Extended OAT Follow-up: Still No Clinical Advantage for Late Stenting

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Extended follow-up from a trial of late stenting of totally occluded infarct-related arteries in stable myocardial infarction (MI) patients shows no reduction in long-term events compared with optimal medical therapy. The findings were published online October 24, 2011, ahead of print in Circulation.

OAT (Occluded Artery Trial), published in 2006, randomized 2,201 stable patients with a total occlusion of the infarct-related artery found 3 to 28 days post MI to optimal medical therapy with or without PCI. The main results showed that PCI did not reduce the primary composite endpoint of death, reinfarction, or class IV heart failure out to 4 years.

In the current analysis, the investigators, again led by Judith S. Hochman, MD, of New York University School of Medicine (New York, NY), extended follow-up for an additional 3 years for the primary endpoint (the first occurrence of death from any cause, nonfatal MI, or class IV heart failure) and angina.

Overall, with the longer follow-up, there was still no difference between treatment groups in the rates of the primary outcome as well as the individual components (table 1).

Table 1. Outcomes at 7 Years

Furthermore, in an as-treated analysis comparing the 953 adjudicated, successful PCI patients with the 1,070 patients in the medical therapy group who did not cross over to PCI within 30 days after randomization, there also was no difference in the primary endpoint (HR 1.04; 95% CI 0.86-1.27; P = 0.68).

Early Symptomatic Benefit for PCI

While the vast majority of patients in both groups reported no angina, the condition was notably less common in the PCI group than the medical therapy group at 4 months (18.6% vs. 25.0%; P = 0.0004), an advantage that persisted up to 3 years. Thereafter, however, no difference was seen at most time points. The likelihood of angina actually decreased over time in both groups, with only 10% to 15% reporting any angina in years 3 to 7.

Use of cardiovascular medications did not differ between groups, with the exception of clopidogrel, which was used more often in the PCI group in the first year. During follow-up, nonprotocol PCI was less likely to be performed in patients assigned to PCI (n = 179) vs. medical therapy (n = 218; HR 0.81; 95% CI 0.68-0.96; P=0.03), while CABG was performed in the same number of patients in each group (n = 47). The reason for nonprotocol revascularization was new MI or unstable angina in 43% of cases, with no difference between treatment groups (P = 0.24).

Among 397 nonprotocol PCI procedures performed, 38% did not include PCI of the infarct-related artery. There was a trend toward less PCI of the infarct-related artery during follow-up in the PCI group (HR 0.79; 95% CI 0.61-1.01; P = 0.06).

In subgroup analysis, no interaction was seen between baseline patient characteristics

and treatment assignment for the primary endpoint. There also was no interaction between treatment assignment and risk defined as a continuous measure (P = 0.81) or risk tertile (P = 0.71).

The investigators also looked at the influence of stent type on outcomes, finding no difference between DES and BMS for the primary outcome at 6 years (P = 0.53) or for rates of nonfatal reinfarction (P = 0.07) and death or reinfarction (P = 0.74).

Follow-up Consistent with Primary Analysis

According to Dr. Hochman and colleagues, data from the Total Occlusion Study of Canada (TOSCA-2) had suggested an apparent attenuation of ventricular remodeling associated with PCI that could result in diverging heart failure rates later in follow-up. But, they say, the results of the extended follow-up from OAT disprove that theory.

In addition, the authors say the subgroup analysis, including patients at highest risk, is “remarkably consistent” with the primary analysis from the OAT trial.

“The present publication presents more robust data with far longer follow-up and confirms no improvement in clinical outcomes with routine PCI for total occlusions in stable post-MI patients,” Dr. Hochman and colleagues write. “As noted, these results apply to patients with at least moderately preserved viability. In light of the excess cost in patients assigned to routine PCI in OAT, these findings should now influence this practice pattern.”

No Real Surprises

In a telephone interview with TCTMD, Jeffrey W. Moses, MD, of NYP/University Hospital of Columbia and Cornell (New York, NY), pointed out that in patients like those in OAT with predominantly single-vessel disease and near-normal ejection fraction with no ischemia, rates of death, MI or congestive heart failure during follow-up would be expected to be low, so the results are not surprising.

“This is a very select, stable group that basically doesn’t get PCI in the first place in routine clinical practice,” Dr. Moses said. “Less than 1% of all PCIs in America are performed in patients like these. The clinical community came to the conclusion to not treat such patients a long time before OAT came along.”

According to Dr. Moses, the most fascinating thing about OAT is the symptomatic benefit over the first two years for angina and dyspnea.

“I’m not advocating PCI for these patients, but it is interesting that even in the most minimally symptomatic group with mainly untreated infarcts, you still see a symptomatic benefit for PCI,” he said. “This has implications for other populations of patients.”

Another issue of interest in OAT, Dr. Moses said, is the cross-over rate in the medical therapy group to PCI of the infarct-related artery. “You have to wonder why that is happening in a minimally symptomatic group,” he commented. “It’s not trivial, so it is something to take away from this.”

 

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Sources:
1. Hochman JS, Reynolds HR, Džavík V, et al. Long-term effects of percutaneous coronary intervention of the totally occluded infarct-related artery in the subacute phase after myocardial infarction. Circulation. 2011;Epub ahead of print.

2. Hochman JS, Lamas GA, Buller CE, et al. Coronary Intervention for Persistent Occlusion after Myocardial Infarction. N Engl J Med. 2006;355:2395-2407.

 

 

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