Risk factors associated with development of atrial fibrillation early after coronary artery bypass grafting

A retrospective study on atrial fibrillation after coronary artery bypass grafting surgery at The National Heart Institute, Kuala Lumpur

Background: Atrial fibrillation (AF) is common after cardiac surgery and has been associated with poor outcome and increased resource utilization. The main objective of this study is to determine the incidence of POAF in Malaysia and identify the predictors of developing POAF. The secondary outcome of this study would be to investigate the difference in mortality and morbidity rates and the duration of intensive care unit (ICU), high dependency unit (HDU) and hospital stay between the two. Methods: This is a retrospective single-center, cross sectional study conducted at the National Heart Institute, Malaysia. Medical records of 637 who underwent coronary artery bypass grafting (CABG) surgery in 2015 were accrued. Pre-operative, operative and post-operative information were subsequently collected on a pre-formulated data collection sheet. Data were then analyzed using IBM SPSS v23. Results: The incidence of POAF in our study stands at 28.7% with a mean onset of 45±33 hours post operatively. Variables with independent association with POAF include advancing age, Indian population, history of chronic kidney disease, left ventricular ejection fraction and beta-blocker treatment. The mortality rate is significantly higher statistically ( p < 0.05), and similarly the incidence of stroke. The incidence of other post-operative complications was also significantly higher statistically. The duration of ICU, HDU and hospital stays were statistically longer ( p < 0.001) with higher rates of ICU readmissions and reintubations seen. Conclusion: We conclude that the incidence of POAF in Malaysia is comparable to the figures in Western countries, making POAF one of the most commonly encountered condition after CABG with similar higher rates of mortality, poor outcomes and longer duration of stay, and therefore increased cost of care. Strategies to reduce the incidence of AF after cardiac surgery should favorably affect surgical outcomes and reduce utilization of resources and thus lower cost of care.

A retrospective study on atrial fibrillation after coronary artery bypass grafting surgery at The National Heart Institute, Kuala Lumpur

Background: Atrial fibrillation (AF) is common after cardiac surgery and has been associated with poor outcome and increased resource utilization. The main objective of this study is to determine the incidence of POAF in Malaysia and identify the predictors of developing POAF. The secondary outcome of this study would be to investigate the difference in mortality and morbidity rates and the duration of intensive care unit (ICU), high dependency unit (HDU) and hospital stay between the two. Methods: This is a retrospective single-center, cross sectional study conducted at the National Heart Institute, Malaysia. Medical records of 637 who underwent coronary artery bypass grafting (CABG) surgery in 2015 were accrued. Pre-operative, operative and post-operative information were subsequently collected on a pre-formulated data collection sheet. Data were then analyzed using IBM SPSS v23. Results: The incidence of POAF in our study stands at 28.7% with a mean onset of 45±33 hours post operatively. Variables with independent association with POAF include advancing age, Indian population, history of chronic kidney disease, left ventricular ejection fraction and beta-blocker treatment. The mortality rate is significantly higher statistically ( p < 0.05), and similarly the incidence of stroke. The incidence of other post-operative complications was also significantly higher statistically. The duration of ICU, HDU and hospital stays were statistically longer ( p < 0.001) with higher rates of ICU readmissions and reintubations seen. Conclusion: We conclude that the incidence of POAF in Malaysia is comparable to the figures in Western countries, making POAF one of the most commonly encountered condition after CABG with similar higher rates of mortality, poor outcomes and longer duration of stay, and therefore increased cost of care. Strategies to reduce the incidence of AF after cardiac surgery should favorably affect surgical outcomes and reduce utilization of resources and thus lower cost of care.

The Effects of Diabetes Mellitus in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

Objective. To investigate the effects of diabetes mellitus (DM) in patients undergoing off-pump coronary artery bypass grafting (OPCAB). Method. A total of 728 patients with DM and 1380 patients without DM who underwent OPCAB treatment from March 2012 to April 2015 were reviewed. The effects of DM on intraoperative variables and postoperative complications were determined using propensity score analysis. Results. Two well-matched subgroups were selected using propensity score analysis (DM = 728, no-DM = 728) to compare the perioperative outcome. The duration of the ICU stay, in hours (55.2 ± 53.0 versus 49.29 ± 51.30, P < 0.05), postoperative new-onset atrial fibrillation (20.9% versus 14.97%, P < 0.05), and postoperative infection (9.2% versus 4.67%, P < 0.05) were greater in DM patients, as indicated by univariate analysis. Conclusion. OPCAB was found to be effective in DM patients, but postoperative infection and postoperative new-onset atrial fibrillation were found to be more likely to occur in DM patients than in other patients. DM was found to be a powerful risk factor for postoperative infection and postoperative new-onset atrial fibrillation.

