Risk-Stratified Evaluation of Amiodarone to Prevent Atrial Fibrillation After Cardiac Surgery

Amiodarone Protocol Provides Cost-Effective Reduction in Postoperative Atrial Fibrillation

BACKGROUND

Postoperative atrial fibrillation (POAF) after cardiac operations results in a significant increase in morbidity, mortality, and health care costs. Prophylactic amiodarone has been shown to reduce the incidence of POAF; however, the cost-effectiveness of a protocol-driven approach remains unknown.

METHODS

All patients with a Society of Thoracic Surgeons risk score enrolled in a prophylactic amiodarone protocol (n = 153) were propensity score matched 1:3 with patients before protocol implementation (n = 3,574). Multivariate logistic and linear regressions assessed the relative risks (POAF reduction and adverse medication effects) in the matched cohort of amiodarone therapy and costs, respectively. TreeAge cost-effectiveness software (TreeAge Software, Inc, Williamstown, MA) modeled the effects of prophylactic amiodarone costs, complication rates, and quality of life.

RESULTS

Of patients eligible for the prophylactic amiodarone protocol, 94.3% (281 of 298) were enrolled. Prophylactic amiodarone significantly reduced the rate of POAF (25.7% vs 16.8%, p < 0.0001). A total of 600 matched patients demonstrate no baseline differences in demographics, comorbidities, disease state, or operative factors, with a significant reduction in POAF without an increase in other associated complications. With the use these adjusted estimates, the prophylactic amiodarone protocol demonstrated a cost savings of $458 per patient. Sensitivity analysis confirmed the protocol is cost-effective for all protocol-related POAF risk reductions below an odds ratio of 0.726.

CONCLUSIONS

Implementation of a prophylactic amiodarone protocol significantly reduced risk-adjusted rates of POAF, with a cost savings of $458 per patient. This analysis demonstrates how rigorous quantitative analysis can evaluate the benefits of quality improvement projects.

Pharmacological strategies for prevention of postoperative atrial fibrillation

Atrial fibrillation (AF) complicating cardiac surgery continues to be a major problem that increases the postoperative risk of stroke, myocardial infarction, heart failure and costs and can affect long-term survival. The incidence of AF after surgery has not significantly changed over the last two decades, despite improvement in medical and surgical techniques. The mechanism and pathophysiology underlying postoperative AF (PoAF) is incompletely understood and results from a combination of acute and chronic factors, superimposed on an underlying abnormal atrial substrate with increased interstitial fibrosis. Several anti-arrhythmic and non-anti-arrhythmic medications have been used for the prevention of PoAF, but the effectiveness of these strategies has been limited due to a poor understanding of the basis for the increased susceptibility of the atria to AF in the postoperative setting. In this review, we summarize the pathophysiology underlying the development of PoAF and evidence behind pharmacological approaches used for its prevention in the postoperative setting.

Evaluation of an evidence-based practice implementation: prophylactic amiodarone following coronary artery revascularization

Postoperative atrial fibrillation is the most frequent dysrhythmia following coronary artery bypass grafting and is associated with complications, additional therapy, and longer hospital stays. Prophylactic amiodarone protocols have been validated as safe and beneficial in the prevention of atrial fibrillation following cardiac surgery. This study evaluates the use of our current treatment protocol, given prophylactically, as feasible and effective in producing similar outcomes in postoperative atrial fibrillation reduction as well as identifies any perioperative risk factors associated with this arrhythmia.

Preoperative Statin use is not Associated with a Reduced Risk of Atrial Fibrillation After Cardiac Surgery

Introduction: Postoperative atrial fibrillation (POAF) is prevalent after cardiac surgery and associated with significant morbidity and costs. Statins are commonly used in this population and may be a preventative strategy for PAOF. We wished to examine the effect of preoperative statin use on the risk of POAF after cardiac surgery. Methods: A retrospective, observational study was conducted using data from 489 adult patients who underwent cardiac surgery at a single institution. Univariate analyses and unconditional logistic regression were used to determine the impact of preoperative statin use on the probability of developing POAF, while controlling for the baseline risk of POAF and the use of amiodarone prophylaxis (AMP). A baseline risk index was calculated for each patient using a previously validated model. Patients with chronic atrial fibrillation or missing data were excluded. Results: Mean patient age was 63 (SD=13) years, 73% were male, 68% underwent isolated coronary artery bypass grafting, 16% underwent isolated valve surgery, with 13% underwent combined CABG and valve surgeries, and 3% underwent other forms of cardiac surgery. POAF occurred in 27% of patients receiving statins and 24% of those not receiving statins (p=0.3792). After controlling for baseline risk of POAF and the use of AMP, we found that preoperative statins were not associated with reductions in POAF (OR=1.19, 95%CI=0.782-1.822, p=0.4118). Conclusions: Multiple factors impact the development of POAF after cardiac surgery including patient demographics, comorbidities, surgical type, and concomitant medications. In this study, after adjustment for these factors the preoperative use of statins did not significantly influence the development of POAF.

