Influence of blood pressure on left atrial size. The Framingham Heart Study

Left atrial dimensions determined by M-mode echocardiography in black and white older (> or =65 years) adults (The Cardiovascular Health Study)

Stroke and atrial fibrillation are common and serious illnesses in the elderly, the risks of which are substantially increased by left atrial (LA) enlargement. Despite growing recognition of the importance of LA enlargement, the distribution and correlates of LA dimension in the elderly have not been well defined. A total of 3,882 women and men aged >65 years were studied. Increased LA dimension was independently associated with increased weight, mitral annular calcium, regional wall motion abnormalities, mitral early peak inflow velocity, and left ventricular (LV) fractional shortening. Increased LA dimension was negatively associated with aortic leaflet thickening. The relation with LV fractional shortening was curvilinear with a nadir at 35% to 40%. LA dimension in black men was approximately 1.9 mm less than in white men in multivariate analyses. Adjustment for spirometric lung volumes and chest dimensions appeared to diminish the race-LA dimension relation. Thus, LA dimension is strongly associated with weight and with several echocardiographic valvular abnormalities; its relation with LV fractional shortening is U-shaped with a nadir at the borderline of LV functional impairment.

Left atrial size in children with hypertension: the influence of obesity, blood pressure, and left ventricular mass

OBJECTIVE

To evaluate the prevalence of left atrial enlargement and the correlates of left atrial size in children and adolescents with essential hypertension.

BACKGROUND

Left atrial enlargement has been associated with increased risk of cardiovascular disease, including stroke in adults. Risk factors for left atrial size in adults with hypertension include age, race, and obesity.

METHODS AND RESULTS

Patients (n =112; average age, 14.2 years) with essential hypertension were studied with echocardiography. The average left atrial dimension was 2.8 (+/- 0.5) cm; 51% patients had left atrial dimension >95% upper confidence limit. The patients with left atrial enlargement had greater body mass index (P <.05) than those without left atrial enlargement. In multiple regression analysis, height, body mass index, systolic blood pressure, and left ventricular geometry were significant independent correlates of left atrial size. Children with eccentric left ventricular hypertrophy were more likely to have a larger left atrial dimension.

CONCLUSIONS

Left atrial enlargement is prevalent in children and adolescents with essential hypertension. This may indicate an increased risk of cardiovascular disease morbidity and mortality. Control of obesity and blood pressure elevation offer two approaches for treatment that may prevent left atrial enlargement.

Heritability of left atrial size in the Tecumseh population

BACKGROUND

Little is known about the determinants of atrial size, and no study has analyzed whether genetic factors are involved in the pathogenesis of LA enlargement.

MATERIALS AND METHODS

We studied the heritability of echocardiographic left atrial size in 290 parents from the Tecumseh Blood Pressure Study and 251 children from the Tecumseh Offspring Study. All data from the parents and children were obtained at the same field office in Tecumseh, USA. Left atrial dimension was determined echocardiographically in accordance with American Society of Echocardiography guidelines with the use of leading-edge-to-leading-edge measurements of the maximal distance between the posterior aortic root wall and the posterior left atrial wall at end systole.

RESULTS

For correlation between the left atrial dimensions of the parents and their offspring, several models were generated to adjust the atrial dimensions in both groups for an increasing number of clinical variables. After removing the effect of age, gender, height, weight, skinfold thickness, and systolic blood pressure, parent-child correlation for left atrial size was 0.19 (P = 0.007). Further adjustment for left ventricular mass and for measuring left ventricular diastolic function increased the correlation to 0.25 (P = 0.001).

CONCLUSIONS

The present data indicate that heredity can explain a small but definite proportion of the variance in left atrial dimension.

Left ventricular mass and atrial volume determined by cine magnetic resonance imaging in essential hypertension

To evaluate the relationship between left atrial volume determined by cine magnetic resonance imaging and progression of left ventricular hypertrophy (LVH), left atrial volume and echocardiographic left ventricular mass (LVM) were measured in 30 hypertensive patients (15 without LVH and 15 with LVH) and 10 normotensive control subjects. We also evaluated the effects of antihypertensive therapy on the cardiac chamber volumes and LVM in hypertensive patients. The cardiac chamber volumes and LVM were indexed by body surface area. Although there were no significant differences in left ventricular chamber volumes among the three groups, both maximum and minimum left atrial volume indexes, and the LVM index were greater in hypertensive patients with LVH than in the other two groups. The LVM index was correlated with maximum left atrial volume index (r = 0.74, P < .0001), and minimum left atrial volume index (r = 0.76, P < .0001), respectively. Furthermore, in multivariate models, the LVM index was significantly correlated with maximum left atrial volume index. In hypertensive patients with LVH, both maximum and minimum left atrial volume indexes, and the LVM index significantly reduced after treatment. The percent of changes in maximum left atrial volume index after treatment was significantly correlated with the percent of changes in LVM index after treatment. In conclusion, our data indicate that LVH is an independent determinant of left atrial enlargement, and both LVH and left atrial enlargement may be reversed by some effective therapeutic interventions.