Electrocardiographic Changes after Coronary Artery Surgery

The electrocardiographic changes early after uncomplicated coronary artery bypass with complete revascularization were examined preoperatively and on the 1st and 3rd postoperative days in 53 patients. Heart rate, PR index, corrected PR interval, corrected P dispersion, corrected duration of QRS complex, corrected QT dispersion, corrected QT interval, rhythm, QRS axis, ST-segment changes, and blocks were determined. Changes in new parameters obtained by different combinations of R, S, and T waves were also studied. On the 1st postoperative day, atrial fibrillation was significantly less prevalent, right bundle branch block increased significantly, and QRS axis was significantly more positive but returned to baseline on the 3rd postoperative day. Postoperative heart rate and PR index were significantly higher than preoperative values. In the postoperative period, corrected PR interval was significantly lower, corrected QRS complex duration was significantly shorter, corrected QT interval was significantly longer, and corrected QT dispersion showed a significant increase on the 1st postoperative day. This study defines electrocardiographic changes in uncomplicated patients with complete revascularization. Any deviations from these findings may alert us to the need for further evaluation of an undesired event.

Predictors of atrial fibrillation following coronary artery bypass surgery

BACKGROUND

New-onset atrial fibrillation is the most common form of rhythm disturbance following coronary artery bypass grafting surgery (CABG). It is still unclear which factors have a significant impact on its occurrence after this procedure. The aim of this study was to evaluate clinical predictors of postoperative atrial fibrillation (POAF) after myocardial revascularization.

MATERIAL/METHODS

We performed a retrospective analysis of 322 patients who underwent the first CABG operation without baseline atrial fibrillation. All subjects underwent laboratory blood tests, echocardiography and selective coronarography with ventriculography. Patients were continuously electrocardiographically monitored during the first 48-72 h after the operation for the occurrence of POAF.

RESULTS

POAF was diagnosed in 72 (22.4%) of the patients. Multivariate logistic regression analysis was used to identify the following independent clinical predictors of POAF: age≥65 years (OR 1.78; 95%CI: 1.06-2.76; p=0.043), hypertension (OR 1.97; 95%CI: 1.15-3.21; p=0.018), diabetes mellitus (OR 2.09; 95% CI: 1.31-5.33; p=0.010), obesity (OR 1.51; 95%CI: 1.03-3.87; p=0.031), hypercholesterolemia (OR 2.17, 95%CI: 1.05-4.25; p=0.027), leukocytosis (OR 2.32, 95%CI: 1.45-5.24; p=0.037), and left ventricular segmental kinetic disturbances (OR 3.01; 95%CI: 1.65-4.61, p<0.001).

CONCLUSIONS

This study demonstrates that advanced age, hypertension, diabetes, obesity, hypercholesterolemia, leukocytosis, and segmental kinetic disturbances of the left ventricle are powerful risk factors for the occurrence of POAF.

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

BACKGROUND

The use of perioperative cardiac medical therapy among patients undergoing coronary artery bypass graft surgery (CABG) has not been closely examined.

OBJECTIVES

The objective of this study was to systematically review the medical literature examining the effects of perioperative cardiac medical therapy on clinical outcomes among patients undergoing CABG.

METHODS

Using the Medline database and online clinical trial databases, we reviewed all randomized controlled trials (RCTs) and observational studies examining the effect of perioperative angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, antilipid agents (including statins), aspirin, beta-blockers, and calcium-channel blockers on clinical outcomes.

RESULTS

Our review identified 27 studies (6 RCTs, 21 observational studies), involving >700,000 patients, that examined the impact of perioperative medical therapy on clinical outcomes after CABG. Although studies provide conflicting results, the literature suggests that perioperative aspirin use may decrease inhospital mortality and myocardial infarction, whereas perioperative angiotensin-converting enzyme inhibitor use does not appear to be beneficial. Perioperative statin use reduces all-cause mortality at 30 days and cardiac death at 60 days and 1 year post-CABG but does not appear to reduce myocardial infarction or congestive heart failure rates. Multiple studies have demonstrated that pre- and postoperative beta-blockers are associated with a decrease in atrial fibrillation. In addition, beta-blockers may reduce inhospital and 30-day mortality, although these results are not consistent across all studies. Calcium-channel blockers do not appear to improve inhospital or 30-day mortality. No studies examined the perioperative use of angiotensin II receptor blockers or nonstatin antilipid agents among CABG patients.

