Reasons for early discontinuing or switching of antiplatelet therapy in elderly patients after acute coronary syndrome.

Objective: This study aims to determine frequency and reasons for prematurely discontinuing or switching antiplatelet therapy in elderly patients admitted with non-ST-elevation acute coronary syndrome (NSTE-ACS).
Method: Patients of 75 years or older admitted with suspected NSTE-ACS were included between 2013 and 2016. Information was extracted from the patients' medical files.
Results: A total of 544 patients were included, 17.3% discontinued aspirin within one year, predominantly (57%) within 30 days. The most common reason was the start of a (non-vitamin-K) oral anticoagulant [(N)OAC], either combined with a P2Y12-inhibitor (43%) or as monotherapy (16%). The P2Y12-inhibitor was discontinued in 31.2% of patients within one year, of which 46% within 30 days. The most common reason was undergoing coronary artery bypass grafting (CABG; 22%). Switching of clopidogrel seldom occurred; however, ticagrelor was switched in 50/179 patients mainly due to dyspnoea (42%). Independent predictors for prematurely discontinuing antiplatelet therapy were undergoing CABG [odds ratio (OR) 3.257 (95% confidence interval [CI] 1.836-5.779)], need for (N)OAC [OR 2.167 (95% CI 1.423-3.300)] and type II ACS as final diagnosis [OR 3.793 (95% CI 1.721-8.361)]. Undergoing percutaneous coronary intervention [OR 0.393 (95% CI 0.243-0.634)] and use of clopidogrel [OR 0.441(95% CI 0.293-0.662)] were independent predictors of continuing antiplatelet therapy.
Conclusion: In elderly patients of at least 75 years with NSTE-ACS, antiplatelet therapy is frequently discontinued prematurely, most often within 30 days. Main reasons for discontinuing are need for (N)OAC, undergoing CABG or type II ACS as final diagnosis and suffering from dyspnoea while on ticagrelor.