Prevalence and outcomes of stent thrombosis with in-stent calcified nodules: substudy from the REAL-ST registry

Mechanisms of Very Late Stent Thrombosis in Japanese Patients as Assessed by Optical Coherence Tomography

BACKGROUND

Although very late stent thrombosis (VLST) remains an important concern, the underlying etiology and clinical characteristics are not fully elucidated in Japanese patients who undergo intravascular imaging-guided percutaneous coronary intervention (PCI) regularly.

METHODS

We identified 50 VLST lesions (bare-metal stent [BMS] [n = 16], first-generation drug-eluting stent [DES] [n = 14] and newer-generation DES [n = 20]) in patients managed in our institutes. The underlying mechanism of VLST was assessed by optical coherence tomography (OCT), and the major etiology of each lesion was determined. The aim of this study was to explore the mechanisms of VLST of BMSs and DESs in Japanese patients.

RESULTS

The median duration since stent implantation was 10 years (range: 1-20). The most frequent etiology of VLST was neoatherosclerotic rupture (44%), followed by neointimal erosion (24%). Edge disease (10%) and evagination (10%) were similarly observed. Malapposition (8%) was deemed to be acquired late by looking at intravascular imaging from the index procedure. Uncovered struts (2%) and in-stent calcified nodule (2%) were the least frequent etiologies. Regardless of etiology, signs of neoatherosclerosis were present in most lesions (82%). Most patients received single (68%) or dual (8%) antiplatelet therapy or oral anticoagulation alone (4%), whereas a considerable proportion of patients discontinued medication (20%). Regarding the treatment strategy, drug-coated balloon was the most frequent strategy (56%), followed by implantation of newer DESs (34%).

CONCLUSIONS

Various mechanisms have been identified in Japanese patients with VLST. In these patients, biological responses seemed to be more relevant than the index procedure-related factors.

Lifetime management of severely calcified coronary lesions: the treatment algorithm focused on the shape of calcification

The concept of lifetime management has not been discussed in the field of percutaneous coronary intervention (PCI), because the durability of drug-eluting stent (DES) is considered to be long enough for most patients. Furthermore, even if in-stent restenosis occurs, the treatment for in-stent restenosis is simple in most cases. On the other hand, the long-term clinical outcomes after DES implantation are worse in severely calcified coronary lesions than in non-calcified lesions. Moreover, the treatment for in-stent calcified restenosis or restenosis due to stent underexpansion is not simple. The concept of lifetime management of severely calcified lesions may be necessary like that of aortic stenosis. Recently, several algorithms have been published in PCI to severely calcified lesions, partly because of the emergence of IVL. These algorithms focus on the selection of cracking and debulking devices for the preparation of stenting. However, the optimal stent expansion does not guarantee the long-term patency, when the target lesion includes calcified nodules. Stent restenosis due to calcified nodules is difficult to manage. In this review article, we propose the algorithm for severely calcified lesions focused on the shape of calcification. We do not need to hesitate stenting when multiple cracks on circumferential calcification are observed by intravascular imaging devices. However, DCB may be an option as final device in some situations, when lifetime management of severely calcified lesions is considered.

Impact of calcified nodule on target lesion failure after stent implantation in hemodialysis patients

BACKGROUND

Little is known about intravascular imaging predictors of cardiac events after drug-eluting stent (DES) implantation in hemodialysis (HD) patients. We aimed to reveal the association between calcified nodules (CN) and target lesion failure (TLF) in HD patients after DES implantation.

METHODS

We enrolled 114 HD patients who underwent DES implantation between October 2016 and October 2020. The patients were divided into a CN group (39%, 44 patients) and a non-CN group (61%, 70 patients). The primary endpoint was the incidence of TLF, including cardiac death, target vessel myocardial infarction, and clinically driven target lesion revascularization.

RESULTS

HD duration was longer, and the calcium burden was higher in the CN group than in the non-CN group. Over a median follow-up of 607 days [interquartile range: 349-965 days], the cumulative incidence curve showed that the CN group had a significantly higher incidence of TLF than the non-CN group (31.8% vs. 11.4% within 3 years, p = 0.008).　On Fine-Gray sub-distribution hazard model analysis, the CN group was associated with an increased rate of TLF (hazard ratio [HR]: 2.86; 95% confidence interval [CI]: 1.21-6.75, p = 0.016). An in-stent CN was observed in 73% of the lesions with target lesion revascularization in the CN group, whereas no in-stent CN was observed in the non-CN group (p = 0.026).

CONCLUSIONS

CN was an independent predictor of TLF in patients undergoing HD. In-stent CN was an important cause of TLF after DES implantation in CN lesions in HD patients; therefore, a different strategy should be considered for treating the lesions.