Methods: Literature review was carried out in the PubMed, ScienceDirect and Ovid electronic databases without any limitation of time frame. Published studies which recorded the preoperative levels of vitamin D and atrial fibrillation after cardiac surgery in the English language were included. The results of the studies were evaluated based on either random or fixed effect model according to the presence of heterogeneity (I2>25%).

Results: A total of 1,865 articles were screened. After the article titles and abstracts were analyzed, six articles involving 769 patients which met the inclusion criteria were included. The results indicated that there was a relationship between preoperative vitamin D levels and postoperative atrial fibrillation (SMD: -0.46, 95% CI: -0.79 to -0.12; p<0.007). Heterogeneity was observed for studies conducted (I2 =76.1%).

Conclusion: We concluded that low preoperative vitamin D levels were associated with the development of atrial fibrillation after cardiac surgery. However, there is a need for large-scale, randomized-controlled trials for preventing the heterogeneity of the results.