Current understanding of Kounis syndrome

The more allergens an atopic patient is exposed to, the easier and quicker anaphylactic shock and Kounis syndrome appear: Clinical and therapeutic paradoxes

Kounis syndrome is a condition that combines allergic, hypersensitivity, anaphylactic or anaphylactoid reactions with acute coronary syndromes including vasospastic angina, acute myocardial infarction and stent thrombosis. This syndrome is a ubiquitous disease affecting patients of any age, involving numerous and continuously increasing causes, with broadening clinical manifestations and covering a wide spectrum of mast cell activation disorders. Drugs, environmental exposures and various conditions are the main offenders. Clinical and therapeutic paradoxes concerning Kounis syndrome therapy, pathophysiology, clinical course and causality have been encountered during its clinical course. Drugs that counteract allergy, such as H2-antihistamines, can induce allergy and Kounis syndrome. The more drugs an atopic patient is exposed to, the easier and quicker anaphylaxis and Kounis syndrome can occur. Every anesthetized patient is under the risk of multiple drugs and substances that can induce anaphylactic reaction and Kounis syndrome. The heart and the coronary arteries seem to be the primary target in severe anaphylaxis manifesting as Kounis syndrome. Commercially available adrenaline saves lives in anaphylaxis but it contains as preservative sodium metabisulfite and should be avoided in the sulfite allergic patients. Thus, careful patient past history and consideration for drug side effects and allergy should be taken into account before use. The decision to prescribe a drug where there is a history of previous adverse reactions requires careful assessment of the risks and potential benefits.

Anaphylactic Shock: Kounis Hypersensitivity-Associated Syndrome Seems to be the Primary Cause

Experiments have shown that anaphylaxis decreases cardiac output; increases left ventricular end diastolic pressure; induces severe early acute increase in respiratory resistance with pulmonary interstitial edema; and decreases splanchnic, cerebral, and myocardial blood flow more than what would be expected from severe arterial dilation and hypotension. This is attributed to the constrictive action of inflammatory mediators released during anaphylactic shock. Inflammatory mediators such as histamine, neutral proteases, arachidonic acid products, platelet-activating factor (PAF), and a variety of cytokines and chemokines constitute the pathophysiologic basis of Kounis hypersensitivity-associated acute coronary syndrome. Although the mechanisms of anaphylactic shock still remain to be elucidated, myocardial involvement due to vasospasm-induced coronary blood flow reduction manifesting as Kounis syndrome should be always considered. Searching current experimental and clinical literature on anaphylactic shock pathophysiology, causality, clinical appearance, and treatment via PubMed showed that differentiating global hypoperfusion from primary tissue suppression due to mast cell mediator constrictive action on systemic arterial vasculature is a challenging procedure. Combined tissue suppression from arterial involvement and peripheral vasodilatation, perhaps, occur simultaneously. In cases of anaphylactic shock treatment targeting the primary cause of anaphylaxis together with protection of coronary vasculature and subsequently the cardiac tissue seems to be of paramount importance.

Kounis syndrome: acute inferior myocardial infarction with atroventricular node block due to ceftriaxone: a first reported case

Cefriaxone is a third-generation cephalosporin that might rarely cause a severe allergic reaction. Acute cardiac emergencies are quite rare in the setting of drug allergies. Here, we report the first case of myocardial infarction and AV-block after intravenous cefriaxone administration.

Stress triggers coronary mast cells leading to cardiac events

OBJECTIVE

Stress precipitates and worsens not only asthma and atopic dermatitis but also acute coronary syndromes (ACSs), which are associated with coronary inflammation. Evidence linking stress to ACS was reviewed and indicated that activation of coronary mast cells (MCs) by stress, through corticotropin-releasing hormone (CRH) and other neuropeptides, contributes to coronary inflammation and coronary artery disease.

DATA SOURCES

PubMed was searched (2005-2013) for articles using the following keywords: allergies, anaphylaxis, anxiety, coronary arteries, coronary artery disease, C-reactive protein, cytokines, chymase, histamine, hypersensitivity, interleukin-6 (IL-6), inflammation, mast cells, myocardial ischemia, niacin, platelet-activating factor, rupture, spasm, statins, stress, treatment, tryptase, and uroctortin.

