Prevention by acebutolol of rhythm disorders following coronary bypass surgery

Perioperative beta-blockers for preventing surgery-related mortality and morbidity in adults undergoing cardiac surgery

BACKGROUND

Randomized controlled trials (RCTs) have yielded conflicting results regarding the ability of beta-blockers to influence perioperative cardiovascular morbidity and mortality. Thus routine prescription of these drugs in unselected patients remains a controversial issue. A previous version of this review assessing the effectiveness of perioperative beta-blockers in cardiac and non-cardiac surgery was last published in 2018. The previous review has now been split into two reviews according to type of surgery. This is an update and assesses the evidence in cardiac surgery only.

OBJECTIVES

To assess the effectiveness of perioperatively administered beta-blockers for the prevention of surgery-related mortality and morbidity in adults undergoing cardiac surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, Biosis Previews and Conference Proceedings Citation Index-Science on 28 June 2019. We searched clinical trials registers and grey literature, and conducted backward- and forward-citation searching of relevant articles.

SELECTION CRITERIA

We included RCTs and quasi-randomized studies comparing beta-blockers with a control (placebo or standard care) administered during the perioperative period to adults undergoing cardiac surgery. We excluded studies in which all participants in the standard care control group were given a pharmacological agent that was not given to participants in the intervention group, studies in which all participants in the control group were given a beta-blocker, and studies in which beta-blockers were given with an additional agent (e.g. magnesium). We excluded studies that did not measure or report review outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, and assessed risks of bias. We assessed the certainty of evidence with GRADE.

MAIN RESULTS

We included 63 studies with 7768 participants; six studies were quasi-randomized and the remaining were RCTs. All participants were undergoing cardiac surgery, and in most studies, at least some of the participants were previously taking beta-blockers. Types of beta-blockers were: propranolol, metoprolol, sotalol, esmolol, landiolol, acebutolol, timolol, carvedilol, nadolol, and atenolol. In twelve studies, beta-blockers were titrated according to heart rate or blood pressure. Duration of administration varied between studies, as did the time at which drugs were administered; in nine studies this was before surgery, in 20 studies during surgery, and in the remaining studies beta-blockers were started postoperatively. Overall, we found that most studies did not report sufficient details for us to adequately assess risk of bias. In particular, few studies reported methods used to randomize participants to groups. In some studies, participants in the control group were given beta-blockers as rescue therapy during the study period, and all studies in which the control was standard care were at high risk of performance bias because of the open-label study design. No studies were prospectively registered with clinical trials registers, which limited the assessment of reporting bias. We judged 68% studies to be at high risk of bias in at least one domain.Study authors reported few deaths (7 per 1000 in both the intervention and control groups), and we found low-certainty evidence that beta-blockers may make little or no difference to all-cause mortality at 30 days (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.47 to 1.90; 29 studies, 4099 participants). For myocardial infarctions, we found no evidence of a difference in events (RR 1.05, 95% CI 0.72 to 1.52; 25 studies, 3946 participants; low-certainty evidence). Few study authors reported cerebrovascular events, and the evidence was uncertain (RR 1.37, 95% CI 0.51 to 3.67; 5 studies, 1471 participants; very low-certainty evidence). Based on a control risk of 54 per 1000, we found low-certainty evidence that beta-blockers may reduce episodes of ventricular arrhythmias by 32 episodes per 1000 (RR 0.40, 95% CI 0.25 to 0.63; 12 studies, 2296 participants). For atrial fibrillation or flutter, there may be 163 fewer incidences with beta-blockers, based on a control risk of 327 incidences per 1000 (RR 0.50, 95% CI 0.42 to 0.59; 40 studies, 5650 participants; low-certainty evidence). However, the evidence for bradycardia and hypotension was less certain. We found that beta-blockers may make little or no difference to bradycardia (RR 1.63, 95% CI 0.92 to 2.91; 12 studies, 1640 participants; low-certainty evidence), or hypotension (RR 1.84, 95% CI 0.89 to 3.80; 10 studies, 1538 participants; low-certainty evidence).We used GRADE to downgrade the certainty of evidence. Owing to studies at high risk of bias in at least one domain, we downgraded each outcome for study limitations. Based on effect size calculations in the previous review, we found an insufficient number of participants in all outcomes (except atrial fibrillation) and, for some outcomes, we noted a wide confidence interval; therefore, we also downgraded outcomes owing to imprecision. The evidence for atrial fibrillation and length of hospital stay had a moderate level of statistical heterogeneity which we could not explain, and we, therefore, downgraded these outcomes for inconsistency.

