Scorpion envenomation-associated myocarditis: A systematic review

BackgroundScorpion envenomation is associated with several complications. One of the most serious complications is the cardiac involvement in the form of myocarditis that remains the main reason for mortalities associated with scorpion envenomation. The present review aims to elucidate clinical and paraclinical findings associated with scorpion-related myocarditis, and to explore different management strategies and subsequent outcomes. MethodsWe searched PubMed, Web of Science, Scopus, and Google Scholar for articles related to keywords of myocarditis associated with scorpion envenomation up to May 1, 2022. Each article was carefully reviewed by two independent researchers. In case of disagreement for inclusion, we sought a third researcher opinion. ResultsA total of 703 cases from 30 case reports and 34 case series were included in our review. Myocarditis associated with scorpion envenomation was usually reported in children presenting with cardiopulmonary symptoms including pulmonary edema (60.7%) and shock or hypotension (45.8%). The most common ECG findings are sinus tachycardia (82%) followed by ST-T changes (64.6%). The management typically included inotropes (especially dobutamine), prazosin, diuretics, nitroglycerine and digoxin, when indicated. Mechanical ventilation was required in 36.7% of the patients. Mortality in confirmed scorpion-related myocarditis cases is estimated at 7.3%. Almost all survived cases showed rapid recovery and improvement in the left ventricular function. ConclusionEven though myocarditis associated with scorpion envenomation is rare, it remains a serious and in some of cases a fatal consequence of scorpion sting. In case of relative presentations, particularly in envenomed children, diagnosis of myocarditis should be considered. Early screening using serial cardiac markers and echocardiography can guide the treatment. Prompt treatment that focuses on cardiogenic shock and pulmonary edema usually results in a favorable outcome. Author summaryScorpion sting can cause a variety of complications. One of the most dangerous complications associated with some scorpion venoms is damage to the heart in the form of myocarditis. Myocarditis is the inflammation of the heart muscle. The mechanism of myocarditis in scorpion sting is unique. The scorpion venom triggers a massive release of epinephrine and norepinephrine hormones, which affect the heart. At first, rapid heartbeats, hypertension, and agitation occurs. Then, as the result of the cardiac dysfunction, respiratory distress, fluid buildup in the lungs and a drop in blood pressure will develop. Children are particularly vulnerable to this condition. Electrocardiograms will reveal signs of heart strain and even dangerous arrhythmias. Serial heart enzyme measurements can help diagnose this condition. Echocardiograms show heart function decline. Respiratory support is critical. Prazosin is helpful for hypertension. Heart failure and its complications are the main targets of treatment. Dobutamine has shown the most promise in treating heart failure. We estimate the mortality rate at 7.4% in the reported cases. With timely management this condition is usually benign, recovery is quick, and survivors rarely experience long-term complications. Physicians should be aware of this potential complication, screen for it and begin appropriate treatment as soon as possible.