Long-term risk of stroke after TIA or minor stroke

Background

Although transient ischemic attacks (TIAs) and minor strokes are common cerebrovascular events, the long-term prognosis in the affected patients remains unclear with respect to the risk of a subsequent stroke.

This systematic review and meta-analysis determined annual and cumulative rates of stroke up to 10 years after TIA or minor stroke.

Methods

The study analyzed data from prospective as well as retrospective cohort studies that reported stroke risk with at least 1-year follow-up in patients with TIA or minor stroke. Data across the studies were pooled using a random-effects meta-analysis.

The primary study outcome was any stroke (ischemic or hemorrhagic, irrespective of etiology; eg, thrombosis, artery-to-artery embolism, cardiac embolism). Study-level characteristics were investigated as potential sources of variability in stroke rates across the studies.

Results

A total of 171,068 patients (median age, 69 years; 57% male) were included. The pooled rate of stroke per 100 patient-years was 5.9 events (95% CI, 5.2-6.8) throughout year 1, 1.8 events (95% CI, 1.6-2.0) per year in years 2 through 5, and 1.7 events (95% CI, 1.3-2.2) per year in years 6 through 10. The 5- and 10-year cumulative incidences of stroke were 12.5% (95% CI, 11.0-14.1) and 19.8% (95% CI, 16.7-23.1), respectively.

When compared with unselected patients, the rates of stroke were lower in studies that involved only patients with TIA (relative risk [RR], 0.68; 95% CI, 0.65-0.71) or with first-ever index events (RR, 0.45; 95% CI, 0.42-0.49).

Conclusions

The main study finding is that patients who have had a TIA or minor stroke are at an ongoing high risk for a subsequent stroke years after the event. This emphasizes the need for long-term stroke prevention measures in such populations.

McMaster editors’ commentary

This study adds to our knowledge of cerebrovascular disease by focusing on the long-term prognosis and the need for ongoing cardiovascular risk modification in patients presenting with a minor (nondisabling) stroke or TIA.

A minor stroke is usually associated with a neurologic deficit lasting >24 hours and acute ischemic changes on brain imaging. A TIA may be more difficult to diagnose, as it typically presents with a focal neurologic deficit lasting <60 minutes, with symptoms that can be minimal or fleeting, clinical signs that may be lacking at the time of presentation, and ischemic changes on brain imaging that may be absent in about half of the patients.