In 49 consecutive patients (27 men and 22 women, age range 44 to 86 years) presenting with acute symptoms and with subsequently proven pulmonary embolism, and without previous lung disease, the 12-lead electrocardiograms obtained at hospital admission were reviewed in a blinded fashion to identify electrocardiographic features suggestive of right ventricular overload. Pulmonary embolism was considered probable in 37 patients (76%), from the presence of greater than or equal to 3 of the following abnormalities: (1) incomplete or complete right bundle branch block (n = 33); which was associated with ST-segment elevation (n = 17) and positive T wave (n = 3) in lead V-1; (2) S waves in leads I and aVL of >1.5 mm (n = 36); (3) a shift in the transition zone in the precordial leads to V-5 (n = 25); (4) Q waves in leads III and aVF, but not in lead II (n = 24); (5) right-axis deviation, with a frontal QRS axis of >90 degrees (n = 16), or an indeterminate axis (n = 15); (6) a low-voltage QRS complex of <5 mm in the limb leads (n = 10); and (7) T-wave inversion in leads III and aVF (n = 16) or leads V-1 to V-4 (n = 13), Which occurred more often in patients with symptoms for >7 days. In the 12 patients with normal electrocardiograms at admission, serial electrocardiograms revealed diagnostic features of embolism in an additional 3 patients. Two-dimensional Doppler echocardiography at admission revealed tricuspid valve regurgitation and an increased right ventricular end-diastolic diameter in all cases. There was no significant difference in the echocardiographically derived peak right ventricular systolic pressure (55 +/- 13 vs 54 +/- 10 mm Hg) or the right ventricular end-diastolic diameter (41 +/- 7 vs 37 +/- 6 mm) between patients with and without abnormal electrocardiograms, respectively. In subdividing the patients with abnormal electrocardiograms into 3 groups depending on the number of electrocardiographic abnormalities (greater than or equal to 7 abnormalities, 5 to 6 abnormalities, 3 to 4 abnormalities), there was no significant difference between any of the subgroups in right ventricular systolic pressure or end-diastolic diameter.
