Larger Left Atrial Size May Increase Stroke Risk in Blacks


Echocardiographically measured left atrial size was significantly related to ischemic stroke and all-cause mortality in a follow-up analysis of 1,886 blacks in the Atherosclerosis Risk in Communities study.

At a median of 9 years follow-up, there were 103 strokes (6.47/1,000 person-years) and 206 deaths (13.3/1,000 person-years) in participants in the Jackson, Miss., cohort of the study. Their mean age was 59 years; 65% were women.

Left atrial size was significantly related to hypertension, diabetes, and body mass index, Dr. Harsha S. Nagarajarao reported at the American Federation for Medical Research Southern Regional meeting in New Orleans.

In an effort to adjust left atrial (LA) size to body size, LA size was indexed to height and was then divided into quintiles, with 377 patients in the top quintile of LA size (2.57–3.55 cm/m) and 1,509 patients in the bottom four quintiles (1.29–2.56 cm/m). Significantly more patients in the top quintile of LA size were hypertensive (74.3% vs. 57%), diabetic (29% vs. 21.3%), and had a higher mean BMI, compared with those with lower LA size (34.6 vs. 29.4 kg/m

In a multivariate analysis, LA size on echocardiogram was significantly associated with ischemic stroke (hazard ratio 1.58) and all-cause mortality (HR 1.47), even after adjustment for age, sex, cigarette smoking, diabetes, hypertension, BMI, ratio of total cholesterol to HDL cholesterol, and triglyceride levels.

Left atrial size remained significantly related to all-cause mortality (HR 1.40) after further adjustment for left ventricular hypertrophy, Dr. Nagarajarao of the University of Mississippi Medical Center, in Jackson, and colleagues reported.

Non-Hispanic whites also have an increased incidence of stroke with increased LA size, but LA size is more important in blacks because of that population's increased stroke risk, Dr. Nagarajarao said in an interview. Blacks have a twofold higher incidence of stroke when compared with non-Hispanic whites, he added.

“Echocardiography may be a potentially useful noninvasive tool in identifying additional risk factors for stroke, and identifying participants with larger LA size may allow us to take preventive measures in identifying risk factors and treating them,” he said.

Last year, investigators at the University of Mississippi Medical Center also reported that echocardiographically derived left ventricular mass index (LVMI) was an independent predictor of incident ischemic stroke among 1,792 blacks in the Jackson cohort, after adjustment for similar cardiovascular risk factors (Stroke 2007;38:2686–91). In addition, the relation between LVMI and stroke remained significant after adding LA size and mitral annular calcification to the multivariable analysis.

Clinicians at the center determine LA size routinely on echocardiography in all patients at risk of stroke, Dr. Nagarajarao said. When asked which measurement is preferred, he said both LVMI and LA size have the potential to be independent predictors of risk factors, adding that it is important to recognize that each is independent of the other.

Previous studies have shown that the BP medication hydrochlorothiazide has reduced LA size when used along with controlling hypertension, although further study is needed to determine whether this has any effect on reducing stroke incidence, he said.

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