Laboratory response to clopidogrel was significantly attenuated in the presence of fluvoxamine compared with the response in the presence of citalopram as tested both by aggregometry ( 32.34.2 % vs 23.43 % , p = 0.04 ) and by vasodilator-stimulated phosphoprotein phosphorylation ( 52.75.1 % vs 35.94.2 % , p = 0.02 ) .