STUDY SELECTIONS

Articles were selected based on their relevance to how stress affects ACS and how it activates coronary MCs, leading to coronary hypersensitivity, inflammation, and coronary artery disease.

RESULTS

Stress can precipitate allergies and ACS. Stress stimulates MCs through the activation of high-affinity surface receptors for CRH, leading to a CRH-dependent increase in serum IL-6. Moreover, neurotensin secreted with CRH from peripheral nerves augments the effect of CRH and stimulates cardiac MCs to release IL-6, which is elevated in ACS and is an independent risk factor for myocardial ischemia. MCs also secrete CRH and uroctortin, which induces IL-6 release from cardiomyocytes. The presence of atherosclerosis increases the risk of cardiac MC activation owing to the stimulatory effect of lipoproteins and adipocytokines. Conditions such as Kounis syndrome, mastocytosis, and myalgic encephalopathy/chronic fatigue syndrome are particularly prone to coronary hypersensitivity reactions.

CONCLUSION

Inhibition of cardiac MCs may be a novel treatment approach.

Kounis syndrome presenting as very late stent thrombosis in an everolimus-eluting stent following wasp stings

Kounis syndrome is the concurrence of acute coronary syndromes with conditions associated with mast cell activation following an allergic insult. We report a 56-year-old man who experienced a ST-segment elevation myocardial infarction after wasp stings. The patient presented without signs of anaphylaxis or shock. Coronary angiography showed an everolimus-eluting stent thrombosis (ST) of the left anterior descending artery occluding the vessel completely which was deployed for stable angina 3 years ago. The patient had been compliant with anti-platelet therapy, and no relevant cardiovascular events occurred until the day of admission. We interpreted our patient's condition as a manifestation of Kounis syndrome. To our knowledge, this is the first case of Kounis syndrome showing very late ST in a second-generation drug-eluting stent caused by wasp stings.

Drug-induced acute myocardial infarction: identifying 'prime suspects' from electronic healthcare records-based surveillance system

BACKGROUND

Drug-related adverse events remain an important cause of morbidity and mortality and impose huge burden on healthcare costs. Routinely collected electronic healthcare data give a good snapshot of how drugs are being used in 'real-world' settings.

OBJECTIVE

To describe a strategy that identifies potentially drug-induced acute myocardial infarction (AMI) from a large international healthcare data network.

METHODS

Post-marketing safety surveillance was conducted in seven population-based healthcare databases in three countries (Denmark, Italy, and the Netherlands) using anonymised demographic, clinical, and prescription/dispensing data representing 21,171,291 individuals with 154,474,063 person-years of follow-up in the period 1996-2010. Primary care physicians' medical records and administrative claims containing reimbursements for filled prescriptions, laboratory tests, and hospitalisations were evaluated using a three-tier triage system of detection, filtering, and substantiation that generated a list of drugs potentially associated with AMI. Outcome of interest was statistically significant increased risk of AMI during drug exposure that has not been previously described in current literature and is biologically plausible.

RESULTS

Overall, 163 drugs were identified to be associated with increased risk of AMI during preliminary screening. Of these, 124 drugs were eliminated after adjustment for possible bias and confounding. With subsequent application of criteria for novelty and biological plausibility, association with AMI remained for nine drugs ('prime suspects'): azithromycin; erythromycin; roxithromycin; metoclopramide; cisapride; domperidone; betamethasone; fluconazole; and megestrol acetate.

LIMITATIONS

Although global health status, co-morbidities, and time-invariant factors were adjusted for, residual confounding cannot be ruled out.

CONCLUSION

A strategy to identify potentially drug-induced AMI from electronic healthcare data has been proposed that takes into account not only statistical association, but also public health relevance, novelty, and biological plausibility. Although this strategy needs to be further evaluated using other healthcare data sources, the list of 'prime suspects' makes a good starting point for further clinical, laboratory, and epidemiologic investigation.

