What are the complications of transient ischemic attack?

Stroke. Most feared complication of a TIA is a stroke. Stroke can potentially be large and very debilitating. Tia necessitates careful evaluation and treatment.
Stroke. If untreated will give stroke, TIA has to be diagnosed as to cause like narrowed artery, blood clot, differentiating from other causes like seizure, migraine etc.
TIA. Is like a tremor before the quake. It should alert you that the body needs to be improved medically to reduce the probability of a full stroke.