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Eur J Cardiothorac Surg 2002;21:159-160
© 2002 Elsevier Science NL
Letter to the Editor |
Pawlaczyk
awa NarkiewiczDepartment of Cardiology and Cardiac Surgery, Medical University of Gdansk, Gdansk, Poland
Received 26 September 2001; received in revised form 12 October 2001; accepted 14 October 2001.
* Corresponding author. Tel.: +48-58-349-2403 fax: +48-58-341-7669
e-mail: jsiebert{at}amg.gda.pl
The authors would like to thank Dr Totaro and his colleagues for their comments, published in their letter in the European Journal of Cardio-thoracic Surgery. Atrial fibrillation (AF) is indeed a complex and interesting issue, and may lead to serious complications at the postoperative stage of some patients. This was the reason for starting the investigation, which is continuing in our department [1]. We agree that the onset of postoperative AF is multifactoral phenomenon caused by the conjunction of particular triggering factors with a predisposed substrate. Amongst this, the most commonly quoted in the literature, are the patient's age [2] and genotype [3] with the type of the procedure followed [4].
We obviously share the opinion of Dr Totaro, that on the one hand some of the postoperative complications that occur, may trigger the onset of postoperative AF while, on the other hand, the presence of AF itself may contribute to the start of a vicious circle of existing, and further complications, with may have serious consequences in some patients.
The published results of our study were based on the on-line arrhythmia analysis used in the ICU, and therefore were limited to a relatively short observation period, on average two postoperative days (POD).
We would like to take this opportunity to present some of the results obtained in further studies which have been carried out in our institution recently, to elucidate the influence of the chosen type the surgical procedure on the incidence of postoperative AF. Most interesting findings which came to our attention are related to the distribution of the frequency of the AF episodes, recorded in the extended period in coronary artery bypass grafting (CABG) and off-pump CABG (OPCABG) patients respectively.
The overall AF incidence in the intensive care unit period was similar in both groups, as was shown in our previously published findings. However, a closer look at the onset incidence over a longer period has shown some important differences in the trends of the two groups. In CABG patients the post-operative incidence of AF gradually increased up to the 4th POD, while in OPCABG patients we have observed the opposite trend with an initial high incidence which was subsequently lowered reaching a minimum on the fourth POD. There is a distinct difference in the rate of new onset of AF episodes observed beyond this short period. These two opposite trends, observed over consecutive postoperative days may depend on different triggering factors.
Our hypothesis is that high AF incidence found on the 4th POD in the CABG group could be caused by delayed general inflammatory response after the exposure to extracorporal circulation [5] as well as the influence of changes in thyroid activity [6]. This may particularly affect the patients with specific individual distribution of myocardial repolarization periods, which is evident genetic in origin [3].
This hypothesis will be tested out in further studies on AF, which is an the intriguing and challenging subject.
References
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