INNOVATION Study Suggests Safety of Deferred Stenting

Deferring stenting in patients with STEMI may safely reduce ultimate infarct size and microvascular obstruction, especially in patients with anterior wall MI, according to findings presented in a Featured Clinical Research session. 

Cheol Woong Yu, MD, PhD, of Korea University Anam Hospital in Seoul, South Korea, presented data from the INNOVATION trial, which examined the impact of primary vs. deferred stenting. Yu and colleagues screened all STEMI patients presenting at two centers in Korea within 12 hours of symptom onset. Patients had ST-segment elevation ≥ 2 mm in two or more continuous EKG leads.

After achieving TIMI 3 flow, patients were randomized to receive either immediate (n = 52) or deferred stenting with intent to stent 3 to 7 days later (n = 52).

For the primary endpoint of infarct size as percentage of left ventricular volume at 30 to 35 days after primary reperfusion as assessed by cardiac MRI, deferred stenting showed a strong tendency to reduce infarct size, as well as size and incidence of microvascular obstruction (Figure).


Differences between groups were more pronounced among patients with anterior wall MI for all parameters, favoring the deferred strategy (P = .025 for infarct size; P = .013 for microvascular obstruction size; P = .025 for microvascular obstruction incidence).

Additionally, mean peak CK-MB measurements were smaller in the deferred vs. the immediate stenting group (199 vs. 260; P = .039), and more deferred than immediate stenting patients reached myocardial brush grade 3 (39 vs. 28; P = .057) and TIMI myocardial perfusion grade 3 (28 vs. 18; P = .085). Incidence of slow or no reflow was similar in each group.

Safety of deferred stenting

“Aggravation of residual stenosis and dissection over time in the deferred stenting group was not significant between the beginning of the second procedure and the first procedure,” Yu said. “No recurrence of ischemia was observed in the deferred stenting group; accordingly, no urgent PCI [was required] in the deferred stenting [group].”

Still, the study had several limitations, according to Yu. The small sample size meant the study was not powered to demonstrate efficacy of deferred stenting. Furthermore, six patients originally assigned to deferred stenting crossed over to the immediate procedure group, which may have contributed to the absence of recurrent ischemia or urgent revascularization.

“Deferred stenting could be performed without additional risk of adverse events with meticulous monitoring during the initial procedure, compared with immediate stenting,” Yu concluded.


  • Yu reports grant or research support from Isu Abxis Co., Ltd, the Korean Society of Interventional Cardiology, Sejong Medical Research Institute and Terumo Corporation. 



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