The established normal ranges for evaluating electrocardiograms (ECG) for persons over 80 years old should be revisited, according to a study published in the American Journal of Geriatric Cardiology, which found a considerably higher average range in the population group.
After analyzing ECG readings from 702 patients 80 years or older who went to the Mayo Clinic for routine annual examinations, the researchers from the Mayo Clinic in Rochester, Minn., discovered that the average cutoffs (beginning and end points) for measuring all three ECG intervals – PR, QRS and QTc intervals – were greater than the current established norms.
“What is normal for a population of middle-aged individuals may not be the same for the steadily increasing elderly population in this country,” said Latha Stead, MD, lead author of the study and chair of the division of emergency medicine research at Mayo Clinic.
The U.S. baby-boomer generation is quickly aging into a geriatric generation. In 1994 one person in eight was elderly; by 2030, that figure will be one in five. As the population ages, physicians need to have appropriate standards to evaluate their cardiac health, whether they have a routine checkup or appear in an emergency department, according to the investigators.
The findings also showed that the intervals, while greater in general, were significantly higher in men, the researchers said. The authors noted that the intervals refer to the times between recorded peaks of the specific motions in a heartbeat as represented on an ECG.
Approximately 18 percent of all patients had a history of cardiac disease.
Basing their reference ranges on the healthy subgroup – 578 patients who either had no history of heart disease or who were taking heart medication – the researchers established averages for each of the three ECG prolonged intervals, in men and women.
In all cases, the investigators found that 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 more than twice as high, the authors wrote.
Based on the findings, Stead and Mayo Clinic colleagues suggest that ECG standards be re-examined for both age and sex for the older population.