Regarding Exercise Capacity Past Age 75 Years, What Is Normal?
By Michael H. Crawford, MD
Professor of Medicine, Lucy Stern Chair in Cardiology, University of California, San Francisco
SYNOPSIS: A group of researchers delivered results that could help inform clinicians about the expected exercise test performance of older patients.
SOURCE: Lander BS, Layton AM, Garofano RP, et al. Average exercise capacity in men and women >75 years of age undergoing a Bruce protocol exercise stress test. Am J Cardiol 2022;164:21-26.
Researchers from Columbia University studied a large cohort of men and women older than age 75 years (n = 2,907) undergoing clinically indicated standard symptom-limited Bruce protocol exercise stress testing from 2009 to 2020. They excluded patients unable to perform a maximal test, defined as > 85% of maximal predicted heart rate achieved, and those with evidence of myocardial ischemia by echocardiography. This left a final population of 2,041 patients (786 women, 1,255 men; mean interquartile age, 79 years). Tests ended upon achieving maximal effort, regardless of the heart rate, but did not stop upon achieving the target heart rate alone. Medications were held before the test at the discretion of the referring physician. Metabolic equivalents of task (METs) were defined as the oxygen consumption on room air at rest, estimated using the FRIEND formula (which was based on data that included older adults). Peak heart rate and blood pressure (BP) were similar between men and women.
Almost all patients completed the first three-minute stage (85% women, 95% men). However, 32% of the women and 65% of men completed stage 2; only 3% of women and 15% of men completed stage 3. Fewer than 1% of either sex completed stage 4. Achieved exercise time and METs were inversely related to age in men and women (P < 0.001). Average exercise time for women declined from about six minutes at age 77 years to four minutes at age 92 years. For men, the average time shortened from seven minutes to five minutes at the same ages. Patients with diabetes or a history of beta-blocker use performed similarly to the entire group. The authors concluded these data would inform clinicians concerning the expected exercise capacity of older adults undergoing Bruce protocol stress testing.
Longevity is delivering more patients older than age 75 years for stress testing, but data on the exercise capacity of such patients are lacking. Most normative data for exercise testing was based on relatively young (age 20-57 years) and healthy populations, which included few women. This study of older patients with clinical indications for exercise stress testing is of interest.
Lander et al found older men can exercise longer than women; consequently, the average METs achieved by men is higher than women (7.7 vs. 6.5). Also, exercise capacity decreases with advancing age, but drops at a faster rate in men. Most patients exercised for at least three minutes and completed stage 1 of the standard Bruce protocol. Twice as many men as women completed stage 2 (65% vs. 32%). Completion of stages 3 or 4 was rare.
This was a relatively large population, which included 786 women. Also, it represents older adults (22 at least age 90 years) undergoing exercise testing for clinical reasons, which is more applicable to the patient care arena. For example, the authors found diabetes or beta-blocker use did not really affect exercise performance.
On the other hand, this was a retrospective, observational study conducted in one institution. The authors did not use other exercise protocols, such as the modified Bruce, Naughton, or Cornell, where exercise times likely would be longer since these protocols were developed for testing less vigorous patients. There were few data on race and ethnicity in the clinical records, but the institution does treat a diverse patient population. In addition, some physicians order pharmacologic stress tests for most older patients under the assumption they will not be able to achieve a maximal test. The population probably represents a healthier subgroup of older patients. Regardless, I believe this study will help inform clinicians about the expected exercise test performance of older patients.
A group of researchers delivered results that could help inform clinicians about the expected exercise test performance of older patients.
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