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Occluded Artery Trial - OAT
Description:
The goal of the trial was to evaluate percutaneous coronary intervention (PCI) compared with medical therapy among stable, high-risk patients with persistent total occlusion of the infarct-related artery post-myocardial infarction (MI).
Hypothesis:
A strategy of routine PCI for total occlusion of the infarct-related artery 3-28 days after acute MI would reduce the occurrence of the composite of death, reinfarction, or New York Heart Association (NYHA) class IV heart failure.
Study Design
- Randomized
Patients Enrolled: 2,166
Mean Follow Up: Median, 5.8 years
Mean Patient Age: Mean age, 59 years
Female: 22%
Mean Ejection Fraction: Mean 48% at baseline
Patient Populations:
Angiography on day 3-28 post-MI with evidence of total occlusion of the infarct-related artery with poor or absent antegrade flow (TIMI flow grade 0 or 1); and met a criterion for increased risk, defined as ejection fraction <50%, proximal occlusion of a major epicardial vessel with a large risk region, or both
Exclusions:
NYHA class III or IV heart failure, shock, serum creatinine concentration >2.5 mg/dl, angiographically significant left main or three-vessel coronary artery disease, angina at rest, or severe ischemia on stress testing
Primary Endpoints:
Death, MI, or NYHA class IV heart failure
Drug/Procedures Used:
Patients with persistent total occlusion of the infarct-related artery 3-28 days post-MI were randomized to PCI with stenting (n = 1,082) or medical therapy (n = 1,084). A core laboratory evaluated the qualifying angiogram.
Concomitant Medications:
Aspirin, anticoagulation if indicated, angiotensin-converting enzyme inhibitors, beta-blockers, and lipid-lowering therapy, unless contraindicated
Principal Findings:
Initial treatment with thrombolytic therapy was used in 19% of patients within the first 24 hours of the index MI. Median time from MI to randomization was 8 days. PCI was successful in 87% of the PCI cohort. Stents were used in 87% of patients, 8% of which were drug-eluting stents, and glycoprotein IIb/IIIa inhibitors in 72%. PCI was performed in 3% of the medical therapy cohort. Medication use at discharge was similar between the groups, with the exception of thienopyridine use, which was higher in the PCI group.
The primary endpoint of death, reinfarction, or NYHA class IV heart failure occurred in 17.2% of the PCI group and 15.6% of the medical therapy group (hazard ratio [HR] 1.16, p = 0.20). Total reinfarction trended higher in the PCI group (7.0% vs. 5.3%, HR 1.36, p = 0.13), as did nonfatal reinfarction (6.9% vs. 5.0%, HR 1.44, p = 0.08). Repeated elevation of cardiac biomarkers within 48 hours of randomization occurred significantly more frequently in the PCI group (10.0% vs. 3.3%, p < 0.001). There was no difference in the individual endpoints of death (9.1% for PCI vs. 9.4% for medical therapy, p = 0.83) or NYHA class IV heart failure (4.4% vs. 4.5%, p = 0.92) between the treatment groups.
Long-term follow-up: Over a median follow-up of 5.8 years (longest 9 years), there was still no difference between the PCI and medical management arms for the primary composite endpoint (22.3% vs. 22.9%, HR 1.07, 95% CI 0.88-1.28, p = 0.86). Individual components, including all-cause mortality (14.6% vs. 16.0, p = 0.85) and reinfarction (7.7% vs. 7.2%, p = 0.27), and any revascularization (excluding protocol PCI) was higher in the medical management arm (21.3% vs. 25.6%, p = 0.03). A significant proportion (38%) of these repeat revascularizations (mostly PCI) did not include revascularization of the infarct-related artery. A trend was observed towards less PCI of the infarct-related artery in the PCI arm (p = 0.06).
Interpretation:
Among stable, high-risk patients with persistent total occlusion of the infarct-related artery post-MI, performance of PCI 3-28 days post-MI was not associated with a difference in the composite of death, reinfarction, or NYHA class IV heart failure through a mean follow-up of 3 years compared with medical therapy.
Despite no reduction in the composite endpoint, PCI was associated with a trend toward higher rates of reinfarction compared with medication therapy. The reinfarctions were not only procedural-related infarcts (i.e., early procedural enzymatic leaks), but true ST elevation reinfarctions that accumulated throughout follow-up. One explanation for the trend toward an increase in reinfarctions with PCI may be embolization resulting in myocardial damage and impaired collateral flow. Presence of persistent total occlusion remains a problem for a sizeable cohort of patients for whom suitable treatment is lacking.
Early reperfusion therapy, the goal of ST-segment elevation MI treatment, with either primary PCI or thrombolysis, is not indicated for patients who present late, often with persistent total occlusion. The present study, the largest randomized trial to date in this population, does not support the hypothesis of late PCI for stable but persistent total occlusion.
These results appear to be sustained over long-term follow-up (median 5.8 years). Lower revascularizations over long-term follow-up in the PCI arm represent subgroup analyses without adjustment for multiple comparisons; a higher risk of periprocedural MIs with PCI early on also needs to be factored in.
References:
Hochman JS, Reynolds HR, Dzavík V, et al., on behalf of the Occluded Artery Trial Investigators. Long-Term Effects of Percutaneous Coronary Intervention of the Totally Occluded Infarct-Related Artery in the Subacute Phase After Myocardial Infarction. Circulation 2011;Oct 24:[Epub ahead of print].
Hochman JS, Lamas GA, Buller CE, et al., on behalf of the Occluded Artery Trial Investigators. Coronary Intervention for Persistent Occlusion After Myocardial Infarction. N Engl J Med 2006;355:2395-407.
Presented by Dr. Judith S. Hochman at the American Heart Association Annual Scientific Sessions, Chicago, IL, November 2006.
Keywords: Thrombolytic Therapy, Myocardial Infarction, Follow-Up Studies, Biomarkers, Drug-Eluting Stents, Heart Failure, Angioplasty, Balloon, Coronary, Thienopyridines
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