Diurnal variation of the P-wave dispersion in chronic ischemic heart diseases.

Objective: Electrocardiographic indices like maximum P-wave duration (P(max)) and P-wave dispersion (PD) can be used to detect patients with atrial conduction disorders, myocardial ischemia and those at risk for atrial fibrillation. Considering the diurnal variation of ischemia in patients with significant coronary lesions, this study was designed to investigate the diurnal variation of eventual atrial conduction abnormalities.

Methods: Forty-eight patients (31 male) with typical angina were grouped according to coronary angiography results as group 1 - 70% or more luminal reduction in at least one of the coronary arteries (n=28), and group 2 - normal coronary arteries (n=20). The difference between the P(max) and minimum P-wave durations (P(min)) is designated as PD. The diurnal P(max), P(min) and PD values were compared between and within the groups.

Results: The morning P(max) value of group 1 was significantly higher than the value of group 2 (112+/-1 vs. 102+/-1 ms, P<0.001). The morning PD of group 1 was significantly higher than that of group 2 (54+/-9 vs. 48+/-1 ms, P<0.05). The morning P(max) of group 1 (112+/-1 ms) was significantly higher than its afternoon (102+/-9 ms) and night (102+/-1 ms) values (P<0.001). The morning PD of group 1 (54+/-9 ms) was higher than the afternoon (40+/-10 ms) and night (43+/-9 ms) PD (P<0.001). No significant difference was observed between the P(max), P(min) and PD values in group 2 (P>0.05).

Conclusion: This study demonstrated that coronary heart disease patients have higher morning P(max) and PD values that may be important regarding prediction of timing and treatment of atrial conduction disorders in myocardial ischemia.