kounis syndrome is the concurrence of acute coronary syndromes ( acs ) with conditions associated with mast cell activation including allergic or hypersensitivity as well as anaphylactic or anaphylactoid reaction.1)2 ) there have been a few reports on extraordinary causes other than wasp stings leading to a drug - eluting stent ( des ) thrombosis as a manifestation of kounis syndrome.3 - 6 ) as far as we knew , very late stent thrombosis ( st ) in a second - generation des following wasp stings has not yet been reported .
we describe a case of very late st in an everolimus - eluting stent as a consequence of wasp stings and present the pathophysiology and clinical implications of this syndrome with a review of the literature .
a 56-year old man was referred by an emergency physician to our hospital with an impression of st - segment elevation myocardial infarction ( stemi ) .
the patient was stung on the arm , neck and head several times by wasps while working on his field about 7 hours prior to admission .
he had a mild allergic reaction involving local pain and urticarial swelling immediately after the incident without signs of anaphylaxis or shock .
just a few minutes after being stung , he started complaining of chest pain and called the emergency service .
his blood pressure was 120/80 mm hg , pulse rate was 90 beats per minute and electrocardiogram revealed st - segment elevation with q wave formation in the anterior leads and reciprocal st - segment depression in the inferior leads ( fig .
his troponin t level was elevated to 1.86 ng / ml . after being given intravenous dexamethasone and antihistamine ,
he had undergone an everolimus - eluting 3.515 mm stent placement ( promus , boston scientific , mn , usa ) in the mid - left anterior descending ( lad ) artery for stable angina 3 years prior in our hospital .
clopidogrel ( 75 mg / d ) was withdrawn 24 months after stent implantation , while aspirin ( 100 mg / d ) had been continued until that day .
coronary angiography demonstrated a thrombosis in the previous stent in the lad artery , completely occluding the vessel ( fig .
the lesion was crossed with a runthrough ns guidewire ( terumo ) and sequential inflations using nimbus pico ( bard ) 1.2512 mm , followed by 2.012 mm balloons to disperse the thrombus .
next , thrombus aspiration with a thrombus aspiration catheter ( thrombuster ii , kaneka corp .
abciximab infusion was started , of which half of the initial bolus was given directly into the left coronary system .
however , thrombolysis in myocardial infarction flow 3 was not established despite these measures . in the end , an everolimus - eluting 3.515 mm stent ( promus element , boston scientific , mn
we did not measure serum tryptase and histamine levels with a half life of 90 minutes and of less than 30 minutes respectively because 7 hours had passed after the onset of symptoms .
he was discharged from the hospital 6 days after the index procedure with dual anti - platelet therapy ( dapt ) .
the patient is currently doing well and is being followed up in the outpatient department .
stent thrombosis is the primary concern regarding long - term safety outcome in the current des era , which is a fatal complication that often leads to myocardial infarction or death .
early st is likely due to clinical factors such as stemi , chronic kidney disease or premature discontinuation of clopidogrel and procedural issues such as stent malapposition , plaque protrusion or vessel dissection , while late or very late st is associated with late - acquired stent malapposition , delayed reendothelialization and neoatherosclerosis with plaque rupture.7 ) the occurrence of acs during the course of an allergic reaction constitutes kounis syndrome.1)2)8 ) st in des due to hypersensitivity reactions to components of des ( metallic strut , impregnated drug and especially polymer ) is known as type iii kounis syndrome.9)10 ) other types include patients with normal coronary arteries ( type i ) and patients with quiescent , pre - existing atheromatous disease ( type ii ) .
these include drugs ( antibiotics , analgesics , non - steroidal anti - inflammatory drugs ) , conditions ( asthma , food allergy , urticaria ) or environmental exposures ( hymenoptera and others stings , shellfish consumption , latex contact).1)2)8 ) myocardial infarction following hymenoptera stings ( bees , wasps and hornets ) is rare with less than twenty documented reports in the literature.11 - 14 ) furthermore , st in des leading to myocardial infarction secondary to wasp envenomation is much rarer and existing report was about first - generation des.15 ) to the best of our knowledge , this case is the first description of very late st in a second - generation des caused by wasp stings as a manifestation of kounis syndrome .
although the exact mechanism of kounis syndrome is still under discussion , mast cell degranulation following an allergic insult is known to play a key role .
chemical mediators released from mast cells such as histamine , neutral proteases ( tryptase and chymase ) , platelet activating factors , cytokines , chemokines and metabolites of arachidonic acid ( leukotrienes and thromboxane ) have been incriminated to induce coronary artery spasm , to promote platelets aggregation , and to transform a pre - existing stable atheromatous plaque to a vulnerable plaque leading to rupture.2)6)9)11 ) other possible mechanisms involve : 1 ) the direct action of wasp venom constituents such as histamine and phospholipase a2,13 ) 2 ) the anaphylactic reaction itself with severe hypotension , and 3 ) adrenalin use which can induce coronary spasm and myocardial damage.16 ) our patient had previously undergone short and large - diameter ( 3.515 mm ) stent implantation without underexpansion or dissection under non - acs conditions .
the current guideline recommends at least 12 months of dapt after des implantation,17 ) and he had received dapt for 2 years and then aspirin until the day of admission .
he developed chest pain just a few minutes after being stung by wasps , had no signs of anaphylaxis or shock and did not receive therapeutic adrenaline .
based on these observations , it is reasonable that we can classify our patient as having kounis syndrome . in the present case ,
recent studies have shown that second - generation dess ( everolimus - eluting or zotarolimuseluting stent ) lead to more favorable healing profiles18 ) and are associated with lower rates of st compared with first - generation dess.19)20 ) in conclusion , kounis syndrome is an uncommon clinical entity , and its diagnosis is difficult to make owing to its variable manifestations .
it is important for clinicians to keep this potential fatal scenario in mind while treating an allergic reaction associated with acute chest pain .
 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 . 
Introduction
Case
Discussion