The prognostic value of the P wave morphology in the discharge ECG in a 5-year follow-up study after myocardial infarction.

The discharge ECG's of 641 patients with acute myocardial infarction (AMI) (WHO categories "definite" and "possible" AMI) were studied to assess the prognostic value of P wave morphology as an index of left ventricular dysfunction. Of 69 patients with abnormal P terminal force (PTF), i.e., --0.03 mm.sec. or more negative, 53.6 per cent died within the next 5 years of ischemic heart disease, compared with 20.4 per cent of 558 patients with normal PTF. The odds ratio (age-corrected risk to die, Mantel-Haenszel test) was 4.1 (95 per cent confidence limits 2.4 to 7.0). The mortality curve of patients with normal PTF was linear whereas there was an abrupt rise in mortality rate during the first six months if PTF was abnormal. Of a group of 15 patients with the frontal axis of the terminal P wave --30 degrees or more negative, 8 died (Odds ratio 4.7; 1.3 to 17.1). Ten patients had atrial fibrillation, and five of them died (Odds ratio 2.; 0.5 to 12.9). In 14 cases the duration of the P wave in Lead II was 0.12 sec. but it showed no relationship to mortality (p less than 0.10). The significance of the P wave morphology on the discharge ECG to long-term survival after MI has been demonstrated. These simple ECG variables, related to left ventricular failure, can easily be put to clinical use to differentiate MI patients who are in greater risk of dying during the chronic phase.