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In selected patients with ST-segment elevation myocardial infarction (STEMI), deferring stenting for up to 12 hours after initial revascularization reduces the risk of ‘no-reflow’ and increases myocardial salvage compared with immediate stenting, according to a proof-of-concept study published online February 27, 2014, ahead of print in the Journal of the American College of Cardiology.

Results of the DEFER-STEMI trial were originally presented at the American College of Cardiology/i2 Scientific Session in San Francisco, CA in March 2013.

In the single-center all-comers study, investigators led by Colin Berry, MD, of the University of Glasgow (Glasgow, Scotland), randomized 101 STEMI patients with at least 1 risk factor for no-reflow to deferred stenting (with intention to stent within 4-16 hours; n = 52) or conventional treatment with immediate stenting (n = 49). All patients had already been successfully reperfused (TIMI 3 flow) with aspiration thrombectomy and/or balloon angioplasty and were receiving antithrombotic therapy.

The median time until the second procedure in the deferred stenting group was 9 hours (range 6-12 hours). During that time, treatment included continuous IV infusion of glycoprotein (GP) IIb/IIIa inhibitor therapy and administration of subcutaneous low-molecular-weight heparin. 

No/Slow-Reflow Cut More Than Fourfold

The incidence of no/slow-reflow post stenting, the primary endpoint, was greatly reduced in the deferred stenting group and the percentage of patients with a final TIMI myocardial blush grade of 3 was higher. Additionally, thrombotic events and distal embolization were less frequent after deferred stenting (table 1). 

Table 1. Angiographic Outcomes

 

Two days after STEMI, gadolinium-enhanced MRI showed a higher rate of microvascular obstruction in the immediate stenting group vs the deferred stenting group. At 6 months, both myocardial salvage and myocardial salvage index were greater with the deferred strategy (table 2).

Table 2. MRI Findings

^a At 2 days post MI.
^b Defined as the difference between the initial area-at-risk assessed by T2-weighted MRI at baseline and the final infarct size revealed by contrast-enhanced MRI at 6 months.
^c  Defined as infarct size at 6 months indexed to the initial area-at-risk.

In addition, in the deferred group, the approach to PCI differed at the second procedure (ie, stenting) compared with immediate stenting, even for the same operators. Maximum stent diameter and length were both larger, indicating that the vessel dimensions had increased, likely due to attenuation of coronary artery tone with time from reperfusion, the authors say. 

In terms of safety, 2 patients in the deferred stenting group suffered a STEMI prior to the second intervention. Both underwent repeat angiography within 30 minutes and received bailout stenting, with no further complications. There were no in-hospital deaths, bleeding events, or cases of contrast-induced nephropathy, although more contrast was used in the deferred stenting group (P < 0.0001).

Over a mean follow-up of 352 days, the incidence of recurrent MI was similar between groups. Three patients in the deferred stenting group and 1 in the immediate stenting group experienced a NSTEMI, while 2 additional patients in the latter group were hospitalized for unstable angina, with one undergoing PCI.

‘Potential New Paradigm’?

“Our strategy of deferred stenting in selected STEMI patients with risk factors for no-reflow represents a potential new paradigm,” the authors assert. “The strategy involves a balance between competing risks and benefits that merits prospective evaluation in a large clinical trial.” 

In an accompanying editorial, David Antoniucci, MD, of Careggi Hospital (Florence, Italy), observes that the strategy appears safe, and if it is validated and adopted, “[GP] IIb/IIIa inhibitors will assume again a central role in primary PCI not only for the reduction of thrombotic burden but also for the prevention of new thrombotic occlusion.”

Moreover, the trial findings are clinically relevant, Dr. Antoniucci writes, since “at least half of patients with AMI could be eligible for a deferred stenting strategy.” He acknowledges, however, that “the increased costs of a second procedure should be balanced by the demonstration of improved clinical outcome [in] a large clinical randomized trial.” 

Deferred Stenting Not the Best Answer 

“We have run into a sort of wall” when it comes to minimizing no-reflow, Jeffrey W. Moses, MD, of NewYork-Presbyterian Hospital/Columbia University Medical Center (New York, NY), told TCTMD in a telephone interview. So far, no method has provided substantial improvement, including local drug infusion and proximal and distal protection, he observed.

“This [study] proves that there is definitely room for improvement in terms of diminishing thrombus burden,” Dr. Moses said, but the deferred strategy presents “enormous issues in terms of cost and potential bleeding risk.” Even though patients had radial access, radial trials have shown that “the most consequential bleeding is not access site bleeding,” he pointed out. Although prolonged GP IIb/IIIa use plays some role in dissolving thrombus, he said that on balance, the extra antithrombotic therapy is a negative because invariably it leads to increased bleeding. “That’s why bivalirudin has become standard of care,” he noted.  

“This is one of the best ways of reducing no-reflow we’ve seen so far,” Dr. Moses acknowledged, “but from the point of view of logistics, cost, and complications, it would be much preferable to achieve the same end in a single [PCI] setting.”

Study Details

Patients’ mean age was 60 years; 69% were male. Randomized patients had to be catheterized via radial access and meet at least 1 of the following inclusion criteria: clinical history (previous MI, age ≥ 65 years, and symptoms lasting longer than 6 hours), culprit coronary artery abnormalities, or clinical signs of acute microvascular injury after initial reperfusion.

Note: Study coauthor Philippe Généreux, MD, is a faculty member of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

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Sources:
1. Carrick D, Oldroyd KG, McEntegart M, et al. A randomized trial of deferred stenting versus immediate stenting to prevent no- or slow-reflow in acute ST-elevation myocardial infarction (DEFER-STEMI). J Am Coll Cardiol. 2014;Epub ahead of print.

2. Antoniucci D. Put off till tomorrow what you can do today. J Am Coll Cardiol. 2014;Epub ahead of print.

 

 

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