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Abstract:
The length of the PR interval in 691 geriatric in-patients was examined for significant relationships in respects of age, sex and abnormality of the recording. No significant difference between sex and abnormality was found. Abnormal tracings were associated with longer PR intervals in both sexes, being most marked in men. Men showed longer PR intervals than women especially when the record was abnormal. No evidence of an age-related lengthening of the PR interval was found but there was a sudden increase between 75 and 80 years of age. PR intervals of less than 0.12 s were found in 3.8%, and 2.7% had intervals of more than 0.22 s. Short PR intervals of the Lown-Ganong-Levine type are not uncommon in old age. Lengthening of the PR interval in the normal range appears to be related to acquired and disease factors and is not due to a gradual ageing process.