The relationship of left atrial appendage peak systolic velocity with the incidence of postoperative atrial fibrillation in patients undergoing cardiac surgery - A prospective observational study

The incidence of POAF is a common occurrence following cardiac surgery therefore, early identification of its occurrence would warrant health care providers to be proactive in treating the common causes of atrial fibrillation (AF) in the immediate post operative period. Since no other study as far as we have searched has worked on studying the correlation between peak systolic velocity of left atrial appendage (LAA) and the incidence of POAF, this study will be conducted.

0. Methodology of measuring Primary objective:

1. A 6VT TEE probe will be inserted and echocardiography images will be obtained with GE Vivid E95 Echocardiography machine (GE Vingmed Ultrasound, Horten, Norway) according to the surgical procedure with the aid of standard TEE guidelines.

2. In mid-esophageal two chamber view (ME 2C) view, the LAA will be identified as a claw- like structure arising from the left atrium. Pulsed wave doppler (PWD) will then be applied with the sample volume taken at one‐third length of the LAA from its base11. The peak positive wave will be measured as peak systolic velocity which is synonymous with LAA peak emptying velocity . Three consecutive values will be taken and averaged. Readings will be taken before sternotomy and after weaning off CPB.

3. Patients will be followed up in ICU and till the day of discharge. AF will be diagnosed upon the detection of abnormality in rhythm electrocardiogram (ECG), that is sustained for a minimum of 30 seconds and characterised by sustained arrhythmia, absent P waves, irregular R-R intervals and different intervals between atrial contractions (cycle < 200 ms).

4. Statistical analysis:

5. • Receiver-operating characteristic (ROC) analysis will be used to determine optimal cutoff valuesof continuous variables for prediction of POAF.

• The area under the ROC curve will be used to quantify the ability of the PSV of LAA to predictincidence of POAF accurately.
• Regression analysis will be used for all possible confounding factors and to assess interaction between variables for assessment of POAF.