Adverse clinical outcomes associated with a low dose and a high dose of aspirin following percutaneous coronary intervention: a systematic review and meta-analysis

Background: Guidelines from the American Heart Association/American College of Cardiology recommend a higher dosage of aspirin daily following Percutaneous Coronary Intervention (PCI), whereas guidelines from the European Society of Cardiology recommend a lower dosage. This study aimed to compare the adverse clinical outcomes associated with a low dose and a high dose of aspirin following PCI. Methods: Electronic databases were searched for studies comparing a low dose with a high dose aspirin following PCI. Adverse clinical outcomes were considered as the endpoints in this study. We calculated Odds Ratios (OR) with 95 % Confidence Intervals (CIs) for categorical variables. The pooled analyses were performed with RevMan 5.3 software. Results: A total number of 25,083 patients were included. Results from this analysis showed that the combination of Cardiovascular (CV) death/Myocardial Infarction (MI) or stroke was not significantly different between a low and high dose of aspirin with OR: 1.08, 95 % CI: 0.98-1.18; P = 0.11. Mortality and MI were also not significantly different between these two treatment regimens following PCI with OR: 0.95, 95 % CI: 0.74-1.23; P = 0.71 and OR: 1.17, 95 % CI: 0.97-1.41; P = 0.09 respectively. However, a high dose of aspirin was associated with a significantly higher rate of Major Adverse Cardiac Events (MACEs) with OR: 1.20, 95 % CI: 1.02-1.41; P = 0.03. Thrombolysis In Myocardial Infarction (TIMI) defined minor bleeding was also significantly higher with a high dose aspirin with OR: 1.22, 95 % CI: 1.02-1.47; P = 0.03. When Stent thrombosis (ST) was compared, no significant difference was found with OR: 1.28, 95 % CI: 0.59-2.58; P = 0.53. Even if TIMI defined major bleeding favored a low dose of aspirin, with OR: 1.42, 95 % CI: 0.95-2.13; P = 0.09, or even if major bleeding was insignificantly higher with a high dose aspirin, with OR: 1.78, 95 % CI: 1.01-3.13; P = 0.05; I-2 = 94 %, higher levels of heterogeneity observed in these subgroups could not be considered significant to any extent. Conclusion: According to the results of this analysis, a high dose of aspirin following PCI was not associated with any significantly higher rate of CV death/MI/stroke, mortality or MI. However, MACEs significantly favored a low dose of aspirin. In addition, TIMI defined minor bleeding was significantly higher with a high dose of aspirin whereas the results for the major bleeding outcomes were not statistically significant. However, due to limited data availability and since the subgroups analyzing major bleeding were highly heterogeneous, further studies are recommended to completely solve this issue.