Left atrial diameter in nonvalvular atrial fibrillation: An echocardiographic study. Stroke Prevention in Atrial Fibrillation Investigators

BACKGROUND

The left atrium (LA) is usually enlarged in patients with nonvalvular atrial fibrillation (AF), but factors associated with LA diameter are incompletely defined.

METHODS AND RESULTS

This transthoracic echocardiographic cohort study includes 3465 participants with nonvalvular AF in 3 multicenter clinical trials. LA diameter determined by M-mode echocardiography was correlated with clinical and echocardiographic features by cross-sectional multivariate regression analyses. The mean LA diameter was 47 +/- 8 mm, on average 6 mm larger in those with AF at the time of echocardiography than in those with sinus rhythm (48 vs 42 mm, P <. 001). Patient age and body weight were independently predictive of LA diameter (P <.0001), but sex, body surface area, and body mass index were not. The estimated independent contribution of atrial rhythm to LA diameter was approximately 2.5 mm. Prolonged duration of AF, left ventricular dilatation and increased muscle mass, mitral regurgitation, annular calcification, and hypertension were additional independent predictors of LA diameter.

CONCLUSIONS

Multiple factors appear to contribute to LA enlargement in patients with nonvalvular AF, including the presence and persistence of the dysrhythmia.

Left atrial size in hypertensive men: influence of obesity, race and age. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

OBJECTIVES

We sought to determine the relations of left atrial (LA) size to blood pressure, obesity, race, age and left ventricular (LV) mass in hypertension.

BACKGROUND

Although obesity, race and age may influence LV mass, their effects on LA size have not been defined in hypertension.

METHODS

Left atrial size was measured in 690 men (58% African-Americans) with mild to moderate hypertension (mean [+/-SD] blood pressure 152 +/- 15/98 +/- 6 mm Hg) and a high prevalence of LV hypertrophy. Effects of LV mass, adiposity, race, age, physical activity, height, weight, sodium excretion, plasma renin activity and heart rate were examined.

RESULTS

Left atrial size was greater (p < or = 0.0001) in obese (44.2 +/- 5.7 mm) than in overweight (41.6 +/- 5.9 mm) or normal weight (38.9 +/- 6.2 mm) patients. Left atrial enlargement (> or = 43 mm) was present in 56% of obese patients compared with 42% of overweight and 25% of normal weight hypertensive men. As age increased, white patients had a greater LA size than African-American patients. Although there was no relation between LV mass and LA size in normal weight patients, there was a significant positive relation in obese patients. On multiple regression analysis, obesity was the strongest independent predictor of increased LA size.

CONCLUSIONS

Obesity is the strongest predictor of LA size in patients with hypertension and amplifies the relation between LA size and LV mass. Race influences effects of age and hypertension on LA size. Because increased LA size and LV mass (also influenced by obesity) are associated with an adverse outcome, these findings underscore the importance of obesity, race and age with regard to the cardiac effects of hypertension.

Left atrial size and the risk of stroke and death. The Framingham Heart Study

BACKGROUND

The medical literature contains conflicting reports on the association of left atrial (LA) enlargement with risk of stroke. The relation of LA size to risk of stroke and death in the general population remains largely unexplored.

METHODS AND RESULTS

Subjects 50 years of age and older from the Framingham Heart Study were studied to assess the relations between echocardiographic LA size and risk of stroke and death. During 8 years of follow-up, 64 of 1371 (4.7%) men and 73 of 1728 (4.2%) women sustained a stroke, and 296 (21.6%) men and 271 (15.7%) women died. Sex-specific Cox proportional-hazards models were adjusted for age, hypertension, diabetes, atrial fibrillation, smoking, ECG left ventricular (LV) hypertrophy, and congestive heart failure or myocardial infarction. After multivariable adjustment, for every 10-mm increase in LA size, the relative risk of stroke was 2.4 in men (95% CI, 1.6 to 3.7) and 1.4 in women (95% CI, 0.9 to 2.1); the relative risk of death was 1.3 in men (95% CI, 1.0 to 1.5) and 1.4 in women (95% CI, 1.1 to 1.7). Adjusting for ECG LV mass/height attenuated the relation of LA size to stroke and death.

CONCLUSIONS

After multivariable adjustment, LA enlargement remained a significant predictor of stroke in men and death in both sexes. The relation of LA enlargement to stroke and death appears to be partially mediated by LV mass.