Patients assigned to generic phosphate-buffered tirofiban were more likely to experience thrombocytopenia compared to patients assigned to citrate-buffered tirofiban or unfractionated heparin, according to post hoc results from the PRISM clinical trial.

Findings were recently published in JACC: Cardiovascular Interventions.

PRISM (Platelet Receptor Inhibitor in Ischemic Syndrome Management) was a randomized, controlled, multicenter, double-blind involving patients with non–ST-segment elevation acute coronary syndrome.


Continue Reading

In the early recruitment phase, Marianna Adamo, MD, of the Thoraxcenter in Rotterdam, the Netherlands and colleagues randomly assigned patients to either 0.6 mg/kg/min phosphate-buffered tirofiban followed by 0.15 mg/kg/min infusion for 48 hours (n=879) or 5000 IU unfractionated heparin followed by an infusion of 1000 IU/h for 48 hours. During the late recruitment phase, patients were assigned to citrate-buffered tirofiban (n=737) or unfractionated heparin (n=742).

Thrombocytopenia was defined as platelet nadir <90 000/mm3 platelet count <100 000/mm3, and as a combination of nadir value <150 000/mm3 and decrease of platelet count ≥50%.  

Researchers found that the rate of thrombocytopenia was significantly higher for patients assigned to phosphate-buffered tirofiban, but not those assigned to unfractionated heparin or citrate-buffered tirofiban (see tables).

Rate of thrombocytopenia (early recruitment phase)

Medication

90 000/mm3

100 000/ mm3

Phosphate-buffered tirofiban

1.7%

2.0%

Unfractionated heparin

0.5%

0.7%

Rate of thrombocytopenia (late recruitment phase) 

Medication

90 000/mm3

100 000/ mm3

Citrate-buffered tirofiban

0.3%

0.7%

Unfractionated heparin

0.1%

0.7%

Patients who developed thrombocytopenia were more likely to discontinue the study prematurely, both at a platelet nadir of <90 000/mm3 (45.8% vs 1.7%) and at a platelet nadir of 100 000/mm3 (42.2% vs 1.6%; P<.001 for all).

In addition, patients who experienced a platelet nadir <100,000/mm3 had a 2-fold increased risk for net adverse cardiovascular events (hazard ratio: 2.36; 95% confidence interval: 1.31-4.23; P=.004).

Thrombocytopenia was associated with a 5- to 10-fold increased risk for thrombolysis in myocardial infarction (TIMI) bleeding and a 2-fold increased risk for net adverse cardiovascular events, the authors concluded.

Reference

Adamo M, Ariotti S, Costa F, et al. Phosphate- or citrate-buffered tirofiban vs unfractionated heparin and its impact on thrombocytopenia and clinical outcomes in patients with acute coronary syndrome. JACC Cardiovasc Interv. 2016;9:1667-1676. doi:10.1016/j.jcin.2016.05.031.