The risk of recurrent stroke is highest in the first few weeks after a first transient ischemic attack (TIA) or stroke. Knowledge of which stroke subtypes have the highest risk for early recurrence allows for a better prioritization of necessary investigations and treatments to prevent a second TIA or stroke.
Lovett and associates performed a meta-analysis on the risk of recurrent stroke assessed by etiologic subtype. The data were derived from two population-based studies, the Oxford Vascular Study and the Oxfordshire Community Stroke Project, and from two other published studies reporting equivalent data. Patients (n=1,709) were classified according to the four following etiologic subtypes of ischemic stroke: large artery atherosclerosis, small vessel stroke, cardioembolic, and undetermined. Only 14% of the primary strokes evaluated were associated with large vessel atherosclerotic stroke; however, this subtype accounted for 37% of recurrences within seven days of the first event.
Compared with other subtypes, patients with stroke due to large vessel atherosclerosis had the highest odds of recurrence at seven days (odds ratio [OR] = 3.3, 95% confidence interval (CI), 1.5-7.0), 30 days (OR = 2.9, 95% CI, 1.7- 4.9), and three months (OR = 2.9, 95% CI, 1.9- 4.5).
At 30 days, patients with small vessel strokes had the lowest risk of recurrence (OR=0.2, 95% CI, 0.1- 0.6), followed by patients with cardioembolic (OR=1.0, 95% CI, 0.6-1.7) or undetermined (OR=1.0, 95% CI, 0.6-1.6) stroke (Table 1; Lovett, 2004).
The recurrence rate for the first year after a lacunar stroke and for the following two years is approximately 10% (Hier, 1991; Sacco, 1991). Only a minority of recurrent strokes are of lacunar etiology, which emphasizes the need for thorough evaluation of patients with lacunar strokes.
Cryptogenic stroke has been clearly associated with a heart defect known as patent foramen ovale (PFO) in patients younger than 55 years (Overell, 2000). There are few reports available concerning stroke recurrence in patients with PFO, and the published event rates vary considerably. In one study by Mas and colleagues, none of the patients with isolated PFO who had a cryptogenic stroke or TIA experienced a recurrent event during a two-year follow-up (Mas, 1995). In a second study on cases of brain infarction (84% of which were cryptogenic) and PFO, the average annual rates of recurrence were 1.9% for stroke and 3.8% for stroke or TIA (Bogousslavsky, 1996).
Cervical artery dissection accounts for up to one fifth of ischemic strokes occurring before 45 years; however, recurrence is uncommon and usually represents a benign condition (Leys, 1997; Bassetti, 1996).
Stroke survivors are also at increased risk of mortality following the first stroke compared with the general population of the same age and sex. Although the mortality risk is greatest during the first 30 days following a stroke, the risk persists for several years. The increased risk of mortality has been attributed to vascular disease, specifically recurrent stroke and other cardiovascular (CV) conditions. In fact, stroke survivors are more likely to die from recurrent stroke and CV events (including MI) as they are from incident stroke (Kannel, 1994; Wilterdink, 1992; Sacco, 1994; Coull, 2004).
- Of the 209 stroke patients who died in the Oxfordshire Community Stroke Project between 31 days and five years after the first stroke, 19% died of the incident stroke, 17% died of a recurrent stroke, and 34% died of other CV events (Dennis, 1993)
- Among 231 patients in the Northern Manhattan Stroke Study (NOMASS) who died between 31 days and five years after the incident stroke, 8% died of the incident stroke, 7% died of a recurrent stroke, and 29% died of other CV events (Hartman, 2001)
- Among 362 patients in the Perth Community Stroke Study who died between 31 days and five years after the incident stroke, 19% died of the incident stroke, 8% died of a recurrent stroke, and 31% died of other CV events (Hankey, 2000)
In summary, the risk of early recurrent stroke is highest in patients with large vessel atherosclerotic stroke, which supports the need for carotid imaging and secondary prevention tactics. Long-term survival after stroke may be improved by appropriate, early, and sustained interventions aimed at preventing subsequent strokes and CV events.
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