Ineffectiveness and potential proarrhythmia of atrial pacing for atrial fibrillation prevention after coronary artery bypass grafting

BACKGROUND: Atrial pacing is often used empirically to suppress atrial ectopy and prevent atrial fibrillation after coronary artery bypass grafting. METHODS: To determine whether atrial overdrive pacing reduces atrial fibrillation and atrial ectopy after coronary artery bypass grafting, 100 patients were randomized to no atrial pacing (Control) versus AAI pacing at 10 beats/min or more above the resting heart rate (Paced), started by postoperative day 1 and continued through day 4. Major end points were new atrial fibrillation and frequency of atrial ectopy during the first 4 days after coronary artery bypass grafting. RESULTS: Atrial fibrillation occurred by day 4 in 13 of 51 (25.5%) Paced and in 14 of 49 (28.6%) Control patients, p = 0.90. Control patients who developed atrial fibrillation had significantly more atrial ectopy than those who did not. Atrial ectopy was paradoxically more frequent in the Paced group (2,106+/-428 versus 866+/-385 per 24 hours, p = 0.0001). Loss of capture, sensing, and consistent atrial pacing occurred frequently during atrial pacing. CONCLUSIONS: Contrary to prevailing opinion and practice, postoperative atrial overdrive pacing significantly increases atrial ectopy and does not reduce the likelihood of atrial fibrillation.     

Intraoperative amiodarone as prophylaxis against atrial fibrillation after coronary operations

BACKGROUND: New onset of atrial fibrillation is a frequent complication after coronary artery bypass grafting and is a major cause of postoperative morbidity. Preoperative oral treatment with amiodarone hydrochloride has been shown to be efficacious as prophylaxis. The present study investigated whether intraoperative use of intravenous amiodarone has a preventive effect on the incidence of atrial fibrillation after coronary revascularization. METHODS: In a prospective study, 150 consecutive patients (mean age, 63 +/- 8 years; 132 men and 18 women) undergoing coronary artery bypass grafting were randomly assigned to one of three groups. Two groups received different doses of intravenous amiodarone (group I, 300-mg bolus and 20 mg x kg(-1) x day(-1) for 3 days; group II, 150-mg bolus and 10 mg x kg(-1) x day(-1) for 3 days) after aortic cross-clamping and one group, placebo (group III). Continuous electrocardiographic online monitoring was performed for 10 days. Arrhythmias were analyzed with respect to type, frequency, duration, and clinical relevance. RESULTS: New onset of atrial fibrillation occurred in 24% of patients in group I, 28% in group II, and 34% in group III (p = not significant). Atrial fibrillation with a rapid ventricular response (>120 beats per minute) was significantly more frequent in the control group (group I, 14%; group II, 24%; group III, 32%; p < 0.05, group I versus group III) and appeared significantly earlier (group I, day 4.3 +/- 2.5; group II, day 4.8 +/- 2.9; group III, day 2.6 +/- 1.3; p < 0.05, group III versus groups I and II). Temporary atrial pacing because of bradycardia (<60 beats per minute) was necessary significantly more often in group I (group I, 48%; group II, 40%; group III, 28%; p < 0.05, group I versus group III). Early mortality rate (group I, 4%; group II, 2%; group III, 4%), rate of perioperative complications (group I, 14%; group II, 20%; group III, 14%), and duration of hospital stay (group I, 14.0 days; group II, 14.4 days; group III, 14.7 days) were not different between groups. CONCLUSIONS: Intraoperative prophylactic use of amiodarone does not prevent new onset of atrial fibrillation in patients undergoing coronary artery bypass grafting and had no effect on outcome. Therefore, intraoperative prophylactic treatment with amiodarone at the tested doses does not appear to be justified.     

