A 63-year-old male patient with a history of hypertension, type 2
diabetes mellitus, prostate cancer and class two obesity was admitted
for altered mental status and hypertensive emergency. During his
hospital stay he developed narrow complex tachycardia and it was
difficult to definitively diagnose the underlying arrhythmia.
Observation of the cool down phenomenon on electrocardiogram allowed us
to make the diagnosis of atrial tachycardia and elegantly ruled out
other causes on the differential. We report this interesting case of
narrow complex tachycardia.