CONCLUSIONS

The perioperative use of cardiac medical therapy among CABG patients remains understudied. Given their proven benefits among patients with cardiovascular disease and their potential to improve outcomes among CABG patients, further studies, particularly large RCTs, are needed.

Do Cardiac Neuropeptides Play a Role in the Occurrence of Atrial Fibrillation After Coronary Bypass Surgery?

BACKGROUND

One of the potential mechanisms to explain the occurrence of postoperative atrial fibrillation (AF) is imbalance of autonomic nervous system tone. The myocardium is innervated not only by cholinergic and adrenergic nerves but also by peptidergic nerves that synthesize and secrete neuropeptides. To investigate the possible role of cardiac neuropeptides in the development of AF after coronary artery bypass grafting (CABG), we analyzed the plasma levels of substance P (SubP), neuropeptide Y (NPY), and angiotensin II (Ang II) in patients who underwent elective on-pump CABG.

METHODS

This prospective study group included 83 consecutive patients scheduled for elective, on-pump CABG. Depressed left ventricular (LV) function (ejection fraction [EF] less than 0.30), concomitant cardiac procedures, history of atrial fibrillation, second or third degree atrioventricular block, implanted pacemaker, postoperative myocardial infarction, use of class I or III antiarrhythmic drug, and hemodynamic deterioration were exclusion criteria. Preoperative and postoperative serum levels of SubP, NPY, and AngII were measured by radioimmunoassay technique.

RESULTS

Postoperative AF occurred in 27 patients (32.5%). Using multivariate logistic regression analyses, only a decrease in SubP level (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 0.767 to 0.99, p = 0.031) and an increase in AngII level (OR = 2.61, 95% CI = 1.002 to 1.021, p = 0.023) after CABG were found to be independently associated with AF. Increased age (p = 0.02), diabetes mellitus (p = 0.023), preoperative use of beta blocker (p = 0.024), proximal right coronary artery involvement (p = 0.024), low preoperative sodium levels (p = 0.023), low LVEF (p = 0.013), and increased mitral E wave deceleration time (p = 0.044) were also associated with AF.

CONCLUSIONS

These results indicate that the increase in AngII and the decrease in SubP after CABG may play a role in the occurrence of postoperative AF. Further studies are needed to define the physiologic and pathologic relevance of these substances at the occurrence of AF in patients who undergo CABG.

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.

The Importance of Intrapericardial Drain Selection in Cardiac Surgery

INTRODUCTION

To explore the impact of intrapericardial and infracardiac drains on pericardial effusions in cardiac surgery.

MATERIALS AND METHODS

Patients undergoing coronary artery bypass grafting were randomized into two groups. At the end of the intervention, an intrapericardial and infracardiac Blake drain was placed in patients in group 1 (n = 97), and an intrapericardial and infracardiac semirigid drain was placed in patients in group 2 (n = 105). In addition, a semirigid drain was placed into mediastinum in all cases. The amount of drainage was calculated at six different time points postoperatively: postoperative 0 to 2 h, postoperative 2 to 4 h, postoperative 4 to 6 h, postoperative 6 to 12 h, postoperative 12 to 24 h, and postoperative 24 to 48 h. The amount of pericardial effusion was estimated by transthoracic echocardiography after the drains were removed.

RESULTS

In all measurements, the amount of drainage from intrapericardial Blake drains was higher, the total amount of drainage being equal to 330.7 +/- 29.4 mL and 193.2 +/- 19.6 mL in the Blake drain and semirigid drain groups, respectively (p = 0.000) [mean +/- SD]. When the drains were removed, the volume of pericardial effusion was 3.86 +/- 0.76 mm in Blake drain group and 7.59 +/- 1.16 mm in semirigid drain group (p = 0.000). The incidence of postoperative atrial fibrillation was 11.3% in the group with Blake drains, and 23.8% in the group with semirigid drains (p = 0.016).

CONCLUSION

The more effective drainage obtained with infracardiac Blake drains compared to semirigid drains helps to reduce the amount of postoperative pericardial effusion and the risk of atrial fibrillation.

Giving IV and Oral Amiodarone Perioperatively for the Prevention of Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Surgery

PURPOSES

We studied the use of perioperative IV and oral administration of amiodarone for the prevention of postoperative atrial fibrillation in patients undergoing coronary artery bypass graft surgery (CABG).

