors were followed for a minimum of 60 months after surgery. The operative mortality was 5.5%. With increased experience annual operative mortality declined to 1.6% in 1974. The insertion of IMA grafts were related to a significant lower operative mortality. Six survivors (5%) underwent repeat procedures within five years after surgery. The five-year survival rate, calculated with the actuarial method, was 87%. Congestive heart failure and triple vessel disease were significantly more common in patients who died of cardiac disease within five years after surgery.

Left ventricular ejection fraction calculated from volumes and areas: underestimation by area method

The ejection fraction is one of the most widely used measurements of left ventricular systolic function. Angiographic measurement of ejection fraction is based on determination of roentgenographic magnification and calculation of end-diastolic and end-systolic volumes, assuming a prolated ellipse. Because it is simple and radiographic magnification may not have been determined, some laboratories have obtained an "ejection fraction" by comparison of end-diastolic and end-systolic areas. A comparison of the two methods was made using ventriculograms of 538 patients from three cardiac catheterization laboratories. The area method of ejection fraction calculation consistently underestimates ejection fraction from left ventricular volumes. A regression equation was derived that allows adjustment of the ejection fraction obtained from areas to that from volumes.

Predictors of perioperative myocardial infarction in coronary artery operation

Postoperative graft patency and thirteen perioperative variables were evaluated as potential risk factors for perioperative myocardial infarction (MI) in 102 consecutive patients undergoing coronary artery bypass grafting. Also, the incidence of perioperative MI and the amount of CK-MB released in the postoperative period were compared in three groups of patients selected according to the myocardial preservation technique employed: (1) topical hypothermia with and (2) without aortic cross-clamping and (3) cardioplegia. A perioperative MI as detected by electrocardiogram, enzymes, and myocardial scintigraphy with technetium 99 developed in 15 patients. Most important predictors of perioperative MI were found to be (1) left main and triple-vessel coronary artery disease, (2) a left ventricular end-diastolic pressure greater than or equal to 15 mm Hg, (3) a decreased ejection fraction (p < 0.05), and (4) cardiopulmonary bypass time > 120 minutes (p < 0.01). The incidence of perioperative MI was 50% in patients with three or more risk factors and 7% in those with less than three risk factors (p < 0.001). Graft patency was similar in patients with or without perioperative MI. Differing myocardial preservation techniques did not influence CK-MB release or the incidence of perioperative MI. Thus, the severity of ischemic heart disease and the length of the cardiopulmonary bypass time were important predictors of perioperative MI while graft patency and myocardial preservation technique did not appear to be related to its incidence in this study.

Coronary artery surgery: indications and recent experience

The comprehensive experience of coronary artery surgery in a Cardiothoracic Unit over a 31-month period is reviewed. Hospital mortality for elective bypass grafting was 3.9% overall and 2.5% in those with good pre-operative left ventricular function. Major influences on hospital mortality were pre-operative left ventricular function, extent of coronary artery disease and extent of the surgical procedure undertaken in terms of number of aortocoronary grafts inserted, coronary endarterectomy and particularly concomitant valve surgery or aneurysm resection. Follow-up experience shows 74% of grafted patients to be symptom-free and 85% symptomatically improved one year after surgery with 70% symptom-free and 80% improved at two years. Early post-operative deaths appear related to early graft closure and recurrence of symptoms postoperatively to late graft closure or progression of coronary disease in the native circulation. The study provides a guide to the relative risks of coronary artery surgery for symptomatic coronary artery disease and expected symptomatic results in the early follow-up period.

Criteria for operability and reduction of surgical mortality in patients with severe left ventricular ischemia and dysfunction

A series of 188 patients who were operated on for left ventricular ischemia and dysfunction is presented. Angina was a prominent symptom in all patients, and a history of congestive heart failure could be elicited in 20%. Mean ejection fraction for the series was 0.35, with 67% having an ejection fraction of 0.35 or less 24%, 0.20 or less. Complete revascularization was accomplished whenever possible; more than 70% of the patients had triple-vessel disease, and single bypass was performed infrequently (5%). Factors thought to be important in achieving a low operative mortality (2.1%) were: precise prebypass monitoring, particularly with the V5 precordial lead; maintaining a low rate-pressure product (less than 12,000) prior to bypass; myocardial preservation with cold hyperkalemic or hyperkalemic-hyperosmolar solution; and careful titration of inotropic and vasodilator drugs. Inotropic drugs and intraaortic balloon pumping were used frequently in this series. The late mortality was 4.3%. Angina was completely relieved or improved in 94% of the patients. Those having a history of congestive heart failure had an increased late mortality rate, four times that of the entire series.

Comparison of the left ventricular volume using the Ahlkerg and Dodge methods

Single plane cine left ventriculography was performed in 24 patients, 12 with normal and 12 with abnormal ventricular shapes. End diastolic and systolic volume and ejection fractions were calculated by two methods (Ahlberg and Dodge). The volumes and ejection fraction from either method were not significantly different. If calculated manually, the Ahlberg method took ten times longer than the Dodge method. At present some steps are difficult but a computer can perform the measurements and calculations, and print the results for ventricular areas.

The use of the systolic time interval for predicting left ventricular ejection fraction ischemic heart disease

A large series of 306 patients with ischemic heart disease was studied with automated systolic time intervals and left ventricular ejection fraction as determined by the angiocardiographic method. It was found the pre-ejection period, left ventricular ejection time, delta values, and PEP/LVET ratio all were related to the ejection fraction. However, in all instances the correlation was too low and the scatter of the data was too large to warrant the use of the systolic time intervals for predicting left ventricular function as indicated by the ejection fraction.

Surgican considerations in management of angina pectoris

In deciding on the best form of treatment for patients with angina pectoris, a substantial number of important factors must be carefully and individually considered. These include symptomatic status, extent and location of occlusive coronary artery disease, left ventricular functional status, and risk factors. Relief of angina pectoris with revascularization surgery can be expected in 80% to 90% of patients, with an operative mortality well below 5% when preoperative left ventricular function is normal or only moderately depressed.

The relationship of patient selection to prognosis following aortocoronary bypass

Operative mortality for the first 787 patients who underwent aortocoronary bypass at Duke University Medical Center was 9.7%. Within 699 patients who underwent elective bypass only, operative mortality was 8.8% before January 1, 1972, and 5.4% subsequently. This apparent variation in operative mortality over time was largely a consequence of changing patterns of patient selection, i.e., a two- to three-fold decrease in the prevalence of ventricular dysfunction. Since January 1, 1972, operative mortality for 444 patients with mild or no heart failure who underwent elective bypass only was 5.0%. The 55 patients with left main disease had 12.7% operative mortality. In the 192 patients without left main disease who had one- or two-vessel disease, operative mortality was 1.0%, whereas, 197 patients with three-vessel disease had a 6.6% operative mortality. The 103 patients with three-vessel disease less than 50 years of age underwent operation with a 2.9% mortality. Although these results demonstrate that selected patients may undergo operation with a mortality approaching 1%, it is not clear that only such low risk patients should be offered surgery. Accurate estimates of benefits and risks of aortocoronary bypass surgery are necessary in the management of specific patients.