Incidence of Post-operative Atrial Fibrillation Secondary to Abdominal Surgery

Summary

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Description

Background and rationale Post-operative AF (POAF), i.e. new-onset AF that occurs secondarily to surgery is considered a phenomenon rather than a definite diagnosis, and continuous anti-coagulation is not recommended in AF of short duration and non-persistent AF.1,2 The most recent guidelines from th...

Background and rationale Post-operative AF (POAF), i.e. new-onset AF that occurs secondarily to surgery is considered a phenomenon rather than a definite diagnosis, and continuous anti-coagulation is not recommended in AF of short duration and non-persistent AF.1,2 The most recent guidelines from the European and American Societies of Cardiology has no specific recommendation regarding management of secondary AF, though referral for an outpatient cardiology clinic can be considered if the condition is not self-limiting.3,4 Despite this, recent data from the Framingham population suggest that secondary AF is not a benign condition,5,6 and some studies have found POAF in relation to non-cardiac surgery to be associated with increased post-operative mortality and stroke.7-9 Currently few prospective studies have been performed in non-cardiac conditions and consequences of secondary AF in patients without known heart disease is not well described. POAF in relation to non-cardiac surgery is common with an average incidence of 10.94%.10 However, the true incidence of POAF in relation to non-cardiac surgery is uncertain, as the available studies are few, heterogenous and often methodologically inadequate.10 Different risk-stratification models exist, however it is still challenging to accurately predict which patients will develop AF both perioperatively and in the years following surgery.11-14 Important risk factors for developing POAF is: age (age 65-74, OR 2.08; age >85, OR 3.56), hypertension (OR 3.66), heart failure (OR 1.64), thyroid disease (OR 6.29), laparotomy vs laparoscopy (OR 3.30) and duration of surgery (> 600 min, OR 1.38).10 The use of electrocardiogram (ECG) in risk stratification for AF and stroke is not yet incorporated in clinical guidelines. However, short and prolonged p-wave and p-wave terminal force in lead V1 (PTFV1) is correlated with AF.15 Myovista (HeartSciences, Southlake, Texas, USA) is a novel ECG utilizing continuous wavelet transform signal processing (wavECG) and can be used to prove left ventricular diastolic dysfunction (LVDD).16 LVDD is other studies associated with AF.17-20 These new biomarkers might improve identification of patients at risk of developing POAF. Purpose The study aims at reporting the true incidence of AF, and associated complications, in relation to abdominal surgery. Concurrently, patients will be characterized by specialized ECG analysis and wavECG. Methods Prospective, single-centre, cohort study of consecutive patients undergoing abdominal surgery. Patients will be identified among elective and acute referrals for Department of Abdominal Surgery at Bispebjerg-Frederiksberg Hospital. The Investigator (Department of Cardiology at Bispebjerg-Frederiksberg Hospital) will ensure signed informed consent prior to any study related examinations. Surgery will be performed at Department of Abdominal Surgery at Bispebjerg-Frederiksberg Hospital independently of study enrolment. No randomization or placebo will be used. ECG measurements will be compared to existing data from a healthy population. Measurements ECG: PR-interval, p-wave area, PTFV1 wavECG: LVDD Heart rhythm monitoring: AF Statistical considerations Consecutive patients attending the Department of Abdominal Surgery at Bispebjerg-Frederiksberg Hospital will be invited to participate in the pre- and post-operative examination programme. The study aim is to identify the true incidence of peri- and postoperative AF. Hence, sample size calculations are uncertain. The expected incidence of AF for non-oesophageal surgery patients is at least 7.63%.10 Pre-operative p-wave indices have shown ability to predict POAF in cardiac surgery population of 105 patients (with incidence 11%).21 wavECG has been used to show LVDD in a study population of 188 patients referred for computed tomography angiography of the heart.16 The study will include 300 patients. Follow-up will be at least 12 months. Parametric statistics is used as normal distribution is expected with two-sample unpaired Student's t-test (continuous variables) and Chi-square and Fisher's exact test (categorical variables) where appropriate. Data is presented with mean (±standard deviation) for continuous variables and frequency (percentages) for categorical variables. All tests are two-sided and a P-value < 0.05 is considered statistically significant. Furthermore, non-parametric Kaplan-Meier (time-to-event) curves will be produced and log rank test (chi-square and hazard ratio) will be used for comparison. IBM SPSS version 22 will be used for statistical analyses.

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