Effect of slow coronary flow on P-wave duration and dispersion.

The slow coronary flow (SCF) phenomenon is often considered to be an incidental angiographic finding; however, several reports have shown it to be associated with cardiac events. In this study we aimed to assess P-wave duration and dispersion (PWD) in patients with SCF and to compare it with that of healthy subjects. Thus, 40 patients with angiographically proven SCF and otherwise normal coronary arteries (group 1) and 36 sex-age-matched healthy subjects (group 2) were included in this study. A 12-lead surface ECG, recorded at a paper speed of 50-mm/s and 2 mV/cm standardization, was obtained from each subject. P-wave duration was measured manually by use of a caliper. The difference between the maximum (Pmax) and minimum P (Pmin)-wave duration was calculated and defined as PWD. All subjects had undergone echocardiographic examination to exclude valvular disorders and wall motion abnormalities. There was no significant difference between the 2 groups in demographies of age, sex, heart rate, or blood pressure. Maximum P-wave duration and PWD were significantly higher in group 1 than in group 2 (120 +/-7 vs 115 +/-5, p = 0.003; 44 +/-12 vs 38 +/-9, p = 0.01, respectively). However, there was no significant difference in Pmin duration (75 +/-9 vs 78 +/-7, p = 0.4). In conclusion; SCF and otherwise normal epicardial coronary artery was found to be associated with prolonged P-wave duration and increased PWD. This may result from microvascular ischemia and/or altered autonomic control of cardiovascular system observed in this group of patients.