The bivalirudin paradox

A series of trials have shown that bivalirudin, a direct thrombin inhibitor that does not require the cofactor antithrombin III to be effective, is a reasonable alternative to unfractionated heparin (UFH) alone or associated with glycoprotein IIb/IIIa antagonists (GPI) in patients undergoing percutaneous coronary interventions (PCI). Particularly in patients with acute coronary syndromes (ACS), the effects of bivalirudin are striking. In the HORIZONS-AMI trial, patients with persistent ST-segment elevation (STEMI) had lower 30-day rates of net adverse clinical events and major bleeding, largely due to the significantly lower 30-day rate of non-coronary artery bypass grafting major bleeding. Bivalirudin also resulted in significantly lower rates of all-cause mortality and cardiac mortality, a benefit that extended up to 3-year follow-up. The beneficial effects of bivalirudin as compared to UFH associated with abciximab were also observed in 1721 non-ST elevation myocardial infarction (NSTEMI) patients undergoing PCI in the ISAR REACT 4 study. Although no difference was found between the two treatment strategies in the 30-day primary endpoint, bivalirudin use resulted in a lower rate of major bleeding. Despite the abundant evidence of benefit provided by bivalirudin in the treatment of ACS and the high level of recommendation received by the most recent Guidelines, its use is still low. The reasons for this underuse are multifactorial, the most likely being the preference of operators for the use of a low-cost agent, like UFH, that can be associated with a GPI. Countering platelet hyperreactivity is still the main goal of interventional cardiologists treating ACS patients invasively, apparently downplaying the pathogenetic role of thrombin in this clinical condition.