AUTHORS' CONCLUSIONS

We found no evidence of a difference in early all-cause mortality, myocardial infarction, cerebrovascular events, hypotension and bradycardia. However, there may be a reduction in atrial fibrillation and ventricular arrhythmias when beta-blockers are used. A larger sample size is likely to increase the certainty of this evidence. Four studies awaiting classification may alter the conclusions of this review.

Perioperative beta-blockers for preventing surgery-related mortality and morbidity

BACKGROUND

Randomized controlled trials have yielded conflicting results regarding the ability of beta-blockers to influence perioperative cardiovascular morbidity and mortality. Thus routine prescription of these drugs in unselected patients remains a controversial issue.

OBJECTIVES

The objective of this review was to systematically analyse the effects of perioperatively administered beta-blockers for prevention of surgery-related mortality and morbidity in patients undergoing any type of surgery while under general anaesthesia.

SEARCH METHODS

We identified trials by searching the following databases from the date of their inception until June 2013: MEDLINE, Embase , the Cochrane Central Register of Controlled Trials (CENTRAL), Biosis Previews, CAB Abstracts, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Derwent Drug File, Science Citation Index Expanded, Life Sciences Collection, Global Health and PASCAL. In addition, we searched online resources to identify grey literature.

SELECTION CRITERIA

We included randomized controlled trials if participants were randomly assigned to a beta-blocker group or a control group (standard care or placebo). Surgery (any type) had to be performed with all or at least a significant proportion of participants under general anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from all studies. In cases of disagreement, we reassessed the respective studies to reach consensus. We computed summary estimates in the absence of significant clinical heterogeneity. Risk ratios (RRs) were used for dichotomous outcomes, and mean differences (MDs) were used for continuous outcomes. We performed subgroup analyses for various potential effect modifiers.

MAIN RESULTS

We included 88 randomized controlled trials with 19,161 participants. Six studies (7%) met the highest methodological quality criteria (studies with overall low risk of bias: adequate sequence generation, adequate allocation concealment, double/triple-blinded design with a placebo group, intention-to-treat analysis), whereas in the remaining trials, some form of bias was present or could not be definitively excluded (studies with overall unclear or high risk of bias). Outcomes were evaluated separately for cardiac and non-cardiac surgery.CARDIAC SURGERY (53 trials)We found no clear evidence of an effect of beta-blockers on the following outcomes.• All-cause mortality: RR 0.73, 95% CI 0.35 to 1.52, 3783 participants, moderate quality evidence.• Acute myocardial infarction (AMI): RR 1.04, 95% CI 0.71 to 1.51, 3553 participants, moderate quality evidence.• Myocardial ischaemia: RR 0.51, 95% CI 0.25 to 1.05, 166 participants, low quality evidence.• Cerebrovascular events: RR 1.52, 95% CI 0.58 to 4.02, 1400 participants, low quality evidence.• Hypotension: RR 1.54, 95% CI 0.67 to 3.51, 558 participants, low quality evidence.• Bradycardia: RR 1.61, 95% CI 0.97 to 2.66, 660 participants, low quality evidence.• Congestive heart failure: RR 0.22, 95% CI 0.04 to 1.34, 311 participants, low quality evidence.Beta-blockers significantly reduced the occurrence of the following endpoints.• Ventricular arrhythmias: RR 0.37, 95% CI 0.24 to 0.58, number needed to treat for an additional beneficial outcome (NNTB) 29, 2292 participants, moderate quality evidence.• Supraventricular arrhythmias: RR 0.44, 95% CI 0.36 to 0.53, NNTB five, 6420 participants, high quality evidence.• On average, beta-blockers reduced length of hospital stay by 0.54 days (95% CI -0.90 to -0.19, 2450 participants, low quality evidence).NON-CARDIAC SURGERY (35 trials)Beta-blockers significantly increased the occurrence of the following adverse events.• All-cause mortality: RR 1.25, 95% CI 1.00 to 1.57, 11,413 participants, low quality of evidence, number needed to treat for an additional harmful outcome (NNTH) 167.• Hypotension: RR 1.50, 95% CI 1.38 to 1.64, NNTH 16, 10,947 participants, high quality evidence.• Bradycardia: RR 2.23, 95% CI 1.48 to 3.36, NNTH 21, 11,033 participants, moderate quality evidence.We found a potential increase in the occurrence of the following outcomes with the use of beta-blockers.• Cerebrovascular events: RR 1.59, 95% CI 0.93 to 2.71, 9150 participants, low quality evidence.Whereas no clear evidence of an effect was found when all studies were analysed, restricting the meta-analysis to low risk of bias studies revealed a significant increase in cerebrovascular events with the use of beta-blockers: RR 2.09, 95% CI 1.14 to 3.82, NNTH 265, 8648 participants.Beta-blockers significantly reduced the occurrence of the following endpoints.• AMI: RR 0.73, 95% CI 0.61 to 0.87, NNTB 76, 10,958 participants, high quality evidence.• Myocardial ischaemia: RR 0.51, 95% CI 0.34 to 0.77, NNTB nine, 978 participants, moderate quality evidence.• Supraventricular arrhythmias: RR 0.73, 95% CI 0.57 to 0.94, NNTB 112, 8744 participants, high quality evidence.We found no clear evidence of an effect of beta-blockers on the following outcomes.• Ventricular arrhythmias: RR 0.68, 95% CI 0.31 to 1.49, 476 participants, moderate quality evidence.• Congestive heart failure: RR 1.18, 95% CI 0.94 to 1.48, 9173 participants, moderate quality evidence.• Length of hospital stay: mean difference -0.45 days, 95% CI -1.75 to 0.84, 551 participants, low quality evidence.