Amiodarone reduces the incidence of atrial fibrillation after coronary artery bypass grafting

OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of postoperative administration of prophylactic amiodarone in the prevention of new-onset postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting. METHODS: In this prospective study 157 patients were randomly divided into two groups: 77 patients (amiodarone group) received intravenous amiodarone in a dose of 10 mg/kg/d for postoperative 48 hours. On postoperative day 2 oral amiodarone was started with a dose of 600 mg/d for 5 days, 400 mg/d for the following 5 days, and 200 mg/d for 20 days, and 80 patients received placebo (control group). RESULTS: Preoperative patient characteristics and operative variables were similar in the two groups. Postoperative atrial fibrillation occurred in 8 patients (10.4%) receiving amiodarone and in 20 (25.0%) patients receiving placebo (P =.017). Duration of atrial fibrillation was 12.8 +/- 4.8 hours for the amiodarone group compared with 34.7 +/- 28.7 hours for the control group (P =.003). The maximum ventricular rate during atrial fibrillation was slower in the amiodarone group than in the control group (105.9 +/- 19.1 beats per minute and 126.0 +/- 18.5 beats per minute, respectively, P =.016). The two groups had a similar incidence of complication other than rhythm disturbances (20.8% vs 20.0%, P =.904). Amiodarone group patients had shorter hospital stays than that of control group patients (6.8 +/- 1.7 days vs 7.8 +/- 2.9 days, P =.014). The in-hospital mortality was not different between two groups (1.3% vs 3.8, P =.620). CONCLUSIONS: Postoperative intravenous amiodarone, followed by oral amiodarone, appears to be effective in the prevention of new-onset postoperative atrial fibrillation. It also reduces ventricular rate and duration of atrial fibrillation after coronary artery bypass grafting. It is well tolerated and decreases the length of hospital stay.     

Intravenous magnesium sulfate prophylaxis for atrial fibrillation after coronary artery bypass surgery

OBJECTIVE: Atrial fibrillation is a rhythm disorder commonly seen early after coronary artery bypass grafting, and it increases morbidity. METHODS: To investigate the effectiveness of magnesium sulfate in the prophylaxis of atrial fibrillation, we conducted a prospective, randomized, placebo-controlled clinical study on 200 consecutive patients in whom we performed elective and initial coronary artery bypass grafting operations. In each group 50% of patients underwent beating-heart operations. In the treatment group 100 patients (76 men and 24 women; mean age, 57.63 +/- 9.68 years) received 24.34 mEq (3 g) of magnesium sulfate in 100 mL of saline solution that was administered over 2 hours (50 mL/h) preoperatively, perioperatively, and at postoperative days 0, 1, 2, and 3. In the control group 100 patients (74 men and 26 women; mean age, 59.96 +/- 9.29 years) received only 100 mL of saline solution according to the same administration schedule as the treatment group. RESULTS: Atrial fibrillation developed in 15 patients from the treatment group and in 16 patients from the control group. The arrhythmia developed after 37.87 +/- 12.76 and 45.26 +/- 15.27 hours in the treatment and control groups, respectively. Although a significant relationship was found between low magnesium sulfate levels and increased incidence of atrial fibrillation (P <.05), when the incidence of postoperative atrial fibrillation is concerned, no significant difference was found between the 2 groups (P >.05). Also, no significant difference was found between operations with cardiopulmonary bypass and beating-heart operations in terms of atrial fibrillation incidence (P >.05). However, atrial fibrillation extended the duration of hospital stay in both groups (P <.05). CONCLUSION: Our findings indicate that magnesium sulfate infusion alone is not sufficient for the prophylaxis of atrial fibrillation.     

Does preoperative atrial fibrillation reduce survival after coronary artery bypass grafting?

