Range of frontal plane QRS axes. Electrocardiograms of subjects in a multiphasic screening program.

The range of mean QRS axes in the frontal plane was determined in electrocardiograms of subjects examined in a program of periodic health screening. Fifty-three of 5,163 individuals had a mean frontal QRS axis between -30 degrees and -60 degrees. Fourteen individuals had an axis between +110 degrees and +133 degrees. These findings suggest that individuals with no history of heart disease may manifest a considerable range of frontal plane QRS axes often to a degree previously considered abnormal. The axes were calculated by the use of leads 1 and 3. Other leads, or the use of the method of Grant, would give different results. Comparison of series of patients can be made only if these variables are understood.