[Anti-ischemia effect of continuous 24-hour infusion of glyceryl trinitrate in patients with stable angina pectoris].

In a placebo-controlled, double-blind trial with intraindividual changes in a randomized sequence, 12 patients received either glyceryl trinitrate (Perlinganit), 3 mg/h, or a placebo (physiological saline) via a perfusion system continuously for 24 hours. All had been shown to have angiographically demonstrated coronary heart disease, stable angina and exercise-inducible ischaemia reaction in the electrocardiogram (ST-segment depression). The ischaemia reaction in the exercise ECG (sum of ST-segment depressions) 90 min after onset of the infusion was improved by a mean of 45% during glyceryl trinitrate compared with the placebo response (P less than 0.001). At the end of the 24-hour period of infusion, however, no significant anti-ischaemic effect was any longer demonstrable (diminution of the ischaemia reaction by 15%). The glyceryl trinitrate-induced effect, after 90 min infusion, on arterial systolic pressure (-14%; P less than 0.01) and heart rate (+17%; P less than 0.001) during standing, was also no longer demonstrable after the 24-hour infusion. Thus the haemodynamic and antiischaemic effects of glyceryl trinitrate in the described dosage were largely absent after continuous 24-hour intravenous infusion. The causes of this rapid loss of effect are most likely to be sought in counter regulatory events, e.g. activation of neurohumoral mechanisms.