Impact of strut-vessel distance and underlying plaque type on the resolution of acute strut malapposition: serial optimal coherence tomography analysis after everolimus-eluting stent implantation.

The consequences of acute strut malapposition in everolimus-eluting stents (EES) are unknown. This study investigated the impact of strut-vessel (S-V) distance and plaque type underneath acute strut malapposition on the mid-term vessel response in EES. Twenty-nine patients (35 EES) underwent optical coherence tomography (OCT) immediately after percutaneous coronary intervention and at 8-month follow-up. S-V distance and plaque type (lipid, calcified, or fibrous) underneath acute strut malapposition were evaluated. Follow-up OCT classified acute strut malapposition as persistent or resolved. The S-V cutoff value for predicting resolved strut malapposition and the incidence of intra-stent thrombi were determined. Among 569 cases of acute strut malapposition, involving 29,168 struts, 139 (24.4 %) were persistent. Mean S-V distance was significantly longer in persistent than in resolved strut malapposition (600 ± 294 vs. 231 ± 95 μm; P < 0.0001). S-V distance ≤380 μm was the best cutoff value for predicting resolved strut malapposition (sensitivity 93.5 %, specificity 69.8 %, area under curve 0.878). Acute strut malapposition with S-V distance ≤380 μm remained persistent more frequently over lipid/calcified than over fibrous plaques (lipid: 13.4 %, calcified: 18.2 %, fibrous: 4.2 %; lipid vs. fibrous, P = 0.001; calcified vs. fibrous, P = 0.02). Intra-stent thrombi were more frequent in stents with ≥1 persistent strut malapposition than in those without [4/11 stents (36.3 %) vs. 0/24 (0 %); P = 0.006]. Lipid and calcified plaque, together with S-V distance, affect the resolution of acute strut malapposition in EES. Persistent strut malapposition is associated with the presence of thrombi at follow-up, which could be the substrate for late stent thrombosis.