BACKGROUND

In the United States, > 500,000 patients undergo CABG each year. Numerous studies to date have suggested that postoperative atrial fibrillation occurs in 30 to 50% of patients, leading to significant morbidity, including hypotension, heart failure, thromboembolic complications, prolonged hospital stay, and increased hospital costs. The objective of this study was to assess the use of IV amiodarone in combination with oral amiodarone to reduce the incidence of postoperative atrial fibrillation.

METHOD

From January 1999 to October 1999, 51 patients scheduled for CABG were randomly selected for participation in the amiodarone administration trial. IV amiodarone, 0.73 mg/min, was administered on call to the operating room for 48 h, followed by oral amiodarone, 400 mg q12h, for the next 3 days. The amiodarone group was case-control matched to the incidence of postoperative atrial fibrillation in 92 patients undergoing CABG using conventional medical therapy during the same period. The primary end point of this study was the incidence of postoperative atrial fibrillation, length of hospital stay, and hospital costs, compared to the control group undergoing CABG during the same time.

RESULTS

Atrial fibrillation occurred in 3 of 51 patients (5.88%) in the amiodarone group, compared to 24 of 92 patients (26.08%) in the control group. Length of hospital stay in the amiodarone group was less than in the control group (5.3 days vs 6.7 days), with a trend toward decrease in hospital costs.

CONCLUSION

The administration of IV amiodarone in conjunction with oral amiodarone for a total dose of 4,500 mg over 5 days appears to be a hemodynamically well-tolerated, safe, and effective treatment in decreasing the incidence of postoperative atrial fibrillation, shortening length of stay, and a trend toward lowering hospital costs, even in patients with significantly reduced left ventricular function (< 30%). A large multicenter study using IV and oral amiodarone should be pursued prior to deciding whether its use should become standard therapy in all patients undergoing CABG in order to decrease the incidence of postoperative atrial fibrillation.

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?

Incidence, Timing, Symptoms, and Risk Factors for Atrial Fibrillation After Cardiac Surgery

• Background Atrial fibrillation is the most common complication after cardiac surgery and a major cause of morbidity and increased cost of care.

• Objectives To examine the incidence, timing, symptoms, and risk factors for atrial fibrillation after cardiac surgery.

• Methods A total of 302 patients were continuously monitored for atrial fibrillation with standard hardwire and telemetry devices during hospitalization after coronary artery bypass graft and/or valve surgery and with wearable cardiac event recorders for 2 weeks after discharge from the hospital. After discharge, patients recorded and transmitted their rhythm by telephone daily and whenever they had symptoms suggestive of atrial fibrillation.

• Results Of the 302 patients, 127 (42%) had atrial fibrillation; 41 had it after discharge, and for 10 it was their first episode. The first episode occurred at a mean of 2.9 days after surgery (SD, 3.1; range, day of surgery to 21 days after surgery). Although palpitations was the most common symptom (17%), most episodes of atrial fibrillation (69%) were not associated with symptoms. Independent predictors of atrial fibrillation were age 65 years or greater, history of intermittent atrial fibrillation, atrial pacing, male sex, white race, and not having hyperlipidemia. Independent predictors of atrial fibrillation after discharge from the hospital were having atrial fibrillation while hospitalized, valve surgery, and pulmonary hypertension.

• Conclusions Atrial fibrillation is common after cardiac surgery and often occurs after discharge from the hospital and without accompanying symptoms. Outpatient monitoring may be warranted in patients with characteristics that place them at increased risk for atrial fibrillation.

Postoperative ventricular arrhythmias after cardiac surgery: immediate- and long-term significance