BACKGROUND: Preoperative atrial fibrillation has been identified as a risk factor for reduced long-term survival after coronary artery bypass grafting. This study sought to determine whether atrial fibrillation is merely a marker for high-risk patients or an independent risk factor for time-related mortality. METHODS: From 1972 to 2000, 46,984 patients underwent primary isolated coronary artery bypass grafting; 451 (0.96% prevalence) had electrocardiogram-documented preoperative atrial fibrillation (n = 411) or flutter (n = 40). Characteristics of patients with and without atrial fibrillation were contrasted by multivariable logistic regression to form a propensity score. With this, comparable groups with and without atrial fibrillation were formed by pairwise propensity-matching to assess survival. RESULTS: Patients with preoperative atrial fibrillation were older (67 +/- 9.0 versus 59 +/- 9.8 years, p < 0.0001), had more left ventricular dysfunction (66% versus 52%, p < 0.0001) and hypertension (73% versus 59%, p < 0.0001), but less severe angina (39% moderate or severe versus 49%, p < 0.0001). Many of these factors are themselves predictors of increased time-related mortality. In propensity-matched patients, survival at 30 days and at 5 and 10 years for patients with versus without atrial fibrillation was 97% versus 99%, 68% versus 85%, and 42% versus 66%, respectively, a survival difference at 10 years of 24%. Median survival in patients with atrial fibrillation was 8.7 years versus 14 years for those without it. CONCLUSIONS: Atrial fibrillation in patients undergoing coronary artery bypass grafting is a marker for high-risk patients; in addition, atrial fibrillation itself substantially reduces long-term survival. Thus, if patients in atrial fibrillation require surgical revascularization, it is appropriate to consider performing a concomitant surgical ablation procedure.     

Amiodarone versus digoxin and metoprolol combination for the prevention of postcoronary bypass atrial fibrillation.

OBJECTIVE: This prospective randomized study aims at evaluation and comparison of the prophylactic effects of amiodarone versus digoxin and metoprolol combination in postcoronary bypass atrial fibrillation. METHODS: A total of 241 consecutive patients undergoing elective coronary artery bypass grafting were randomly allocated into three groups. Patients in Group1 (n=77) received metoprolol 100 mg/24 h per oral (P.O.), preoperatively, 2x0.5 mg digoxin intravenously on the operating day and digoxin 0.25 mg P.O.+metoprolol 100 mg P.O. on the first postoperative day until discharge. Patients in Group 2 (n=72) received totally 1200 mg intravenous/24 h amiodarone which the 300 mg - bolus dose/1 h was given as soon as the operation had been finished. On the next day patients were administered 450 mg/24 h amiodarone i.v. and 600 mg/day in three doses P.O. were given until discharge. Group 3 (n=92) was the control group with no antiarrhythmic prophylaxis. RESULTS: Preoperative patient characteristics and operative parameters were similar in three groups. Atrial fibrillation occurred in 13 patients (16.8%) in Group 1, six patients (8.3%) in Group 2 and 31 patients (33.6%) in Group 3. CONCLUSION: Both study groups were effective in the prevention of postcoronary bypass atrial fibrillation with respect to control (P<0.01 in Group 1 and P<0.001 in Group 2).     

Long-Term Prevention of Atrial Fibrillation After Coronary Artery Bypass Surgery: Comparison of Quinidine, Verapimil, and Amiodarone in Maintaining Sinus Rhythm

A bstract Aim of Study : To evaluate the necessity and efficacy of quinidine fumarate, verapimil, or amiodarone prophylaxis for sinus rhythm maintenance in patients who experienced atrial fibrillation after coronary artery bypass surgery. Methods : Between 1992 and 1995, this prospective, randomized, placebo-controlled study examined 120 patients in whom atrial fibrillation occurred and was restored to sinus rhythm by pharmacological therapy or direct current cardioversion in the immediately postoperative period after coronary artery bypass surgery. There were no significant differences in perioperative characteristics among the patients, who were randomly separated into four groups in the course of discharge. In group 1 (n = 30), patients did not receive antiarrhythmic drugs. Quinidine fumarate was given in group 2 (n = 30), verapimil in group 3 (n = 30), and amiodarone in group 4 (n = 30). Patients were monitored six times over a 90-day postoperative period by 24-hour Holter monitoring and routine examination. Results : The recurrent atrial fibrillation usually developed within 15 days of discharge. Atrial fibrillation occurred in one patient (3.33%) in group 1, and two each (6.66%) in groups 2, 3, and 4. Atrial fibrillation was asymptomatic and occurred with slow ventricular response in groups 3 and 4. Side effects occurred in 5 patients (16.6%) given quinidine, 1 patient given amiodarone, but in no patient given verapimil. Conclusions : There were no significant differences in the maintenance of sinus rhythm among the four groups, so we suggest that long-term prevention of atrial fibrillation in patients with coronary artery bypass grafting was not necessary at the postdischarge period.     

