Perioperative use of cardiac medical therapy among patients undergoing coronary artery bypass graft surgery: a systematic review

Results of emergency coronary artery bypass grafting for acute myocardial infarction: importance of intraoperative and postoperative cardiac medical therapy

BACKGROUND

The results of emergency coronary artery bypass grafting (CABG) for acute myocardial infarction (AMI) are less than satisfactory, and readmission for cardiac events is common.

METHODS AND RESULTS

105 patients underwent emergency CABG for AMI. We examined the long-term results of emergency CABG for AMI from the viewpoints of preoperative, intraoperative, and postoperative factors. The operative mortality rate was 11.4%. Risk factors for early death were age ≥80 years, shock, veno-arterial bypass, creatine kinase isoenzyme Mb ≥100 U/L, non-use of a left internal thoracic artery graft and an extracorporeal circulation time ≥120 min. Risk factors for late cardiac events were ejection fraction <40%, non-use of human atrial natriuretic peptide (hANP) therapy, angiotensin II receptor blockers (ARB) and aldosterone blockers, and a 3-month postoperative brain natriuretic peptide level ≥200 pg/ml.

CONCLUSIONS

Early results of this study are similar to those seen in previous reports, whereas late phase results yield some new and interesting findings. We suggest that intraoperative hANP, and postoperative aldosterone blocker and ARB, following CABG for AMI, will, through control of the renin-angiotensin-aldsterone system, inhibit left ventricular remodelling, reduce the extent of infarction, and improve cardiac function, yielding a favourable long-term prognosis.

Treatment of hypertension in patients undergoing coronary artery by-pass grafting

Hypertension occurs in up to 80% of patients scheduled to coronary artery by-pass grafting (CABG). In hemodynamically stable patients all anti-hypertensive drugs should be continued till a day of surgery. For vast majority of patients there is no need to use blood pressure lowering agents during CABG, however it is necessary to maintain blood pressure level and avoid extreme blood pressure variations. Upon CABG hypotensive therapy should be modified to the needs of the individual patient and should be monitored individually. Treatment of hypertension ought to be started with caution with lowest possible dosage. Aggressive therapy is strongly discouraged to avoid hemodynamic collapse. Beta-blockers should be administered to all CABG patients unless contraindicated.

Nitric oxide and the CABG patient

The post surgery success of coronary artery bypass grafting (CABG) is counteracted by thrombosis and de-endothelialization, intimal hyperplasia and, over the long term, atherosclerosis. There are many reasons to assume that in CABG patients vascular bioavailability of NO generated by the endothelium plays an important role for graft function. This holds true for factors such as graft type, harvesting and storage, the type of surgery, non-pharmacologic prevention of risk factors, for example, regular physical activity (if feasible), and drug therapy. Although the precise role of graft endothelial NO bioavailability for graft patency and clinical endpoints is still uncertain, current data rather speak in favor of NO indicating that the potential of vasoprotective activities of NO in the CABG patient deserves further investigation.

Treatment recommendations to prevent myocardial ischemia and infarction in patients undergoing vascular surgery

During major vascular surgery (MVS), patients are at high risk for developing unrecognized myocardial infarction (MI) and myocardial ischemia. In reducing postoperative morbidity and mortality, preoperative cardiac risk stratification and adequate medical therapy play a pivotal role. Based on literature and current opinions, medical treatment should comprise at least a combination of beta-blockers, aspirin, and statins. beta-Blockers exert their beneficial effects predominantly through heart rate control, leading to reduced oxygen demand during surgery. A heart rate between 65 and 70 bpm should be achieved. Irrespective of their lipid-lowering effects, statins seem to improve postoperative cardiac outcome by stabilizing coronary artery plaques, thereby preventing atherosclerotic plaque rupture. Aspirin reduces platelet activation and vasoconstriction, thereby limiting ischemic events and reducing nonfatal MI by 34%. Adding clopidogrel to low-dose aspirin might be beneficial toward postoperative cardiac outcomes; however, the effect on the incidence of postoperative bleeding complications may be a problem for future studies to resolve. Whereas beta-blockers inhibit the effect of catecholamines, alpha(2)-agonists inhibit catecholamine release and may be used in the perioperative setting when beta-blockers are contraindicated. Despite the blood pressure-lowering effect and anti-inflammatory properties of angiotensin-converting enzyme inhibitors, the literature does not support their use in patients undergoing MVS. The possible use of calcium antagonists before MVS should be further evaluated in high-risk patients with contraindications to beta-blockers, such as asthma, conduction abnormalities, or a history of stroke. Although nitrates are widely used for treating angina pectoris, the beneficial effect of their use in patients undergoing MVS remains controversial. Therefore, nitrates are not routinely used in the perioperative setting. The current American College of Cardiology/American Heart Association guidelines do not recommend prophylactic coronary revascularization before noncardiac surgery in patients with stable coronary artery disease.

