Received 8 May 2008; accepted 11 September 2008. published online 03 November 2008.
Background
Treadmill exercise testing provides prognostic and clinical information that is not available for patients with lower extremity disabilities who undergo pharmacologic stress tests. We sought to determine whether arm ergometer (AXT) exercise capacity in resting metabolic equivalents (METs) and hemodynamic and electrocardiographic responses to AXT are predictors of survival, myocardial infarction (MI), or coronary revascularization, individually or as a composite.
Methods
A prospective cohort of 359 veterans aged 63 ± 11 (SD) years, who were unable or unwilling to perform treadmill exercise, underwent AXT stress testing for clinical reasons between 1997 and 2002 and were followed for 63 ± 24 months to an end point of death or December 31, 2006. Average annual mortality, MI, revascularization, and combined event rates were 5.2%, 1.7%, 2.2%, and 7.1%, respectively.
Results
By univariate analysis, AXT METs were highly predictive of survival (P < .01; hazard ratio 0.58, 95% confidence interval 0.46-0.70). A greater delta (peak-rest) heart rate, peak exercise systolic blood pressure, and rate pressure product were associated with survival and event-free outcome (all P < .02). A positive exercise electrocardiogram was predictive of death, revascularization, and combined events (all P < .01), and borderline predictive of MI (P = .058). By Wald χ2 analysis, age, clinical variables, exercise capacity in METs, a positive exercise electrocardiogram, and delta heart rate all had statistically significant incremental prognostic value (P < .05) for survival.
Conclusion
In older veterans with lower extremity disabilities and more comorbidities than most study populations, arm exercise capacity, delta heart rate, and a positive electrocardiogram were independently predictive of survival and/or adverse cardiovascular outcomes.
Department of Internal Medicine, Washington University School of Medicine, St. Louis Veterans Administration Medical Center, St. Louis, MO
Reprint requests: Wade Martin, MD, Cardiology Division 111A/JC, St. Louis Veterans Administration Medical Center, 915 North Grand, St. Louis, MO 63106.
Doctor Ilias, who is currently affiliated with the Division of Cardiology of the University of Texas Medical Center at Houston, was supported by an American Medical Association Foundation Seed Grant Research Award for 2007 (Chicago, IL) and by a Washington University Mentors in Medicine research award for 2007 (Washington University, St. Louis, MO). Doctor Xian was supported by National Institutes of Health grants RO1 DA020810, RO1 AG022381-03, and RO1 AG022982-01 (Washington, DC). Ms Inman and Dr Martin were supported by a Merit Review grant from the Veterans Administration (Washington, DC).
ABSTRACT