Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm

Background: Paroxysmal atrial arrhythmias especially atrial fibrillation (AF) are frequently encountered in adult patients with atrial septal defect (ASD). Previously it was shown that maximum P wave duration and P wave dispersion in 12-lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. The aim of this study was to determine whether P maximum and P dispersion in adult patients with ASD and without AF are increased as compared to healthy controls. In addition, the relationship of pulmonary to systemic flow ratio (Qp/Qs) and these P wave indices were investigated. Methods and results: Sixty-two consecutive patients [39 women, 23 men; mean age 33±13 years (range 16 to 61 years)] with ostium secundum type ASD and 47 healthy subjects [25 women, 22 men; mean age 36.6±9.5 years (range 18 to 50 years)] were investigated. P maximum, P minimum and P dispersion (maximum minus minimum P wave duration) were measured from the 12-lead surface ECG. There were no significant differences with respect to age (P=0.08), gender (P=0.3), heart rate (P=0.3), left atrial diameter (P=0.5) and left ventricular ejection fraction (P=0.3) between patients and controls. Pulmonary artery peak systolic pressure was significantly higher in patients with ASD as compared to controls (P<0.0001). P maximum was significantly longer in patients with ASD as compared to controls (P<0.0001). In addition, P dispersion of the patients was significantly higher than controls (P=0.001). P minimum was not different between groups (P=0.12). Mean Qp/Qs of the patients with ASD was 2.5±0.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r=0.34; P=0.006) and P dispersion (r=0.61; P<0.0001). Conclusions: Prolongation of P maximum and increased P dispersion could represent mechanical and electrical changes of atrial myocardium in patients with ASD. These changes of atrial myocardium may be more prominent with higher left to right shunt volumes.