Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular diastolic dysfunction in patients at risk of atrial fibrillation.

BACKGROUND: Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular (LV) diastolic dysfunction in patients at risk of atrial fibrillation (AF) may be assessed by high-resolution electrocardiography of P wave.
OBJECTIVES: To determine how left atrial size, left atrial pressure and LV diastolic dysfunction, measured noninvasively by transthoracic echocardiography, influence atrial conduction time.
METHODS: Signal-averaged electrocardiography of P wave and echocardiogram were performed on 70 patients (average age of 63+/-10 years; 37 male and 33 female), divided into three groups: group A, patients with paroxysmal AF (n=29); group B, patients with type 2 diabetes mellitus and arterial hypertension, but without AF (n=23); and group C, healthy control patients (n=18). Standard statistical methods were used.
RESULTS: Filtered P wave duration, measured by signal-averaged electrocardiography, was significantly prolonged in group A and group B compared with control group C (138+/-12 ms and 125+/-9 ms versus 117+/-8 ms; P </= 0.001 and P </= 0.01, respectively). Left atrial diameter, area and volume were significantly increased in group A compared with group C (P </= 0.01, P </= 0.05 and P </= 0.001, respectively), but no significant differences were found in these dimensions between group B and group C. Left atrial pressure, determined with the Doppler echocardiographic parameter ratio of early diastolic transmitral velocity to mitral annular early diastolic velocity, was significantly higher in group A, as well in group B, than group C (P </= 0.05, P </= 0.01). As well, impaired LV relaxation was present more often in group A (42%) and group B (50%).
CONCLUSION: Atrial conduction delay in patients at risk of AF (patients with diabetes and hypertension in group B) was associated with increased left atrial pressure and impaired LV relaxation. Patients with paroxysmal AF (group A) presented left atrial dilation, increased left atrial pressure and impaired LV relaxation, and these factors were associated with more significantly prolonged atrial conduction in group A than in group B.