Usefulness of left atrial and left ventricular chamber sizes as predictors of the severity of mitral regurgitation.

Left ventricular (LV) and left atrial (LA) chamber sizes are frequently used to assist in assessing the severity of mitral regurgitation (MR). To study the reliability of these measurements in the clinical setting 2-dimensional echocardiographic measurements of the left ventricle and left atrium were obtained in 92 consecutive patients with MR present on both angiography and Doppler echocardiographic examinations performed within 2.8 +/- 2.5 days of each other. The accuracy of chamber dimensions in identifying severe MR (angiographic grade 3 to 4+) was determined in the total population and the following patient subgroups: (1) isolated chronic MR with preserved LV function inclusive of all rhythms; (2) isolated chronic MR, preserved LV function and sinus rhythm; (3) isolated chronic MR with LV dysfunction; (4) chronic MR associated with other valvular disease; and (5) acute MR. Only in subgroup 2 were chamber sizes reliable in identifying severe MR. Atrial dimensions provided the most accurate assessment with an LA volume greater than 58 ml, anteroposterior dimension greater than 45 mm and superoinferior dimension greater than 55 mm, with sensitivities of 75, 75 and 88%, specificities of 83, 100 and 83%, positive predictive values of 92, 100, and 93% and negative predictive values of 56, 60, and 71%, respectively. LV dimensions had excellent positive predictive values but lower sensitivities. Normalizing for body surface area did not improve the accuracy of uncorrected dimensions. Although increased LA and LV dimensions can identify severe MR, smaller dimensions do not exclude this diagnosis. With acute MR, atrial fibrillation, LV dysfunction or associated valvular disease, these dimensions are not reliable.