Electrocardiographic poor R wave progression III. The normal variant.

Electrocardiographic poor R wave progression (PRWR) is found in patients with anterior myocardial infarction, left ventricular hypertrophy and right ventricular hypertrophy, and is also seen in apparently normal individuals. Technical and constitutional factors that might contribute to PRWP in normal subjects were examined. Prospective analysis of the effect of precordial lead misplacement and respiratory variation on the surface ECG was performed in 68 hospitalized patients. Both false positive and false negative PRWP were created with superior and inferior lead position change respectively. The incidence and mechansim of true PRWP were analyzed by retrospective analysis of ECGs and records of 100 individuals with normal findings, and 50 additional individuals with mitral valve prolapse, at cardiac catheterization with coronary angiography. PRWP occurred in 8% (8/100) of normals and was not related to age, sex, height, weight, body surface area, ponderal index, thoracic skeletal abnormalities, ECG frontal axis, serum cholesterol, arterial blood pressure or mitral valve prolapse. In view of the voltage changes produced by alteration of lead placement, one tail of a normal distribution of null planes may account for PRWP in subjects without disease.