AF is frequent after cardiac surgery. However, ventricular arrhythmias are less known. The purpose of the study was to evaluate the causes and the prognostic significance of severe ventricular arrhythmias occurring after cardiac surgery. For 10 years, among 2,100 cardiac surgeries, 16 (0.8%) patients (13 men, 3 women; age 49-71 years, mean 62 +/- 9 years) without previous ventricular arrhythmias, with preserved left ventricular ejection fraction, and without acute cause of ventricular arrhythmias, developed VF (n = 4) or a sustained VT between 3 days and 3 weeks after cardiac surgery (coronary artery bypass grafting [n = 6], valve replacement [n = 10]). Rapid AF (n = 5) or slow AF (n = 1) were present at the time of VT/VF. Programmed ventricular stimulation occurred after up to three extrastimuli in the basal state and after infusion of 20-30 micrograms of isoproterenol. An echocardiogram, coronary angiography, Holter monitoring with heart rate variability (HRV) study were performed. Ventricular stimulation was negative in six patients (with AF); sustained and clinical VT was induced in 10 patients with a left ventricular ejection fraction > 0.40, except in one patient. Valvular prothesis and coronary bypass graftings were normal. In all patients, HRV was normal before surgery and decreased after cardiac surgery; before versus after surgery, respectively, HR 69 +/- 9 and 89 +/- 30 beats/min (P < 0.01), SDNN 117 +/- 31 and 50 +/- 11 ms (P < 0.001), low frequency (LF) 474 +/- 658 and 51 +/- 40 ms2 (P < 0.05), high frequency (HF) 115 +/- 23 and 33 +/- 32 ms2 (P < 0.05), LF:HF 4 +/- 3 and 1 +/- 0.6 (P < 0.01). Follow-up lasted from 6 months to 10 years (mean 3 +/- 2 years). In patients without induced VT, 1 patient died from asystole, 1 had an ICD but no subsequent events, and the other 4 untreated patients are free of events. Patients with induced VT were treated with amiodarone and beta-blockers except in one patient who died from extracardiac complications. Six of nine patients had no inducible VT with this treatment and are alive; 3 patients had inducible VT, 1 died suddenly before implantation of ICD, and 2 patients are alive with an ICD; recurrent VTs were noted in one patient and received an ICD. In conclusion, recent heart surgery may increase the risk of ventricular arrhythmias. The reduction of indexes reflecting sympathetic and parasympathetic tone could facilitate the occurrence of atrial arrhythmias (and then VT) in patients without ventricular arrhythmogenic substrate or the development of VT/VF in patients with a latent previous ventricular arrhythmogenic substrate. In patients without inducible VT, the prognosis is excellent and an ICD is not recommended in these patients. In those with inducible VT, there is a high incidence of responders to antiarrhythmic drugs with a favorable prognosis.

Increased dispersion of refractoriness in patients with atrial fibrillation in the early postoperative period after coronary artery bypass grafting

INTRODUCTION

Increased atrial effective refractory period (AERP) dispersion is well correlated with vulnerability to atrial fibrillation (AF). However, the preoperative electrophysiologic characteristics of atrial abnormalities that may play an important role in the development of AF postoperatively in patients with coronary artery bypass grafting (CABG) have not been investigated in detail.

METHODS AND RESULTS

Fifty-six consecutive patients who underwent CABG were enrolled in this study. Eighteen patients (14 men and 4 women; mean age 57.7 +/- 5.2 years) with AF in the early postoperative period and 38 patients (28 men and 10 women; mean age 56.3 +/- 6.4 years) without AF were compared with regard to preoperative clinical, echocardiographic, angiographic, and electrophysiologic parameters. Preoperative PA interval and AERP dispersion values were higher (P < 0.05) in patients who developed AF in the early postoperative period. PA interval (P < 0.05, odds ratio = 1.64, 95% confidence interval 1.17-2.30), AERP in the high right atrium (AERP(HRA); P < 0.05, odds ratio = 0.94, 95% confidence interval 0.91-0.97), AERP in the right posterolateral atrium (AERP(RPL); P < 0.05, odds ratio = 0.79, 95% confidence interval 0.63-0.98), AERP in the distal coronary sinus (AERP(DCS); P < 0.05, odds ratio = 0.84, 95% confidence interval 0.74-1.02), and AERP dispersion (P < 0.001, odds ratio = 1.29, 95% confidence interval 1.12-1.47) were independently related to post-CABG AF in univariate analysis. Increases in preoperative PA interval and AERP dispersion were found to be associated with a high risk for development of post-CABG AF.

CONCLUSION

AERP dispersion is a suitable electrophysiologic indicator for atrial vulnerability. The presence of increased preoperative AERP dispersion and PA interval may indicate patients at high risk for development of AF in the early postoperative period after coronary artery bypass grafting.

Role of amiodarone in reducing atrial fibrillation after cardiac surgery in adults

Atrial fibrillation is a common occurrence after cardiac surgery and the source of financial expenditure and complications. A critical literature review was undertaken to examine the use of amiodarone therapy to prevent or manage atrial fibrillation after cardiac surgery. Evidence strongly suggests that perioperative treatment of cardiac patients with amiodarone may reduce the incidence of atrial fibrillation with minimal adverse effects. Further study is warranted to determine the optimal timing and dosing, for the drug's most cost-effective use.