Short bowel syndrome and clopidogrel non-responsiveness: a new indication for platelet aggregometry?

To cite: Hadley G, Harrison P, Adlam D, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2013-202241 DESCRIPTION A 74-year-old woman presented with unstable angina. Coronary angiography demonstrated severe single-vessel coronary disease and a 3×12 mm bare metal stent placed in the right coronary artery. She had a history of short bowel syndrome following emergency resection for ischaemic bowel just 2 years prior to receiving a long-term total parenteral nutrition (TPN). In view of clinical uncertainty surrounding effects of short bowel syndrome and TPN on clopidogrel responsiveness, platelet function testing was conducted. Aspirin responsiveness was assessed by light transmission aggregometry (LTA; figure 1A–C) and whole blood impedance aggregometry (WBA) using the multiplate (figure 2A,B). Results by both approaches confirmed adequate aspirin responsiveness. Clopidogrel responsiveness was only partial when assessed by LTA (figure 1) and absent when assessed by WBA (figure 2). When ticagrelor was used in place of clopidogrel, 90% inhibition of platelet aggregation was achieved by LTA. This was confirmed using the Verify Now P2Y12 test. Dual antiplatelet therapy with aspirin and clopidogrel showed a 4% inhibition of platelet aggregation compared with 69% with aspirin and ticagrelor. Medications were taken orally (not crushed). Incidence of the rare but catastrophic complication of stent thrombosis is substantially reduced by potent platelet inhibition with dual antiplatelet therapy, most commonly with aspirin and clopidogrel. Inhibition of platelet aggregation by clopidogrel shows considerable variation between patients.