AUTHORS' CONCLUSIONS

According to our findings, perioperative application of beta-blockers still plays a pivotal role in cardiac surgery, as they can substantially reduce the high burden of supraventricular and ventricular arrhythmias in the aftermath of surgery. Their influence on mortality, AMI, stroke, congestive heart failure, hypotension and bradycardia in this setting remains unclear.In non-cardiac surgery, evidence shows an association of beta-blockers with increased all-cause mortality. Data from low risk of bias trials further suggests an increase in stroke rate with the use of beta-blockers. As the quality of evidence is still low to moderate, more evidence is needed before a definitive conclusion can be drawn. The substantial reduction in supraventricular arrhythmias and AMI in this setting seems to be offset by the potential increase in mortality and stroke.

Vitamin C for the Prevention of Postoperative Atrial Fibrillation after Cardiac Surgery: A Meta-Analysis

PURPOSE

Several studies have investigated the administration of vitamin C (vitC) for the prevention of postoperative atrial fibrillation (AF) after cardiac surgery. However, their findings were inconsistent. The purpose of this meta-analysis was to evaluate the efficacy of vitC as prophylaxis for the prevention of postoperative AF in cardiac surgery.

METHODS

A systematic search of PubMed, EMBASE, Google Scholar, the Cochrane Library, and clinical trial registries, was performed. 9 studies, published from August 2001 to May 2015, were included, with a total of 1,037 patients. Patients were randomized to receive vitC, or placebo.

RESULTS

Cardiac surgery patients who received vitC as prophylaxis, had a significantly lower incidence of postoperative AF (random effects OR=0.478, 95% CI 0.340 - 0.673, P < 10(-4)). No significant heterogeneity was detected across the analyzed studies (I(2)=21.7%), and no publication bias or other small study-related bias was found.

CONCLUSION

Our findings suggest that VitC is effective as prophylaxis for the prevention of postoperative AF. The administration of vitC may be considered in all patients undergoing cardiac surgery.

Perioperative beta-blockers for preventing surgery-related mortality and morbidity

BACKGROUND

Randomized controlled trials have yielded conflicting results regarding the ability of beta-blockers to influence perioperative cardiovascular morbidity and mortality. Thus routine prescription of these drugs in unselected patients remains a controversial issue.

OBJECTIVES

The objective of this review was to systematically analyse the effects of perioperatively administered beta-blockers for prevention of surgery-related mortality and morbidity in patients undergoing any type of surgery while under general anaesthesia.

SEARCH METHODS

We identified trials by searching the following databases from the date of their inception until June 2013: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Biosis Previews, CAB Abstracts, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Derwent Drug File, Science Citation Index Expanded, Life Sciences Collection, Global Health and PASCAL. In addition, we searched online resources to identify grey literature.

SELECTION CRITERIA

We included randomized controlled trials if participants were randomly assigned to a beta-blocker group or a control group (standard care or placebo). Surgery (any type) had to be performed with all or at least a significant proportion of participants under general anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from all studies. In cases of disagreement, we reassessed the respective studies to reach consensus. We computed summary estimates in the absence of significant clinical heterogeneity. Risk ratios (RRs) were used for dichotomous outcomes, and mean differences (MDs) were used for continuous outcomes. We performed subgroup analyses for various potential effect modifiers.

