Reduction of exercise-induced myocardial perfusion defects by isosorbide-5-nitrate: assessment using quantitative Tc-99m-MIBI-SPECT.
BACKGROUND
Although nitrates were introduced more than 100 years ago and have been used for the treatment of angina pectoris, there are still some open questions concerning the mechanism of their action on myocardial ischemia. There are also insufficient data regarding the influence of any anti-ischemic medication on the results of myocardial perfusion scintigraphy.


METHODS
To assess the influence of a mononitrate, 30 patients with stable angina pectoris, coronary stenosis > or = 70% and normal left ventricular function were examined using quantitative Tc-99m-MIBI exercise-single photon emission computed tomography (SPECT). On the same day, 5 h after a randomized double-blind dose of 60 mg sustained-release isosorbide-5-nitrate or placebo, SPECT was repeated with identical stress protocol. The results were analyzed using a semi-automatic polar coordinate program that allows definition of areas with significant decreased blood flow expressed as a percentage of standard vessel area.


RESULTS
In the vessel areas with the largest perfusion defects, the mean defect size decreased after isosorbide-5-nitrate from 38.2 +/- 31.0% to 29.1 +/- 33.8% (reduction by 24%; P < 0.05) and increased from 35.2 +/- 27.6% to 36.6 +/- 27.4% after placebo (increase by 4%; P = NS). The difference between defect size changes was also significant (P < 0.05).


CONCLUSIONS
Acute administration of sustained-release isosorbide-5-nitrate significantly reduces the size of exercise-induced perfusion defects as assessed using quantitative Tc-99m-MIBI-SPECT.
Göller
V
V
Abteilung Innere Medizin II, Universität Ulm, Germany.
Clausen
M
M
Henze
E
E
Giesler
M
M
Schmidt
A
A
Kochs
M
M
Hombach
V
V
D000328:Adult; D000368:Aged; D003326:Coronary Circulation / Q000187:drug effects; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D006801:Humans; D007548:Isosorbide Dinitrate / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
D017256:Technetium Tc 99m Sestamibi; D007548:Isosorbide Dinitrate; C030397:isosorbide-5-mononitrate