ACC 2009: ABOARD: Immediate Cath No Better Than Next-Day Intervention for NSTE-ACS Patients

March 30, 2009

March 30, 2009 (Orlando, Florida) There was no benefit of immediate over next-day catheterization on the primary end point of MI, defined as troponin peaks, or on secondary clinical end points in non-ST-elevation ACS (NSTE-ACS) patients in the ABOARD study.

The trial results were presented at the American College of Cardiology 2009 Scientific Sessions by Dr Giles Montalescot (Institut de Cardiologie, Pitié-Salpêtrière Hospital, Paris, France). He explained that many previous studies have investigated the issue of early-vs-late intervention in NSTE-ACS patients, but "early" in these studies varied from three to 96 hours and "late" was generally very late, from 50 to 1464 hours. "We wanted to look at whether there was an advantage of really early (ie, immediate) intervention, compared with taking these patients to the cath lab the next day, which has never really been tested before," Montalescot said. He described the immediate intervention as "a primary-PCI strategy for non-ST-elevation ACS patients."

In the study, 352 patients with moderate- to high-risk NSTE-ACS (TIMI score>3) were randomized to immediate catheterization or next-day catheterization. PCI was performed with triple-antiplatelet therapy in both study groups. A radial access for PCI was used in 84% of patients, and a drug-eluting stent was used in 52%. CABG was performed in 11% of the patients. The median time from randomization to sheath insertion was 1.2 hours in the immediate group and 20.5 hours in the next-day group.

The primary end point, peak troponin I levels during hospitalization, was not different between the two groups.

ABOARD: Primary End Point

Primary end point Immediate group Next-day group p
Median peak troponin I value (interquartile range) 2.0 (0.3-7.16) 1.7 (0.3-7.2) 0.70

The key secondary end point--death, new MI (CK-MB), or urgent revascularization at one month--was not different between the two groups, nor were other efficacy outcomes or safety end points. And no subgroup that benefited from either approach could be identified. However, the immediate group did have a hospital stay that was shorter by one day.

"Our study confirms that there is no optimal timing for catheterization in the first 24 hours after presentation for NSTE-ACS and suggests that immediate catheterization/PCI with strong antiplatelet therapy is an acceptable strategy," Montalescot said. "This information may be particularly useful in high-volume centers with a rapid turnover and an activated cath lab when the patient presents," he added.

Earlier Revascularization vs More Time for Meds to Work

Discussant Dr Eric Bates (University of Michigan Medical Center, Ann Arbor) noted that the benefit of immediate revascularization had to be weighed against the idea that delaying PCI for a few hours gives time for antithrombotic medications to work. He pointed out that the background medical therapy in this study was "truly remarkable," with very high doses of clopidogrel on board (some patients were loaded with 900 mg); very high rates of use of aspirin, beta-blockers, statins, and ACE inhibitors; and 60% of patients on abciximab. He suggested therefore that the study was more a test of "facilitated PCI" than primary PCI for NSTE-ACS patients.

He cautioned that although underpowered for clinical events, the immediate group showed a slight trend toward a higher rate of death/MI than the next-day group, and he suggested that it might be better to wait for three to four hours before doing PCI in NSTE-ACS patients to allow medical therapy to reach peak levels.

But Dr Gregg Stone (Columbia University Medical Center, New York), a member of the discussion panel, warned against overinterpreting small trends in clinical events in such a small trial. "We have to take those observations with a grain of salt," he commented.

Consistent With TIMACS

Another panel member, Dr Shamir Mehta (McMaster University, Hamilton, ON), pointed out that the ABOARD results were "very consistent" with his similar trial--TIMACS, which was presented at last year's American Heart Association meeting and reported by heartwire at that time. "The early group in TIMACs also went to the cath lab very early--within three hours--and we found no additional benefit the earlier they went, but there was also no early hazard. These trials suggest that it is not wrong to take patients to the cath lab immediately. This is a perfectly acceptable management strategy."

Interventionalists Won’t Lose Sleep Over These Results

Several panel members expressed relief that they would not have to treat all NSTE-ACS patients with the same urgency as STEMI patients. "A lot of interventionalists will be relieved that they don't have to rush all their non-ST-elevation ACS patients to the cath lab immediately on presentation," Stone said. Another interventional cardiologist on the panel added: "I'm happy that I can get a few extra hours of sleep and won't have to get up for these patients in the middle of the night."