Prevention of atrial fibrillation after coronary artery bypass grafting via atrial electromechanical interval and use of amiodarone prophylaxis

In our previous study, we defined a cut-off point of 120 ms for atrial electromechanical interval (AEMi) to determine the risk of atrial fibrillation (AF) occurrence. Accordingly, the present study sought to investigate whether or not a prophylactic perioperative administration of amiodarone could reduce the incidence of AF in a high-risk group (AEMi >120 ms) undergoing coronary artery bypass grafting (CABG). In this prospective, randomized study, 100 patients with AEMi >120 ms received either amiodarone (n=50) or placebo (n=50). The endpoints were AF occurrence after CABG and hospital and intensive care unit (ICU) lengths of stay after CABG. The incidence of postoperative AF was significantly higher in the placebo group than that of the amiodarone group (88% of patients in control group vs. 16% of patients in amiodarone group, P<0.0001). The prophylactic therapy with amiodarone significantly reduced the ICU length of stay (2.28+/-1.00 vs. 3.60+/-0.90 days, P<0.0001) and hospital length of stay (5.64+/-2.35 vs. 7.78+/-1.46 days, P<0.0001). The incidence of postoperative AF among patients with high AEMi was significantly reduced by a prophylactic amiodarone treatment, resulting in shorter ICU and hospital stays.

Dose-related effect of statins on atrial fibrillation after cardiac surgery

BACKGROUND

Atrial fibrillation (AF) is the most common heart rhythm abnormality after cardiac surgery. It increases morbidity and prolongs hospital stay. A role for statins in the prevention of AF has been suggested. We hypothesized that the incidence of postoperative AF due to statin therapy is dose-related.

METHODS

A retrospective study of 680 consecutive patients undergoing coronary bypass graft surgery and/or aortic valve replacement was done. Excluded were 57 patients (8.4%) with history of AF, permanent pacemakers, and those receiving antiarrhythmic medication. Preoperative statin treatment and occurrence of postoperative AF were examined using propensity score matching to adjust for differences in patient characteristics between the statin and no-statin groups.

RESULTS

The cohort comprised 623 patients. The statin group had a 27.1% incidence of postoperative AF vs 38.3% in the no-statin group (adjusted odds ratio [OR], 2.00; 95% confidence interval, 1.24 to 3.24; p = 0.004). Simvastatin (40 mg) and atorvastatin (40 mg) demonstrated the greatest effect on postoperative AF at 15.6% and 21.2%, respectively, vs no statins (respective adjusted ORs, 3.89 [p < 0.0001] and 2.76 [p = 0.012]). Intermediate-dose (20 mg) statins were also effective against AF, at 24.4% for simvastatin (adjusted OR, 2.32; p = 0.004) and 26.4% for atorvastatin (adjusted OR, 1.99, p = 0.047). Low-dose statins, simvastatin or atorvastatin (10 mg), did not influence postoperative AF.

CONCLUSIONS

Statin treatment may reduce the incidence of AF after cardiac surgery. Higher-dose statins have the greatest preventative effect, whereas low-dose statins do not influence postoperative AF.

Clinical review: treatment of new-onset atrial fibrillation in medical intensive care patients--a clinical framework

Atrial fibrillation occurs frequently in medical intensive care unit patients. Most intensivists tend to treat this rhythm disorder because they believe it is detrimental. Whether atrial fibrillation contributes to morbidity and/or mortality and whether atrial fibrillation is an epiphenomenon of severe disease, however, are not clear. As a consequence, it is unknown whether treatment of the arrhythmia affects the outcome. Furthermore, if treatment is deemed necessary, it is not known what the best treatment is. We developed a treatment protocol by searching for the best evidence. Because studies in medical intensive care unit patients are scarce, the evidence comes mainly from extrapolation of data derived from other patient groups. We propose a treatment strategy with magnesium infusion followed by amiodarone in case of failure. Although this strategy seems to be effective in both rhythm control and rate control, the mortality remained high. A randomised controlled trial in medical intensive care unit patients with placebo treatment in the control arm is therefore still defendable.

Potential Use of Statins to Prevent Atrial Fibrillation After Coronary Artery Bypass Surgery

Objective:

To review the published literature evaluating the effectiveness of statin therapy for preventing postoperative atrial fibrillation (POAF) after coronary artery bypass graft (CABG) surgery,

Data Sources:

A MEDLINE search was performed (1950–October 2007) using the search terms statins, HMG-CoA reductase inhibitors, coronary artery bypass graft, cardiac surgery, and atrial fibrillation,

Study Selection and Data Extraction:

All articles published in English describing or evaluating the use of statins in humans to prevent atrial fibrillation (AF) were included. Additional pertinent articles were identified from reference lists.

Data Synthesis:

POAF is a common complication following CABG surgery that is associated with significant morbidity. Current preventive strategies include the use of β-blockers and antiarrhythmic drugs such as amiodarono and Sotalol. Accumulating evidence suggests that statins may also reduce the risk of POAF. Numerous studies in nonsurgical cardiovascular patients have found reduced rates of AF with statins. In patients who have undergone CABG, several observational studies have also documented benefit. One randomized controlled trial reported a significant reduction in the risk of POAF and reduced length of hospital stay in patients given preoperative atorvastatin beginning 7 days before surgery. Ongoing research suggests that statins may reduce the risk of AF through pleiotropic effects independent of cholesterol lowering such as reductions in inflammation, oxidative damage, neurohormonal activation, and thrombosis.

Conclusions:

While the current evidence evaluating the use of statins to prevent POAF is encouraging, definitive conclusions cannot be drawn. However, because statins are widely used in cardiac patients for other indications and are not associated with the risks inherent to antiarrhythmic drugs, their value as an adjunct to current preventive strategies (or POAF deserves further study. Additional research is needed to examine the effectiveness of statins in risk-stratified patients undergoing CABG surgery and the impact on patient outcomes and attributed costs.

Amiodarone Prophylaxis: Impact on Atrial Fibrillation and Outcomes after Cardiac Surgery

This continuing feature will update readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number one killer in the United States, and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, pharmacists can have a significant impact on prevention and treatment—if they keep current with developments in drug therapy.