Glucose-insulin-potassium solutions improve outcomes in diabetics who have coronary artery operations

BACKGROUND: This study was undertaken to determine whether glucose-insulin-potassium (GIK) would improve myocardial performance and limit morbidity after coronary artery bypass grafting in diabetic patients. METHODS: Forty consecutive coronary artery bypass grafting patients with medically treated diabetes mellitus were prospectively randomly assigned to either a GIK group (n = 20; 500 mL D5W + 80 U regular insulin + 40 mEq KCl 30 mL/hour) or a no-GIK group (n = 20; D5W at 30 mL/hour). The GIK was begun at anesthetic induction and continued for 12 hours postoperatively. RESULTS: Patients treated with GIK had higher postoperative cardiac indices (2.88 +/- 0.50 versus 2.20 +/- 0.39 L/minute per square meter; p < 0.0001), lower inotrope scores (0.40 +/- 0.68 versus 1.25 +/- 1.44; p = 0.05), less weight gain (5.80 +/- 3.76 versus 13.85 +/- 6.52 pounds; p < 0.0001), and had shorter times of ventilator support (8.35 +/- 2.60 versus 13.45 +/- 7.33 hours; p = 0.0128). They had a significantly lower prevalence of atrial fibrillation (15% versus 60%; p = 0.003), and shorter hospital stays (6.70 +/- 1.52 versus 10.15 +/- 6.62 days; p = 0.02). CONCLUSIONS: Substrate enhancement with GIK in diabetic patients improved myocardial performance and resulted in faster recovery after coronary artery bypass grafting.     

The efficacy of supplemental magnesium in reducing atrial fibrillation after coronary artery bypass grafting

BACKGROUND: Atrial fibrillation after coronary artery bypass is reported from 17% to 53%. Hypomagnesemia after this surgery is considered a contributing factor. METHODS: Two hundred-two coronary bypass patients were randomized to magnesium (n = 105) or placebo (n = 97). The experimental group received 80-mg magnesium sulfate per kilogram ideal weight in 100 mL dextrose 5% water 30 minutes preoperatively. Postoperatively, patients received 8-mg magnesium sulfate per kilogram ideal weight intravenous per hour more than 48 hours. The control group received dextrose 5% water at these intervals. RESULTS: After the first bolus serum magnesium was experimental 4.75 mg/dL versus control 1.91 mg/dL, p less than 0.001, and remained different until postoperative day 4 (experimental 2.33 mg/dL vs control 2.26 mg/dL, p = 0.24). Atrial appendage and strap muscle were analyzed after the first bolus and after revascularization. There were no differences between groups in tissue magnesium or calcium. Urinary magnesium was elevated in the experimental (experimental 324.5 mg/24 hours, vs control 45.1 mg/24 hours, p = 0.01). Calcium excretion was higher (experimental 370 mg/24 hours vs control 186 mg/24 hours, p < 0.001) and was associated with lower serum calcium. Serum calcium was higher in the control through the fourth postoperative day. The incidence of atrial fibrillation was experimental 32 of 105 (30.5%) versus control 41 of 97 (42.3%) p = 0.08. Atrial fibrillation was different on the first postoperative day (experimental 3/105, 2.9% vs control 9/97, 9.3%), p = 0.05. CONCLUSIONS: Overall prophylactic magnesium supplementation does not significantly reduce atrial and ventricular arrhythmias. The only significant benefit of magnesium supplementation was on the first postoperative day.     

Effect of low-dose amiodarone and magnesium combination on atrial fibrillation after coronary artery surgery

BACKGROUND: To evaluate whether postoperative administration of intravenous low-dose amiodarone and magnesium sulfate (MgSO(4)) combination would reduce the incidence of atrial fibrillation following coronary artery bypass grafting (CABG) in normomagnesemic high-risk patients for postoperative atrial fibrillation (POAF). METHODS: A total of 136 patients undergoing elective CABG and had > or =3 risk factors for POAF were prospectively randomized to one of three groups, to receive a single dose of amiodarone (5 mg/kg) and MgSO(4) (1.5 g) (combination group, n = 44), or an equal dose of amiodarone (amiodarone group, n = 44) or equal volumes of saline (control group, n = 48) at early postoperative period. Continuous electrocardiographic (ECG) monitoring was performed for the first 48 hours and an ECG was recorded every 8 hours later. POAF longer than 30 minutes or for any length requiring treatment, and the drug-related side effects were recorded. RESULTS: The study population showed a homogeneous distribution regarding risk factors for POAF and there was no significant difference in patient characteristics, echocardiographic variables, or operative variables among three groups. POAF developed in 4 patients in combination group, in 16 patients in amiodarone group and in 16 patients in control group, representing a 24% relative risk reduction between the combination group and control group (p = 0.023). No statistically significant difference regarding incidence of POAF was observed between amiodarone and control groups. CONCLUSIONS: Combined prophylactic therapy with amiodarone and MgSO(4) at the early postoperative period without a maintenance phase is an effective, simple, well-tolerated, and possibly cost-effective regimen to prevent POAF in normomagnesemic, high-risk patients.     

Fibrillation in patients subjected to coronary artery bypass grafting

OBJECTIVE: Atrial fibrillation is the most frequently encountered postoperative arrhythmic complication after coronary artery bypass grafting. Ischemic preconditioning has proved a potent endogenous factor in suppressing ischemia-reperfusion-induced arrhythmias. The protective effect of ischemic preconditioning on atrial fibrillation after coronary artery bypass grafting has not been studied. The purpose of the present study was to investigate whether ischemic preconditioning had an effect on postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting. METHODS: Eighty-five patients undergoing coronary artery bypass grafting were randomized into ischemic preconditioning and control groups. Holter data from 24-hour electrocardiography were collected 1 day before the operation to the second postoperative day. Atrial fibrillation was registered as positive if any atrial fibrillation event occurred. RESULTS: The overall incidence of postoperative atrial fibrillation and sustained atrial fibrillation was 34.1% and 27.1%, respectively. The occurrence of atrial fibrillation was significantly lower in the ischemic preconditioning group (21.4% in patients undergoing ischemic preconditioning and 46.5% in control subjects, P =.015). Preoperative recent unstable angina did not influence the incidence of atrial fibrillation. Patients with atrial fibrillation had longer intensive care unit stays and compromised postoperative hemodynamic outcomes. Binary logistic regression analysis showed that ischemic preconditioning, preoperative mean heart rate, and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation. CONCLUSIONS: Postcoronary artery bypass grafting atrial fibrillation is associated with more complicated postoperative outcome. Higher preoperative heart rate and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation. Recent unstable angina is not related to the occurrence of postcoronary artery bypass grafting atrial fibrillation. Ischemic preconditioning significantly suppresses postcoronary artery bypass grafting atrial fibrillation, suggesting that ischemic preconditioning can be used as an effective prophylactic method for postoperative atrial fibrillation.     

Prophylactic use of amiodarone against postoperative atrial fibrillation after cardiac surgery

We investigated the effect of amiodarone on prevention of post-operative atrial fibrillation (POAF) after cardiac surgery. Thirty cases of amiodarone (AMD) group including elective coronary artery bypass grafting and valve operation were enrolled from January 2007 to January 2010. The control (C) group consisted of 45 cases treated before 2007. Amiodarone was administered orally for the total of 14 days; 400 mg 7 days before the surgery, and a half dose after the surgery. POAF occurred significantly less in AMD group (4/30 : 13.3%) than in C group (13/45 : 28.9%) [p = 0.029]. With regard to duration of POAF, that of AMD group was significantly shorter than that of C group (16.0 hours vs 40.23 hours : p = 0.018). This research suggested that amiodarone might be effective in preventing POAF.     

