Echocardiographic Left Atrial Function Assessment and Atrial Fibrillation Post-Coronary Artery Bypass Surgery

The aim of this study to investigate the correlation between preoperative LA function using 2D echocardiography and left atrium 2D speckle tracking strain echocardiography and the development of Post Operative AF after CABG.

the investigators chose electrocardiography as a reference standard for detection of Post Operative AF. LA dysfunction is diagnosed with Echocardiography

Atrial fibrillation (AF) is one of the most common postoperative complications following cardiac surgery. This in turn translates into longer hospitalization, increased cost of hospitalization as well as association with thromboembolic events and mortality .

Despite new-onset postoperative atrial fibrillation (NoPOAF) occurring in 20-40% of patients following coronary artery bypass graft (CABG) surgery, the underlying mechanisms are not well established. However, it has been traditionally thought to be transient and benign to the patient.

Recent evidence suggests that POAF may be more 'malignant' than previously thought, associated with follow-up mortality and morbidity.

Previously, increased left atrial (LA) size and LA dysfunction have been shown to be related to the subsequent development of atrial fibrillation (AF), stroke, myocardial infarction, and heart failure.

Also, recent studies suggest that LA dysfunction caused by the effects of oxidative stress, inflammation, and atrial fibrosis, has a role. In other words, by acute functional depression, preoperative LA dysfunction may be the starting point of the development of POAF after coronary artery bypass grafting (CABG).(8) Therefore, as the improvement in the evaluation of LA function, preoperative LA dysfunction may emerge as an important component in the identification of patients with the risk of POAF after CABG surgery.

Echocardiography is the most common diagnostic method for assessing atrial function but the technique has some limitations. Traditionally, assessment of left atrial function has been performed by measuring volumes with 2D echocardiography. Additionally, it can be assessed with transmitral Doppler and pulmonary vein Doppler. Recently, an alternative method has been incorporated, namely, measurement of myocardial deformation with color tissue Doppler-derived strain.

However, this method has several limitations, such as suboptimal reproducibility, angle-dependence, signal artifacts and the fact that it only measures regional strain and does not obtain information about the curved portion of the atrial roof. To overcome these limitations in the quantification of atrial function, the use of speckle tracking echocardiography (STE) strain has been proposed. This technique is not derived from Doppler but rather from 2D echocardiography, it is angle-independent, and allows us to measure global as well as regional atrial strain. STE is a new technique of 2D echocardiography image analysis that allows the study of regional atrial myocardial deformation expressed by a dimensionless parameter.

2-dimensional (2D) speckle tracking strain imaging is a feasible and reproducible technique for the assessment of LA function by evaluating LA deformation dynamics.

Eligibility Criteria:
Inclusion Criteria:

* • Patients with preoperative sinus rhythm who were referred for elective isolated CABG (no other concomitant cardiac or extracardiac procedures).

  * Patient age more than18 years old.

Exclusion Criteria:

* • Any type of arrhythmia other than sinus.

  * Hyperthyroidism or hypothyroidism.
  * Renal failure requiring hemodialysis .
  * Moderate to severe valvular heart disease.
  * Current use of antiarrhythmic drugs .
  * Recent myocardial infarction within a month before surgery.
  * Patient with redo CABG.