Investigating the prevalence of AF (atrial fibrillation) rhythm and its risk factors in patients undergone CABG (coronary artery bypass grafting) at Imam Khomeini Hospital from April 2006 to March 2009

Author Name(s): Ghasemali Mish Mast Nahi, Mahmood Alemohammad
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Abstract

AF is the most frequent arrhythmic complication after CABG. The aim of this study was to identify the incidence and risk factors of AF in a cross sectional study of the patients who underwent CABG surgery in Imam Khomeini hospital. Methods: Between April 2006 and March 2009, data of patients who underwent CABG in Imam Khomeini hospital were gathered. 545 patients were included in this study randomized .we had excluded the patients who didn’t have complete data for our study or have a history of arrhythmia before surgery. we divided patients in two groups: the patients who developed post CABG, AF(AF group),and the other who didn’t develop this complication(No AF group).Multivariate analysis(odds ratio, p value) was used to identify independent predictors of post CABG AF. Some of Our major variables was preoperative like age, sex, BMI, history of diabetes, HTN, hyperlipidemia, COPD, smoking history ,family history of CAD, renal insufficiency and LVEF Some was intraoperative like cross clamp time, perfusion time and some was post operative like prolonged ventilation (>24 hours), re-operative , bleeding and mortality Result: post operative AF occurred in 48(8.8%) of patients. multivariate analysis identified age>65 years (p value=0.033 , OR=1.97 ) as a predictor of post CABG AF. also hospital mortality was significantly higher in AF group(12.5% in AF group vs 4.4% in No AF group with p value=0.029 , OR=3.08).other variables didn’t have significant differences between two groups and didn’t identify as risk factors of AF. Conclusion: Although the incidence of AF in this study was not as many as other studies that may show lower incidence in Iranian patients compared with other nations,the higher mortality rate in AF group shows that we should improve our post-op surveillance to diagnose AF as an early complication specially in high -risk patients like old patients(>65 years)and treat the patients who need interventions to decrease the mortality of this complication after surgery.

Introduction

Atrial Fibrillation (AF) : Heart muscle experiences a kind of irregular contraction under certain conditions in which it completely blocks the blood movement. Such arrhythmia is called fibrillation which is involving atria and ventricles. Usually, fibrillation is caused by re-entry phenomenon in which impulses are branched in numerous irregular circuits (1). In AF, ventricles are not able to pump the blood, and they reduce efficiency of ventricles by 30-20%. In such situations, patient can do normal activities fully and live for many years, while overall efficiency of the heart is lower (2). AF is also created by multiple arterial parasystolic foci that each of these foci creates extremely high rate impulse. It also creates electrical stimulates, and irregular and weak waves emerge in ECG as result. Additionally, none of the stimulus is not transmitted, and only arterial depolarization wave reaches occasionally to ventricles through AV node, and it creates an irregular ventricular rhythm. In comparing AF waves with natural sine wave(SAN), it can be said that each sine pacemaker is in the form of concentric circles like waves created and expanded by dropping a stone in the water pond, while multiple irregular waves in atrial fibrillation is like raining and creation of multiple small waves on the surface of water pond (3). AF occurs in a variety of chronic heart diseases in which atria are essentially loose heart in each heart cycle and they do not participate in ventricular filling (4)..
AF rhythm is most common arrhythmia after CABG operation, that its prevalence is 10 to 40% according to various reports [8-5]. This arrhythmia occurs mainly during days 2 to 4 days after CABG operation that its peak incidence is in the second day after the operation [10,9, 7]. AF is characterized by irregular atrial activity . AF arrhythmia may occur in healthy individuals, especially due to emotional stress after operation, exercise, acute poisoning with alcohol or severe irritation of the vagus (vasovagal response) [11].

 

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