After analyzing readings from more than 700 patients who were aged 80 years or older, the researchers discovered that the average cutoff periods (ie, beginning and endpoint) for measuring all 3 electrocardiography (ECG) intervals -- PR, QRS, and QT -- were greater than the current established norms. The findings also showed that the intervals, although greater in general, were significantly higher in men.

"What is normal for a population of middle-aged individuals may not be the same for the steadily increasing elderly population in this country," says lead author Latha Stead, MD, Chair of the Division of Emergency Medicine Research, Mayo Clinic, Rochester, Minnesota.

The researchers studied ECG results from 702 patients who came to the Mayo Clinic for routine annual examinations. Forty-six percent (n = 331) were men, and nearly 18% of all patients had a history of cardiac disease. Basing their reference ranges on the healthy subgroup (n = 578 patients) who either had no history of heart disease or who were taking heart medication, the researchers established averages in women and men for each of the 3 ECG prolonged intervals.

In all cases, the average interval cutoffs for women were higher than the standards set out in the current medical literature. For men, the cutoffs were considerably higher; in some cases, they were more than twice as high. Based on the findings, the researchers suggest that ECG standards should be re-examined for both age and sex in the older population.

SOURCES: Mayo Clinic

Copyright © 2009 P\S\L Consulting Group Inc. All rights reserved. Republication or redistribution of P\S\L content is expressly prohibited without the prior written consent of P\S\L. P\S\L shall not be liable for any errors, omissions or delays in this content or any other content on its sites, newsletters or other publications, nor for any decisions or actions taken in reliance on such content.