SNPs (single nucleotide polymorphisms) in regulatory regions of GNAS gene impact upon cardiac performance in vivo showed no association with the systolic function of the heart, because the cardiac function is not only described by the systolic function, but also by the diastolic function, the question is whether the GNAS Haplotypes affect the diastolic function having therefore an influence on the outcome. Methods: We examined 255 patients undergoing coronary aortic bypass grafting. Two millilitre blood was withdrawn to identify the two important SNPs of the GNAS gene and the patients receive an intraoperative evaluation of the diastolic heart function. Gene extraction was performed, followed with its genotyping using the polymerase chain reaction technique. The Haplotypes were matched to the echocardiographic results of the transoesophageal echo which were performed in the cardiosurgical operations theatre. For a two group comparison we used the χ² test or the Fisher's exact test if any expected count was less than five. For categorical variables with more than two possible values, exact P-values have been estimated. A two-sided P-value <0.05 was considered statistically significant. All statistical tests were done using SPSS version 24 (IBM 2016, USA). The results show a correlation between diastolic dysfunction and age, ß blocker therapy, previous myocardial infarction and glucose intolerance. But unfortunately the SNPs of the gene GNAS does not seem influence the diastolic dysfunction and the link between the different outcomes between the GNAS haplotypes stays unknown.