21st European Meeting on Hypertension and Cardiovascular Prevention
The association between left atrium enlargement (LAE) and increased cardiovascular morbidity and mortality is of clinical importance. Michele Bombelli, MD University of Milano-Bicocca, Monza, Italy, presented data from the PAMELA (Pressioni Arteriose Monitorate E Loro Associazioni) Study showing that among subjects with a normal sized left atrium, 11.8% developed LAE within 10 years. Baseline left atrial diameter (LAD), female sex, office systolic blood pressure (SBP), and left ventricular mass index (LVMI) were independent predictors of LAE.
The PAMELA Study was comprised of 1,045 subjects (mean age 47 years, range 25 to 74; ~50% men) without LAE who were randomly selected from the general population of Monza (Italy). Office systolic (S) and diastolic (D) blood pressure (BP); home SBP and DBP (mean of 2 self measurements); 24 hour SBP and DBP; office, home and 24 hour heart rate (HR); LVMI, LAD by echocardiography, as well as height and weight were collected for all subjects between 1990 and 1992 and again between 2000 and 2002. Pathological LAE was defined as LAD ≥3.9 cm in women and ≥4.1 cm in men; left ventricular hypertrophy (LVH) was defined as LVMI ≥106 g/m2 and ≥111 g/m2 respectively. Reference values for office, home and 24 hour SBP/DBP were 140/90 mmHg, 132/83 mmHg, and 125/79 mmHg, respectively.
Over the 10 years of the study 11.8% (123/1045) of the participants developed LAE. The incidence of a new onset LAE was progressively higher from the lowest to the highest tertile of office, home, and 24 hour SBP (p <0.0001 for trend). The incidence was progressively more frequent in subjects with more frequently elevated BP (p for trend <0.0001). The incidence of new onset LAE was also progressively higher from the lowest to the highest tertile of LVMI (p <0.0001 for trend), and from the lowest to the highest tertile of BMI, plasma total cholesterol and blood glucose (p <0.0001 for trend). The incidence of LAE was not affected by heart rate.
On multivariate analysis the factors independently involved with new onset LAE were baseline LAD, female sex, office SBP, and LVMI (Table 1).
Table 1. Independent Predictors of Left Atrium Enlargement
|Odds Ratio||95% CI||P value|
|Baseline LAD||38.12||14.85, 97.83||<0.0001|
|Female sex||3.79||2.25, 6.36||<0.0001|
|Office SBP||1.02||1.01, 1.03||= 0.0028|
|LVMI||1.01||1.00, 1.03||= 0.0383|
LAD=left arterial diameter; SBP=systolic blood pressure; LVMI=left ventricular mass index
Although the study is limited by the fact that left atrial volume was not measured Prof. Bombelli noted that the decision was made to proceed with the analysis because there are data showing that LAD is an independent predictor of cardiovascular events, at least in hypertensive subjects; and also because there are guidelines for the classification of left atrium size as normal or abnormal, which are based on left atrium diameter.