Features of atherosclerosis in patients with angina and no obstructive coronary artery disease

Aim

To assess the atherosclerotic burden and morphological characteristics of coronary arteries using optical coherence tomography (OCT) in patients presenting with angina with non-obstructive coronary artery disease (ANOCA).

Methods

• Single-centre observational study.
• Consecutive patients with ANOCA undergoing an invasive coronary function test (acetylcholine test and physiology assessment with hyperaemic indexes using adenosine) for suspected coronary vasomotor disfunction.
• In OCT mainly lipid index and prevalence of vulnerable plaques were assessed. Vulnerable plaque was defined as plaque with at least one of the following: presence of fibroatheroma, macrophage infiltration, neovascularization, plaque erosion.
• Patients were divided into two groups: those who had coronary vasospasm triggered by acetylcholine (ACH+) and those who did not have spasm (ACH-). Additionally, patients with epicardial and microvascular spams were compared.

Results

• Between February 2019 and January 2020 altogether 75 patients were enrolled: 59 in ACH+ group and 16 in ACH- group.
• Baseline characteristic did not differ between two groups and the study population was composed of mostly women (93%) with a mean age of 55 years. Approximately half of the patients had hypertension (51%), hypercholesterolaemia (45%) and smoking history (51%).
• ACH+ patients had higher lipid index (820 vs. 270; p=0.03), greater prevalence of vulnerable plaques (66% vs. 38%; p=0.04) and neovascularization (37% vs. 6%; p=0.02) as compared to ACH- patients.
• No significant differences in lipid index (885 vs 668; p=0.51) and prevalence of vulnerable plaques (64% vs. 68%; p=0.78) between patients with epicardial and microvascular spams were observed.

Main message

Despite recent advancement in knowledge regarding different types of non-obstructive coronary artery disease (both in patients with acute coronary syndrome and stable angina), this disease still presents a heterogenous clinical conundrum. Although in past studies it was shown that greater plaque vulnerability may be associated with coronary arteries spasm, ANOCA is considered by many physicians a rather benign condition with treatment tailored for symptoms relief (ie. mainly calcium channel blockers and nitrates) with no significant benefits in terms of prognosis.

In the current study, the authors, with the use of OCT, showed that patients with ANOCA have higher lipid index, plaque vulnerability and neovascularisation as opposed to those without obstructive coronary artery disease and coronary spasm. Interestingly, no differences in plaque morphology were observed when comparing patients with epicardial and microvascular spam. Those results could, in future, lead to a change of lifestyle and change in treatment of patients with ANOCA with a greater emphasis on drugs used to reduce future cardiovascular adverse events or plaque vulnerability such as statins or ACEI.

However, bigger studies are needed to confirm these findings as well as assess long term clinical outcomes of ACH+ patients as compared to ACH- patients. Moreover, larger studies could allow analysis of particular markers of plaque vulnerability (and not only their combination) along with more detailed analysis of the male population with this disease.