AF is an undesired but frequent complication of CABG observed in 10–40% of cases. It prolongs a patient's stay in the intensive care unit or hospital, and it disturbs a patient's comfort. In addition, AF postpones full recovery after CABG. Thus, many drugs have been used prophylactically in order to prevent POAF: beta-blockers, calcium channel blockers, magnesium sulphate, and amiadarone. All of these drugs have different indications or counter indications [2–4].
Reducing the frequency of arrhythmia of a patient after CABG reduces both the duration of hospitalization and medical costs. Studies have shown that 25–30% of the patients had temporary supraventricular arrhythmia attacks despite using β-blockers. As is widely known, β-blockers are not indicated for those with poor ventricle function who frequently demonstrate arrhythmia. Instead, amiodarone is recommended for these patients .
However, the sufficiency and reliability of amiodarone in preventing arrhythmia is controversial. Oral amiodarone is known to be insufficient for preventing postoperative arrhythmia, but sometimes the preoperative loading dose can prove sufficient. Amiodarone given during the preoperative period has been reported to react with anesthetic agents and cause pulmonary dysfunction, hypotension, hepatic dysfunction, and low heart flow. However, Daoud et al. have reported that preoperative amiodarone use does not increase the risk of postoperative mortality and morbidity [4, 5]. Similarly, we did not observe any side effects in the amiodarone group in the present study. According to our observations, both drugs are safe.
Our results indicate that amiodarone is significantly more effective than magnesium sulphate in treating total arrhythmia. However, this may be because the ventricular extrasystoles frequently disappear in the absence of any medication. The two groups showed no differences in the rate of recovery from supraventricular arrhythmia.
Magnesium is a cation that functions by lengthening the refractory period at the atrioventricular node. Thus, magnesium likely has an important role in preventing and treating atrial fibrillation, especially considering that serum magnesium levels below 0.8 mmol/L trigger atrial fibrillation. Thus, dose loading with magnesium can prevent the arrhythmia caused by the postoperative decrease in this caution.
In our study we observed that the serum magnesium levels were low in the postoperative period, although never below 0.8 mmol/L .
Many comparative studies and meta-analyses have been published on this issue. In a meta-analysis evaluating atrial fibrillation after CABG, the frequency of POAF was determined to be 32.3%. POAF is frequently concomitant with renal insufficiency and infection. In this meta-analysis, preoperative COPD and older age were determined to be risk factors for POAF. The investigators concluded that atrial fibrillation is an important complication of CABG, and they suggested preventing it by administering β-blockers and ACE inhibitors .
Çağlı et al. performed a study that combined amiodarone and MgSO4, and they concluded that together these agents are tolerable and work more effectively in high-risk patients than they do on their own . A different study showed that older age and lower magnesium plasma levels are the most important risk factors of POAF. This same study reported that amiodarone was effective for POAF, whereas magnesium prophylaxis had no effect [5–8]. In our study, we administered amiodarone to patients with AF despite magnesium prophylaxis; we administered amiodarone orally, following an initial loading dose.
Studies have examined the effects of medications other than prophylaxis following AF. Parenteral magnesium was reported to be superior to amiodarone in studies of acute atrial tachyarrhythmia . Davey et al. have shown that magnesium sulphate slows the heart rate and prevents supraventricular arrhythmia. They also found that AF frequently returns to normal sinus rhythm in patients treated with magnesium sulphate. Lastly, they reported that magnesium-related hypotension and bradycardia are potential risk factors for AF .
In a meta-analysis evaluating eight different clinical studies, the use of different doses of magnesium sulphate, placebo, amiodarone, and diltiazem following atrial fibrillation was examined. During the first hour following its application, magnesium was found to be superior to other anti-arrhythmics for controlling ventricular speed (patients with a heartbeat of less than 100/min). Magnesium was also significantly more effective than placebo or diltiazem for restoring normal sinus rhythm within the first 15 hours. As a result, magnesium sulphate effectively controls heart rhythm following AF . In another study, magnesium was found to be effective at preventing postoperative ventricular arrhythmia in a dose-dependent manner .