Cerebral atherosclerosis and coronary calcification.

Cerebral Atherosclerosis and Coronary Calcification To the Editor: We read with great interest the article by Vliegenthart et al1 concerning an association between stroke and coronary calcification. It is of interest whether coronary calcification is correlated with cerebral atherosclerosis. We also believe that coronary calcification could play a crucial role in the incidence of cerebral infarctions. We would like to show a possible relationship between coronary calcification and cerebral atherosclerosis and then we would like to compare their study and ours. At the PL Tokyo Health Care Center, 31 646 Japanese subjects (19 901 men and 11 745 women) received physical checkups between April 1, 2001, and March 31, 2002. Among them, brain checkup and helical CT of the chest were done in 1100 subjects (865 men, 245 women). Mean age was 53.8 years (SD, 10.9 years), 54.0 years (SD, 10.8 years) in men and 53.1 years (SD, 11.2 years) in women. Brain MRI and magnetic resonance angiography (MRA) were produced by a 1.5-Tesla superconducting system (Stratis II, Hitachi Medical Co). Axial T1-weighted (repetition time/echo time 400/20 ms) and T2-weighted (repetition time/echo time 4750/120 ms) images were performed on MRI. The slice/gap thickness of the MRI was 6.0/0.5 mm, and the matrix size was 224 256. The number of acquisitions was 2. MRA was applied by 3-dimensional time-of-flight technique. The slice thickness was 0.6 mm, and the matrix size was 140 140. Helical CT was used with CT-W3000 (Hitachi Medical Co). The slice thickness was 5 to 10 mm, and the matrix size was 256 256. Scan areas included the root of aorta through the heat. The total number of slices was 40. Lacuna was defined as T1-hypointense and T2-hyperintense areas (3 mm diameter 15 mm). MRA score of atherosclerosis was classified from grade 1 to 4. In grade 1 (normal), blood flow signal intensities were displayed clearly in the A3 segment of the anterior cerebral artery, M3-4 segment of the middle cerebral artery, or P3-4 segment of the posterior cerebral artery. In grade 2 (mild atherosclerosis), blood flow signal intensities were seen equivocally in the distal portion of the A3 segment, M3 segment, or P3 segment. In grade 3 (moderate atherosclerosis), blood flow signal intensities were absent in the distal portion of the A3 segment, distal portion of the M3 segment, or distal portion of P3 segment. Finally, in grade 4 (severe atherosclerosis or obstruction), blood flow signal intensities were absent in the A1 segment of the proximal portion of A3 segment, M1 segment of the proximal portion of the M3 segment, or P1 segment of the proximal portion of P3 segment. Total atherosclerotic score was calculated as 3 to 12 in the anterior, middle, and posterior cerebral arteries. One experienced neurologist and 2 diagnostic radiologists reviewed brain MRI and MRA. Three experienced diagnostic radiologists reviewed chest CT. Calcium score was determined according to the method of Agatston et al.2 Coronary calcification was diagnosed as calcium score 500 and a density of 130 Hounsfield units in the epicardial coronary arteries. One hundred forty-nine subjects (131 men, 18 women) had coronary calcification. The incidence of calcification was 12.5%, 14.2% in men and 6.5% in women. The mean age of the calcification group was 63.9 years (SD, 8.7 years), 63.1 years (SD, 8.6 years) in men and 70.3 years (SD, 6.6 years) in women. That of the noncalcification group was 52.3 years (SD, 10.4 years), 52.4 years (SD, 10.3 years) in men and 51.9 years (SD, 10.5 years) in women. The frequency of diabetes mellitus (fasting plasma glucose 126 mg/dL or current medication), hypertension (systolic pressure 140 mm Hg, diastolic pressure 90 mm Hg, or current medication), or hypercholesterolemia (total cholesterol 220 mg/dL or current medication) was significantly higher in the coronary calcification group compared with the noncalcification group. Current or history of smoking was also seen more frequently in subjects with coronary calcification. The number of lacunas did not differ between subjects with and without coronary calcification. The MRA score was associated with hypertension and diabetes mellitus. Severity of cerebral atherosclerosis and incidence of coronary calcification were increased by age in our adult subjects. The atherosclerotic score was significantly higher in subjects with coronary calcification than in those without calcification. In logistic regression analysis, there were no statistical associations between coronary calcification and the degree of cerebral atherosclerosis when adjusted for diabetes mellitus, hypertension, hypercholesterolemia, and smoking. An ageadjusted model showed a statistical tendency between coronary calcification and cerebral atherosclerosis in women (odds ratio, 3.7) but not in men (odds ratio, 1.3). Vliegenthart et al1 report the association between coronary calcification and stroke history in Rotterdam older inhabitants. We evaluated the degree of cerebral atherosclerosis in individuals with coronary calcification on the basis of the retrospective data of helical CT, brain MRI, and MRA. Our data indicated that subjects with coronary calcification had higher cerebral atherosclerotic score and several cardiovascular risk factors. The calcification subjects were 10 years older than the noncalcification subjects. We would like to know the mean age of subjects with calcium scores 500 in the study of Vliegenthart et al. In addition, what is the frequency of hypertension, diabetes mellitus, and hypercholesterolemia and the smoking history in those subjects? Vliegenthart et al suspect the possibility that most of stroke types may consist of lacunar infarctions in their study. Our data of brain checkups show that asymptomatic lacunar infarction occurs in 20% to 30% of healthy senile subjects. We would like to know neuroradiological data if they performed brain CT, MRI, or MRA in subjects with calcium scores 500. The percentage of calcium scores 500 was lower in our study (12.5%) than in the Rotterdam study (27.5%). Vliegenthart et al applied electron-beam CT scan. A severe degree of coronary calcification on conventional helical CT was detected in our subjects. Helical CT is known to be restricted for the quantitative measurement of coronary calcification compared with electronbeam CT.3 The age of subjects also differs between their study and ours. The mean age was 70.8 years (SD, 5.5 years) in the study of Vliegenthart et al1 and 53.8 years (SD, 10.9 years) in our subjects. A previous report suggests that calcium score increases with age in older adults.4 In our study, coronary calcification and cerebral atherosclerosis are associated with age and several cardiovascular risk factors. Age-adjusted logistic analysis discloses a statistical tendency between coronary calcification and cerebral atherosclerosis in our female subjects. Further long-term studies are needed to determine whether coronary calcification is an independent risk factor of stroke in the Japanese population.