Study Suggests Referring Patients with Abnormal Stress Heart Rate Recovery for SPECT Imaging


March 6, 2009

Researchers at the Section of Cardiology, Department of Medicine, University of Chicago Hospitals said their findings, published in the March 1 issue of the American Journal of Cardiology, Vol. 103, Issue 5, suggest SPECT perfusion imaging should be conducted on patients who have abnormal heart rate recovery (HRR) on routine exercise treadmill testing.

Abnormal HRR after maximal exercise treadmill testing predicts adverse cardiac outcomes, although whether abnormal HRR on exercise treadmill testing should prompt further diagnostic cardiac testing is unknown. This prompted the research team to determine the prevalence of high-risk stress SPECT myocardial perfusion imaging (MPI) findings in patients with abnormal HRR.

A total of 509 men who had been referred for exercise stress MPI and were without other abnormal exercise treadmill testing findings (ischemic electrocardiographic changes or exercise treadmill testing - induced angina) were included in this study. Abnormal HRR was defined as a decrease in heart rate 12 beats at one minute after maximal exercise.

The study found 11 percent of the patients had abnormal HRR. Patients with abnormal HRR had significantly more mild or greater coronary heart disease, severe coronary heart disease, left ventricular dysfunction, and composite high-risk MPI findings compared with those without abnormal HRR. Researchers found on multivariate logistic regression analysis, abnormal HRR was found to be an independent predictor of mild or greater coronary heart disease with a 95 percent confidence interval, severe coronary heart disease, and composite high-risk MPI findings.

The study concluded abnormal HRR on exercise treadmill testing was associated with a high prevalence of abnormal and high-risk stress MPI findings, even in patients without other exercise treadmill testing findings that traditionally would prompt further testing.

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