CHICAGO – Delaying stent implantation in patients with ST-segment elevation myocardial infarction failed to reduce the rate of mortality, heart failure, myocardial infarction, or repeat revascularization, compared with conventional percutaneous intervention in the randomized, controlled DANAMI 3-DEFER trial.
Among 1,215 patients with ST-segment elevation MI (STEMI) who were randomized to receive either standard primary percutaneous coronary intervention (PCI) with immediate stent implantation or deferred stent implantation 48 hours after the index procedure, the rate of the primary composite endpoint of all-cause mortality, hospital admission for heart failure, recurrent infarction, or any unplanned revascularization of the target vessel within 2 years was 18% in the immediate treatment group and 17% in the deferred stent implantation group, a nonsignificant difference, Dr. Henning Kelbæk reported at the annual meeting of the American College of Cardiology.
Dr. Henning Kelbæk
Procedure-related myocardial infarction, bleeding requiring transfusion or surgery, contrast-induced nephropathy, or stroke occurred in 5% and 4% of patients in the groups, respectively, he said.
Although some might be relieved to know there won’t be a need for doing a second procedure, the findings are a disappointment in that preliminary findings suggested a benefit when stenting is delayed for several hours to several days after angioplasty, said Dr. Kelbæk of Roskilde Hospital (Denmark).
The thinking was that medication given during the delay might help diminish residual blood clots, thereby reducing the risk of distal embolization, which occurs in 7% of cases, and which can occur despite successful treatment of the culprit artery lesion by primary PCI with stent implantation, he explained, noting that slow- or no-flow occurs in 10% of cases.
It is possible that the study may not have been large enough to detect overall differences in the two treatment groups. It is also possible that patients at the highest risk for developing another arterial blockage could potentially benefit from a delay, especially given that a small but significant improvement in left ventricular function was detected 18 months after treatment among patients who underwent deferred stenting (left ventricular ejection fraction, 60% vs. 57% in the immediate treatment group), but such patients were excluded from DANAMI 3-DEFER (the Third Danish Study of Optimal Acute Treatment of Patients with ST-segment Elevation Myocardial Infarction: Deferred stent implantation in connection with primary PCI), he said.
He added that he and his coinvestigators will “look carefully for possible ‘hypothesis-generating’ findings in subsets of patients – both those who might have benefited from the deferred-treatment strategy and, equally important, those in whom this strategy might have worsened their condition.”
Patients were enrolled into DANAMI 3-DEFER during March 2011–February 2014 at four primary PCI centers in Denmark. All were adults with acute onset symptoms lasting 12 hours or less, and ST-segment elevation of 0.1 mV or more in at least 2 contiguous electrocardiographic leads, or newly developed left bundle branch block. Those in the deferred treatment group were only randomized to that group if stabilized flow could be obtained in the infarct-related artery. Median follow-up was 42 months.
The findings indicate that at this point, deferred stent implantation cannot be recommended as a routine procedure for STEMI patients treated with primary PCI, Dr. Kelbæk concluded. The findings were published online simultaneously with the presentation (Lancet. 2016 Apr 3. doi: 10.1016/S0140-6736[16]30072-1).
The DANAMI-3-DEFER trial was funded by the Danish Agency for Science, Technology and Innovation and Danish Council for Strategic Research. Dr. Kelbæk reported having no disclosures.