Stents: Avoiding Catastrophic Events

A review by a team of Italian researchers compares the available therapies for reducing stent thrombosis in patients with acute coronary syndrome.

Patients who have an episode of acute coronary syndrome (ACS) often undergo percutaneous coronary intervention (PCI). Afterward, patients usually require dual antiplatelet therapy to prevent thrombosis. The standard of care is currently aspirin and clopidogrel. Older stents were often plagued with post-intervention complications, including stent thrombosis (ST). Newer, second-generation drug-eluting stents (DES) have improved clinical outcomes, but ST remains a problem that can be catastrophic.

ST may develop due to procedural complications such as stent underexpansion, dissection at the stent edge, plaque rupture in the residual atherosclerotic lesion, and medial fracture. Other causes of ST can include delayed arterial healing, hypersensitivity reactions to the stent itself, stent malapposition, and new atherosclerotic deposition.

In some patients, clopidogrel non-responsiveness may precipitate clinical ischemic events. Clinicians can measure clopidogrel responsiveness using various laboratory tests. Non-responsiveness limits the use of clopidogrel in these patients, creating a need for an alternative treatment. Alternatives include newer drugs that inhibit ADP-induced platelet aggregation, such as prasugrel and ticagrelor.

In a review published online on December 4, 2012, in Angiology, and titled “Pharmacotherapeutic Considerations for the Use of Prasugrel and Ticagrelor to Reduce Stent Thrombosis in Patients With Acute Coronary Syndrome,” a team of Italian researchers concisely compares the available therapies. They discuss head-to-head trials of each drug with clopidogrel, and lament the lack of head-to-head data for the 2 new drugs. They summarize trials that show the following:

• Ticagrelor treatment significantly reduced mortality in comparison with clopidogrel, while prasugrel did not. They further note that, in general, patients in the ticagrelor study had higher risk factors and the dose of clopidogrel may have been too low.
• Prasugrel and ticagrelor have similar effects in increasing spontaneous bleeding episodes. They recommend dose reductions and adjunctive proton pump inhibitors in patients at risk for gastrointestinal bleeding.
• They suggest that further research is needed to determine if prasugrel and ticagrelor will prevent late ST.

Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.