Narrow Complex Tachycardia Not Cured With Adenosine

The 2 ECGs below are from a case report in JAMA by Drs Sharma & Wu (JAMA 322: 2127–8. 12/3/19) of a 30 year old man with several days of flu-like symptoms who awoke with palpatations. The second tracing shows a narrow complex tachycardia, that broke transiently with adenosine, but then reoccurred. The story and tracing are classic for fascicular VT. It typically occurs in males, 15–40 years old, in response to some external stress, like an illness. It does not respond permanently to adenosine, but does respond to IV and long-term, to oral verapamil, as did this reported case. These patients rarely get syncope or sudden death so do not require an ICD. Fascicular VT should be in the differential of relatively narrow complex tachycardia in the ED, especially if it does not abate with adenosine.