More participants in the citalopram group had an increase 30 ms from baseline to week 3 ( 7 in citalopram versus 1 in placebo ; Fisher 's exact p = 0.046 ) , but only slightly more in the citalopram group met a gender-specific threshold for prolonged QTc ( 450 ms for males ; 470 ms for females ) at any point during follow-up ( 3 in citalopram versus 1 in placebo , Fisher 's exact p = 0.611 ) .