Incidence of ischemic stroke in relation to asymptomatic carotid artery atherosclerosis in subjects with normal blood pressure. A prospective cohort study.
BACKGROUND
Approximately 10-20% of stroke cases have normal blood pressure (BP). The objective of this study was to explore whether the risk of ischemic stroke is related to the carotid intima-media thickness (CIMT) and atherosclerotic lesions in a cohort of subjects with normal BP.


METHODS
Common CIMT and the presence of carotid plaque were determined by B-mode ultrasound in 6,103 subjects, randomly recruited between 1991 and 1994 from the 'Malmo Diet and Cancer' study. Normal BP was defined as BP <140/90 mm Hg, without pharmacological treatment for hypertension. Carotid artery atherosclerosis (CAA) was defined as CIMT > or =0.81 mm or/and the presence of plaque (i.e. focal CIMT >1.2 mm). The incidence of ischemic stroke was followed over a mean period of 10.7 years.


RESULTS
A total of 2,228 subjects (791 men and 1,437 women) had normal BP. During the follow-up, 34 patients suffered a first-ever ischemic stroke (crude incidence: 1.51/1,000 person-years). The Prevalences of CAA in subjects with and without stroke were 68.6 and 39.0%, respectively. It was estimated that the subjects with CAA had a 3-fold higher risk of ischemic stroke (RR: 3.33, 1.37-8.14), independent of other cardiovascular risk factors. Each increase of 1 standard deviation (0.13 mm) in CIMT increased the stroke risk by 43% (RR: 1.43, 1.002-2.02). Several factors were found to have a notable relation with CAA, including age, male sex, smoking, diabetes, systolic BP, HbA1c (glycosylated hemoglobin) and cholesterol.


CONCLUSIONS
CIMT and atherosclerotic lesions are independent clinical markers for ischemic stroke among normotensive individuals.
Li
Cairu
C
Epidemiological Research Group, Department of Clinical Sciences, Lund University, Malmö University Hospital, Malmö, Sweden. cairu.li@med.lu.se
Engström
Gunnar
G
Berglund
Göran
G
Janzon
Lars
L
Hedblad
Bo
B
D001794:Blood Pressure; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002340:Carotid Artery Diseases / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging*; D017540:Tunica Media / Q000000981:diagnostic imaging*; D018608:Ultrasonography, Doppler