Prospective investigation of calcium score in optical coherence tomography-guided revascularization to identify lesions with low risk for stent under expansion: the CORAL study

The optical coherence tomography (OCT)-based calcium scoring system was developed to guide optimal lesion preparation strategies for percutaneous coronary intervention (PCI) of calcified lesions. However, the score was derived retrospectively, and a prospective investigation is lacking. The CORAL (UMIN000053266) study was a single-arm, prospective, multicenter study that included patients with calcified lesions with OCT-calcium score of 1-2 to investigate whether these lesions could be optimally treated with a balloon-only preparation strategy using a non-compliant/scoring/cutting balloon. The primary endpoint was strategy success (successful stent placement with a final percent diameter stenosis [%DS] < 20% and Thrombolysis In Myocardial Infarction flow grade III without crossover to rotational atherectomy/orbital atherectomy/intravascular lithotripsy [RA/OA/IVL]). A superiority analysis for the primary endpoint was performed by comparing the study cohort with a performance goal of 83.3%. One hundred and eighteen patients with 130 lesions were enrolled. The mean age was 79.0 ± 10.3 years, and 79 patients (66.9%) were male. The OCT-calcium score was 1 for 81 lesions (62.3%) and 2 for 49 lesions (37.7%). The %DS improved from 47.0 ± 14.8% preprocedure to 11.1 ± 5.6% postprocedure. Stent expansion ≥ 70% was achieved in 90.2%. The strategy success rate was 93.1% (95% confidence interval: 87.3-96.8), and superiority against the performance goal was achieved without any crossover to RA/OA/IVL (P = 0.0027). The OCT-calcium score could identify mild/moderately calcified lesions treatable by PCI with the balloon-first strategy using a non-compliant/scoring/cutting balloon for predilatation, with a high strategy success rate. These results support the intravascular imaging-based treatment algorithm for calcified lesions proposed by CVIT.