Off-pump coronary artery bypass grafting does not decrease the incidence of atrial fibrillation

Predicting postoperative atrial fibrillation after myocardial revascularization without cardiopulmonary bypass: A retrospective cohort study

INTRODUCTION

Considering the threat imposed by postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG) and the potential benefits of off-pump CABG, the objective of this study was to describe the incidence and identify predictor factors for POAF in patients undergoing CABG without cardiopulmonary bypass (CPB).

METHODS

In this retrospective cohort study, we enrolled patients undergoing CABG without CPB between December 2008 and December 2011. The independent variables evaluated in this study were major patients' characteristics (age, sex, and ethnia), associated comorbidities (systemic arterial hypertension, diabetes mellitus, thyroid dysfunction, chronic renal failure (CRF), chronic obstructive pulmonary disease, and ischemic stroke), and the revascularization approach (the number of grafts used, the revascularized branch, and the choice of vascular graft (arterial or venous). The dependent variable was the onset of atrial fibrillation after the procedure.

RESULTS

Two hundred and eighty patients were included in the present study. The overall incidence of POAF after off-pump CABG was 5.0%. In the univariate analysis, the presence of chronic renal failure (odds ratio [OR], 3.01 [1.00-9.06], P = .049) and the use of venous-origin graft alone (OR, 9.67 [1.15-81.56], P = .037) were associated with an increased risk or POAF. These findings were confirmed after multivariate analysis, for both CRF (OR, 3.31 [1.05-10.46], P = .042) and the use of venous-origin graft alone (OR, 9.81 [1.13-85.35], P = .039).

CONCLUSION

Off-pump coronary artery bypass grafting proved a safe and effective procedure, with low postoperative atrial fibrillation occurrence, for myocardial revascularization. Chronic renal insufficiency and the use of venous-origin graft solely proved to be independent predictor factors for PAOF.

Leukocyte filtration and aprotinin: synergistic anti-inflammatory protection

Cardiopulmonary bypass activates an array of cellular and humoral inflammatory mechanisms that culminate in diverse or organ-specific injury. A manifestation of inflammatory injury to the heart, atrial fibrillation ranks among the most frequent and potentially life-threatening postsurgical complications. Pulmonary manifestations of the inflammatory response are also of major concern. Neutrophils activated by passage through the extracorporeal circuit inflict local injury and provoke the inflammatory cascade by producing oxyradicals and proinflammatory factors. This study tested if a combination of leukocyte depletion and aprotinin suppression of neutrophils could minimize postbypass atrial fibrillation and pulmonary dysfunction. In part one, two randomized groups of 90 patients undergoing primary coronary artery bypass grafting received full Hammersmith aprotinin alone (control group) or combined with leukofiltration (study group) and were prospectively examined. The dual treatment decreased the incidence of postoperative atrial fibrillation (7 of 90, 7.8%) by 67% versus aprotinin alone (21 of 90, 23.3%). Respiratory gas exchange in these patients was assessed from pulmonary shunt fraction. In the first two hours postbypass, pulmonary shunt fraction in the dual treatment group increased 40% less than in the group receiving aprotinin alone (p = 0.002), and subsided more quickly and completely over the next six hours. In part two, the cardiopulmonary bypass group receiving aprotinin+leukofiltration was retrospectively compared with 45 patients undergoing off-pump coronary revascularization. A strong, albeit not statistically significant trend (p= 0.08) toward a lower incidence of atrial fibrillation was found in the dual treatment group versus the off-pump group (8 of 45, 17.8%). These findings suggest that combining mechanical and pharmacologic suppression of the systemic inflammatory response could mitigate its deleterious arrhythmic and pulmonary complications.

Atrial Fibrillation After Cardiac Surgery: Pathophysiology and Treatment

Atrial fibrillation (AF) occurs in 25% to 60% of patients after cardiac surgery. It is most consistently associated with advanced age and valvular heart operations. Despite improving knowledge of the pathophysiology of chronic AF, postoperative AF remains an obstinate clinical problem. It is associated with an increased risk of stroke, longer hospital stay, and higher hospital expenditure. Consequently, there has been great interest in strategies to prevent and treat this arrhythmia. Treatment for postoperative AF may require immediate electrical cardioversion for hemodynamically unstable patients. Heart rate control is useful in most patients, with anticoagulation considered after 48 hours. Antiarrhythmic therapy is often effective in restoring sinus rhythm but its use needs to be balanced against the patient's risk of proarrhythmic side effects such as torsade de pointes.

