Anaphylactoid Reaction from Trimethoprim-Sulfamethoxazole with Subsequent T-wave Inversions in a Young Patient with Dermatomyositis.

Dermatomyositis is a disease of inflammation and vasculopathy, characterized by proximal muscle weakness and classic cutaneous eruptions. Often, patients show signs of lung, esophageal, and cardiac involvement. Cardiac involvement in dermatomyositis and other inflammatory myosidities can result in conduction abnormalities, ventricular dysfunction, and hypertrophy. Some patients will become symptomatic from the sequelae of the impairment, progressing to the onset of heart failure, pericarditis, or arrhythmias. Others might remain clinically asymptomatic, with evidence of cardiac involvement of their disease seen only with electrocardiograms and imaging. A preexisting damaged myocardium is more susceptible to the damaging effects of the chemical mediators and the stress of an anaphylactic reaction. Patients with dermatomyositis often have subclinical manifestations of cardiac involvement that can predispose them to more severe and life-threatening consequences of anaphylaxis and anaphylactoid reactions. The present case report documents a patient with dermatomyositis whose disease was not complicated with cardiac involvement yet who ultimately showed lasting cardiovascular effects from an anaphylactoid reaction. This case highlights the dangers of allergic reactions in patients with inflammatory myopathies, such as dermatomyositis, as they can have more profound cardiovascular manifestations of the reactions and develop enduring changes to their myocardium.