Effect of aging on the electrocardiogram.

Previous cross-sectional population studies have shown age differences in electrocardiographic wave patterns, including lower wave amplitudes and a leftward shift of the frontal plane axis in older people. However, cross-sectional results may be due to cohort differences and the data imply only that these changes actually occur in persons as they age. In order to examine electrocardiographic changes with aging in the same persons, serial recordings, obtained 10 years apart, were taken in 440 healthy male participants of the Normative Aging Study, who were 23 to 66 years old on their first examination. At examination 1, R and S wave amplitudes were smaller and frontal plane axis measurements were shifted to the left in older men. Longitudinal changes in these same variables were consistent with the cross-sectional results. In addition, the P-R and Q-T interval durations were longer, the QRS duration was shorter and the T wave amplitude was smaller at the second examination. The longitudinal rate of change of S wave amplitude varied among age groups, decreasing more in younger men. Thus, some previously described cross-sectional age differences truly represent longitudinal age trends in electrocardiographic patterns.