Acute treatment of ST-segment elevation myocardial infarction (STEMI) with either deferred stent implantation or ischemic postconditioning failed to reduce adverse events, according to 2 studies of the DANAMI (Danish Study of Optimal Acute Treatment of Patients with ST-segment Elevation Myocardial Infarction) 3 trial program.
Investigators Henning Kelbæk, MD, of the Roskilde Hospital, Roskilde, Denmark, and Thomas Engstrøm, MD, DMSci, PhD, of the Rigshopitalet University, Copenhagen, each presented 1 of the 2 studies during a late-breaking clinical trial session at the 2016 American College of Cardiology Scientific Sessions & Expo.
According to Dr Kelbæk, patients who have a clot in a large coronary artery are at risk for distal embolization, which occurs in about 7% of all cases, and for having flow disturbed during the manipulation of the STEMI lesion.
“We know that if these things occur, patients have a worse prognosis,” he said during a press conference. “So what we aimed to do was try to impair this prognosis by … delaying the implantation of the stent that might cause disruption of the clot and distal embolization and disturbances of flow. The concept was that if we waited for 48 hours, the clot would have dissolved totally or partially and [caused fewer] complications.”
For the study, Dr Kelbæk and fellow DANAMI 3-DEFER researchers followed 1207 patients for 3.5 years to determine the effect of deferred stenting on the primary end point—a composite of death, heart failure, new myocardial infarction (MI), and retreatment of the same artery.
At follow-up, the primary end point did not differ between deferred and conventional stenting (hazard ratio [HR]:0.99; confidence interval [CI]: 0.75-1.29; P=.92).
In secondary end point analysis, echocardiography performed 18 months after the index procedure demonstrated a higher rate of left ventricular ejection fraction (LVEF) with deferred stenting (60% vs 57%; P=.04).
“Deferring stent implantation in patients with STEMI does not improve the outcome when we follow patients up to 3 years,” Dr Kelbæk concluded. “But it does seem that heart function might be a little better in this group, and it might turn into an improved outcome with time.“
In a separate study, DANAMI 3-iPOST (ischemic postconditioning), Dr Engstrøm and colleagues sought to examine the concept of reducing reperfusion injury with ischemic postconditioning.
During ischemic postconditioning, the occluded artery is first reopened to enable reperfusion, Dr Engstrøm said at the press conference. “Then with an adequately sized balloon, you, after 60 seconds, reocclude the artery to stop reperfusion,” he explained. “After another 30 seconds, you deflate the balloon to enable perfusion to come back.”
As a result, final reperfusion to the myocardium is established in a much more gentle manner, Dr Engstrøm said, which may reduce trauma.
To test this hypothesis, researchers enrolled 1243 STEMI patients and randomly assigned them to receive either conventional percutaneous coronary intervention (n=617) or ischemic postconditioning (n=617).
At follow-up (mean: 37.5 months), event-free survival, the primary end point, did not significantly differ between groups (HR:0.93; P=.66).
Secondary outcomes, including all-cause and cardiovascular mortality, heart failure hospitalization, and recurrent MI, were also similar between groups.
In other analyses, researchers performed echocardiography at 18 months in a subset of patients and found that among those who received postconditioning, there were higher rates of LVEF (52.7% vs 50.8%; P<.05) and LVEF anterior infarcts (49.5% vs 45.9%; P=.04), as well as a higher number of patients with an LVEF >45% (80% vs 72%; P=.015).
- Engstrøm T, Kelbæk H, Helqvist S, et al. LBCT III. The third Danish study of optimal acute treatment of patients with ST-segment elevation myocardial infarction: ipostconditioning during primary PCI. Presented at the 65th Annual Scientific Session and Expo of the American College of Cardiology. April 2-4, 2016; Chicago, IL.
- Kelbæk H, Høfsten DE, Køber L, et al. Deferred vs conventional stent implantation in patients with ST-segment elevation myocardial infarction (DANAMI3-DEFER): an open-label, randomized controlled trial. Lancet. 2016. doi: 10.1016/S01410-6736(16)30072-1.
- Kelbæk H, Køber L, Helqvist S, et al. LBCT III. The third Danish study of optimal acute treatment of patients with ST-segment elevation myocardial infarction: deferred stent implantation in connection with primary PCI. Presented at the 65th Annual Scientific Session and Expo of the American College of Cardiology. April 2-4, 2016; Chicago, IL.