MAIN RESULTS

We included 89 randomized controlled trials with 19,211 participants. Six studies (7%) met the highest methodological quality criteria (studies with overall low risk of bias: adequate sequence generation, adequate allocation concealment, double/triple-blinded design with a placebo group, intention-to-treat analysis), whereas in the remaining trials, some form of bias was present or could not be definitively excluded (studies with overall unclear or high risk of bias). Outcomes were evaluated separately for cardiac and non-cardiac surgery. CARDIAC SURGERY (53 trials)We found no clear evidence of an effect of beta-blockers on the following outcomes.• All-cause mortality: RR 0.73, 95% CI 0.35 to 1.52, 3783 participants, moderate quality of evidence.• Acute myocardial infarction (AMI): RR 1.04, 95% CI 0.71 to 1.51, 3553 participants, moderate quality of evidence.• Myocardial ischaemia: RR 0.51, 95% CI 0.25 to 1.05, 166 participants, low quality of evidence.• Cerebrovascular events: RR 1.52, 95% CI 0.58 to 4.02, 1400 participants, low quality of evidence.• Hypotension: RR 1.54, 95% CI 0.67 to 3.51, 558 participants, low quality of evidence.• Bradycardia: RR 1.61, 95% CI 0.97 to 2.66, 660 participants, low quality of evidence.• Congestive heart failure: RR 0.22, 95% CI 0.04 to 1.34, 311 participants, low quality of evidence.Beta-blockers significantly reduced the occurrence of the following endpoints.• Ventricular arrhythmias: RR 0.37, 95% CI 0.24 to 0.58, number needed to treat for an additional beneficial outcome (NNTB) 29, 2292 participants, moderate quality of evidence.• Supraventricular arrhythmias: RR 0.44, 95% CI 0.36 to 0.53, NNTB six, 6420 participants, high quality of evidence.• On average, beta-blockers reduced length of hospital stay by 0.54 days (95% CI -0.90 to -0.19, 2450 participants, low quality of evidence). NON-CARDIAC SURGERY (36 trials)We found a potential increase in the occurrence of the following outcomes with the use of beta-blockers.• All-cause mortality: RR 1.24, 95% CI 0.99 to 1.54, 11,463 participants, low quality of evidence.Whereas no clear evidence of an effect was noted when all studies were analysed, restricting the meta-analysis to low risk of bias studies revealed a significant increase in all-cause mortality with the use of beta-blockers: RR 1.27, 95% CI 1.01 to 1.59, number needed to treat for an additional harmful outcome (NNTH) 189, 10,845 participants.• Cerebrovascular events: RR 1.59, 95% CI 0.93 to 2.71, 9150 participants, low quality of evidence.Whereas no clear evidence of an effect was found when all studies were analysed, restricting the meta-analysis to low risk of bias studies revealed a significant increase in cerebrovascular events with the use of beta-blockers: RR 2.09, 95% CI 1.14 to 3.82, NNTH 255, 8648 participants.Beta-blockers significantly reduced the occurrence of the following endpoints.• AMI: RR 0.73, 95% CI 0.61 to 0.87, NNTB 72, 10,958 participants, high quality of evidence.• Myocardial ischaemia: RR 0.43, 95% CI 0.27 to 0.70, NNTB seven, 1028 participants, moderate quality of evidence.• Supraventricular arrhythmias: RR 0.72, 95% CI 0.56 to 0.92, NNTB 111, 8794 participants, high quality of evidence.Beta-blockers significantly increased the occurrence of the following adverse events.• Hypotension: RR 1.50, 95% CI 1.38 to 1.64, NNTH 15, 10,947 participants, high quality of evidence.• Bradycardia: RR 2.24, 95% CI 1.49 to 3.35, NNTH 18, 11,083 participants, moderate quality of evidence.We found no clear evidence of an effect of beta-blockers on the following outcomes.• Ventricular arrhythmias: RR 0.64, 95% CI 0.30 to 1.33, 526 participants, moderate quality of evidence.• Congestive heart failure: RR 1.17, 95% CI 0.93 to 1.47, 9223 participants, moderate quality of evidence.• Length of hospital stay: mean difference -0.27 days, 95% CI -1.29 to 0.75, 601 participants, low quality of evidence.

AUTHORS' CONCLUSIONS

According to our findings, perioperative application of beta-blockers still plays a pivotal role in cardiac surgery , as they can substantially reduce the high burden of supraventricular and ventricular arrhythmias in the aftermath of surgery. Their influence on mortality, AMI, stroke, congestive heart failure, hypotension and bradycardia in this setting remains unclear.In non-cardiac surgery, evidence from low risk of bias trials shows an increase in all-cause mortality and stroke with the use of beta-blockers. As the quality of evidence is still low to moderate, more evidence is needed before a definitive conclusion can be drawn. The substantial reduction in supraventricular arrhythmias and AMI in this setting seems to be offset by the potential increase in mortality and stroke.