Long-term results (three-year) of emergency coronary artery bypass grafting for patients with unstable angina pectoris

Satisfactory results are achieved by elective coronary artery bypass grafting (CABG), but the results of emergency CABG are less than satisfactory and readmission for cardiac events is common. We examined long-term results of emergency CABG for unstable angina pectoris from the viewpoints of preoperative, intraoperative, and postoperative factors. Subjects were 154 patients who underwent emergency CABG for unstable angina pectoris. Operative mortality rate was 1.9%. Univariate analysis showed female gender, chronic renal failure, hemodialysis, nonuse of human atrial natriuretic peptide (hANP), nonuse of angiotensin II receptor blockers and aldosterone blockers, 3-month postoperative brain natriuretic peptide level > or =200 pg/ml, and 3-month postoperative aldosterone level > or =100 pg/ml as risk factors for late cardiac events. Multivariate analysis confirmed nonuse of hANP, nonuse of aldosterone blockers, 3-month brain natriuretic peptide level > or =200 pg/ml, and 3-month aldosterone level > or =100 pg/ml as risk factors. Intraoperative hANP infusion and postoperative treatment with aldosterone blockers and angiotensin II receptor blockers can control the renin-angiotensin-aldosterone system, inhibit left ventricular remodeling, decrease extent of infarction, and improve cardiac function, yielding a favorable long-term prognosis. The best results are obtained by combining good surgical technique and perioperative management with the long-term outcome in mind.

A practical approach to the management of patients with atrial fibrillation

Atrial fibrillation is the most commonly encountered clinical arrhythmia and continues to grow in incidence. Current management involves highly individualised therapies based on underlying concomitant disease processes and symptoms. Moreover, there are numerous therapeutic permutations involving anticoagulation, rate-limitation and antiarrhythmic strategies. This review serves to update the clinician with a practical approach to each patient population and on current advances in management.

Statin use and neurologic morbidity after coronary artery bypass grafting: A cohort study

BACKGROUND

Statin use before surgery has been associated with reduced morbidity and mortality after vascular surgery. The effect of preoperative statin use on stroke and encephalopathy after coronary artery bypass grafting (CABG) is unclear.

METHODS

A post hoc analysis was undertaken of a prospectively collected cohort of isolated CABG patients over a 10-year period at a single institution. Primary outcomes were stroke and encephalopathy. Univariable analyses identified risk factors for statin use, which were applied to a propensity score model using logistic regression and patients were divided into quintiles of propensity for statin use. Controlling for propensity score quintile, the odds ratio (OR) of combined stroke and encephalopathy (primary endpoint), cardiovascular mortality, myocardial infarction, and length of stay were compared between statin users and nonusers.

RESULTS

There were 5,121 CABG patients, of whom 2,788 (54%) were taking statin medications preoperatively. Stroke occurred in 166 (3.2%) and encephalopathy in 438 (8.6%), contributing to 604 patients (11.8%) who met the primary endpoint. The unadjusted OR of stroke/encephalopathy in statin users was 1.053 (95% confidence interval [CI] 0.888-1.248, p = 0.582). Adjustment based on propensity score resulted in balance of stroke risk factors among quintiles. The propensity score-adjusted OR of stroke/encephalopathy in statin users was 0.958 (95% CI 0.784-1.170, p = 0.674). There were no significant differences in cardiovascular mortality, myocardial infarction, or length of stay between statin users and otherwise similar nonusers.

CONCLUSIONS

In this large data cohort study, preoperative statin use was not associated with a decreased incidence of stroke and encephalopathy after coronary artery bypass grafting.

The impact of intravenous aspirin administration on platelet aspirin resistance after on-pump coronary artery bypass surgery

Aspirin resistance continues to be a major challenge in patients after coronary artery bypass grafting (CABG). We investigated the impact of intravenous aspirin on platelet function in this clinical setting. Forty-two patients received 100 mg of oral aspirin once daily, beginning on day 1 after the operation. Between day 6 and 8 post operation one oral dose was replaced by an intravenous dose of 300 mg. Platelet function analyzer (PFA-100) closure times (CT), turbidimetric platelet aggregation (TPA) and impedance platelet aggregation (IPA) induced by arachidonic acid (AA), collagen and ADP were measured prior to and 1 h and 24 h after intravenous aspirin. Results obtained prior to the intravenous aspirin were compared with respective values from 120 healthy individuals. Despite the postoperative oral aspirin that was given once daily, ADP-induced TPA (ADPTPA) and IPA values induced by AA, ADP or collagen were significantly greater in patients than in controls, while PFA-100 CT were significantly shorter. Intravenous aspirin induced a significant reduction of platelet aggregability as measured by collagen/epinephrine (CEPI) CT, TPA and IPA induced by AA and collagen 1 h and 24 h after administration. Intravenous aspirin was not found to influence collagen/ADP (CADP) CT and IPA induced by ADP. Concomitantly, the number of patients with laboratory aspirin resistance as measured by CEPI-CT and TPA but not by IPA induced by AA or collagen dropped significantly. Agreement in the detection of aspirin responders and non-responders among platelet function tests was poor. Our findings indicate that the intravenous aspirin appears to be a promising approach for reducing laboratory aspirin resistance during the postoperative phase of CABG.