Novel Devices Present New Treatment Options for STEMI

Interventionalists today have a widening array of stents to choose from when treating STEMI patients. During a session at TCT 2015, three presenters examined new data on a novel BMS, a bioresorbable scaffold and contemporary DES.

Mesh-covered stent

TCT Course Director Gregg W. Stone, MD, of NewYork-Presbyterian Hospital/Columbia University Medical Center, New York, N.Y., presented on the MGuard polymer mesh-covered BMS (InspireMD) in STEMI patients and the evolution of outcomes compared with conventional stents in the MASTER I and MASTER II trials.

MASTER I was “really positive in many regards,” he said. Rates of complete ST-segment resolution were higher after PCI with MGuard compared with BMS or DES. The reduction in mortality was close to being statistically significant with MGuard at 30 days and 1 year, with the tradeoff being higher TLR at 1 year with MGuard. 

While enrollment in MASTER II was voluntarily suspended after 310 patients due to a higher than expected rate of stent dislodgement with MGuard Prime, no patients experienced an endpoint event arising from stent dislodgement, he said.

Pooling data from MASTER I and MASTER II created a population of 743 randomized patients. Although stent failure was higher with MGuard than conventional stents in the pooled analysis (5.6% vs. 1.3%; P = .03), angiographic success was higher with MGuard (91.6% vs. 84.9%; P = .005), Stone reported. Additionally, there was a trend toward higher ST-segment resolution with MGuard (57.5% vs 50.7%; P = .07). One-year cardiac mortality was lower (0.8% vs. 2.7%; P = .052), but ischemia-driven TLR was higher than with conventional stents (10.3% vs. 1.4%; P < .0001).

The substantially higher clinical restenosis rates observed with MGuard reflect the fact that it is a “high-profile BMS,” Stone said. “An adequately powered randomized trial with a DES version of the MGuard is warranted to determine whether outcomes of patients with STEMI undergoing primary PCI are improved with this novel
device.”

Bioresorbable scaffold

Patrick W. Serruys, MD, PhD, of Imperial College, London, reemphasized 6-month results of the ABSORB STEMI TROFI II study. The data were previously presented at the European Society of Cardiology Congress in September 2015. 

For the study, the researchers randomized 191 STEMI patients to receive the Absorb Bioresorbable Vascular Scaffold (Abbott Vascular; n = 95) or Xience Xpedition (Abbott Vascular; n = 96). 

Serruys pointed out that previously there was “no head-to-head comparison to assess the early phase of the arterial healing response to a bioresorbable scaffold implantation in patients with STEMI relative to the healing of everolimus metallic DES.”

Nominal scaffold/stent diameter was higher with Absorb BVS compared with Xience Xpedition (mean 3.25 mm vs. 3.12 mm; P = .005) and post-dilatation was more frequent (50.5% vs. 25.5%; P < .001). Noninferiority was met for Absorb BVS vs Xience Xpedition for the primary endpoint of optical frequency domain imaging-derived healing score (1.74 vs. 2.8; P < .001 for noninferiority). There was a trend toward better healing in the BRS group (P for superiority = .053). Clinical event rates were low at 6 months.

“Absorb in the setting of STEMI resulted in nearly complete arterial healing,” Serruys said. However, “These findings cannot be extrapolated to other bioresorbable devices with different materials or strut thickness.”

A new default strategy

Second-generation DES “have overcome the problem of incomplete healing seen with first-generation stents,” Tullio Palmerini, MD, of the University of Bologna, Italy, said during a presentation.

Palmerini provided an overview of contemporary studies that examined the use of second-generation DES in STEMI. Regardless of whether they have permanent or bioresorbable polymers, second-generation devices “appear not only more effective but even safer than BMS in patients with STEMI,” he said. “For these reasons, [second-generation DES] should be considered as the default strategy in STEMI, provided that there are no contraindications to prolonged DAPT.”  

Disclosures:

• Palmerini reports receiving consultant fees/honoraria from Abbott Vascular.
• Serruys reports no relevant conflicts of interest.
• Stone reports relationships with multiple device companies.