Delayed myocarditis after a black spider bite
Title: Delayed Myocarditis After a Black Spider Bite
Consent: The patient gave his informed consent (and is even interested in reading the article if published!) - Anonymity was ensured in all the pictures.
Question: Can a Spider Bite be the Most Probable Cause of an Irreversible Myocarditis?
Brief Clinical History
A 52 year old healthy gentleman presented to our Emergency Department (ED) for one week duration of chest pain, shortness of breath and orthopnea. Patient reports that one month ago he was bitten in the leg by a “small black spider” in Erbil, Iraq. He noticed redness and irritation around the bite around two days afterwards. One day later, his erythema progressed to form a large vesicle that was drained and debrided and was then discharged home. 2 weeks afterwards, he started having the above symptoms.
Misleading Elements:
Remote history of bite, normal review of system, vital signs, blood work including troponin, electrocardiogram and physical exam (except for a 4 x 4 cm healed ulcer on the anterior aspect of his distal right leg with surrounding subjective paresthesias).
Helpful details and diagnosis:
Chest X Ray showed mild congestion. Echocardiography done showed moderate global left ventricle hypokinesia with a low ejection fraction. Cardiac MRI with gadolinium showed epicardial and mid myocardial layers involvement suggesting myocarditis.
Educational and clinical relevance:
The Black Widow Spider (BWS) belongs to the genus Latrodectus and is found commonly all over the world, and is generally found in the Mediterranean basin.
These bites may present as variable clinical scenarios, ranging from benign complications such as local damage to more fatal conditions. Within the first couple of hours of the BWS bite, patients may experience severe muscular pain and cramping in the back, abdomen and thighs.
Autonomic nervous system stimulation by the venom may cause hypertension, tachycardia and diaphoresis.
An accurate diagnosis of myocarditis is difficult because of the inaccuracy and variability of clinical history, EKG and cardiac markers. Myocardial biopsy is definitive but invasive. Cardiac magnetic resonance is the method of choice of diagnosing myocarditis. When performed early, it can not only help in making the accurate diagnosis of an acute myocarditis, but also determine the severity and serve as a baseline for later follow-up.
Acute myocarditis has been reported after scorpion and snake bites, however its been rarely reported after a BWS bite. To the best of our knowledge, there has been no reporting of irreversible heart failure secondary to BWS bites before this case but a repeat echocardiogram of our patient four months later showed persistent decrease in his ejection fraction.
Conclusion:
BWS bites have a large spectrum of manifestations, ranging from benign localized complications to systemic and even fatal outcomes. Acute myocarditis after a BWS bite has been described in the literature despite its rarity, but our case was the first with irreversible outcome on the heart.
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