Sustained reduction of exercise perfusion defect extent and severity with isosorbide mononitrate (Imdur) as demonstrated by means of technetium 99m sestamibi

Background, The impact of long-acting nitrates on the extent and severity o f stress-induced myocardial ischemia is not well described, especially afte r long-term treatment. Methods. Forty patients with chronic stable angina and reversible ischemia on an exercise stress myocardial perfusion single photon emission computed tomography (ex-SPECT) mere prospectively studied in a 6-week period, At bas eline, rest thallium-201/exercise stress technetium 99m sestamibi SPECT was performed, followed by treatment with extended-release isosorbide 5-mononi trate (5-ISMN, Imdur), Follow-up ex-SPECT was performed 5 days and 6 weeks after the initiation of therapy with extended-release 5-ISMN. The exercise treadmill testing (ETT) protocol and exercise duration of the follow-up stu dies were the same as that of the baseline ETT, Defect extent and severity were analyzed both by means of an automated quantitative method, with CEqua l software, and visually, with a 20-segment scoring system (which was also used to derive a summed stress score [SSS]), Results. In the 6-week study period, significant reductions occurred in bot h the extent and the severity of exercise-induced ischemia by means of quan titative SPECT (13.8% [P < .0003] and 12.7% [P < .0003], respectively), The re was no significant change in these variables between stages 2 (day 5) an d 3 (6 weeks), indicating no development of tolerance to the nitrate effect , Similar reductions were noted by means of the visual analysis (SSS reduct ion of 13.0% [P < .002]) in the entire study period. Conclusions. Patients with chronic-stable-angina treated with a long-acting nitrate demonstrate improvement in myocardial perfusion defect extent and severity in an extended period by means of both visual and quantitative ana lysis of sequential exercise testing to the same rate-pressure product end point.