Assessment of the Risk Factors and Outcomes for Postoperative Atrial Fibrillation Patients Undergoing Isolated Coronary Artery Bypass Grafting

BACKGROUND

Atrial fibrillation is the most common complication of cardiac surgery and is associated with significant morbidity and mortality. Recognizing patients at high risk for developing postoperative atrial fibrillation (POAF) may help identify those who could benefit from strategies to prevent POAF. This study was conducted to delineate outcomes and to assess risk factors for POAF among Taiwanese patients undergoing coronary artery bypass grafting (CABG).

METHODS

From January 2009 until February 2012, this prospective study included 266 consecutive patients admitted to our hospital with coronary artery disease. All patients underwent isolated CABG. Patients with preoperative permanent atrial fibrillation and concomitant surgery were excluded. Multiple risk factors associated with the incidence of POAF were collected and evaluated.

RESULTS

POAF occurred in 126 of 226 patients (47.37%). Univariate analysis revealed that significant risk factors for the condition were age, gender, diabetes, dyslipidemia, smoking, impaired renal function, impaired cardiac function, and increased serum electrolytes. Multivariate analysis showed dyslipidemia [hazard ratio (HR): 0.418; 95% confidence interval (Cl): 0.190-0.915, p = 0.029], impaired renal function as indicated by an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) (HR: 3.174; 95% CI: 1.432-7.037, p = 0.004), and serum sodium (HR: 1.112; 95% Cl: 1.047-1.182, p = 0.001) prior to cardiopulmonary bypass as significant. Moreover, POAF was associated with lower 30-day, 1- and 3-year cumulative survival rates and higher early postoperative complications.

CONCLUSIONS

Patients with isolated CABG who were administered β-blockers, angiotensin converting enzyme inhibitor/angiotensin receptor blockers treatment, and lipid therapy before CABG were associated with reduced POAF, while those with impaired renal function and higher serum sodium before CABG predisposed POAF in a Taiwanese population.

KEY WORDS

Atrial fibrillation (AF); Coronary artery bypass grafting (CABG); Coronary artery disease (CAD); Postoperative atrial fibrillation (POAF).

Comparison of the effects of on-pump and off-pump coronary artery bypass surgery on cerebral oxygen saturation using near-infrared spectroscopy

BACKGROUND

Central nervous system complications are the most clinically important of those affecting mortality in patients undergoing coronary artery surgery. Newly developed sophisticated techniques and surgical interventions obviating the need for cardiopulmonary pumps have facilitated avoidance of these complications. In this study, we compared the impact of on-pump and off-pump coronary artery bypass surgery on cerebral oxygenation using near-infrared spectroscopy.

METHODS

This study included 40 patients with no comorbidities who were scheduled for on-pump (n = 20) and off-pump (n = 20) cardiac surgery. Preoperative and postoperative Standardized Mini-Mental State Examination (SMMSE) scores, perioperative mean arterial blood pressure (MAP), hematocrit (Hct), peripheral oxygen saturation (SpO2), regional cerebral oximetry values (rSO2), body temperature, and partial pressure of carbon dioxide (PCO2) were recorded, for all patients. Intergroup and intragroup comparisons were then performed.

RESULTS

The mean operative time was longer in the on-pump group. SMMSE scores were similar and relevant postoperative values were lower in both groups. Perioperative MAP, PCO2, and SpO2 were similar in both groups. SpO2 and PCO2 did not differ from baseline levels in either group, while the postextubation MAP at 2 h postoperatively remained low. Hct levels decreased during the perioperative and postoperative periods, while the body temperature declined perioperatively and to a greater degree in the on-pump group. The intraoperative and postoperative rSO2 decreased in both groups. In the on-pump group, the decrease in rSO2 was more prominent during the interval between the start and closure of the sternotomy.

CONCLUSIONS

Physiological alterations that occur during coronary artery surgery affect cerebral oxygenation during and after the operation irrespective of the application of a cardiopulmonary pump. Cerebral oxygenation decreases to a greater extent during on-pump surgery; however, probably because of the neuroprotective effects of hypothermia, the postoperative changes resemble those of off-pump surgery.

