Researchers to present results of HORIZONS-AMI trial at TCT scientific symposium

Focus on impact and benefits of bivalirudin therapy

Two subset analyses from the landmark HORIZONS-AMI trial show that the anticoagulant bivalirudin lowers major bleeding and cardiac death versus the combination of heparin and a GP IIb/IIIa inhibitor in patients with ST-segment myocardial infarction (STEMI) who have disease of the left anterior descending artery (LAD), while in STEMI patients at highest risk for death, bivalirudin also confers the greatest mortality benefit.

Two teams of European researchers will report on one-year results from these two substudies at the 21st annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, sponsored by the Cardiovascular Research Foundation (CRF). Both will be presented as poster abstracts (TCT-306 and TCT-304) on Tuesday, September 22 between 8:00 a.m. and 10:00 a.m. in Hall D of The Moscone Center.

The landmark HORIZONS-AMI trial, sponsored by CRF, is expected to significantly impact the way that patients are treated. Two-year data from the trial will also be presented as a Late Breaking Trial on Friday, September 25 at TCT.

The two abstracts examine additional important information regarding outcomes of patients with acute myocardial infarction (AMI). One of the substudies focuses on primary angioplasty in acute anterior myocardial infarction with bivalirudin compared to unfractionated heparin plus GpIIb/IIIa inhibitors. This includes patients with massive heart attacks and the effect of pharmacotherapy in these patients. The other substudy examines the benefits of bivalirudin therapy in the highest risk patients who present with a heart attack.

A research team lead by Jochen W-hrle, MD, University of Ulm (Ulm, Germany) looked at clinical outcomes in patients with ST segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) of left anterior descending (LAD) coronary artery disease compared to non-LAD lesions. Investigators evaluated the impact of bivalirudin versus unfractionated heparin (UFH) plus a glycoprotein IIb/IIIa inhibitor (GPI) on clinical outcomes in patients with STEMI undergoing primary PCI of the LAD.

In the international, large-scale prospective HORIZONS-AMI trial (Principal Investigator: Gregg Stone, MD), 3,602 patients were randomized to bivalirudin monotherapy vs. UFH+GPI. Of these, 1,445 patients underwent primary PCI of the LAD, whereas 1,884 patients underwent primary PCI of only non-LAD lesions. The occurrence of MACE (death, reinfarction, ischemic target vessel revascularization or stroke), major bleeding and net adverse clinical events (NACE = MACE or major bleeding) at 12 months were assessed in the two groups.

In comparing patients undergoing LAD versus non-LAD primary PCI, the rates of net adverse clinical events (19.3% vs. 15.4%), MACE (14.1% vs. 10.3%), death (5.6% vs. 2.8%) and cardiac death (4.2% vs. 1.9%) were significantly higher (all p<0.05) in LAD patients, whereas the rates of major bleeding (8.4% vs. 7.3%,>

Patients with LAD lesions were also randomized to treatment with bivalirudinIn patients treated with bivalirudin as compared to UFH+GPI, NACE (18.3% vs. 20.2%, said Dr. W-hrle.

Patients undergoing primary PCI of LAD as compared to non-LAD lesions had significantly higher one-year rates of NACE, MACE, death and cardiac death. In patients undergoing PCI of LAD lesions, anticoagulation with bivalirudin monotherapy rather than unfractionated heparin + GPI resulted in significant lower rates of major bleeding and cardiac death.

High-Risk Patients A related study from Italy looked at who gained the greatest benefit of bivalirudin monotherapy (BIV) in the treatment of STEMI patients undergoing primary PCI and found the patient cohort that gained the most was the highest risk subject population. According to the lead researcher, Guido Parodi, MD, PhD, FESC, Associate Chief Invasive Cardiology, Careggi Hospital, University of Florence (Florence, Italy), "It was completely contrary to our expectations. In particular, we found that in those patients at the highest risk for dying at one year, randomization to bivalirudin instead of heparin plus a GPIIb/IIIa antagonist appeared to provide the greatest mortality benefit."

In this substudy of the HORIZONS-AMI trial, bivalirudin monotherapy (BIV) was compared to unfractionated heparin (UFH) plus glycoprotein IIb/IIIa inhibitors (GPI). BIV resulted in a reduction of major bleeding, a decrease in 30-day and 1-year mortality and enhanced freedom from net adverse clinical events (NACE) in patients with STEMI undergoing primary PCI. Whether the beneficial effects of BIV are related to patient risk category is not known.

In HORIZONS-AMI, 3,602 STEMI patients were treated within 12 hours of symptom onset and underwent primary PCI to BIV monotherapy vs. UFH+GPI. Patients were classified as low (score from 0 to 2), medium (score from 3 to 5), and high risk (score >5) according to the CADILLAC Risk Score based on 7 clinical variables (baseline EF<40%, renal insufficiency, Killip class ≥ 2, final TIMI flow< 3, age > 65, anemia, and 3V disease).

Among 2,530 evaluable HORIZONS-AMI trial patients, 1,522 pts (60%) were classified as low risk, 531 patients (21%) were classified as medium risk and 477 patients (19%) were classified as high risk.

Among high risk patients, there was a significantly lower rate of myocardial infarction (3.6% vs. 7.9%) and non-significant trends toward less stent thrombosis (2.2% vs. 4.0%), composite major adverse cardiovascular events (18.2% vs. 25.4%), and NACE (27.1% vs. 34.5%) rates with BIV therapy as compared with UFH + GPI, with no differences in ischemic TVR and stroke rates in the 2 groups.

The researchers concluded that in STEMI patients undergoing primary PCI, treatment with BIV compared to UFH + a GPI reduces major bleeding and 1-year mortality. Numerical reductions in major bleeding in BIV patients were present in all risk groups, whereas patients at high risk of mortality had the greatest survival advantage with BIV.

"While all risk categories of patients experienced a numerical decrease in 1-year mortality when randomized to bivalirudin, the relative reduction in mortality for those at highest risk of dying was nearly 50%, with an absolute reduction of 7.5%, suggesting that for every 100 high risk patients treated with bivalirudin rather than heparin plus a GPIIb/IIIa antagonist, seven more patients will be alive at one year after treatment," said Dr. Parodi. "Ongoing analyses are needed to determine if this mortality benefit in the patients at highest risk for death is due to a greater risk for, and reduction in bleeding in this cohort."

Source: Cardiovascular Research Foundation