Final IVUS-measured minimal stent area tied to adverse events in left main CAD

WASHINGTON — A small final minimal stent area measured by IVUS after PCI in patients with left main CAD may be associated with adverse outcomes in the long term, according to data presented at the American College of Cardiology Scientific Session.

Researchers performed a substudy of the EXCEL trial to evaluate 3-year outcomes of 633 patients who underwent IVUS-guided PCI with a cobalt-chromium everolimus-eluting stent (Xience, Abbott Vascular). Of those, 504 were included in the final analysis.

Akiko Maehara, MD, director of the Intravascular Imaging Core Laboratory and MRI Core Laboratory at the Cardiovascular Research Foundation Clinical Trials Center and assistant professor of medicine at Columbia University College of Physicians and Surgeons, reported data from the substudy here.

Maehara noted that characteristics did not significantly differ between patients in the low, intermediate and high tertiles of minimal stent area as measured by IVUS. However, left main stent diameter was lower in patients in the lowest tertile of minimal stent area vs. those in the intermediate and higher tertiles (3.3 mm vs. 3.5 mm and 3.7 mm, respectively; P < .01).

Additionally, patients in the lowest minimal stent area tertile vs. the highest tertile had smaller minimal stent area (7.5 mm² vs. 12.5 mm²; P < .01), smaller vessel area at the minimal stent area (19.3 mm² vs. 24.8 mm²; P < .01), smaller mean stent area (8.9 mm³/mm vs. 13.6 mm³/mm; P < .01) and smaller mean vessel area (19 mm³/mm vs. 25.1 mm³/mm; P < .01) in the left main segment.

At 3 years, the primary outcome of death, MI or stroke occurred in more patients in the group with the smallest minimal stent area vs. the largest minimal stent area (19.4% vs. 9.6%; P = .01). Overall rates of all-cause death (13.8% vs. 5.2%; P = .01), MI (10.5% vs. 3.7%; P = .02) and stent thrombosis (3.1% vs. 0%; P = .03) were also higher in the group of patients with the smallest minimal stent area vs. the largest area.

Similar results were seen when evaluating left main-related outcomes only, Maehara said. The rate of the post-hoc endpoint of cardiac death, MI, stent thrombosis or ischemia-driven revascularization was higher in patients with the smallest IVUS-measured minimal stent area (19.7% vs. 11.3%; P =. 05), as were the rates of cardiac death (6.8% vs. 1.9%; P = .03), left main-related MI (9.4% vs. 3.1%; P = .03) — especially spontaneous MI (4.5% vs. 0.6%; P = .03) — and left main-related stent thrombosis (3.1% vs. 0%; P = .03).

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In adjusted models, the researchers found that larger final IVUS-measured minimal stent area was related to lower event rates within 3 years (adjusted HR = 0.89; 95% CI, 0.8-0.99), according to Maehara. Moreover, distal left main lesion location predicted outcomes (adjusted HR = 2.1; 95% CI, 1-5.33). Using this as an endpoint, the researchers concluded that the cutoff value of the left main minimal stent area is 9.8 mm².

Maehara also noted that 68% of PCI cases were performed using IVUS guidance, and in half of these cases, the procedure was changed by IVUS findings. – by Melissa Foster

Reference:

Maehara A. Abstract 903-08. Presented at: American College of Cardiology Scientific Session; March 17-19, 2017; Washington, D.C.

Disclosure: Maehara reports receiving grant or research support and/or consultant fees or honoraria from Boston Scientific, OCT Medical Imaging and St. Jude Medical.