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The exercise treadmill test: Estimating cardiovascular prognosis

Cleveland Clinic Journal of Medicine. 2008 June;75(6):424-430
June 1, 2008|Cleveland Clinic Journal of Medicine
Todd D. Miller, MD
Author and Disclosure Information

Todd D. Miller, MD
Professor of Medicine, Co-Director, Nuclear Cardiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN

Address: Todd D. Miller, MD, Mayo Clinic, Gonda 5, 200 First Street SW, Rochester, MN 55905; e-mail miller.todd@mayo.edu

Dr. Miller has disclosed that he has financial relationships with the Bristol Myers Squibb, KAI Pharmaceuticals, King Pharmaceuticals, Radiant Medical, TargeGen, and TherOx corporations.

ABSTRACTAbnormal hemodynamic responses to exercise treadmill testing may indicate an increased risk of coronary events and death, even if evidence of ischemia is absent. Exercise duration and the blood pressure, heart rate, and heart rhythm responses to exercise have prognostic significance.

 

KEY POINTS

  • Of the prognostic factors, exercise duration is the one most strongly associated with risk of coronary events and death, independent of age, sex, or known presence and severity of coronary artery disease.
  • A decrease in blood pressure with exercise can reflect severe coronary artery disease or left ventricular systolic dysfunction.
  • A heart rate that does not increase adequately during exercise or does not recover rapidly after exercise is associated with an increased risk of death.
  • Exercise training may help to improve the prognosis of patients with an abnormal hemodynamic response to exercise caused by poor general health.

Short ventricular ectopies: Significance uncertain

Single ventricular premature contractions, couplets, or short episodes of nonsustained ventricular tachycardia occur during or soon after exercise treadmill testing more commonly than the sustained ventricular arrhythmias mentioned above. The prognostic significance of these ectopies is controversial. A recent review found that ventricular ectopy during exercise testing or recovery was associated with an increased death rate in 13 out of 22 studies.39 Fifteen of these studies included patient populations with symptomatic or known coronary artery disease; the other 7 studies were in healthy people without symptoms (eg, being screened for employment).

Jouven X, et al. Long-term outcome in asymptomatic men with exercise-induced premature ventricular depolarizations. N Engl J Med 2000; 343:826–833. Copyright © 2000, Massachusetts Medical Society. All rights reserved.
Figure 4. Percentage without death from cardiovascular causes among subjects with an exercise test that was positive for ischemia, subjects with frequent premature ventricular depolarizations during exercise, and subjects with neither a positive exercise test nor frequent premature ventricular depolarizations. The data were analyzed by Cox proportional hazards methods. Cox estimates were adjusted for age, tobacco use, diabetic status, body mass index, level of physical activity, systolic blood pressure, heart rate at rest, total cholesterol level, presence or absence of premature ventricular depolarizations before exercise, and presence or absence of premature ventricular depolarizations during recovery from exercise. Data were censored if subjects died of other causes.

Jouven et al40 found that among 6,101 asymptomatic male French civil servants without clinically evident cardiovascular disease who underwent exercise testing, 2.3% had frequent premature ventricular contractions (defined as > 10% of all ventricular beats) and 4.4% had ECG changes during exercise that indicated ischemia. Having frequent premature ventricular contractions was associated with a higher risk (RR = 2.67) of cardiovascular death over 23 years of follow-up, independent of ischemia (Figure 4).

Frolkis et al41 evaluated 29,244 patients referred to Cleveland Clinic for exercise treadmill testing and found a low prevalence of frequent ventricular ectopy (3% during exercise, 2% after exercise, and 2% both during and after exercise). The 5-year mortality rate was higher in patients with frequent ventricular ectopy during exercise vs those without (9% vs 5%, P < .001) and was even higher in those with frequent ventricular ectopy in recovery vs those without (11% vs 5%, P < .001). After adjusting for confounding variables, only frequent ventricular ectopy in recovery, but not during exercise, was associated with an increased death rate (adjusted hazard ratio 1.5; 95% CI 1.1–1.9; P = .003).

The associations between exercise-induced ventricular ectopy and ischemia and left ventricular function are unclear.

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