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Implantation strategy may reduce incidence rate of scaffold thrombosis
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Bioresorbable vascular scaffolds appear to have a thrombosis rate as high as 3% over 1 year, but in a new study this rate was decreased by 70% with use of a bioresorbable vascular scaffold-specific implantation strategy.
For a multicenter registry study, researchers evaluated 1,305 consecutive patients (mean age, 64 years) who received a bioresorbable vascular scaffold (BVS) to treat de novo lesions in the context of acute or stable coronary syndrome at two participating German hospitals and two Swiss hospitals from May 2012 to December 2014 (1,870 BVS; mean, 1.4 ± 0.8 BVS/patient). The researchers evaluated clinical/procedural characteristics, mortality and data on scaffold thrombosis, including incidence rates, angiographic characteristics and possible mechanisms. The researchers also sought to identify clinical and angiographic predictors of scaffold thrombosis. Follow-up evaluations occurred at 485 days (range, 312-652 days).
Overall, there were 36 definite, four probable and two possible incidences of scaffold thrombosis. Of those incidences, 21 (50%) occurred early, 10 (24%) occurred within 1 day and were classified as “acute,” and 11 (26%) occurred within 1 month and were classified as “subacute.” Late scaffold thrombosis occurred in 11 (26%) patients, and very late scaffold thrombosis occurred in 10 (24%).
The 30-day thrombosis rate was 1.8% and the 12-month rate was 3%.
Of the 42 patients with scaffold thrombosis, the following presentations were observed: 40 with ACS or sudden cardiac death; 22 with STEMI; nine with non-STEMI; and three with unstable angina. Multivariable analysis revealed independent associations between scaffold thrombosis and ostial lesions (P = .049) and impaired left ventricular ejection fraction (P = .019). Discontinuation of dual antiplatelet therapy occurred in nine patients who had scaffold thrombosis, and in six of these patients this suspension was premature. A strong association was seen between lower postprocedural minimum lumen and reference vessel diameters and scaffold thrombosis (P < .0001). A rapid increase in scaffold thrombosis risk was identified for patients with postprocedural minimum lumen diameters of less than 2.4 mm (for BVS measuring 2.5-3 mm) and 2.8 mm (for 3.5 mm BVS).
The researchers conducted a comparison of the outcomes of patients treated later in the study with a BVS-specific implantation protocol vs. patients treated with a standard protocol (early experience). The BVS-specific protocol was intended to address the issue of incomplete BVS expansion. The researchers found that the Kaplan-Meier incidence of scaffold thrombosis at 1 month was 2.7% among patients in the early experience group and 1% in the BVS implantation protocol group; at 12 months, the incidence of scaffold thrombosis was 3.3% for patients in the early experience group and 1% in the BVS implantation protocol group (log rank P = .023). The significance of this effect persisted after adjustment for multivariable propensity score (HR = 0.19; 95% CI, 0.05-0.7).
“In a multicentric, all-comer cohort of consecutive patients, [scaffold thrombosis] is a particularly severe event with a 12-month incidence as high as 3%, but it can be addressed by taking particular precautions at the time of implantation,” the researchers wrote. “Further studies are needed to confirm the predictive value of measuring minimum lumen diameter as a guide to clinical outcomes following implantation of coronary bioresorbable scaffolds in patients with ischemic heart disease.” – by Jennifer Byrne
Disclosure: Some of the researchers report financial ties with Abbott Vascular.
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