Published: September 10, 2012
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
- These studies were published as abstracts and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- The ability to perform a cardiac stress exercise test strongly predicts survival.
- Note that those who could not finish the exercise test had significantly higher rates of myocardial infarction (MI) and revascularization, but not death.
BALTIMORE -- The ability to perform a stress exercise test strongly predicts survival, but an inability to complete the test may be diagnostic for severe disease, according to two Brazilian studies.
In one study, 11.6% of 391 patients who did not reach 85% of their maximum heart rate had higher ischemia scores on SPECT myocardial perfusion imaging compared with those who completed the test, reported Andrea De Lorenzo, MD, of Clinica de Diagnostico por Imagem in Rio de Janeiro, and colleagues.
Those who could not finish the exercise test had significantly higher rates of myocardial infarction (MI) and revascularization, but not death, during a 2-year follow-up, De Lorenzo said here at the annual meeting of the American Society of Nuclear Cardiology.
In addition, a history of MI and the summed difference score independently predicted submaximal exercise.
De Lorenzo and colleagues concluded that chronotropic incompetence may be a marker of myocardial ischemia. However, it may not even be necessary to send these patients to have a pharmacologic stress test, De Lorenzo told MedPage Today.
"Perhaps we should begin to look at chronotropic incompetence as a diagnosis. Perhaps they don't need a second test and we send them to the cath lab," she said.
De Lorenzo added that the study was small and they are still recruiting more patients to determine the significance of their findings.
Overall, patients with chronotropic incompetence and perfusion defects did worse than those with chronotropic incompetence and normal SPECT scans.
Age and diabetes were not significantly different among those who could and could not exercise. Patients exercised on average for 6 to 8 minutes before they stopped.
In a second study, Joao Vitola, MD, PhD, of Quanta Diagnostico Nuclear in Curitiba, Brazil, and colleagues found that in a population of patients older than 75 those who could complete a stress exercise test had better survival than those who could not.
Researchers analyzed data from 1,358 consecutive patients, mean age 79, and slightly more than half of them women (54%).
A total of 41% of patients were able to complete the exercise test and 15% were able to perform a combination of low-level exercise plus dipyridamole. The remaining patients required pharmacologic stress alone.
"Being able to exercise was the strongest independent predictor of survival compared to any form of pharmacologic stress," they concluded.
The hazard ratio was 2.54 (95% CI 1.75 to 3.68, P<0 .001="" o:p="">0>
Two other variables were significant risk factors:
- Male gender: HR 1.47 (95% CI 1.06 to 2.03, P=0.02)
- Ejection fraction less than 50%: HR 1.48 (95% CI 1.03 to 2.11, P=0.03)
Having abnormal perfusion, diabetes, and known coronary artery disease did not reach significance.
The strongest predictor of death in the cohort that could exercise was having an abnormal perfusion scan (HR 2.46, 95% CI 1.17 to 5.18), the authors stated.
POSTED BY: Steven Almany M.D.