The mitral L wave: a marker of advanced diastolic dysfunction in patients with atrial fibrillation.

BACKGROUND: The prominent mid-diastolic filling wave (mitral L wave) indicates advanced diastolic dysfunction in patients in sinus rhythm. The aim of the present study was to determine the clinical implications of the mitral L wave in patients with atrial fibrillation (AF). METHODS AND
RESULTS: Ninety-nine consecutive non-valvular chronic persistent AF patients were enrolled. The mitral L wave was defined as a distinct mid-diastolic flow velocity following the E wave with a peak velocity>20 cm/s. The prevalence of the L wave in AF patients (34/99, 34%) was significantly higher than that observed in patients in sinus rhythm during the same study period (23/946, 2.4%, p<0.001). Patients with AF and L wave were older, more frequently female and had a slower heart rate, shorter isovolumic relaxation times, larger E wave velocities and lower early diastolic mitral annulus velocity (E') resulting in the higher E/E' compared to those without L waves. The left atrial volume index was significantly larger in patients with an L wave. The Valsalva maneuver decreased, and leg elevation increased, the amplitude of the L wave in the subset of patients who received these procedures.
CONCLUSIONS: The appearance of the mitral L wave in AF is relatively common, and its presence indicates advanced diastolic dysfunction, including elevated filling pressures and distended noncompliant LA.