Brain injury due to anaphylactic shock: broadening manifestations of Kounis syndrome

Anaphylactic shock is a real and life threatening medical emergency which is encountered in every field of medicine. The coronary arteries seem to be the primary target of anaphylaxis resulting in the development of Kounis syndrome. Kounis syndrome is a pan-arterial anaphylaxis -associated syndrome affecting patients of any age, involving numerous and continuously increasing causes, with broadening clinical manifestations and covering a wide spectrum of mast cell activation disorders. Recently, Kounis-like syndrome affecting the cerebral arteries was found to be associated with mast cell activation disorders. In anaphylactic shock, the decrease of cerebral blood flow is more than what would be expected from severe arterial hypotension. This is attributed to the early and direct action of anaphylactic mediators on cerebral vessels. While adrenaline is a life saving agent in the treatment of anaphylactic shock, it contains sodium betabisulfite as preservative and should be avoided in sulfite allergic patients. Potential allergens encountered in endodotic practice include formocresol, zinc compounds thiurams, sodium dimethyldithiocarbamade, and mercaptobenzothiazole that might have synergistic action. All these agents together with analgesics, antibiotics, antiseptics, formaldehyde, latex, local anaesthetics and metals used in dental practice, in general, can induce anaphylactic shock. Practitioners should be aware of these consequences. A careful history of previous atopy and reactions is of paramount importance for safe and effective management.

Coronary hypersensitivity disorder: the Kounis syndrome

BACKGROUND

When allergy or hypersensitivity and anaphylactic or anaphylactoid insults lead to cardiovascular symptoms and signs, including acute coronary events, the result might be the recently defined nosologic entity Kounis syndrome. Vasospastic allergic angina, allergic myocardial infarction, and stent thrombosis with occluding thrombus infiltrated by eosinophils and/or mast cells are the 3 reported variants of this syndrome.

OBJECTIVE

The purpose of this review was to highlight and consolidate the recent literature on allergic angina and allergic myocardial infarction and to propose new therapeutic modalities for stabilizing mast cells.

METHODS

A search for current literature on the pathophysiology, causality, clinical appearance, variance, prevention, and treatment of Kounis syndrome was conducted.

RESULTS

Kounis syndrome is caused by inflammatory mediators such as histamine; neutral proteases, including tryptase, chymase, and cathepsin-D; arachidonic acid products; platelet-activating factor; and a variety of cytokines and chemokines released during the mast-cell activation. Platelets with Fc γ receptor (FcγR) Ι, FcγRII, FcεRI, and FcεRII also have a role in the activation cascade. The same mediators released from the similar inflammatory cells are involved in acute coronary events of nonallergic etiology. These cells are not only present in the involved region before plaque erosion or rupture but also release their contents just before an acute coronary event. Pro-inflammatory mediators similar to those found in Kounis syndrome are found in some cases with nonallergic etiology, suggesting that this is a more general problem. The acute coronary and cerebrovascular events in Kounis syndrome may be prevented by the inhibition of mast-cell degranulation. Substances and natural molecules that protect the mast-cell surface and stabilize the mast-cell membrane are emerging as novel agents in the prevention of acute coronary and other arterial events.

CONCLUSIONS

The 3 reported variants of Kounis syndrome-vasospastic allergic angina, allergic myocardial infarction, and stent thrombosis with occluding thrombus-are caused by inflammatory mediators. Agents that inhibit mast-cell degranulation may be efficacious in preventing the acute coronary and cerebrovascular events of Kounis syndrome.

Intraoperative myocardial infarction: Kounis syndrome provoked by latex allergy

We report the case of a 43-year-old man with anaphylactic shock and concurrent ST-elevation myocardial infarction during a planned inguinal hernia surgery. This event occurred shortly after introduction of latex into the surgical field. Coronary angiography revealed a 70% occlusive lesion in the right coronary artery. Further discussion with the patient revealed a potential latex allergy. Skin prick testing showed marked sensitisation to latex. The patient was subsequently diagnosed with the type II variant of Kounis syndrome.

