Well, you are 11 years older, so some changes to your heart in relationship to the Citalopram may have occurred. In addition, other medications, OTC and Prescriptions, supplements, etc. should be considered.
Here's an article that gives a balanced view of your concern, though not predicating it on long term use of Citalopram. If you note in the article, concerns of the elderly are expressed concerning QTc prolongation in relation to dose and age.