Optimized Implantation Strategy Reduces Bioresorbable Coronary Scaffold Thrombosis Incidence

In a study conducted at 2 German and 2 Swiss hospitals, the 12-month incidence of scaffold thrombosis (ScT) reached 3%, although this rate was significantly reduced when an optimized implantation strategy was implemented.¹

Previous studies, such as clinical evaluations of the ABSORB trials,² have suggested an elevated incidence of bioresorbable vascular scaddold (BVS) thrombosis. Researchers of the present study investigated occurrence rates, clinical and angiographic characteristics, and possible mechanisms of ScT in all-comer patients undergoing BVS implantation.

The analysis was limited to operators who consistently complied with the following implantation strategy guidelines: “pre-dilation with noncompliant balloon up to the same size as the reference vessel diameter (RVD), BVS implantation only in case of full expansion of the noncompliant percutaneous transcatheter coronary angioplasty balloon as demonstrated by angiography in 2 orthogonal planes, implantation of a BVS of the same size as the RVD at 10 to 12 atm, and post-dilation with noncompliant balloons up to a maximum of 0.5 mm larger at 14 to 16 atm.”

“The implantation protocol used was an independent predictor of ScT, and, in line with results from DES [drug eluting stents], treatment of ostial lesions and low LVEF [left ventricular ejection fraction] were also identified as possible predisposing factors,” the authors wrote in their study, published in the Journal of the American College of Cardiology.

“Although it is acknowledged that the other possible predictors of ScT (eg malapposition) exist, the present data emphasize the importance of vessel sizing and of the implantation techniques in reducing the rate of this complication.”

A total of 1305 patients (mean age: 64 years; 78% male)  received 1870 BVS implantations. Researchers examined clinical and procedural characteristics, mortality rates, and ScT data at 485 days.

They observed ScT in 42 patients overall. The incidence of probable and definite ScT at 30 days was 1.8% and at 12 months was 3.0%, without differences among centers (P=.60). Twenty-two of the ScTs (52%) presented as ST-segment elevation myocardial infarction and 6 (17%) presented as sudden cardiac death. Nine (21%) of the ScTs occurred after suspended dual antiplatelet therapy, and 6 of these cases had suspended the therapy prematurely.

A multivariable analysis demonstrated that ostial lesions (P=.049) and impaired LVEF (P=.019) were independently associated with ScT. The lower post-procedural minimum lumen diameters were staples of ScT (all P<.0001). ScT risk increased rapidly for post-procedural minimum lumen diameters below 2.4 mm for the 2.5 mm to 3.0 mm BVS, and below 2.8 mm for the 3.5 mm BVS.

When researchers implemented a BVS-specific implantation strategy, the 12-month ScT rates decreased from 3.3% to 1.0%, and this drop remained significant after adjusting for multivariable propensity score (hazard ratio: 0.19; 95% confidence interval: 0.05-0.70; P=.012).

Future studies should aim 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.

References

1. Puricel S, Cuculi F, Weissner M, et al. Bioresorbable Coronary Scaffold Thrombosis: Multicenter Comprehensive Analysis of Clinical Presentation, Mechanisms, and Predictors. J Am Coll Cardiol. 2016; 67(8):921-31. doi: 10.1016/j.jacc.2015.12.019.
2. Kraak RP, Hassell ME, Grundeken MJ, et al. Initial experience and clinical evaluation of the Absorb bioresorable vascular scaffold (BVS) in real-world practice: the AMC Single Centre Real World PCI Registry. EuroIntervention. 2015;10(10):1160-1180. doi: 10.4244/EIJY14M08_08.