Kounis syndrome (allergic acute coronary syndrome): different views in allergologic and cardiologic literature

The clinical picture of myocardial ischemia accompanying allergic reactions is defined in the cardiologic literature as Kounis syndrome (KS) or allergic angina/myocardial infarction. In PubMed, a search for "Kounis syndrome", "allergic angina" or "allergic myocardial infarction" retrieves more than 100 results (among case reports, case series and reviews), most of which are published in cardiology/internal medicine/emergency medicine journals. In allergologic literature, heart involvement during anaphylactic reactions is well documented, but Kounis syndrome is hardly mentioned. Single case reports and small case series of angina triggered by allergic reactions have been reported for many years, and involvement of histamine and others mast cell mediators in the pathogenesis of coronary spasm has long been hypothesized, but the existence of an allergic acute coronary syndrome (ACS) is still questioned in the allergologic scientific community. Putative mechanisms of an allergic acute coronary syndrome include coronary spasm or heart tissue-resident mast cell activation (precipitating coronary spasm or inducing plaque rupture and coronary or stent thrombosis) due to systemic increase of allergic mediators, or heart tissue-resident mast cell activation by local stimuli. Indeed, the pathogenic mechanism of an ACS after an allergic insult might be related to direct effects of mast cell mediators on the myocardium and the atherosclerotic plaque, or to exacerbation of preexisting disease by the hemodynamic stress of the acute allergic/anaphylactic reaction. Which of these mechanisms is most important is still unclear, and this review outlines current views in the cardiologic and allergologic literature.

Kounis syndrome: a new twist on an old disease

Kounis syndrome is the concurrence of acute coronary syndromes with conditions associated with mast cell activation, such as allergies or hypersensitivity and anaphylactic or anaphylactoid insults that can involve other interrelated and interacting inflammatory cells behaving as a 'ball of thread'. It is caused by inflammatory mediators such as neutral proteases including tryptase and chymase, arachidonic acid products, histamine, platelet activating factor and a variety of cytokines and chemokines released during the activation process. Platelets with FCεRI and FCεRII receptors also participate in the above cascade. Vasospastic allergic angina, allergic myocardial infarction and stent thrombosis with occluding thrombus infiltrated by eosinophils and/or mast cells constitute the three reported variants of this syndrome. Kounis syndrome is a ubiquitus disease that represents a magnificent natural paradigm and nature's own experiment, in a final trigger pathway implicated in cases of coronary artery spasm and plaque rupture. Kounis syndrome can complicate anesthesia, vaccination, medical therapy and stent implantation and it seems to be associated with coronary allograft vasculopathy and takotsubo syndrome, it can often be confused with hypersensitivity myocarditis and can be the cause of unexplained sudden death. Kounis syndrome has revealed that the same mediators released from the same inflammatory cells are present in acute coronary events of nonallergic etiology. These cells are not only present in the culprit region before plaque erosion or rupture but they release their contents just before an actual coronary event. Therefore, does Kounis syndrome represent a magnificent natural paradigm and nature's own experiment in a final trigger pathway implicated in cases of coronary artery spasm and plaque rupture showing a novel way towards our effort to prevent acute coronary syndromes? Drugs, substances targeting the stem cell factor that is essential for mast cell development, proliferation, survival, adhesion and homing as well as monoclonal antibodies and natural molecules that protect mast cell surface and stabilize mast cell membrane could emerge as novel therapeutic ways capable to prevent acute coronary and acute cerebrovascular events.

Two questions for Kounis syndrome: can we use magnetic resonance imaging in the diagnosis and does ST elevation correlates with troponin levels?

