Unmasking the Connection: Cardiac Arrest in Stiff Person Syndrome.

Stiff person syndrome (SPS) is a rare autoimmune neurologic disorder that may be accompanied by severe spasms and autonomic instability. We present a man in his 30s with SPS who developed whole-body spasms, severe hypoxemic respiratory failure, and subsequent pulseless ventricular tachycardia/ventricular fibrillation during an attempted extubation at an outside hospital. Initial evaluation demonstrated hyperthermia, shock, ST-segment depression, markedly elevated troponin, and transient severe left ventricular systolic dysfunction; coronary angiography and computed tomography pulmonary angiography excluded obstructive coronary artery disease and pulmonary embolism. After transfer, electrocardiography showed sinus bradycardia with marked QT/QTc (corrected QT interval) prolongation, and while the patient was receiving amiodarone, transesophageal echocardiography showed recovery of left ventricular ejection fraction to 51%, and cardiac magnetic resonance imaging showed patchy mid-wall late gadolinium enhancement with increased T1 and T2 signal compatible with clinically suspected myocarditis. Because endomyocardial biopsy was not performed, the cause of the myocardial injury remained uncertain. Severe hypoxemia, possible sepsis-related myocardial dysfunction, acquired QT prolongation and medication effects, autonomic instability, and cardiac magnetic resonance-supported myocarditis were considered potentially interacting contributors. After recurrent non-sustained ventricular tachycardia and a prior ventricular tachycardia/ventricular fibrillation arrest without a single clearly reversible cause, an implantable cardioverter-defibrillator was placed for secondary prevention. This case illustrates the diagnostic uncertainty surrounding cardiac arrest in SPS and emphasizes the need to evaluate reversible arrhythmic triggers.