[Prevention of myocardial ischemia during exercise 8 hours after use of transdermal nitrate derivatives]

A controlled (placebo) double blind trial of a 20 cm2 transdermal system delivering 10 mg of Trinitrin per 24 hours, was carried out in 18 patients with stable angina and significant coronary artery disease. The exercise stress tests were performed at the same time of day using Bruce's protocol and computerised analysis (Case Marquette) after a 48 hour wash out period. All patients had two basal positive and reproducible exercise tests interrupted because of induced anginal pain and/or greater than or equal to 3.5 mm ST depression. There was no significant difference between the basal exercise stress tests and those performed after placebo. With the active drug the onset of ischaemia was delayed (ST less than -1 mm = 217 +/- 122 sec vs 150 +/- 70 sec with placebo, p less than 0.01); the duration of exercise was prolonged (419 +/- 119 sec vs 328 +/- 94 sec with placebo, p less than 0.01); for the same theoretical maximal heart rate, the ST depression was less (-1.6 +/- 0.9 mm vs -2.1 +/- 0.7 mm with placebo, p less than 0.01). On the other hand, the double rate pressure product was unchanged at rest and on effort. These results obtained after a 48 hour therapeutic window show statistically significant benefits with an increase in exercise tolerance and a decrease in myocardial ischaemia 8 hours after the application of transdermal Trinitrin system.