Does Off-pump Coronary Artery Bypass Reduce the Prevalence ofAtrial Fibrillation?

INTRODUCTION

To examine whether or not off-pump CABG (Coronary Artery Bypass Reduce) reduces the incidence of AF after cardiac surgery.

METHODS

The study was carried out in 939 consecutive coronary artery disease patients with sinus rhythm from which 383 patients underwent off-pump CABG, and 556 patients were operated through on-pump CABG. All patients were monitored postoperatively during intensive care unit (ICU) stay. Then, the incidence and predictive risk factors of post operative AF (POAF) in two groups were determined and compared with each other.

RESULTS

Overall, the mean age of the patients was 56.0±12.8 years with 234 patients (24.9%) being older than 65 years. POAF developed in 38 patients (9.9%) of the off-pump and in 93 patients (16.7%) of the on-pump CABG. There was significant difference between two groups when considering the incidence of POAF (P=0.002). Among preoperative risk factors, age>65 years had a significant association with the incidence of AF in both groups. This study also showed that most of the POAF cases converted to sinus rhythm after treatment. Moreover, these finding demonstrated that conversion to sinus rhythm is significantly more probable in off-pump group (P=0.006).

CONCLUSION

A reduced prevalence of POAF could be observed in patients with off-pump as compared with on-pump techniques. Furthermore, conversion to sinus rhythm in off-pump group was significantly more probable than on-pump group.

Postoperative complications of coronary artery bypass grafting surgery

Coronary artery bypass grafting (CABG) surgery continues to be an effective and well-used intervention for coronary artery disease. Older patients and those with sicker hearts will become the norm. In spite of increased risk for patients undergoing CABG, overall mortality rates have decreased. Nursing contributions to these improved outcomes cannot be overestimated. Continued understanding and appreciation of these complications will be necessary to effectively care for patients and create optimal outcomes.

Atrial fibrillation after cardiac transplantation: experience in 498 consecutive cases

BACKGROUND

Some contemporary surgical treatments for atrial fibrillation involve creating only a subset of the lesions made in the classic Cox Maze procedure. This subset often consists of pulmonary vein isolation and partial cardiac denervation. Orthotopic heart transplantation, by necessity, results in pulmonary vein isolation, albeit with total cardiac denervation. Although postoperative atrial fibrillation (POAF) and atrial fibrillation may differ in cause, they have similar underlying mechanisms and often respond to the same treatments. Therefore, we reviewed the incidence of POAF in heart transplant recipients to assess the antiarrhythmic effects of pulmonary vein isolation and cardiac denervation.

METHODS

We reviewed the charts of 498 consecutive patients who underwent orthotopic heart transplantation at a single institution during a 15-year period.

RESULTS

Twenty-seven patients (5.4%) experienced POAF within 60 days of transplant. In 9 of these patients, POAF occurred within 2 weeks of a biopsy-proven transient rejection episode; excluding these patients from the analysis revealed a non-rejection-associated POAF rate of 18 of 489 patients (3.7%).

CONCLUSIONS

Despite the long ischemic times, extensive manipulation of the transplanted heart, and the postoperative administration of proarrhythmic inotropic agents that cardiac transplantation typically involves, this procedure is associated with a low incidence of POAF, particularly if patients in whom rejection and POAF were temporally related are excluded. These findings suggest that complete cardiac denervation and pulmonary vein isolation protect heart transplant recipients from POAF, thus supporting the notion that similar lesions may be useful in the treatment of other types of atrial fibrillation.

Association of Met439Thr substitution in heat shock protein 70 gene with postoperative atrial fibrillation and serum HSP70 protein levels

BACKGROUND

Atrial fibrillation (AF) is a common arrhythmia encountered following cardiac surgery. Previously, we have shown that higher expression of heat shock protein (HSP) 70 was associated with decreased incidence of postoperative AF (PoAF), suggestive of an antiarrhythmic role.

OBJECTIVE

We have hypothesised that Met493Thr substitution of one of the important hsp70 genes may cause loss of these protective antiarrhythmic effects. We therefore set out to examine the influence of hsp70 genotype on the incidence of PoAF.

