Combined protocols for myocardial perfusion imaging in patients with hypertension.

Objective: Patients diagnosed previously with hypertension submitted to exercise testing for myocardial scintigraphy often respond with excessive elevation of the blood pressure, even when baseline blood pressure is normal, resulting in interruption of the test or false positive results for coronary artery disease. The aim of this study was to evaluate the haemodynamic changes and the safety of the combined examination protocols of dipyridamole plus handgrip exercise and of dipyridamole plus symptom-limited exercise testing on a treadmill in patients with hypertension.

Methods And Results: We performed scintigraphic myocardial single photon emission computed tomography in 240 patients with hypertension as follows: in 27 patients who were administered dipyridamole alone, in 126 patients who were administered dipyridamole and were also submitted to isometric handgrip exercise and in 87 patients who were administered dipyridamole and were also submitted to treadmill, symptom-limited exercise (modified Bruce protocol). Mean systolic blood pressure, mean diastolic blood pressure and heart rate did not rise excessively in patients submitted to exercise testing (192 +/- 18 mm Hg, 106 +/- 14 mm Hg and 111 +/- 21 bpm for the dipyridamole plus handgrip group and 180 +/- 28 mm Hg, 104 +/- 10 mm Hg and 149 +/- 19 bpm for the dipyridamole plus treadmill group, respectively), with two patients from each exercise group presenting a maximum systolic blood pressure higher than 220 mm Hg and no subsequent major cardiac complications (such as death, myocardial infarction, unstable angina or life-threatening arrhythmia). Moreover, patients in these exercise groups experienced fewer non-cardiac side effects than with dipyridamole alone, while attaining a good level of exercise stress.

Conclusions: Both combined dipyridamole and exercise protocols for scintigraphic myocardial single photon emission computed tomography in patients with hypertension are safe and increase heart rate without an excessive elevation in blood pressure. Consequently, they can be recommended for clinical use. Dipyridamole combined with treadmill, symptom-limited exercise would be the first choice, with dipyridamole and isometric handgrip exercise reserved for patients with physical handicaps.