Background: The percentage of peak predicted heart rate that is accepted to consider as sufficient a given exercise test is 85%. However, the optimal value of such rate and other exercise parameters for the purposes of myocardial single-photon emission tomography is not well established.
Patients and methods: With the aim of establishing the minimal levels of maximal heart rate, product heart rate x systolic blood pressure and ventilatory oxygen uptake to obtain an adequate diagnostic efficacy of myocardial perfusion scintigraphy, 159 patients with coronary artery disease or suspicion of this without previous myocardial infarction were studied with stress test single photon emission tomography with 99mTc-methoxi-isobutil-isonitrile. All the patients were coronary angiography tested.
Results: Sensitivity and negative predictive value were significantly higher at levels of heart rate > 80% (93 vs 78%; p = 0.002 and 94 vs 56%; p = 0.0004), product heart rate x systolic blood pressure > 18,000 (88 vs 78%; p = 0.04 and 84 vs 52%; p = 0.004) and > 5 METs (85 vs 77%; p = 0.002 and 74 vs 69%; p = 0.03).
Conclusions: Sensitivity and negative predictive value of stress test single photon emission tomography with 99mTc-methoxi-isobutil-isonitrile are low if levels higher than 80% of heart rate, 18,000 of product of heart rate x systolic blood pressure and 5 METs have not been achieved.