Risk Factors for Post-Coronary Artery Bypass Grafting (CABG) Atrial Fibrillation and the Role of Aspirin and Beta Blockers in its Prevention

Background: Atrial fibrillation/flutter (AF) is the most common arrhythmia following coronary artery bypass grafting (CABG) and it increases morbidity and mortality associated with this procedure. The purpose of this study was to evaluate the predictability of this arrhythmia using previously identified risk factors and to assess the efficacy of recommended prophylactic beta blocker (BB) therapy in the prevention of post CABG AF. Methods: We performed a retrospective chart analysis of consecutive patients undergoing elective CABG during 1 year period. Patients who developed new onset AF after the surgery were designated as cases and those who did not, as controls. 41 different variables were analyzed using Chi-square test and independent sample t-test. Multivariate analysis was carried out using logistic regression model. Results: 23% patients undergoing CABG developed AF during post-operative period. Statistically significant differences were observed between the two groups in terms of age, use of peri-operative Aspirin (ASA), current smoking, previous history of AF, left atrial size, history of congestive heart failure (CHF) and brain natriuretic peptide (BNP) levels. In terms of prophylactic therapy, preoperative BB did not independently protect against post CABG AF. On multivariate analysis, only age, use of ASA and previous history of AF remained as independent predictors of post CABG AF. Conclusion: In our study population, the use of preoperative BB did not independently decrease the risk of post-CABGAF. Age, peri-operative ASA use and previous history of AF remained strong independent predictors of post- operative AF.

Interventions for preventing post-operative atrial fibrillation in patients undergoing heart surgery

BACKGROUND

Atrial fibrillation is a common post-operative complication of cardiac surgery and is associated with an increased risk of post-operative stroke, increased length of intensive care unit and hospital stays, healthcare costs and mortality. Numerous trials have evaluated various pharmacological and non-pharmacological prophylactic interventions for their efficacy in preventing post-operative atrial fibrillation. We conducted an update to a 2004 Cochrane systematic review and meta-analysis of the literature to gain a better understanding of the effectiveness of these interventions.

OBJECTIVES

The primary objective was to assess the effects of pharmacological and non-pharmacological interventions for preventing post-operative atrial fibrillation or supraventricular tachycardia after cardiac surgery. Secondary objectives were to determine the effects on post-operative stroke or cerebrovascular accident, mortality, cardiovascular mortality, length of hospital stay and cost of treatment during the hospital stay.

SEARCH METHODS

We searched the Cochrane Central Register of ControlLed Trials (CENTRAL) (Issue 8, 2011), MEDLINE (from 1946 to July 2011), EMBASE (from 1974 to July 2011) and CINAHL (from 1981 to July 2011).

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) that included adult patients undergoing cardiac surgery who were allocated to pharmacological or non-pharmacological interventions for the prevention of post-operative atrial fibrillation or supraventricular tachycardia, except digoxin, potassium (K(+)), or steroids.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted study data and assessed trial quality.

MAIN RESULTS

One hundred and eighteen studies with 138 treatment groups and 17,364 participants were included in this review. Fifty-seven of these studies were included in the original version of this review while 61 were added, including 27 on interventions that were not considered in the original version. Interventions included amiodarone, beta-blockers, sotalol, magnesium, atrial pacing and posterior pericardiotomy. Each of the studied interventions significantly reduced the rate of post-operative atrial fibrillation after cardiac surgery compared with a control. Beta-blockers (odds ratio (OR) 0.33; 95% confidence interval) CI 0.26 to 0.43; I(2) = 55%) and sotalol (OR 0.34; 95% CI 0.26 to 0.43; I(2) = 3%) appear to have similar efficacy while magnesium's efficacy (OR 0.55; 95% CI 0.41 to 0.73; I(2) = 51%) may be slightly less. Amiodarone (OR 0.43; 95% CI 0.34 to 0.54; I(2) = 63%), atrial pacing (OR 0.47; 95% CI 0.36 to 0.61; I(2) = 50%) and posterior pericardiotomy (OR 0.35; 95% CI 0.18 to 0.67; I(2) = 66%) were all found to be effective. Prophylactic intervention decreased the hospital length of stay by approximately two-thirds of a day and decreased the cost of hospital treatment by roughly $1250 US. Intervention was also found to reduce the odds of post-operative stroke, though this reduction did not reach statistical significance (OR 0.69; 95% CI 0.47 to 1.01; I(2) = 0%). No significant effect on all-cause or cardiovascular mortality was demonstrated.

