Although the absolute value of shear stress is not sufficient to directly provoke mechanical destruction of the fibrous cap, localized high shear stress might be a trigger of fibrous cap rupture.
The guidewire recrossing point and the location of a stent link at the SB orifice had an influence on the ISA. KBD with optimal conditions under 3D-OCT guidance may reduce SB restenosis.
Background:
Coronary calcification inhibits stent expansion. We sought to establish an intravascular ultrasound–derived calcium score to predict stent underexpansion.
Methods:
This is a retrospective observational study including de novo lesions that underwent intravascular ultrasound–guided stenting and had maximum superficial calcium angle >270°. Lesions with angiographic calcium not treated with atherectomy or scoring/cutting balloon before stent implantation were randomly divided into derivation and validation cohorts. The end point was stent expansion (minimum stent area/average of reference lumen area) at the maximum calcium site, and stent expansion <70% was considered underexpansion.
Results:
The morphological characteristics associated with stent underexpansion in derivation cohort were (1) superficial calcium angle >270° longer than 5 mm (regression coefficient, −13.0 [95% CI, −18.1 to −7.8],
P
<0.0001), (2) 360° of superficial calcium (regression coefficient, −14.2 [95% CI, −22.8 to −5.5],
P
=0.001), (3) calcified nodule (regression coefficient, −8.3 [95% CI, −14.3 to −2.2],
P
=0.007), and (4) vessel diameter <3.5 mm (regression coefficient, −9.4 [95% CI, −16.0 to −2.7],
P
=0.006). The calcium score (0-4) was significantly correlated with poor stent expansion (regression coefficient, −8.1 [95% CI, −10.5 to −5.7],
P
<0.0001) in the validation cohort as well as in the atherectomy cohort (regression coefficient, −4.8 [95% CI, −7.2 to −2.5],
P
<0.0001) with significant interaction between validation and atherectomy cohorts (
P
interaction
=0.02). In lesions without angiographic calcium, all calcium severity parameters were less than in the validation cohort, and stent underexpansion was observed in only 1.5% (1/67) of lesions.
Conclusions:
This intravascular ultrasound calcium score provides the interventionalists with a reliable tool to identify calcified stenoses at risk for stent underexpansion and requiring adjunctive calcium modification before stent implantation.
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