Side of brain infarction and long-term risk of sudden death in patients with symptomatic carotid disease

Background and Purpose - Current publications suggest increased risk of sudden death in experimental animals with acute right insular lesions and in patients with recent right- sided brain infarction, particularly if the insula is involved. Methods - Using 3 different time definitions, we related long- term risk of sudden death to presence and side of brain infarction on the baseline brain scan and handedness in 2885 patients with symptomatic carotid disease. Results - In 1295 patients without brain infarction, 5- year risk of sudden death was 5.3% ( 24- hour definition); in those with left- sided infarction ( n = 471), 8.8%; in those with right- sided infarction ( n = 477), 6.0%; and in those with bilateral infarction ( n = 535), 9.7%. After accounting for differences of other risk factors ( eg, previous myocardial infarction) in Cox regression, adjusted hazard ratios ( HRs) compared with no infarction were as follows: left- sided HR, 1.45 ( 95% confidence interval [ CI], 1.00 to 2.10); right- sided HR, 0.96 ( 95% CI, 0.62 to 1.47); and bilateral HR, 1.40 ( 95% CI, 0.98 to 2.00). Insular infarction occurred in 41 patients; none died suddenly. Left- handed or ambidextrous patients ( n = 183) had a lower risk of sudden death than right- handers; the adjusted HR for left- handed or ambidextrous patients was 0.24 ( 95% Cl, 0.07 to 0.70). These results were essentially the same for the 10- and 60- minute definitions of sudden death. Conclusions - In the long- term, left- sided, not right- sided, brain infarction is associated with increased risk of sudden death. Left- handed or ambidextrous patients have a lower risk of sudden death than right- handed patients, suggesting a role for the brain.