NEW YORK (Reuters Health) – Direct stent implantation without balloon dilatation can be safely performed in some patients undergoing percutaneous coronary intervention for ST-segment elevated MI (STEMI), and the strategy may improve outcomes, according to a report in the American Journal of Cardiology online September 12.

“Direct stenting in eligible lesions in patients with STEMI may result in improved TIMI flow, ST-segment resolution, and survival, thereby confirming and extending the results of previous smaller studies,” the authors report.

Those previous studies, explain Dr. Martin Moeckel, at Charite Campus Virchow-Klinikum in Berlin, Germany, and an international team, had suggested that direct stenting in STEMI is feasible and may reduce microcirculatory dysfunction by causing less distal embolization.

In the current study, the investigators report outcomes at 1-year from the HORIZONS-AMI trial, in which 2,528 STEMI patients underwent stenting of a single native coronary artery lesion. Direct stenting without balloon dilatation was attempted at the discretion of the operator in 698 of the patients and was successful in 677.

Rates of postprocedural TIMI grade 3 flow were significantly higher in the direct-stenting group (93.3%) than the conventional-stenting group (86.1%; p<0.0001), the team found, and rates of ST-segment resolution at 60 minutes were also greater (74.8% vs 68.9%; p=0.01).

At 1-year follow-up, there was no significant difference in major adverse cardiovascular events with direct or conventional stenting (9.0% vs 10.7%; p=0.21), and rates of target vessel revascularization were identical at 4.8% with both stenting strategies, according to the report.

However, all-cause mortality was significantly reduced in the direct stenting group (1.6% vs 3.8%; p=0.01), the authors report. On multivariate adjustment for baseline differences, direct stenting was still associated with reduced all-cause mortality risk (hazard ratio 0.42; p=0.02).

“Although the mechanism was not directly assessed in the present study,” Dr. Moeckel and colleagues comment, “improvements in microcirculatory perfusion from reduced distal embolization and slow reflow may underlie the observation of improved survival with direct stenting, consistent with the greater rate of ST-segment resolution observed.”

Nonetheless, they caution that unknown confounders might have affected the findings despite multivariate adjustment, so “the results of the present study should be considered exploratory and hypothesis generating.”

Reference:

Comparison of Direct Stenting With Conventional Stent Implantation in Acute Myocardial Infarction

Am J Cardiol 2011.