Kounis syndrome (KS) is an acute coronary vasospasm after exposure to an allergen due to mast cell degranulation and existing mediators. Various drugs, conditions, and environmental exposures can cause KS. We presented 2 cases, 1 of whom had taken an antiflu drug (containing paracetamol, pseudoephedrine, and dextromethorphan). His electrocardiogram (ECG) showed inferior ST elevations (2 mm) with normal cardiac biomarkers. His cardiac magnetic resonance imaging showed hypokinesis and myocardial hibernation on apical septum and on the left ventricle. The second patient took a pill of naproxen sodium. The ECG showed 1-mm ST elevation in leads DII, V5, and V6. His troponin was markedly elevated. These cases showed that there seems to be no correlation with ECG and troponin levels in KS. In addition, for patients in whom KS type 1 is expected without troponin elevation, noninvasive cardiac magnetic resonance imaging study seems to be appropriate for the diagnosis of KS.

[Kounis syndrome]

Kounis syndrome was described in 1991 by Kounis and Zavras as the coincidental occurrence of acute coronary syndromes with allergic reactions (anaphylactic or anaphylactoid). Today, allergic angina and allergic myocardial infarction are referred to as Kounis syndrome, and the latter has been reported in association with a variety of drugs, insect stings, food, environmental exposures and medical conditions, among other factors. The incidence is not known, as most of the available information comes from case reports or small case series. In this article, the clinical aspects, diagnosis, pathogenesis, related conditions and therapeutic management of the syndrome are discussed.

Kounis syndrome is likely culprit of coronary vasospasm induced by capecitabine

Capecitabine administration has been associated with various allergic reactions including acneiform skin rash, linchenoid photosensitive eruption, exudative non healing scalp, skin reactions, pyogenic granuloma, subacute cutaneous systemic lupus erythematosus, exudative hyponychia dermatitis, and hand–foot syndrome. A patient who developed ventricular fibrillation following capecitabine-induced coronary vasospasm and necessitating cardioverter-defibrillator implantation was published recently in J Oncol Pharm Practice. The authors attributed this reaction to capecitabine cardiotoxicity, but capecitabine hypersensitivity is closely associated with Kounis syndrome. Tests and measures which will help to confirm, prevent and treat cardiac hypersensitivity to antineoplastic agents are recommended.

Eosinophilic responses to stent implantation and the risk of Kounis hypersensitivity associated coronary syndrome

The use of drug eluting stents constitutes a major breakthrough in current interventional cardiology because it is more than halves the need of repeat interventions. It is incontrovertible that coronary stents, in general, have been beneficial for the vast majority of patients. A small increase in thrombosis, following DES implantation, is offset by a diminished risk of complications associated with repeat vascularization. However, late and, especially, very late stent thrombosis is a much feared complication because it is associated with myocardial infarction with increased mortality. Despite that stent thrombosis is thought to be multifactorial, so far clinical reports and reported pathology findings in patients died from coronary stent thrombosis as well as animal studies and experiments, point toward a hypersensitivity inflammation. The stented and thrombotic areas are infiltrated by interacting, via bidirectional stimuli inflammatory cells including eosinophils, macrophages, T-cells and mast cells. Stented regions constitute an ideal surrounding for endothelial damage and dysfunction, together with hemorheologic changes and turbulence as well as platelet dysfunction, coagulation and fibrinolytic disturbances. Drug eluting stent components include the metal strut which contains nickel, chromium, manganese, titanium, molybdenum, the polymer coating and the impregnated drugs which for the first generation stents are: the antimicrotubule antineoplastic agent paclitaxel and the anti-inflammatory, immunosuppressive and antiproliferative agent sirolimus. The newer stents which are called cobalt-chromiun stents and elute the sirolimus analogs everolimus and zotarolimus both contain nickel and other metals. All these components constitute an antigenic complex inside the coronary arteries which apply chronic, continuous, repetitive and persistent inflammatory action capable to induced Kounis syndrome and stent thrombosis. Allergic inflammation goes through three phases, the early phase, the late phase and the chronic phase and these three phases correspond temporally with early (acute and sub acute), late and very late stent thrombosis. Bioabsorbable allergy free poly lactic acid self expanding stents, nickel free stainless steel materials, stent coverage with nitric oxide donors and antibodies with endothelial progenitor cell capturing abilities as well as stents eluting anti-inflammatory and anti-allergic agents might be the solution of this so feared and devastating stent complication.