METHODS AND RESULTS

We prospectively recruited 244 Caucasian patients undergoing elective coronary artery bypass surgery. The median age was 65 years (40-80 years). PoAF was defined as the characteristic arrhythmia lasting for at least 15 min, occurring within first week following surgery and requiring treatment. This occurred in 48 patients (19.7%). Validated Met493Thr substitution in hsp70-Hom was determined using established techniques. Of 244 patients, genotype was determined for 242 cases. The three genotypes (MM, MT, and TT) were present at frequencies of 0.66, 0.31, and 0.03, respectively, and were in Hardy-Weinberg equilibrium. In unifactorial analysis patients carrier or homozygous for 493Thr mutation had significantly higher incidence of PoAF (Pearson chi(2) = 4.3, p = 0.037). Multivariate analysis confirmed the positive association of hsp70-Hom with PoAF (OR, 2.43; p = 0.016) independent of age, sex, previous myocardial infarction, number of distal anastomoses, and duration of ventilation, respectively. Serum HSP70 was ranging from 0.74 to 31.91 ng/ml (median, 2.89) and was not correlated with PoAF. Presence of 493Thr mutation was also significantly correlated with higher levels of serum HSP70 (p = 0.009).

CONCLUSIONS

Our data show that a mutation in hsp70-Hom gene is associated with higher incidence of PoAF. These findings are consistent with our previous results and may suggest that patients harbouring this substitution will have less endogenous myocardial protection against AF in stressful situations.

Effects of Beating- versus Arrested-Heart Revascularization on Cardiac Autonomic Regulation and Arrhythmias

BACKGROUND

Altered autonomic regulation after cardiac operations precipitates cardiac arrhythmias, affects repolarization, and increases the risk of sudden cardiac death. We sought to clarify how the 2 different techniques of coronary artery bypass grafting (CABG), namely conventional CABG using cardiopulmonary bypass (on-pump) and beating-heart CABG without cardiopulmonary bypass (off-pump), affect cardiac autonomic regulation and arrhythmic disturbances postoperatively.

METHODS

We included 57 consecutive patients, 28 in the on-pump group and 29 in the off-pump group. The electro-cardiographic recordings were performed on the preoperative day and the fourth, seventh, and twenty-eighth day after operation. Fifteen-minute digital recordings were taken; one channel was used to record electrocardiogram and the other breathing. Detailed analyses of arrhythmia, heart rate, and heart rate variability indices were performed on respective days to assess sympathetic and parasympathetic modulation of the heart and relate it to detected arrhythmic disturbances.

RESULTS

Total power, low-frequency power, which indicates baroreceptor-mediated sympathetic modulation, and high-frequency power, indicating parasympathetic vagal modulation, declined significantly in both groups after CABG (P < .001); however, 7 days after CABG, total and high-frequency power were better preserved in the off-pump group. Mean RR interval was longer in the off-pump group at 7 (P= .006) and 28 days (P= .008) after surgery. The total incidence of arrhythmic events was higher in the on-pump group on the seventh day (P = .017, adjusted odds ratio = 8.6, 95% confidence interval 1.4-80.3).

CONCLUSIONS

The results show profound impairment of cardiac autonomic regulation after CABG, showing better preserved cardiac autonomic modulation 7 days after beating-heart revascularization. Evidence suggests that slower restoration of heart rate and increased incidence of arrhythmic events after CABG using cardiopulmonary bypass are the result not only of impaired cardiac autonomic regulation but also of the involvement of additional factors of nonautonomic origin.

Intravenous and oral amiodarone for the prevention of postoperative atrial fibrillation in patients undergoing off-pump coronary artery bypass surgery

BACKGROUND

Atrial fibrillation is still a frequent complication that increases morbidity after coronary artery bypass grafting. This prospective randomized study is designed to define efficacy of postoperative amiodarone prophylaxis in preventing atrial fibrillation after off-pump coronary artery bypass grafting.

METHODS

One hundred forty-four patients who underwent elective off-pump coronary artery bypass grafting were enrolled for the study. Seventy-six patients (amiodarone group) received 5 mg/kg loading amiodarone infusion in the first postoperative hour, followed by 10 mg/kg for the first 24 hours. After 24 hours, patients received 600 mg/day amiodarone orally for 7 days and 200 mg/day until the end of the postoperative first month. Sixty-eight patients received placebo (control group).

