Left atrial function and ventricular filling in hypertensive patients with paroxysmal atrial fibrillation

We evaluated left atrial dimensions and function, as well as left ventricular structure and filling, in hypertensive patients with paroxysmal atrial fibrillation.

In hypertensive patients, left atrial dilation and enhanced volume transport may facilitate arrhythmias.

Left ventricular two-dimensional and M-mode echocardiograms and pulsed Doppler echocardiography of transmitral flow were performed in 17 consecutive primary hypertensive patients with paroxysmal atrial fibrillation (group EHf) and in 34 patients with high blood pressure without this arrhythmia (group EH). Seventeen normal subjects (group N) were also investigated. Groups were matched for age and gender.

The EH and EHf groups had similar systolic arterial pressures ([mean +/- SD] group EH 185 +/- 27, group EHf 173 +/- 25 mm Hg, p = NS) and left ventricular mass index (group EH 154 +/- 55, group EHf 131 +/- 57.8 g/m2, p = NS), and their M-mode left ventricular systolic wall stress and fractional shortening were comparable to those of normal subjects. M-mode left atrial maximal (group N 37.8 +/- 6, group EH 37.9 +/- 4.6, group EHf 44.6 +/- 6.7 mm, p < 0.05 for group EHf vs. groups N and EH) and minimal diameters and the diameter preceding atrial contraction (group N 31 +/- 3.6, group EH 34.5 +/- 5, group EHf 40.4 +/- 6.9 mm, p < 0.001 for group EHf vs. group N; p < 0.05 for group EHf vs. group EH) were greater in group EHf than in group EH and group N subjects, whereas only the latter diameter was increased in group EH (p < 0.05 vs. group N), so that left atrial fractional shortening was higher than normal only in group EH (group N 10.8 +/- 4.4%, group EH 14.6 +/- 5.5%, group EHf 9.3 +/- 5.3%; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05). The pulsed Doppler ratio of early to late transmitral flow rates (E and A wave velocity/time integrals x mitral annulus area) was lower than normal in group EH (group N 2.9 +/- 2.2, group EH 1.75 +/- 0.8, group EHf 2.8 +/- 0.8; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.001; group EHf vs. group N, p = NS) and was "normalized" in group EHf, early flow being increased in this group (group N 42 +/- 13, group EH 39 +/- 29, group EHf 60 +/- 17 ml; group EHf vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05).

These results suggest that the occurrence of paroxysmal atrial fibrillation in hypertension is associated with enlargement of the left atrium, depression of its contractile function and "normalization" of the pattern of left ventricular filling and is independent of left ventricular hypertrophy and systolic wall stress. The mechanisms linking these variables remain undefined.