Author + information
- Katrijn Jansen, MD,
- Navin Mani, BS,
- Praveen Mehrotra, MD,
- Timothy C. Tan, MBBS, PhD,
- Xin Zeng, MD, PhD,
- Danya Dinwoodey, MD,
- Michael H. Picard, MD and
- Judy Hung, MD∗ ()
- ↵∗Blake 256, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114.
Left atrial (LA) volume has been shown to be a prognostic indicator of cardiovascular (CV) events and a marker of diastolic dysfunction (1,2). Normative values for indexed LA volume (LAVi) have been established to be 22 ± 6 ml/m2 (3). Yet, these values are on the basis of small sample size studies, from a period with different imaging technology and using inconsistent measurement techniques.
We aimed to re-examine the normal reference standards for LAVi in a contemporary healthy population. We searched our institutional database for a 1-year period to identify healthy subjects with normal echocardiograms. Medical records were comprehensively reviewed to select healthy patients (no CV risk factors, pulmonary or renal disease). LA volume was calculated by the biplane area–length method (3). Diastolic parameters were assessed. Furthermore, a healthy validation subset of 20 subjects was examined prospectively.
From June 2009 to June 2010, 285 healthy subjects were identified and LA volumes measured. The mean LAVi was 30.3 ± 6 ml/m2 (mean age 38.3 ± 14.8 years, 61.4% women) with no difference observed between men and women (30.3 ± 7.0 ml/m2 vs. 30.5 ± 6.0 ml/m2, p = 0.81) and no age differences in absolute or indexed LA volumes in the entire healthy cohort or by sex.
Mean diastolic parameters were normal. Thirty percent of subjects had a LAVi ≥34 ml/m2—a cutoff used to identify those with abnormal diastolic function (1). E/A, average E′, and E/E′ were not significantly different between this group and those with a LAVi <34 ml/m2. The prospective cohort of 20 healthy subjects, matched to age (38.3 ± 7.0 years), sex (60% women), and body surface area (1.8 ± 0.2 m2) had similar mean LAVi to the retrospective cohort (31.7 ± 6.0 ml/m2 vs. 30.3 ± 7.0 ml/m2; prospective vs. retrospective p = 0.35).
Reassessment of LAVi in a contemporary healthy cohort suggests that normative reference ranges of LAVi should be higher than previously reported. In the present study, the mean LAVi in healthy subjects was 30.3 ± 6.5 ml/m2, 38% higher compared with current reference values for mean normal LAVi (22 ± 6 ml/m2) (3) (Fig. 1).
Various factors may account for the discrepancy between previously reported values and our results. Current reference values are on the basis of relatively small sample size studies and obtained from a period with different imaging technology. With improved spatial resolution in current imaging systems, measurement of LA boundaries may be more accurate. The confluence of the pulmonary veins may also be better visualized, thus avoiding inadvertent extension of the LA length measurement into the pulmonary vein—an error that results in smaller LA volumes. In addition, there has been a lack of consistency in methods used to calculate LAVi. Prior studies have reported LA volumes using biplane area-length, biplane Simpson’s, and prolate ellipsoid methods (1,2,4).
LAVi is considered a marker of diastolic dysfunction (1), with a current cutoff value of 34 ml/m2 used to indicate elevated left ventricular filling pressures in the setting of an E/E′ between 9 and 14. In our study, however, 30% of healthy subjects had a LAVi ≥34 ml/m2 in the presence of normal echocardiographic indexes of left ventricular filling pressures.
This study is a retrospective analysis, and measurements were not performed blinded to the clinical data and thus are subject to selection and information bias.
In conclusion, reassessment of LAVi in a contemporary healthy cohort suggests higher normative reference ranges than previously published. Establishing normative values for LA volumes are important for clinical decision making, given the significant association that has been reported between increased LA volume and prognosis in a wide range of CV diseases.
- American College of Cardiology Foundation
- Pritchett A.M.,
- Jacobsen S.J.,
- Mahoney D.W.,
- Rodeheffer R.J.,
- Bailey K.R.,
- Redfield M.M.
- Thomas L.,
- Levett K.,
- Boyd A.,
- Leung D.Y.,
- Schiller N.B.,
- Ross D.L.