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© 2004 European Association of Cardio-Thoracic Surgery
What is the optimal medical treatment for stable cardiac surgical patients who go into atrial fibrillation after their operation?
a Department of Cardiothoracic Surgery, Manchester Royal Infirmary, Oxford Road, Manchester, M13 9WL, UK
* Corresponding author. Tel.: +44-7801548122 Received August 28, 2003; received in revised form September 1, 2003; accepted September 10, 2003
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was which medical strategy is the optimal treatment for stable patients going into atrial fibrillation post cardiac surgery. Altogether 281 papers were found from medline and 83 from the Cochrane Central Register of Controlled Trials using the reported search, of which 12 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. We conclude that there is very little evidence to support any one strategy over another.
Key Words: Evidence-based medicine; Thoracic surgery; Atrial fibrillation
You are a locum registrar, called to see a 70-year-old lady who has gone into fast AF, 2 days post coronary arterial bypass surgery. She is stable with a BP of 100/60 and a rate of 160, and she feels a little sick but is otherwise well. The operation was uncomplicated, and looking at her past history you find that she was diabetic and had an MI 2 years ago, but had a normal EF at the angiogram and never had an episode of AF pre-operatively. You ask the nurse what the protocol is for stable AF in this hospital. She replies that two of the consultants use Digoxin, two use amiodarone and one of the surgeons insists on sotalol for all his stable patients. She adds that the surgeon that she is currently under has just gone on holiday, and she is not sure who is now looking after this patient. You decide to give digoxin, but as this problem occurs so frequently you also decide to look up the evidence for the best treatment in this case. 1.1. Three-part question In [stable patients going into AF post CABG] which [medical treatment] is the best treatment for [time to discharge or survival or rate control or return to sinus rhythm].1.2. Search strategy Medline 1966–Aug 2003 using the OVID interface [exp Cardiac surgical Procedures/OR open heart surgery.mp OR Coronary art$ bypass graf$.mp OR cardiac surgery.mp OR CABG.mp OR] AND [exp atrial fibrillation/ OR atrial fibrillation.mp OR supraventricular arrhythmi$.mp or atrial arrhythmi$.mp OR atrial tachycardi$.mp] AND Maximally sensitive RCT filter LIMIT to Human studies.The above search was then repeated in the Cochrane Central Register of Controlled Trials. 1.3. Search outcome Two hundred and eighty-one papers were found from Medline and 83 papers were found in the Cochrane Central Register of Controlled Trials. Twelve relevant papers were selected as providing the best evidence [1–12]. Of note if two papers were found investigating the same combination of drugs, only the best paper was included. These papers are presented in Table 1.
1.4. Comment(s) The most remarkable result of this BET is the lack of double-blinded Prospective Randomised Controlled trials, which are of an adequate size to provide conclusive results in this very important area. It is difficult to make many conclusions after considering the studies presented. Cochrane et al. could find no significant differences between digoxin and amiodarone. Hjelms et al. found that conversion rates were similar between digoxin and procainamide, although procainamide produced faster conversion but significant hypotension. Wafa et al. demonstrated superior rate control with flecainide compared to digoxin although again, flecainide occasionally caused hypotension. Campbell et al. showed that sotalol caused hypotension in 85% of their patients, and Di Biasi et al. showed comparable results with propafenone and amiodarone although propafenone produced a more rapid conversion. Newer class III drugs such as Ibutilide and Dofetilide have also been evaluated although again the papers presented have not demonstrated a clear advantage. Interestingly Frost et al. presented a paper that included a placebo group. After 3 h 24% of patients in the placebo group had converted back to sinus rhythm. In an attempt to compare the various studies graphically we placed all studied drugs with their rates of conversion to sinus rhythm into Fig. 1. It must be noted that the time at which conversion to sinus rhythm was recorded varied greatly among studies and this is not reflected in the figure.
Although there have been several large PRCTs in prophylactic regimes for AF post cardiac surgery, the largest PRCT that we could find in post operative AF treatment is less than 100 in number despite reported incidences of 20–30% of AF post cardiac surgery worldwide. Thus until larger studies are conducted, it is difficult to provide a unified, evidence based, strategy for the treatment of AF post cardiac surgery. 1.5. Clinical bottom line There is very little evidence to support any one strategy over another. Amiodarone and digoxin seem to be low in side effects and around a quarter of patients will spontaneously revert to sinus rhythm within a few hours.
ICVTS on-line discussion Author: Dr. Philippe Gersbach, CHUV, Dept. of Thoracic and Cardiovascular Surgery, CCV - CHUV, Lausanne 1001, Switzerland Date: 13-Oct-2003 Message: This article deserves special attention for a very useful and well-conducted investigation and for especially informative results. The review of more than 350 articles is of special interest for all those who are involved in the management of cardiac surgical patients. First of all, it clearly demonstrates that the effects of numerous drugs commonly used to treat postoperative atrial fibrillation (AF) are unpredictable in individuals and, mostly, that there is no strategy that has yet been proven to be superior in groups. Strikingly and against the current opinion, pure antiarhythmic drugs were not found superior to the old digoxin in this indication. On the other hand, this article points indirectly to the poor design of a large majority of studies since only 3.4% of all papers on this topic were found to present an acceptable level of evidence (2b). This incredibly low proportion should be kept in mind by future authors and reviewers, and also stimulate further research. Moreover, whilst it is generally admitted that pharmacological trials should appraise the importance of a possible placebo effect, only one among the 364 studies analyzed by the authors was placebo-controlled; and this single study found that as much as 25% of cardiac surgical patients return to sinus rhythm in the 3 hours following placebo administration. This important piece of information evidences the absolute necessity for a systematic assessment of the placebo effect possibly involved in various postoperative AF treatments. Finally, it has to be pointed out that the authors have focused on the medical treatment of postoperative AF. it can be suspected that a methodic analysis of the results of the numerous trials analyzing AF prophylaxis in cardiac surgical patients would lead to similar results. doi:10.1016/S1569-9293(03)00215-9
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Abstract
1. Clinical scenario