Drugs don’t work; atrial fibrillation prevention after bypass surgery

This study compared the effectiveness of drugs for prevention of atrial fibrillation in patients that underwent coronary artery bypass grafting (CABG). 

Coronary artery disease, characterized by narrowing of the arteries and disrupted blood supply to the heart muscle, is a leading cause of death worldwide. Therefore, many therapies aim to restore optimal blood supply in order to reduce the risk of future fatal heart attacks and heart arrhythmias (abnormal rhythm).

Coronary artery bypass grafting (CABG) is a surgical procedure in which the blocked coronary artery is bypassed by another piece of blood vessel that was harvested from the patient's body (usually from the leg or chest). Though CABG has therapeutic advantages it also has some adverse effects, for example atrial fibrillation.

Atrial fibrillation is an arrhythmia of the heart where the atria (the chambers that receive blood into the heart) quiver instead of beat. It is associated with considerable morbidity (having a disease condition) and mortality (death), including an increased risk of stroke, renal failure, and heart failure. Postoperative (subsequent to an operation) atrial fibrillation is common, affecting 25% to 40% of patients after CABG.

Numerous trials have examined interventions for the prevention of postoperative atrial fibrillation but none have compared between the effectiveness of different drugs on its occurrence.

This study analyzed 2,177 patients who underwent CABG.

Overall, 84% of the participants used preventive drug treatment for subsequent atrial fibrillation. Beta-adrenergic blocking agents were the most commonly used medications for prevention (72%).Other medications used were Amiodarone, calcium channel blockers and other antiarrhythmic drugs.

30% of all patients (646) developed sustained atrial fibrillation after the surgery. Those who developed postoperative atrial fibrillation were commonly older, had higher blood pressure, taller and had worse renal (kidney) function.

Following analysis, only the use of  Amiodarone (antiarrhythmic medication that affects the rhythm of heartbeats) was associated with a trend towards decreased postoperative atrial fibrillation. This decrease was insignificant because the frequency of atrial fibrillations was reduced only by 4% compared to the average frequency measured under other drug treatment.

The use of Sotalol (another antiarrhythmic drug), beta blockers and calcium antagonists (both are drugs used to lower blood pressure) was not associated with decreased odds of postoperative atrial fibrillation.

This study was unable to demonstrate a positive therapeutic effect (decrease in atrial fibrillation rates) for any of the drugs examined  compared with alternatives or no treatment  in patients that underwent CABG.

This analysis focused on high-risk patients and therefore, these findings may not be representative of lower-risk populations. Furthermore, many of the patients didn’t show consistency taking the drugs effecting subsequent analysis.