Effect of bivalirudin compared with unfractionated heparin plus abciximab on infarct size and myocardial recovery after primary percutaneous coronary intervention: the horizons-AMI CMRI substudy.

BACKGROUND: Myocardial infarct size is a strong independent predictor of mortality in patients with ST-elevation myocardial infarction (STEMI). In the Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, bivalirudin compared with unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor reduced cardiac mortality in STEMI patients, which was attributed to reduced major bleeding. Whether a possible reduction in infarct size with bivalirudin may have contributed to the enhanced survival with this agent is unknown.

METHODS: Cardiac magnetic resonance imaging was performed within 7 days and after 6 months in 51 randomized patients from a single center in HORIZONS-AMI trial (N = 28 bivalirudin, N = 23 heparin plus abciximab). Infarct size, microvascular obstruction (MVO), left ventricular ejection fraction (LVEF), and LV end-diastolic and end-systolic volume indices were evaluated.

RESULTS: Infarct size was not significantly different after treatment with bivalirudin compared with heparin plus abciximab either within 7 days (median 9.3% [interquartile range 4.9%, 26.6%] vs. 20.0% [5.9%, 28.2%], P = 0.28) or at 6 months 6.7% [3.8%, 20.0%] vs. 8.2% [1.8%, 16.5%], P = 0.73). MVO was present in 28.6% versus 34.8% of patients respectively (P = 0.63). LVEF and LV volume indices also did not significantly differ between the two groups at either time period, nor were differences in myocardial recovery evident.

CONCLUSIONS: In conclusion, in the HORIZONS-AMI Cardiac magnetic resonance imaging (CMRI) substudy, cardiac magnetic resonance imaging within 7 days and at 6 months after primary percutaneous coronary intervention (PCI) did not demonstrate significant differences in infarct size, MVO, LVEF, or LV volume indices in patients treated with bivalirudin compared with unfractionated heparin plus abciximab.