AUTHORS' CONCLUSIONS

Prophylaxis to prevent atrial fibrillation after cardiac surgery with any of the studied pharmacological or non-pharmacological interventions may be favored because of its reduction in the rate of atrial fibrillation, decrease in the length of stay and cost of hospital treatment and a possible decrease in the rate of stroke. However, this review is limited by the quality of the available data and heterogeneity between the included studies. Selection of appropriate interventions may depend on the individual patient situation and should take into consideration adverse effects and the cost associated with each approach.

Perioperative beta-blockers for preventing surgery-related mortality and morbidity: a systematic review and meta-analysis

BACKGROUND

Perioperative beta-blockers are suggested to reduce cardiovascular mortality, myocardial-ischemia/infarction, and supraventricular arrhythmias after surgery. We reviewed the evidence regarding the effectiveness of perioperative beta-blockers for improving patient outcomes after cardiac and noncardiac surgery.

METHODS

Eleven large databases were searched from the time of their inception until October 2005. Various online-resources were consulted for the identification of unpublished trials and conference abstracts. We included randomized, controlled trials comparing perioperative beta-blockers with either placebo or the standard-of-care. Of the 3680 retrieved titles, 69 met inclusion criteria for analysis. Odds ratios (OR) assuming random effects were computed in the absence of significant clinical heterogeneity.

RESULTS

Beta-blockers reduced the frequency of ventricular tachyarrhythmias [OR (cardiac surgery): 0.28, 95% CI 0.13-0.57; OR (noncardiac surgery): 0.56, 95% CI 0.21-1.45], atrial fibrillation/flutter [OR (cardiac surgery): 0.37, 95% CI 0.28-0.48], other supraventricular arrhythmias [OR (cardiac surgery): 0.25, 95% CI 0.18-0.35; OR (noncardiac surgery): 0.43, 95% CI 0.14-1.37], and myocardial ischemia [OR (cardiac surgery): 0.49, 95% CI 0.17-1.4; OR (noncardiac surgery): 0.38, 95% CI 0.21-0.69]. Length of hospitalization was not reduced [weighted mean difference (cardiac surgery): -0.35 days, 95% CI -0.77-0.07; weighted mean difference (noncardiac surgery): -5.59 days, 95% CI -12.22-1.04] and, in contrast to previous reports, beta-blockers did not reduce mortality [OR (cardiac surgery): 0.55, 95% CI 0.17-1.83; OR (noncardiac surgery): 0.78, 95% CI 0.33-1.87], and they had no influence on the occurrence of perioperative myocardial infarction [OR (cardiac surgery): 0.89, 95% CI 0.53-1.5; OR (noncardiac surgery): 0.59; 0.25-1.39].

CONCLUSIONS

Beta-blockers reduced perioperative arrhythmias and myocardial ischemia, but they had no effect on myocardial infarction, mortality, or length of hospitalization.

Pharmacologic Prophylaxis

New-onset atrial fibrillation (AF) occurs frequently in patients after cardiac surgery. The purpose of this study was to review the published trials and to provide clinical practice guidelines for pharmacologic prophylaxis against postoperative AF. Trials of pharmacologic prophylaxis against AF after heart surgery were identified by searching MEDLINE, the Cochrane Controlled Trials Register, and the bibliographies of published reports. Evidence grades and clinical recommendation scores were assigned to each prophylactic drug based on published evidence. Ninety-one trials were identified. The primary study design was a randomized, controlled trial of one drug vs placebo/usual care. Pharmacologic therapies that are reviewed include Vaughan-Williams class II agents (ie, beta-receptor antagonists) [29 trials; 2,901 patients], Vaughan-Williams class III agents (ie, sotalol and amiodarone) [18 trials; 2,978 patients], Vaughan-Williams class IV agents (ie, verapamil and diltiazem) [5 trials; 601 patients], and Vaughan-Williams class I agents (ie, quinidine and procainamide) [3 trials; 246 patients], as well as digitalis (10 trials; 1,401 patients), magnesium (14 trials; 1,853 patients), dexamethasone (1 trial; 216 patients), glucose-insulin-potassium (3 trials; 102 patients), insulin (1 trial; 501 patients), triiodothyronine (2 trials; 301 patients), and aniline (1 trial; 32 patients). A consistent finding in this review is that antiarrhythmic drugs with beta-adrenergic receptor-blocking effects (ie, class II beta-blockers, sotalol, and amiodarone) demonstrated successful prophylaxis. Furthermore, those therapies that did not inhibit beta-receptors generally failed to demonstrate a decreased incidence in postoperative AF. While sotalol and amiodarone have been shown in some studies to be effective, their safety and the incremental prophylactic advantage in comparison with beta-blockers has not been conclusively demonstrated. On the basis of evidence that has been reviewed and graded for quality, it is recommended that strong consideration should be given to the prophylactic administration of Vaughan-Williams class II beta-blocking drugs as a means of lowering the incidence of new-onset post-cardiac surgery AF.

