Original: A Randomized Trial of Deferred Stenting versus Immediate Stenting to Prevent No-or Slow Reflow in Acute ST-Elevation Myocardial Infarction (DEFER-STEMI). Reference: David Carrick et al. J Am Coll Cardiol. 2014. Epub ahead of print.
No Reflow physiopathology involves microvascular obstruction secondary to thrombus embolization, spasm or microvascular thrombosis, and happens in approximately 10% of PCI procedures.
The rationale behind deferred stenting during PCI was try to reduce no reflow by allowing time to reduce thrombus burden and recover microvascular function. Study hypothesis was that once normal flow to the artery was restored, deferral of stenting with an intention to stent 4 to 16 hrs. later would reduce the occurrence of no reflow.
Treatment protocol to defer stenting included transfer to the Coronary Care Unit under continuous intravenous infusion of Tirofiban 0.15 µg/kg/min) and administration of subcutaneous enoxaparin (1 mg/kg 12 hourly) for up to 16 hours. Of 411 patients undergoing PCI between March and November 2012 in a center, 101 were randomized to immediate stenting (n=49) or deferred stenting (n=52).
Post stenting no/slow reflow incidence (primary end point) was significantly lower in the deferred stenting group (OR 0.16, IC 95% 0.04 to 0.59; p=0.006). Distal embolization and intra procedural thrombotic events were also less frequent in the deferred group. The deferred group also showed a significant reduction of thrombus angiographic evidence between first and second procedures (98.1% vs. 62.7%; p<0.0001).
Secondary end points included MRI evaluation at 2 days and 6 months after infarction, which showed greater left ventricular mass, salvaged with the deferred stenting strategy. Two patients randomized to deferred stenting presented recurrent ST myocardial infarction prior to second procedure. They both received emergency PCI with no further complications.
Although there was a greater volume of contrast used in the deferred group (278 ml vs 205 ml; p<0.0001), no cases of contrast nephropathy were observed.
Conclusion
Deferred stenting strategy reduced no flow rate and increased myocardial salvage percentage compared to the conventional strategy of PCI with immediate stenting
Editorial Comment
This radical change of strategy seems no to be viable for all patients referred to PCI; in fact, only 25% of evaluated patients were finally randomized. Selection was not only based on the several inclusion and exclusion criteria, but also on the fact that more than a third of the cardiologists in the center were this study took place simply randomized no patients.
Although these treatments also increase the risk of bleeding, no bleeding problems occurred in the deferred group probably because radial artery access was used in all patients. More bleeding events could be expected due to anti thrombotic medication during deferral. However, no bleeding complications occurred in the deferred group probably because radial artery access was one of the inclusion criteria. Finally, a randomized multicenter study that tested this hypothesis should analyze cost, bound to be higher because of a second procedure.
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