Intravenous magnesium for prevention of atrial fibrillation after coronary artery bypass surgery: a systematic review and meta-analysis

Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass surgery. The objective of this study was to assess the effectiveness of intravenous magnesium in preventing postoperative atrial fibrillation. A meta-analysis of eight identified randomized controlled trials, reporting comparisons between magnesium and control was undertaken. The primary outcome was incidence of postoperative atrial fibrillation. Our review revealed that use of intravenous magnesium is associated with a significant reduction in the incidence of atrial fibrillation after coronary artery bypass surgery, with a relative risk of 0.64 (95% confidence interval = 0.47, 0.87, and p = 0.004).     

Tranexamic acid reduces bleeding and the need for blood transfusion in primary myocardial revascularization

BACKGROUND: The objective of this study was to study the effect of low-dose tranexamic acid (TA) on postoperative bleeding and coagulation variables after coronary artery bypass grafting operation. METHODS: Fifty patients undergoing primary coronary artery bypass grafting were randomly assigned to receive either placebo (0.9% NaCl; n = 25) or 10 mg/kg TA followed by infusion of 1 mg/kg per hour during the operation (n = 25). Data measured included blood loss, transfusion, reoperation, fibrinogen level, fibrinogen split products, platelet size, and platelet function. Measurements were made after induction of anesthesia, after heparin administration, during patient warming, after skin closure, and 24 hours after operation. RESULTS: Patients in the TA study group weighed less. Other demographic characteristics were similar between groups. Postoperative bleeding was less in the TA group (194 +/- 135 mL versus 488 +/- 238 mL, p < 0.001), whereas blood requirement was higher in the control group (1.68 +/- 1 versus 0.52 +/- 0.9 U of packed cells per patient, p < 0.001). The percent of patients exposed to blood products was significantly less in the TA group (36% versus 100%, p < 0.001). Fibrinogen split products were lower in the TA group during bypass (p < 0.001). Fibrinogen levels fell in both groups during cardiopulmonary bypass. Platelet number and function were reduced equally in both groups by cardiopulmonary bypass. Other test results were not different between groups. CONCLUSIONS: The use of low-dose TA during coronary artery bypass grafting significantly reduced the coagulopathy-induced postoperative bleeding and allogeneic blood products requirement. The low levels of fibrinogen split products during bypass in the study group reflect the inhibiting effect of TA in fibrinolysis. Tranexamic acid had no effect on platelet function during cardiopulmonary bypass.     

Coronary artery bypass grafting with left internal mammary artery and right gastroepiploic artery, with and without bypass

