A Revised Optical Coherence Tomography–Derived Calcium Score to Predict Stent Underexpansion in Severely Calcified Lesions

Abstract

Background

Severe calcification is the morphology most strongly associated with stent underexpansion.

Objectives

The aim of this study was to revise an optical coherence tomography (OCT)–derived calcium score to predict stent underexpansion in severely calcified lesions (angle >270°) using a point-based system.

Methods

A retrospective observational study was conducted in which 250 de novo lesions undergoing OCT-guided stenting, with angiographically visible calcium and optical coherence tomographic maximum superficial calcium angle >270°, not subjected to atherectomy or specialty balloon treatment before stent implantation, were randomly divided into derivation (n = 167) and validation (n = 83) cohorts. The endpoint was stent expansion (minimum stent area/average of reference luminal area) at the maximum calcium deposition site, and stent expansion <70% was considered underexpansion.

Results

Stent underexpansion was present in 19.6% of lesions (49 of 250). In the multivariable linear regression model, the morphologic characteristics associated with stent expansion in the derivation cohort were: 1) calcium >270° with a length longer than 3 mm (regression coefficient = −10.3; 95% CI: −17.8 to −2.8; P = 0.007); 2) calcium angle of 360° (regression coefficient = −15.5; 95% CI: −25.2 to −5.8; P = 0.002); and 3) minimum calcium thickness >0.30 mm (regression coefficient = −12.4; 95% CI: −19.1 to −5.6; P = 0.0004). In the validation cohort, the calcium score (range: 0-3) was significantly correlated with stent expansion (regression coefficient = −9.1; 95% CI: −12.6 to −6.1; P < 0.0001).

Conclusions

This revised OCT-derived calcium score can serve as a reliable tool for identifying severely calcified lesions at risk for stent underexpansion.