Significance of a prominent S wave in leads I and V6 in the electrocardiograms of middle-aged and elderly hospital patients.

The significance of a priminent S wave leads I and/or V6 in electrocardiograms of persons aged 30 years or over was studied in 1249 patients who died at hospital. A priminent S wave was found in 4.1% in lead I, in 10.5% in lead V6, and in 2.3% simultaneously in both leads in 171 patients in whom no pulmonary or cardiac disease was observed at autopsy. The occurrence of a prominent S wave in leads I and/or V6 was significantly more frequent in patients with cardiopulmonary diseases than in those without these conditions. This ECG sign was not, however, highly specific for any disease. S wave patterns were frequently found in conditions causing right ventricular overload. The SI and/or SV6 patterns were also common in patients with myohy. It is concluded that a prominent S wave in lead I alone or together with lead V6 in ECGs of middle-aged and elderly patients suggests the presence of a disease affecting the pulmonary criculation or the left ventricle of the heart.