Electrocardiographic evidence of left atrial hypertension in acute myocardial infarction.

The relationship between mean left atrial pressure (LAm) and P-wave abnormalities in lead V1 of standard 12-lead electrocardiograms was evaluated in 30 patients with acute myocardial infarction. In each patient pulmonary artery diastolic pressure or pulmonary wedge pressure was measured, and these values were used as an estimate of LAm. Electrocardiograms recorded at the time of the pressure measurements were used for P-wave analysis. Patients with a history of hypertension were excluded from analysis. There was a significant correlation between the magnitude of the P terminal force in lead V1 (PTF-V1) and the estimated LAm (r = -0.78, P < 0.001). Sixteen patients had a normal PTF-V1 on admission; 11 of them had a normal LAm. All 14 patients with an abnormal PTF-V1 (more negative than -0.03 mm-sec) on admission had