Acute coronary stent thrombosis: A case of type 3 Kounis syndrome

Type III Kounis Syndrome Caused by Iodine Contrast Media After Improvement of Allergic Symptoms

Kounis syndrome is an acute coronary syndrome (ACS) caused by an allergic reaction that almost always occurs immediately and simultaneously with allergic symptoms. We present a case of Kounis syndrome type III that developed after complete resolution of contrast-induced anaphylaxis in a 60-year-old man with a coronary stent placed in the proximal left anterior descending (LAD) artery branch for ischemic heart disease. Contrast-enhanced computed tomography revealed anaphylactic shock. Symptoms quickly improved with intramuscular adrenaline injection; however, chest pain appeared after approximately 30 min. ECG revealed ST-wave elevation in the precordial leads. Coronary angiography revealed acute stent thrombosis with total occlusion of the proximal LAD, and percutaneous coronary angioplasty was performed. We diagnosed Kounis syndrome based on the allergic symptoms and ACS. Because some cases of Kounis syndrome develop after anaphylactic symptoms have resolved, it is advisable to follow-up patients with allergic symptoms and pay attention to chest symptoms and ECG changes, especially when they have a history of noted or treated coronary artery disease.

Exploring Variations in Etiology and Clinical Presentations of Kounis Syndrome Across Pediatric and Adult Populations: A Comprehensive Review

Kounis syndrome (KS), recognized as a rare yet significant form of acute coronary syndrome precipitated by allergy-mediated mechanisms, poses diagnostic challenges due to its varied clinical presentations and under-recognition. Despite its relevance across diverse populations, comprehensive insights into age-specific characteristics and management remain limited. The analysis of 420 studies yielded a total of 466 case reports of Kounis syndrome, categorized into pediatric (n = 31) and adult (n = 435) populations. After rigorous screening, 330 adult and 20 pediatric case reports were included for further analysis. Triggering factors were identified, with drugs (other) being the most prevalent in both groups. The breakdown of triggering factors, such as drugs (antibiotics), bee/wasp stings, and contrast media, was elucidated. Variations in presenting symptoms, diagnostic investigations, and treatment modalities between pediatric and adult populations were observed. Notably, all pediatric cases were diagnosed with subtype I Kounis syndrome and demonstrated favorable outcomes without any reported fatalities, whereas adult cases exhibited a broader range of Kounis subtypes. Mortality was recorded solely in adult case reports, with no fatalities reported among pediatric cases. These findings underscore the importance of understanding the nuances in the clinical presentation and management of Kounis syndrome across different age groups.

Cellular and Molecular Mechanisms of Mast Cells in Atherosclerotic Plaque Progression and Destabilization

Mast cells (MCs) are commonly recognized for their crucial involvement in the pathogenesis of allergic diseases, but over time, it has come to light that they also play a role in the pathophysiology of non-allergic disorders including atherosclerosis. The involvement of MCs in the pathology of atherosclerosis is supported by their accumulation in atherosclerotic plaques upon their progression and the association of intraplaque MC numbers with acute cardiovascular events. MCs that accumulate within the atherosclerotic plaque release a cocktail of mediators through which they contribute to neovascularization, plaque progression, instability, erosion, rupture, and thrombosis. At a molecular level, MC-released proteases, especially cathepsin G, degrade low-density lipoproteins (LDL) and mediate LDL fusion and binding of LDL to proteoglycans (PGs). Through a complicated network of chemokines including CXCL1, MCs promote the recruitment of among others CXCR2+ neutrophils, therefore, aggravating the inflammation of the plaque environment. Additionally, MCs produce extracellular traps which worsen inflammation and contribute to atherothrombosis. Altogether, evidence suggests that MCs actively, via several underlying mechanisms, contribute to atherosclerotic plaque destabilization and acute cardiovascular syndromes, thus, making the study of interventions to modulate MC activation an interesting target for cardiovascular medicine.

Analysis of clinical characteristics of Kounis syndrome induced by contrast media

BACKGROUND

Understanding the relationship between contrast agents and Kounis syndrome (KS) is mainly based on case reports. The purpose of this research is to explore the clinical characteristics of contrast media induced KS.

METHODS

We searched for contrast-induced KS case reports through Chinese and English databases from 1991 to October 31, 2021.

RESULTS

A total of 26 patients (19 men and 7 women,) were included, with a median age of 60 years (range 30-83). The contrast agents that cause KS mainly included gadolinium-based contrast agent (7 cases), iodine-containing contrast media (12 cases). KS mainly occurred within 30 min after administration and mainly manifests as chest pain and allergic reactions. Electrocardiogram (ECG) mainly showed ST elevation. Echocardiography mainly revealed normal. Coronary angiography showed normal, coronary vasospasm, stent thrombosis, occlusion and stenosis. After treatment with steroids, antihistamines and anti-ischemic therapy, 24 patients recovered completely and 2 patients died.

CONCLUSIONS

KS is a rare adverse reaction of contrast media. Radiologists should recognize this rare but serious disease to ensure rapid diagnosis and proper management.

Some Perspectives on Hypersensitivity to Coronary Stents

The development of coronary stents has represented a revolution in the treatment of coronary heart disease. Beyond their many advantages, stents also have their limitations and complications. Allergic reactions to coronary stents are more common than acknowledged. These stented patients are exposed to foreign substances inserted in direct contact with the coronary intima. Hypersensitivity to stent components and drugs prescribed after stent insertion together with any environmental exposure seem to contribute to these adverse reactions. Patients can present to the hospital with a wide range of symptoms and multiple complications, the most important ones being instent restenosis and stent thrombosis. Although not very common (and not always easy to identify), allergic reactions after coronary or peripheral stents should be taken into account. Careful selection of patients (for elective stent implantation) depending on the propensity to allergies, although hard to achieve, represents a key factor in reducing the number of these complications.