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Judith S. Hochman, MD

Photo courtesy of the American Heart Association

The Occluded Artery Trial (OAT) was presented by study chair Judith S. Hochman, MD, on behalf of all investigators. This large multicenter trial was conducted at 217 sites around the world in 27 countries. There is no question that early reperfusion enhances left ventricular function and survival in patients with ST-segment elevation myocardial infarction (STEMI). This trial, however, set out to answer the question of whether or not late reperfusion would reduce by 25% the occurrence of a composite endpoint of death, reinfarction, or heart failure (NYHA class IV). The investigators hypothesized that opening arteries later (3 to 28 days post-MI) would decrease adverse remodeling, increase the electrical stability of the heart, and increase collateral development.

This trial was designed to study stable patients, therefore those with shock, rest or low threshold angina, class III-IV congestive heart failure, significant left main or 3 vessel coronary artery disease, hemodynamic/electrical instability or a creatinine level greater than 2.5 mg/dL were excluded. Patients had to have a proximal occlusion or an ejection fraction less than 50% to participate in the study. Eligible patients were randomized to one of two treatment arms: percutaneous coronary intervention with stenting and optimal medical therapy (PCI group) or optimal medical therapy alone (MED). A total of 2,166 of patients were randomized from 2000 to 2005, 1,082 in the PCI group and 1,084 in the MED group. The trial lost very few patients to follow-up (0.7% in PCI and 1.1% in MED).

The trial results were somewhat unexpected. There was no difference between the two groups in death, reinfarction, or heart failure (hazard ratio (HR) 1.16 [95% CI, 0.92 − 1.45]; p=0.20). The rates of these primary events were 17.2% in the PCI group and 15.6% in the MED group. “The rate of severe heart failure was much lower than we projected”, commented Dr. Hochman. In terms of nonfatal myocardial reinfarction, an increase in risk was seen in the PCI group (6.9%) versus the MED group (5.0%), with an HR of 1.44 ([95% CI, 0.96 − 2.26]; p=0.08). The investigators conducted additional subgroup analysis to determine if any other factors were related to the increase in risk. No significant differences were found when subgroups such as age, gender, race, ethnicity, ejection fraction, presence of diabetes, Killip class, the artery where the infarction occurred, or the time from MI to randomization were analyzed.

What does this mean for clinicians? Aggressive medical intervention without revascularization may be an appropriate approach for patients that have a profile similar to the OAT population. The results of the OAT trial were published online on November 13, 2006 in the New England Journal of Medicine (www.nejm.org; Hochman et al; DOI 10.1056/NEJMoa066139). Economic and quality of life trial results will be reported separately.