BACKGROUND: Total arterial and off-pump revascularization are increasingly used in coronary artery bypass grafting. This study describes our experience with the exclusive use of both left internal thoracic artery and gastroepiploic artery by means of a median sternotomy, with and without cardiopulmonary bypass, in a subgroup of patients with two-vessel disease. METHODS: From January 1995 to July 2000, 171 consecutive patients were reviewed in a prospective database. Ninety-one patients underwent coronary artery bypass grafting without cardiopulmonary bypass (group A), and 80 patients were operated on under cardiopulmonary bypass with aortic cross-clamp and cardioplegia (group B). RESULTS: Patient data were similar in both groups except for the Euroscore (mean; 3.4+/-6.1, group A versus 2.5+/-4.5, group B; Euroscore > 6: 26.4%, group A versus 10%, group B; p < 0.05) and ejection fraction (mean, 54.6%+/-15.8%, group A versus 63.1%+/-12.7%, group B; p < 0.001). Severe aortic calcification was present in 6 group A patients, versus no patient in group B. Operative time was shorter in group A (185 versus 213 minutes, p < 0.0001), with less distal anastomoses (2.26 versus 2.5, p < 0.05). Conversion to cardiopulmonary bypass occurred in 1 patient, who was excluded from the study. Bleeding was higher in group A (852.6+/-288 mL versus 712.4+/-274 mL, p < 0.05), but transfusion was similar in both groups. Atrial fibrillation, postoperative inotropic support, and hospital stay were similar in both groups. Myocardial infarction was less frequent in group A (1 versus 4). Postoperative intraaortic balloon pump was used in 2 patients (group B). One patient died (group A) and 1 had an embolic stroke (group B). After discharge, 2 more patients died (group A, day 91; group B day 141), and 1 patient suffered an embolic stroke (group B). One patient in each group presented with dysfunction of the gastroepiploic artery graft requiring successful percutaneous transluminal angioplasty on the right posterolateral artery. CONCLUSIONS: These results suggest that off-pump coronary artery bypass grafting using the left internal thoracic artery and gastroepiploic artery is safe even in high-risk patients. This approach allows an absolute no-touch technique of the aorta.     

Atrial fibrillation after isolated coronary bypass surgery

Postoperative atrial fibrillation (Af) remains a significant source of morbidity after coronary artery bypass grafting (CABG). Prophylactic therapy with beta-adrenergic blockers or amiodarone hydrochloride is reported to reduce the incidence of Af. We studied the incidence of Af retrospectively and considered the risk factors for it. Ninety-three patients who underwent isolated CABG from April 2003 to March 2004 are included in this study. Postoperative Af was observed in 22 (25%) patients. Ten of them were operated on off-pump procedure, and 14 had any type of beta-adrenergic blockers preoperatively. The mean age of the group of postoperative Af is 69.7 +/- 9.2 years old (older than the non-Af group: 65.5 +/- 10 years old, p = 0.087). And the preoperative left atrial size was larger in the Af group than in the non-Af group (43.4 +/- 6.1 versus 40.6 +/- 5.4mm, p = 0.064) Major embolic complication occurred in only 1 (1.1%) patient of non-Af group. We observed postoperative Af in 25% of patients after CABG. Older age and larger left atrial size may relate to the incidence of Af, and appropriate anticoagulant therapy and medication of beta-blockers are important for the patients who have such risk factors.     

The importance of age as a predictor of atrial fibrillation and flutter after coronary artery bypass grafting

The purpose of this study was to identify factors associated with atrial fibrillation and flutter after coronary artery bypass grafting. The study group consisted of a consecutive series of 5807 patients who underwent coronary artery bypass grafting alone and who were in sinus rhythm preoperatively. Atrial fibrillation and flutter were identified during continuous monitoring or by clinical symptoms and signs; they occurred in 17.2% of the patients. The prevalence of atrial fibrillation and flutter was directly related to age at operation, varying from 3.7% in patients aged less than 40 years to 27.7% in patients aged 70 and over. In a multivariate analysis, age remained the most important independent predictor of atrial fibrillation and flutter (p less than 0.001). Other independent predictors of atrial fibrillation and flutter were chronic airflow limitation (p = 0.006), preoperative beta-adrenergic blockers (p = 0.011), and chronic renal failure (p = 0.04). Extent of coronary disease at catheterization, history of a previous myocardial infarction, heart size on chest x-ray film, and all operative factors measured, apart from year of operation, were unassociated with atrial fibrillation and flutter. Thus atrial arrhythmias after coronary artery bypass operations are most strongly related to advanced age and are unassociated with preoperative left ventricular function and extent of coronary disease.     

