Determination of blood alcohol concentration (BAC) in heart disease patients is crucial for clinical and forensic purposes; enzymatic ethanol assays are widely used to determine blood alcohol content for individuals admitted to a hospital. In some instances, this hospital data is later used as evidence in a court of law. As the enzymatic assay targets, but does not exclusively measure, ethanol, it is theoretically possible that interference could occur and produce a falsely elevated result, leading to wrongful convictions or other consequences. This study examined the potential of clinically relevant levels of one potential interferent, lactate dehydrogenase (LDH) enzyme, to cause significant and falsely elevated results and compared this method with chemical and new HS-GC/FID methods. The study was conducted on 48 individuals (24 myocardial infarction patients, 24 healthy volunteers) in Tripoli, Libya. The BAC (mg/dL) results for healthy and myocardial infarction patients showed a significant difference using the enzymatic method and no difference using the HS-GC/FID method. A clear difference with high significance of BAC appears for myocardial infarction patients by using the enzymatic and HS-GC/FID methods. The Pearson correlation coefficient between LDH levels and BAC by the enzymatic method is 0.76, indicating a strong positive correlation. This suggests that as LDH levels increase, BAC levels also tend to increase (LDH interference may contribute to falsely elevated ethanol readings in myocardial infarction patients), affecting the accuracy of BAC determination. HS-GC/FID is advised over the enzymatic approach, particularly in individuals with myocardial infarction (elevated LDH levels).