Abstract W MP70: Short and Long-term Risk of Stroke After a Transient Neurological Attack (TNA) versus TIA: Population-based Study

Abstract

BACKGROUND: The distinction between a TIA and a transient neurological attack (TNA i.e. a TIA-like event not satisfying the NINDS Criteria for a clinically definite TIA) has important implications for clinical practice. Patients with TIA require intensive long-term secondary prevention of stroke, but there are conflicting estimates of the risk of stroke after TNA. METHODS: In a United Kingdom population-based study (Oxford Vascular Study) of all incident and recurrent TNAs and TIAs from 2002-2012, we prospectively classified all first events in the study period as TIAs (based on NINDs criteria) versus TNAs (including isolated transient neurological symptoms not satisfying the NINDS criteria) versus other conditions (migraine aura, epilepsy, etc). Kaplan-Meyer (KM) risk of stroke was determined at 10-years by long term regular face-to-face follow up. RESULTS: Among 1648 first events, 594 were NINDS-defined TIAs (mean/SD age= 73.5/13.1 years), 658 were TNAs (67.1/15.5) and 396 were other diagnosis (62.8/18.2). During 8328 person/years of follow-up there were 195 recurrent strokes: 106 in patients with a first TIA, 83 after a TNA and 6 in patients with another diagnosis. The actuarial risk of stroke at 10 years was higher after a TIA than after a TNA (22.9% vs 17.6%, adjusted HR= 1.46, 1.09-1.95, p=0.01), but the risk after a TNA was considerably higher than in patients with other diagnoses (17.6% vs 3.0%, p<0.0001). Rates of use of preventive medication at one-month follow-up in patients with TIA versus TNA were 97.1% vs 75.4% for antithrombotics, 71.4% vs 53.3% for statins, and 72.9% vs 64.1% for antihypertensives. However, medication rates declined more rapidly on longer-term follow-up in patients with TNA versus TIA. CONCLUSION: The long-term risk of stroke after a TNA was almost as high as after a strictly-defined TIA, although use of preventive medication was more intensive after TIA. The relatively high risk of stroke in patients with TNA appears to justify detailed investigation and similar levels of intensity of secondary prevention to patients with TIA.