Data from CLIMA registry shows that simultaneous presence of four optical coherence tomography (OCT) plaque vulnerability features are associated with a seven-fold increased risk of future major coronary events. The study, led by Prati et al., is recently published in the European Heart Journal.
Vulnerable plaques are typically characterized by a large superficial lipid pool, thin fibrous cap, and macrophage infiltration. These high-risk features may be identified by optical coherence tomography (OCT), a high-resolution intracoronary imaging modality.
The prospective, multicenter CLIMA registry aimed to evaluate the relationship between plaque morphology of the left anterior descending artery (LAD) and the risk of major coronary events (primary endpoint; a composite of cardiac death or target-segment myocardial infarction [MI]). A total of 1003 patients (median age: 66 years; females: 24.6%) with adequate OCT assessment of untreated proximal LAD free from significant stenosis (> 50%) were enrolled over a period of four years. OCT assessment identified 1776 non-culprit plaques, with a mean length of 13.2 mm (IQR 6.6–20.6). Predefined high-risk features included minimum lumen area (MLA) < 3.5 mm² (present in 39.5% of the lesions), fibrous cap thickness (FCT) < 75 µm (18.2%), maximum lipid arc > 180° (40.9%), and macrophage infiltration (57.5%).
At one year, primary endpoint events occurred in 37 patients (3.7%), including 25 cardiac deaths (2.5%) and 13 target-segment MI (1.3%). All four OCT-defined high-risk features were individually associated with the primary endpoint: MLA < 3.5 mm² (HR 2.1, 95% CI: 1.1–4.0), FCT < 75 µm (HR 4.7, 95% CI: 2.4–9.0), lipid arc circumferential extension > 180° (HR 2.4, 95% CI: 1.2–4.8), and macrophage infiltration (HR 2.7, 95% CI: 1.2–6.1). The simultaneous presence of four high-risk features in the same plaque was observed more frequently in patients who experienced the primary endpoint event (18.9% vs. 3.0%). Patients with the combined vulnerability criteria had a seven-fold higher risk of cardiac mortality or MI (HR 7.5, 95% CI: 3.1-18.6, P < 0.001).
“Our registry confirmed that OCT has the potential to identify patients at higher risk for subsequent coronary events… Whilst in the published studies on plaque vulnerability progressive angina accounted for most of the events, the CLIMA registry, carried on with a high resolution imaging modality, was specifically conceived to address the impact of plaque features on the occurrence of major endpoints, such as target-vessel MI and cardiac death within the first year of follow-up.” – Dr. Prati et al.
The study had some limitations. The main limitation was the observational design of the study. In addition, the simultaneous presence of four high-risk features was uncommon (3.6%) and had a low sensitivity (18.9%) with a low positive predictive value (19.4%) in the study population. Also, the favorable effect of medications such as statins on plaque morphology was not taken into account. Lastly, the study analyzed only the proximal target lesions that were located > 5 mm from the stent edge, and OCT was performed only on the target vessel.