Interventions for preventing post-operative atrial fibrillation in patients undergoing heart surgery

BACKGROUND

Post-operative atrial fibrillation is a common complication of cardiac surgery and has been associated with increased incidence of other complications including post-operative stroke, increased hospital length of stay and increased cost of hospitalisation. Prevention of atrial fibrillation is a reasonable clinical goal and, consequently, many randomised trials have evaluated the effectiveness of pharmacological and non-pharmacological interventions. We systematically reviewed the literature and prepared meta-analyses to better understand the role and effects of various prophylactic therapies against post-operative atrial fibrillation.

OBJECTIVES

To assess the effects of pharmacological and non-pharmacological interventions for preventing post-cardiac surgery atrial fibrillation.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE and CINAHL from earliest achievable date to June 2003. We hand searched references from reports and earlier reviews. We searched abstract books and CD-ROMs from annual scientific meetings of American College of Cardiology, American Heart Association, North American Society of Pacing and Electrophysiology and European Heart Organization between 1997-2003. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials comparing pharmacological interventions or non-pharmacological interventions with control treatment, placebo or usual care for the prevention of post-operative atrial fibrillation in post-coronary artery bypass grafting or combined CABG and valvular surgery.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Fifty eight studies were included with a total of 8565 participants. Interventions included were amiodarone, beta blockers, solatol and pacing. Results favoured treatment for post-operative atrial fibrillation. The data for stroke favoured treatment by a non-significant effect size of 0.81, 95% confidence interval 0.51 to 1.28. Similarly, a positive indication for length of stay was derived but it too was not significant with a weighted mean difference of -0.66, 95% confidence interval -0.95 to -0.37. A positive result for cost of hospitalisation in favour of treatment was achieved, but the statistic is not significant due to low power and large standard deviations: a weighted mean difference of -2717, 95% confidence interval 7518 to 2084. Beta-blockers had the greatest magnitude of effect across 28 trials (4074 patients) with an odds ratio (random) of 0.35, 95% confidence interval 0.26 to 0.49. Across all treatment, the odds ratio favoured treatment with a ratio (random) of 0.43, 95% confidence interval 0.37 to 0.51.

REVIEWERS' CONCLUSIONS

Intervention is favoured across the three pharmacological interventions studied and the one non-pharmacological intervention, pacing. The length of stay data favoured treatment (-0.66, 95% confidence interval -0.95 to -0.37).

Interventions on prevention of postoperative atrial fibrillation in patients undergoing heart surgery: a meta-analysis

BACKGROUND

Postoperative atrial fibrillation (AF) is a common complication of cardiac surgery and has been associated with increased incidence of other complications and increased hospital length of stay (LOS). Prevention of AF is a reasonable clinical goal, and, consequently, many randomized trials have evaluated the effectiveness of pharmacological and nonpharmacological interventions for prevention of AF. To better understand the role of various prophylactic therapies against postoperative AF, a systematic review of evidence from randomized trials was performed.

METHODS AND RESULTS

Fifty-two randomized trials (controlled by placebo or routine treatment) of beta-blockers, sotalol, amiodarone, or pacing were identified by systematic literature search. The 3 drug treatments each prevented AF with the following odds ratios (ORs): beta-blockers, 0.39 (95% CI, 0.28 to 0.52); sotalol, 0.35 (95% CI, 0.26 to 0.49); and amiodarone, 0.48 (95% CI, 0.37 to 0.61). Pacing was also effective; for biatrial pacing, the OR was 0.46 (95% CI, 0.30 to 0.71). The influence of pharmacological interventions on LOS was as follows: -0.66 day (95% CI, 2.04 to 0.72) for beta-blockers; -0.40 day (95% CI, 0.87 to 0.08) for sotalol; and -0.91 day (95% CI, 1.59 to -0.23) for amiodarone. The influence for biatrial pacing was -1.54 day (95% CI, -2.85 to -0.24). The incidence of stroke was 1.2% in all the treatment groups combined and 1.4% in controls (OR, 0.90; 95% CI, 0.46 to 1.74).

