Immediate versus delayed intervention for patients with acute coronary syndromes

For some patients with acute coronary syndromes, the strategy of immediate intervention at a medical centre does not appear to result in differences in outcomes in comparison with an intervention performed the next working day, according to a study in the 2 September issue of JAMA.

"The optimal intervention in the treatment strategy of patients presenting with acute coronary syndromes without ST-segment elevation (NSTE-ACS) has been debated for years," the authors write in background information for the study. "Numerous studies, randomised trials, and meta-analyses have investigated the potential benefits of invasive over conservative strategies, and most have suggested a prolonged advantage of an invasive approach for the prevention of death of myocardial infarction [MI; heart attack], particularly among high-risk patients."

Gilles Montalescot, MD, PhD, of the Institut de Cardiologie, Centre Hospitalier Universitaire Pitié-Salpêtrière, Paris, and colleagues from The Angioplasty to Blunt the Rise of Troponin in Acute Coronary Syndromes Randomized for an Immediate or Delayed Intervention (ABOARD) study evaluated data from 352 patients with acute coronary syndromes at 13 high-volume medical centres in France with 24-hour facilities for treatment of primary percutaneous coronary intervention (e.g. balloon angioplasty or stent placement) from August 2006 through September 2008. The patients, all of whom had acute coronary syndromes without ST-segment elevation (a certain pattern on the electrocardiogram [ECG]), were randomised to undergo an immediate invasive strategy or an invasive strategy scheduled on the next working day. The primary end point was the peak troponin value (biomarker indicating heart muscle involvement or damage) during hospitalisation. The key secondary end point was the composite of death, myocardial infarction, or urgent revascularization at one-month follow-up.

"Time from randomisation to sheath insertion [beginning of the catheterisation procedure] was 70 minutes with immediate intervention vs. 21 hours with delayed intervention," the authors report. "Troponin I release, as reflected by peak value collected during hospitalisation, did not differ between the two strategies in the immediate and delayed intervention groups. The probability of MI as measured by the curves of troponin peak values was similar with either strategy." The authors also found that "the key secondary end point was observed in 13.7 percent of the group assigned to receive immediate intervention and 10.2 percent of the group assigned to receive delayed intervention. The other end points, as well as major bleeding, did not differ between the two strategies." The authors note that hospital stay was significantly reduced with the immediate strategy compared with the delayed intervention strategy.

"This study demonstrates the feasibility of immediate catheterisation and revascularisation in patients who present with NTSE-ACS but does not show that this strategy is superior to catheterisation scheduled on the next working day," the authors write. "Thus, rapid or urgent catheterisation appears preferable in high-risk or unstable patients, while the benefit in other situations may be limited to practicality and length of hospital stay," the authors conclude.

(Source: JAMA/Archives: JAMA: September 2009)