Benefits and risks of P2Y12 inhibitor preloading in patients with acute coronary syndrome and stable angina

Treatment with P2Y12 inhibitors is an integral part of the standard of care for patients undergoing percutaneous coronary intervention. However, the most appropriate timing for P2Y12 inhibitor administration remains unclear, and the value of "preloading" with P2Y12 inhibitors prior to cardiac catheterization is controversial. While pre-catheterization treatment with P2Y12 inhibitors is performed with the goal of decreasing adverse cardiovascular events, this potential benefit must be weighed against the increased risk of bleeding complications and operative delay if coronary artery bypass graft surgery is indicated. A number of studies have been conducted to evaluate the utility of preloading with P2Y12 inhibitors prior to cardiac catheterization for varying indications including stable angina and acute coronary syndrome (ACS). In this article, we review the literature and discuss the advantages and disadvantages of the preloading strategy. Several individual studies offer inconclusive and even conflicting findings. However, when taken in sum, these studies allow for several conclusions about the utility of P2Y12 inhibitor pretreatment. The existing literature demonstrate that preloading is associated with some degree of reduction in adverse ischemic events, although this benefit comes with an increased risk of bleeding complications. The appropriateness of preloading therefore varies based on the indication for catheterization, likely justified in patients with ACS but unlikely to benefit patients with stable angina.