CONCLUSIONS

Beta-blockers, sotalol, and amiodarone all reduce risk of postoperative AF with no marked difference between them. There is evidence that use of these drugs will reduce LOS. Biatrial pacing is a promising new treatment opportunity. There was no evidence that reducing postoperative AF reduces stroke; however, data on stroke are incomplete.

The efficacy and safety of intravenous propafenone versus intravenous amiodarone in the conversion of atrial fibrillation or flutter after cardiac surgery

OBJECTIVE

The primary objective was to evaluate the efficacy of propafenone compared with amiodarone in the reversion of atrial fibrillation or flutter. The secondary objective was the assessment of the tolerance of propafenone versus amiodarone.

DESIGN

An open, randomized trial.

SETTING

A single university hospital.

PARTICIPANTS

Forty patients who gave their informed consent.

INTERVENTIONS

These patients underwent cardiac bypass surgery or aortic valvular replacement. For treatment of postsurgical arrhythmias, they either received intravenous propafenone, 1 to 2 mg/kg in a 10-minute bolus, followed by an infusion of 420 mg in 24 hours, or amiodarone, 2.5 to 5 mg/kg, in a 10-minute bolus followed by an infusion of 900 mg in 24 hours.

MEASUREMENTS AND MAIN RESULTS

Sinus rhythm was restored in 12 of 18 (67%) propafenone patients and in 17 of 22 (77%) amiodarone patients. If the early success time-limit had been fixed at 60 minutes, the proportion would have been 41% (7/17) for propafenone versus 14% (3/22) for amiodarone, and that difference is nearly significant (p = 0.07 Fisher's exact test). However, after 210 minutes, 50% of the propafenone patients regained sinus rhythm versus only 25% of the amiodarone patients. Hemodynamic parameters improved with time in both groups without showing any statistically significant difference.

CONCLUSIONS

The results suggest that propafenone produces a more prompt effect in converting patients from atrial fibrillation or flutter to normal sinus rhythm.

Atrial fibrillation and flutter after coronary artery bypass surgery: epidemiology, risk factors and preventive trials

Atrial fibrillation and atrial flutter are common arrhythmias after coronary artery bypass grafting. Although the consequences of the arrhythmia are generally not life-threatening, it constitutes a major clinical problem often requiring conversion to sinus rhythm. Atrial fibrillation or flutter can result in hypotension, heart failure, pneumonia, and stroke. This article reviews the literature on epidemiology, electrophysiology, risk factors, and preventive trials. The major conclusions are: (1) In patients undergoing coronary artery bypass surgery, the incidence of postoperative atrial fibrillation or flutter is 20-30%, the peak incidence being on the second or third postoperative day. (2) The strongest independent preoperative predictor for atrial fibrillation or flutter is the patients' age. (3) Intra-atrial conduction delay recorded pre and peroperatively may predict development of atrial fibrillation. (4) Peroperative inducibility of atrial fibrillation by pacing the right atrium may identify patients at risk for postoperative atrial fibrillation. (5) Development of postoperative atrial fibrillation or flutter has not been associated with peroperative or postoperative events. (6) The specificity and sensitivity of age and other possible relevant factors for prediction of atrial fibrillation or flutter after coronary artery bypass grafting is low. (7) No effective prophylactic regimen has yet been established.

Incidence and prevention of supraventricular tachyarrhythmias after coronary bypass surgery

Supraventricular tachyarrhythmias are a frequent complication encountered after coronary artery bypass grafting. A retrospective survey of 102 consecutive patients undergoing exclusive bypass grafting at St. Mary's Hospital supplemented by a review of 16 published reports over a period of 10 years revealed a mean incidence of post-operative tachyarrhythmia of 33.4% in 1344 patients (range 11.4-100%). One hundred and thirty two patients undergoing exclusive bypass surgery, were randomised prospectively in double blind fashion to receive either oral timolol or matched placebo approximately 24 hours after surgery. In the 66 patients receiving timolol, there was a significant reduction of post-operative arrhythmias compared to the 66 patients receiving placebo: from 19.7 to 7.5% (P less than 0.05). Of all arrhythmias, two thirds appeared under 48 hours after surgery. In the timolol group, 4 patients developed systemic hypotension. This was readily reversed by withdrawing the drug. No other side effects were noted. The use of oral timolol after coronary artery surgery significantly lowers the incidence of post-operative supraventricular arrhythmias.