By Chris
Kaiser, Cardiology Editor, MedPage Today
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
Action Points
- 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="">
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.
