NEW YORK (Reuters Health) – Left atrial volume rather than diameter is more strongly associated with thromboembolic risk markers in patients with mitral stenosis, and should be used to guide anticoagulation decisions, according to a French study.

In the introduction to their paper in the American Journal of Cardiology online September 2, Dr. David Messika-Zeitoun at Bichat Hospital, Paris, and colleagues point out that guidelines recommend anticoagulation for patients with mitral stenosis if the left atrium is enlarged based on measurement of the diameter.

The researchers compared the association of left atrial (LA) diameter or left atrial volume with well documented markers of thromboembolic risk — peak LA appendage emptying velocity (LAAv) and LA spontaneous contrast density measured during transesophageal echocardiography.

The study involved 80 patients with mitral valve area <1.5 cm² undergoing transthoracic echocardiography. “LA diameter was measured as recommended in the parasternal long-axis view. LA volume was calculated using the biplane area-length method in 4- and 3-chamber views as previously validated,” according to the report. The researchers found that LA volume indexed to body surface area differentiated patients with normal LAAv from low LAAv (86 vs 71 mL/m², p<0.01), but LA diameter did not (50 vs 48 mm, p = 0.13.) Results were similar when using spontaneous contrast as the marker of thromboembolic risk. Using a LA volume of 60 mL/m² rather than a LA diameter of 50-55 mm “would have changed the indication for anticoagulation in 51% to 77% of patients,” Dr. Messika-Zeitoun and colleagues calculate. They conclude that LA volume instead of LA diameter should guide anticoagulation in patients with mitral stenosis in sinus rhythm, and they point out that “changing the practice from measuring LA diameter to LA volume only slightly prolongs the echocardiographic examination.” Reference:
Usefulness of Left Atrial Volume Versus Diameter to Assess Thromboembolic Risk in Mitral Stenosis

Am J Cardiol 2010.