RESULTS

Preoperative characteristics and operative variables of the patients were similar in both groups. Incidence of new-onset atrial fibrillation and maximal ventricular rate response were recorded. The incidence of new-onset atrial fibrillation (11.8% versus 26.5%) (P = .025) and maximal ventricular rate response (109 +/- 13.8 beats/min versus 124.5 +/- 13.9 beats/min) (P = .011) were significantly lower in the amiodarone group. Duration of atrial fibrillation was 17.5 +/- 8.1 hours for the amiodarone group compared with 32.7 +/- 12 hours for the control group (P = .002).

CONCLUSION

Postoperative intravenous amiodarone prophylaxis followed by oral amiodarone significantly reduces the incidence of atrial fibrillation after off-pump coronary artery bypass grafting and the ventricular rate during atrial fibrillation.

Preoperative beta-blocker use reduces atrial fibrillation in off-pump coronary bypass surgery

BACKGROUND

Atrial fibrillation (AF) after coronary artery bypass graft surgery constitutes the most common sustained arrhythmia and results in many complications. The purpose of this study was to assess the effects of prophylactic use of beta-blockers against atrial fibrillation in off-pump surgery patients in the early postoperative period.

METHODS

From 2002 to 2005, 78 patients were enrolled and 41 patients received 50 mg metoprolol succinate daily, which was initiated minimum four days before surgery. Preoperative beta-blocking therapy was continued until the morning of surgery. Thirty-seven patients were free of beta-blocker therapy. Esmolol was used within same range of doses in both groups during operations. Both groups received metoprolol succinate following operations. The frequency of AF occurrence was analysed from the operation time to the sixth postoperative day.

RESULTS

Sixteen patients developed AF with an overall incidence of 22.5%. Four patients from the study group and three patients from the control group were excluded from the study because of transfer to on-pump surgery. There was no difference with regard to the number of grafts carried out, duration of operations and ventilation, intensive care unit stay and inotropic need among groups. Length of hospital stay did not differ among groups either. There was a higher incidence of postoperative AF in patients without beta-blocker prophylaxis (11.7-32.4% P=0.049).

CONCLUSION

Low-dose postoperative beta-adrenergic blockade is valuable for patients who receive these medications before off-pump coronary artery bypass grafting procedures and may be beneficial against AF in all patients.

Predictors of Early Postoperative Atrial Fibrillation after Off-Pump Myocardial Revascularization

Objective

We determined the incidence and the predisposing factors of atrial fibrillation (AF) after aorta nontouch coronary artery bypass grafting without extracorporeal circulation.

Methods

From February 2001 to November 2005, 1359 patients (1159 men, 85.3%) of mean (±SD) age 64.8 (±9.8) years, who underwent off-pump coronary artery bypass grafting (OP-CAB), were prospectively enrolled. Demographics, perioperative data, and comorbidities were recorded in all patients. A 24-hour rhythm monitoring was performed in all patients until hospital discharge.

Results

Among 1359 patients, 273 (20.1%) had development of atrial fibrillation in the early postoperative period. Patients with AF had higher mean (±SD) age, 68.3 (±8.8) years, compared with control subjects [63.9 (± 9.9)] (P ≤ 0.0005). Univariate analysis showed that apart from age, history of arterial hypertension (P ≤ 0.02), chronic obstructive pulmonary disease (P ≤ 0.02), and the use of bilateral internal mammary arteries (P≤< 0.01) were predisposing factors for the development of AF. Logistic regression analysis showed that age, history of arterial hypertension, and the use of bilateral internal mammary arteries were predisposing factors for early postoperative AF after OP-CAB.

Conclusions

Atrial fibrillation occurred in approximately 20% of patients undergoing OP-CAB, mainly in older patients with arterial hypertension who received bilateral internal mammary artery grafts.

Revascularization with off-pump coronary artery surgery: what appears new is actually the old rediscovered

The enormous progress in interventional cardiology during the last 10 years has resulted in a major change in the spectrum of patients referred for coronary artery bypass grafting. Several large retrospective analyses, meta-analyses, and the randomized trials that addressed different aspects of ONCAB and OPCAB to date have compared the two surgical strategies. It is suggested that patients may achieve an excellent outcome with either type of procedure, and individuals' outcomes more likely depend on factors other than whether they underwent ONCAB or OPCAB. Nevertheless, there appear to be trends in most studies. These trends include less blood loss and need for transfusion, less myocardial enzyme release up to 24 h, less early neurocognitive dysfunction, and less renal insufficiency after OPCAB and propensity to lower costs, thereafter proving OPCAB to be safe and clinically effective. Here, we review the physiological advantages and clinical outcomes of OPCAB for myocardial revascularization and examine whether either strategy is superior and in which patients.