Predictors of atrial fibrillation after off-pump coronary artery bypass graft surgery

OBJECTIVE: Atrial fibrillation is the most common complication after coronary artery bypass graft surgery. This arrhythmia may lead to hemodynamic compromise, prolonged hospitalization, and increased risk for cerebral thromboembolism. Older age is the only variable consistently associated with the development of postoperative atrial fibrillation; however, no strong predictive model exists. The purpose of this study was to identify perioperative characteristics associated with new-onset atrial fibrillation in patients undergoing off-pump coronary artery bypass grafting. DESIGN: Prospective, observational. SETTING: University tertiary care hospital. PARTICIPANTS: One hundred sixty consecutive patients undergoing off-pump coronary artery bypass grafting. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Incidence of postoperative atrial fibrillation was the major outcome. Atrial fibrillation occurred in 33 patients (20.6%). Multivariate analysis identified reintervention (odds ratio 26.8), revascularization of the ramus medianus (odds ratio 3.9), and age (odds ratio 1.069 per year) as the only independent predictors of postoperative atrial fibrillation. All patients were in sinus rhythm at hospital discharge. One hospital death was noted. CONCLUSIONS: Despite the less invasive approach, the incidence of postoperative atrial fibrillation is high after off-pump coronary artery bypass grafting. Older age, grafting of the ramus medianus, and a redo operation were predictors of new-onset postoperative atrial fibrillation. It is possible that left atrial stretching with heart dislocation during revascularization of the lateral wall could lead to postoperative atrial fibrillation.     

Prophylactic effect of magnesium infusion against postoperative atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is a common complication of cardiac operation. For the development of postoperative AF, various risk factors have been identified over the years. In a recent study, it was detected that low serum magnesium levels was an independent predictor of AF after coronary artery bypass grafting (CABG). The purpose of this study was to assess the prophylactic effect of intravenous magnesium infusion on postoperative AF. METHODS: A total of 62 consecutive patients who had elective, first time cardiac operation on cardiopulmonary bypass were prospectively categorized to 2 group. In the treatment group, 30 patients received 8.3 mmol of magnesium sulfate in 100 ml of saline solution that was administered over 4 hours, preoperatively, just after admission in the ICU, and at the postoperative day 1, 2, 3, and 4. RESULTS: Postoperative AF occurred in 3/30 (10.0%) patients in the treatment group and in 14/32 (43.8%) patients in the control group (p<0.01). The arrhythmia developed on the 2.9 postoperative day on average. The postoperative length of hospital stay was significantly shortened in the treatment group (15.9 +/- 4.0 days) than that in the control group (20.5 +/- 7.0, p < 0.01). CONCLUSION: Our findings indicate that magnesium sulfate infusion is effective for the prophylaxis of post operative AF.     

Magnesium infusion dramatically decreases the incidence of atrial fibrillation after coronary artery bypass grafting

BACKGROUND: Atrial fibrillation (AF) is one of the most common complications of cardiac surgery. Magnesium, like several other pharmacologic agents, has been used in the prophylaxis of postoperative AF with varying degrees of success. However, the dose and the timing of magnesium prophylaxis need to be clarified. The purpose of this study was to assess the effect of intermittent magnesium infusion on postoperative AF. METHODS: A total of 200 consecutive patients who had elective, isolated, first-time coronary artery bypass grafting were prospectively randomized to two groups. Patients in the magnesium group (n = 100) received 6 mmol MgSO4 infusion in 100 mL 0.9% NaCl solution (25 mL/h) the day before surgery, just after cardiopulmonary bypass, and once daily for 4 days after surgery. Patients in the control group (n = 100) received only 100 mL 0.9% NaCl solution (25 mL/h) at the same time points. RESULTS: Postoperative AF occurred in 2 (2%) patients in the magnesium group and in 21 (21%) patients in the control group (p < 0.001). Atrial fibrillation started, on average, 49.4 +/- 16.8 hours postoperatively. The postoperative length of hospital stay was not significantly different in patients with AF (7.4 +/- 8.0 days) compared with patients without AF (5.4 +/- 1.1 days; p = 0.236). CONCLUSIONS: The use of magnesium in the preoperative and early postoperative periods is highly effective in reducing the incidence of AF after coronary artery bypass grafting.