Coronary Bypass Surgery for Stable Angina and Unstable Angina Pectoris

Staged revascularization in critically ill patients with coronary artery disease

BACKGROUND

Critically ill patients undergoing bypass surgery experience a higher mortality and morbidity.

HYPOTHESIS

The study was undertaken to evaluate the efficacy and value of percutaneous transluminal coronary angioplasty (PTCA) as a bridge to coronary artery bypass graft surgery (CABG) in high-risk patients with refractory unstable angina or cardiogenic shock.

METHODS

We present 11 seriously unstable patients with severe multivessel coronary artery disease undergoing culprit vessel PTCA. Angioplasty was performed not as a definitive procedure but rather as a bridge to surgical revascularization. All the patients had sustained at least one myocardial infarction prior to catheterization, all had refractory unstable angina, eight patients had only a single patent coronary artery, and five patients were in cardiogenic shock.

RESULTS

Following PTCA, all patients enjoyed a stable in-hospital period. One patient died 12 weeks after successful PTCA while awaiting second CABG. Seven patients subsequently underwent CABG and are doing well. The remaining three patients were also advised to undergo CABG, but elected to continue medical management.

CONCLUSIONS

Coronary angioplasty of the culprit vessel may play a role as a bridge to surgery in critically ill patients.

The effect of insulin cardioplegia on atrial fibrillation after high-risk coronary bypass surgery: a double-blinded, randomized, controlled trial

Atrial fibrillation after coronary bypass (CABG) surgery is an important cause of morbidity and increased resource utilization. Insulin-enhanced cardioplegia may reduce postoperative arrhythmias by improving aerobic myocardial metabolism and mitigating the deleterious effects of ischemia. We performed a double-blinded, randomized, controlled clinical trial to determine if insulin-enhanced cardioplegia decreases the risk of post-CABG atrial fibrillation in a high-risk patient population. We randomized 501 patients undergoing urgent CABG to receive insulin-enhanced (Humulin R 10 IU/L, Insulin group, n = 243) or standard (Control group, n = 258) blood cardioplegia during cardiopulmonary bypass. Patients were monitored by using continuous electrocardiography for a minimum of 3 days postoperatively. All standard cardiac medications, including beta-adrenergic blockers, were continued postoperatively. Insulin-enhanced cardioplegia did not result in a significant reduction in postoperative atrial fibrillation. Furthermore, we failed to detect a difference in the incidence of conduction defects, ventricular tachycardia, or pacemaker requirements between insulin and placebo patients. Atrial fibrillation was the most common arrhythmia, occurring in 31% of all patients. Independent predictors of atrial fibrillation were elderly age, preoperative atrial fibrillation, and renal insufficiency. Right bundle branch block was the most common conduction abnormality. Predictors of right bundle branch block were elderly age, female sex, and circumflex coronary artery disease. The incidence of postoperative ventricular tachycardia, left bundle branch block, and permanent pacemaker requirement was small. We conclude that insulin-enhanced cardioplegia does not reduce the incidence of postoperative atrial fibrillation in high-risk CABG patients.

IMPLICATIONS

We conducted a double-blinded, randomized, placebo-controlled trial of insulin-enhanced cardioplegia in 501 patients undergoing urgent coronary bypass surgery. Insulin did not decrease the incidence of postoperative atrial fibrillation when compared with placebo. We also failed to demonstrate a difference in the incidence of other postoperative arrhythmias between the two groups of patients.

The importance of completeness of revascularization during long-term follow-up after coronary artery operations

Completeness of revascularization after coronary artery bypass operation has been shown to improve short- and medium-term outcome. The purpose of this study was to assess the independent contribution of completeness of revascularization to long-term outcome. A total of 2057 patients with multivessel disease with complete revascularization and 803 with incomplete revascularization, mean age 57 +/- 9 years, was studied. The patient groups were similar except for more prior myocardial infarctions, worse left ventricular function, and more three-vessel disease in the incomplete revascularization group. Complications of perioperative infarction and stroke were not different between those having complete versus incomplete revascularization. The hospital death rate for patients having complete revascularization during the period of study was 0.7% versus 1.5% for those having incomplete revascularization (p = 0.06). Length of hospital stay for the two groups of patients also was not different. At late follow-up (mean 11.7 years for complete and 10.8 years for incomplete) patients who had incomplete revascularization had a significantly higher prevalence of recurrent angina. Multivariate analysis demonstrated the strongest predictors of incomplete revascularization to be number of vessels diseased and left ventricular function (ejection fraction). The multivariate correlates of survival were older age, left ventricular dysfunction, and completeness of revascularization. Completeness of revascularization correlated with improved overall patient survival, as well as survival in patients with normal left ventricular function. Furthermore, the curves continued to separate over time, such that the difference was greater at 8 years than at 4 years, although by 12 years the curves started to converge.

Factors predictive of operative mortality among coronary artery bypass subsets

As risk-adjusted outcome is increasingly being used to make clinical decisions and to assess and improve quality of care, it is important to develop simple, stable models for predicting outcome. Here we address the hypothesis that a risk factor for increased operative mortality at coronary artery bypass grafting may have differential effects in subgroups of patients defined by the presence or absence of other risk variables. We used a series of univariate and multivariate analyses to identify a group of ten patient-related preoperative characteristics independently predictive of operative death in the total population of 12,712 patients undergoing coronary artery bypass grafting at 43 Department of Veterans Affairs medical centers participating in the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Study. Separate logistic regression models were then developed for each of 14 clinically important subgroups defined by the presence or absence of seven risk variables. Odds ratios for operative death and estimated operative mortality were calculated from these subgroup regression models. Of 65 comparisons of pairs odds ratios of preoperative risk variables between the subgroups with and without a second risk variable, only five were found to be significant (p < 0.05 without adjustment for multiple comparisons); this is only slightly more than would be expected by chance alone. Risk factors for increased operative death appear to have similar odds ratios for subgroups of patients defined by a second risk variable. This finding greatly simplifies the use of predicted operative mortality in clinical decision making and quality assessment and improvement in coronary artery bypass grafting.

Chronic stable angina pectoris. Risk stratification and treatment

Workup of stable angina patients begins with careful history taking and evaluation of various risk factors, physical examination, and a resting electrocardiogram (ECG). A noninvasive exercise stress test is valuable for risk stratification. Abnormalities on a resting ECG or equivocal results on a stress test warrant an exercise test combined with thallium scintigraphy, which is more sensitive and specific. Cardiac catheterization is advisable for patients with chest discomfort and multiple risk factors, even if results of thallium testing are negative. Patients with severe or progressive angina or congestive heart failure should also have cardiac catheterization. Nitrates, beta-adrenergic blockers, and calcium channel blockers are cornerstones of medical therapy. Revascularization with coronary artery bypass graft is recommended for patients with left main coronary artery disease, left ventricular dysfunction, or severe proximal three-vessel coronary artery disease. Percutaneous transluminal coronary angioplasty (PTCA) is a good alternative for one- or two-vessel disease. Three-vessel PTCA can be accomplished, but its real role still remains to be established.