Reduced Atrial Fibrillation in Patients Immediately Extubated After Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

We analyzed data from patients undergoing off-pump isolated coronary artery bypass grafting surgery (OPCABG) to determine if immediate extubation in the operating room affected the incidence of postoperative atrial fibrillation.

METHODS

The study group comprised 2,376 consecutive OPCABG patients operated on between January 1, 2000, and December 31, 2004, by 22 surgeons at 18 hospitals. The data were subjected to univariate, multivariate analysis of variance, and logistic analysis. Logistic regression of matched groups was used to eliminate the effect of some confounding variables.

RESULTS

Patients immediately extubated after surgery had a reduced incidence of atrial fibrillation (10.6% versus 18.5%; p < 0.001), shorter length of stay (4.8 +/- 3.5 versus 6.3 +/- 5.2 days; p < 0.001), and also reduced mortality (1.1% versus 2.4%; p = 0.04). Logistic analysis identified as significant factors for postoperative atrial fibrillation, postoperative ventilator usage (p < 0.001; odds ratio [OR] = 1.63; 95% confidence interval [CI]: 1.24 to 2.14), male sex (p = 0.002; OR = 1.51; 95% CI: 1.17 to 1.96), previous CABG (p = 0.005; OR = 0.43; 95% CI: 0.24 to 0.78). Congestive heart failure may also be a contributing factor. In patient groups matched for their risk of mortality, postoperative ventilator use (p < 0.001; OR = 1.80; 95% CI: 1.31 to 2.47), increasing age, and male sex were all statistically significant risk factors. When patient groups were matched on a combination of factors including preoperative beta-blocker usage, pulmonary disease, and smoking, postoperative ventilator use (p = 0.005; OR = 1.66; 95% CI: 1.16 to 2.38), along with increasing age, male sex, and previous CABG (reduced odds of atrial fibrillation developing) were statistically significant.

CONCLUSIONS

Immediate extubation after OPCABG appears to reduce the incidence of postoperative atrial fibrillation independent of comorbidities.

"Renal dose" dopamine is associated with the risk of new-onset atrial fibrillation after cardiac surgery

OBJECTIVE

"Renal dose" dopamine (rDA; 1-3 microg/kg per min) is administered to patients after cardiac surgery to preserve or improve renal function. Many of these patients develop new-onset postoperative atrial fibrillation or atrial flutter (pAF) that could be related to rDA administration. The objective of this investigation was to determine whether there was an association between rDA and new-onset pAF in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CABG).

SETTING

Research hospital.

SUBJECTS

The study population consisted of 1,731 patients undergoing CABG.

INTERVENTIONS

CABG with and without rDA.

DESIGN

After approval by the institutional review board, a retrospective study using the Cardiothoracic Anesthesia Patient Registry was undertaken to determine the association between rDA and pAF in patients undergoing CABG. Patients with a documented history of atrial fibrillation, those who required inotrope use during or after surgery, and those having valve surgery were excluded.

MEASUREMENTS AND MAIN RESULTS

One-thousand seven-hundred thirty-one patients undergoing CABG during the period of January 1, 2000, through June 30, 2002, were the study population; of these, 15.0% (260/1,731) developed pAF. The incidence of pAF was 23.3 % (41/176) among patients who received rDA and 14.1% (219/1,555) among those who did not receive rDA. In the multivariable logistic regression model, patient age, gender, chronic obstructive pulmonary disease or asthma, and rDA were associated with pAF (p < .01). Receipt of rDA increased the odds of developing pAF by 74%, independent of the effect of other variables.

CONCLUSIONS

Renal-dose dopamine is associated with a 1.74 odds ratio of pAF developing after CABG.

Inflammation of atrium after cardiac surgery is associated with inhomogeneity of atrial conduction and atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is common after cardiac surgery. Abnormal conduction is an important substrate for AF. We hypothesized that atrial inflammation alters atrial conduction properties.

