Background: Atrial fibrillation (AF) that develops post-cardiac surgery is related to an elevated risk of stroke and mortality. It represents a significant burden on health care resources, including increased hospitalization time and expenses. Methods: This study was done on eighty-two patients who underwent coronary artery bypass grafting (CABG), mitral valve replacement (MVR), aortic valve replacement (AVR), or a combined procedure (CAB-valve) from January 2017 to March 2019. Post-operatively, patients were classified into Group (A); fifty patients without PCAF, and Group (B); thirty-two patients with PCAF. Results: After controlling for clinical and surgical risk factors by multivariate analysis, PCAF independent predictors were high body mass index (p-value 0.027 ), Isolated CABG (p-value 0.046),Mitral Valve Procedure (p-value0.008), Aortic valve Procedure (p-value 0.033), Combined CABG and Valve (p-value 0.002), prolonged Cross Clamp Time (p-value 0.011), E/e´( p-value 0.026), E/A(p-value<0.001), PV Peak Systolic Velocity (p-value0.022), PV Peak Diastolic Velocity(p-value 0.050) and abnormal LV DFG (DFG I, p-value 0.011 );( DFG II & III, p-value <0.001. Conclusions: LV diastolic dysfunction is a strong, independent risk factor for atrial fibrillation following cardiac surgery. The assessment could help risk stratification of heart surgery patients. Key words: AF, LV diastolic dysfunction, PCAF.