Submaximal target heart rate and the detection of myocardial ischemia by stress myocardial perfusion imaging using the treadmill exercise Bruce protocol.
OBJECTIVE
It has been postulated that if patients fail to achieve their age-predicted target heart rate (THR: 85% of predicted maximal HR), the electrocardiographic changes following exercise treadmill test (ETT) and also scintigraphic results of this stress protocol for myocardial perfusion imaging (MPI) are unreliable. We decided to assess the ability of submaximal ETT in provoking ischemia as determined by MPI.


METHODS
One hundred and nine patients (60 female, 49 male, mean age: 50.8+/-11.4, range: 32-76 years), were prospectively assessed with MPI after stress protocol of ETT. Forty-nine patients failed to attain THR. Myocardial perfusion imaging was performed based on the 1-day protocol, using Technetium-99m sestamibi (99mTc-MIBI).


RESULTS
Sixty patients attained THR, of which 28 patients (46.7%) had normal myocardial perfusion pattern and 32 patients (53.3%) had scintigraphic evidence of ischemia. The remaining 49 patients had submaximal ETT, of which 15 patients (30.6%) had normal results and 34 patients (69.4%) had scintigraphic evidence of ischemia. Although ischemia was more common in those patients with submaximal ETT, however the difference was not statistically significant (p+/-0.088).


CONCLUSIONS
Ischemia is more common in patients who had performed a sub-maximal ETT. It could be a logical hypothesis that ischemic heart disease may limit the ability of patients to complete ETT and therefore, it would not be judged that submaximal ETT is always insufficient for MPI. In these settings, in patients who fail to attain the THR, it would be possible to proceed to the stress MPI test.
Research Institute for Nuclear Medicine, Tehran University of Medical Sciences, Tehran, Iran. gholamrezanejhad@razi.tums.ac.ir
Ali
A
Gholamrezanezhad
Sahar
S
Mirpour
Hadi
H
Hajimohammadi
Aydin
A
Pourmoslemi
D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D015425:Myocardial Reperfusion; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi