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Stress-only myocardial perfusion imaging: a new paradigm?

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Patients with normal stress myocardial perfusion imaging on single-photon emission computed tomography (SPECT) don’t need additional rest imaging, say researchers from The Methodist Hospital in Houston, Texas.

While current guidelines advise that SPECT imaging be done both after stress and at rest, “We have advocated for over one decade a stress imaging protocol followed by rest imaging only in patients with equivocal or clearly abnormal studies,” lead author Dr. Su Min Chang and colleagues write. The advantages, they add, include less radiation exposure and lower costs, as well as improved efficiency because the cameras are freed up for other patients.

In a study to be published in the Journal of the American College of Cardiology in January (and available now online), the investigators reviewed their data on nearly 17,000 consecutive patients (mean age, 59.2 years) who underwent gated stress SPECT for clinical indications. Stress-only SPECT was done in 8034 patients. In another 8820 patients, in line with the stated protocol, stress SPECT was followed by rest imaging because the stress images were considered either abnormal or equivocal.

In the stress-only group, there were 1042 deaths (12.96%) over a mean follow-up of 5.05 years, for an annualized unadjusted mortality rate of 2.57%. There were 1122 deaths (12.72%) over an average of 4.35 years among the patients who also required rest imaging, yielding an annualized unadjusted mortality rate of 2.92% (p = 0.02).

However, the authors report, “Statistical significance was lost in all…comparisons when adjusted for baseline characteristics.”

Survival was associated with age, sex, diabetes status, coronary artery disease status, and exercise capacity, but not with the SPECT protocol, according to the article.

Patients in the stress-only group received a 61% lower radiopharmaceutical dosage, the researchers added.

In an editorial, Dr. Ami E. Iskandrian, at the University of Alabama in Birmingham, comments, “The health costs, radiation dose, and patient comfort demand that we become flexible in our selection of imaging protocols; the status quo is no longer tenable. This change in imaging protocol combined with recent and future developments should radically change the perception that myocardial perfusion imaging is an all-day procedure.”

“The current article,” Dr. Iskandrian conclude, “reinforces this concept and provides assurance that omitting the rest study does not compromise patient safety.”

Reference:
J Am Coll Cardiol 2009.