METHODS AND RESULTS

Normal mongrel canines (n=24) were divided into 4 groups consisting of anesthesia alone (control group); pericardiotomy (pericardiotomy group); lateral right atriotomy (atriotomy group); and lateral right atriotomy with antiinflammatory therapy (methylprednisolone 2 mg/kg per day) (antiinflammatory group). Right atrial activation was examined 3 days after surgery. Inhomogeneity of conduction was quantified by the variation of maximum local activation phase difference. To initiate AF, burst pacing was performed. Myeloperoxidase activity and neutrophil cell infiltration in the atrial myocardium were measured to quantify the degree of inflammation. The inhomogeneity of atrial conduction of the atriotomy and pericardiotomy groups was higher than that of the control group (2.02+/-0.10, 1.51+/-0.03 versus 0.96+/-0.08, respectively; P<0.005). Antiinflammatory therapy decreased the inhomogeneity of atrial conduction after atriotomy (1.16+/-0.10; P<0.001). AF duration was longer in the atriotomy and pericardiotomy groups than in the control and antiinflammatory groups (P=0.012). There also were significant differences in myeloperoxidase activity between the atriotomy and pericardiotomy groups and the control group (0.72+/-0.09, 0.41+/-0.08 versus 0.18+/-0.03 DeltaOD/min per milligram protein, respectively; P<0.001). Myeloperoxidase activity of the antiinflammatory group was lower than that of the atriotomy group (0.17+/-0.02; P<0.001). Inhomogeneity of conduction correlated with myeloperoxidase activity (r=0.851, P<0.001).

CONCLUSIONS

The degree of atrial inflammation was associated with a proportional increase in the inhomogeneity of atrial conduction and AF duration. This may be a factor in the pathogenesis of early postoperative AF. Antiinflammatory therapy has the potential to decrease the incidence of AF after cardiac surgery.

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.

Do off-pump techniques reduce the incidence of postoperative atrial fibrillation in elderly patients undergoing coronary artery bypass grafting?

BACKGROUND

Atrial fibrillation is the most common postoperative complication in patients undergoing coronary artery bypass grafting (CABG) with advancing age having been shown to have a significant association with its incidence. This study aims to assess whether off-pump coronary artery bypass (OPCAB) reduces the incidence of atrial fibrillation in elderly patients.

METHODS

A meta-analysis of all observational studies reporting a comparison between the two techniques in elderly patients (> 70 years) between 1999-2003 was performed. The primary outcome of interest was the incidence of postoperative atrial fibrillation. The quality of each study was evaluated by examining three items: patient selection, matching of the off-pump and cardiopulmonary bypass patient groups, and assessment of outcome. Meta-regression analysis was undertaken to see the effects of study size and quality on the calculated odds ratio.

RESULTS

Eight studies fulfilled our inclusion criteria, all of which were nonrandomized. In total the studies identified 3017 subjects, of which 764 had off-pump surgery (25%) and 2253 underwent cardiopulmonary bypass (75%). Meta-analysis showed that after off-pump surgery there was a significantly lower incidence of postoperative atrial fibrillation in these patients (odds ratio 0.70, 95% confidence interval [CI] 0.56-0.89). Meta-regression analysis including study characteristics did not show any associations affecting the calculated odds ratio of atrial fibrillation.

CONCLUSIONS

Our study demonstrates a reduced incidence of postoperative atrial fibrillation in an elderly population with off-pump as compared with cardiopulmonary bypass techniques. We appreciate, however, that our statistical analysis uses nonrandomized published data and that the results must be treated with caution. If this finding is confirmed by a large-scale randomized trial, it has significant implications on the operative strategy employed for this patient group.

Religious Beliefs Shorten Hospital Stays? Psychology Works in Mysterious Ways: Comment on Contrada et al. (2004)

A study by R. J. Contrada et al. (2004; see record 2004-13299-001) suggested that religious involvement affects recovery from coronary artery bypass graft surgery. This finding makes a significant contribution to the growing literature on the role of religion in health and illness, yet it is unlikely to have a comparable impact on coronary artery bypass graft surgery research. Why? What determines the importance of psychosocial predictors of medical outcomes? How can health psychologists increase the impact of biopsychosocial research?