Comparison of left atrial size and pulmonary capillary pressure with P wave of electrocardiogram.

The amplitude and duration of P waves in Leads II (P II), P terminal force in V1, (PV1) and the sums of P II and PV1 were compared in 37 subjects with left atrial size obtained by echocardiographic technique in 36 instances and with hemodynamic estimates of pulmonary capillary wedge pressures in 16 cases. The 22 females and 15 males were subdivided into the following groups. Group I, four normal subjects, Group II, 11 patients with predominant aortic insufficiency (two of whom had a mild mitral insufficiency); Group III, 14 patients with mitral valve disease, seven of whom had mitral insufficiency (two with minimal aortic insufficiency) Group IIIa) and seven had mitral stenosis (Group IIIb); Group IV, eight patients with miscellaneous disorders, i.e., coronary artery disease (5), hypertension (2), and idiopathic hypertrophic subaortic stenosis (1). Good correlations were obtained between left atrial size and P in Lead II (P II) (r = 0.74; p less than 0.001) and between P terminal force in V1 (PV1) and left atrial size (r = -0.69; p less than 0.001). In Group IV good correlation between PV1 and atrial size was noted. Some correlation between the sum of P II and PV1 and left atrial size (r = 0.51; p less than 0.02) was noted, but a better correlation was obtained in the patients with aortic insufficiency (r = 0.80; p less than 0.01). Pulmonary capillary wedge pressures were not reflected in changes in P II or PV1, except for the group with mitral stenosis (Group IIIb). Adding P II to PV1 improved the correlation with wedge pressure for the entire group.