Influence of Isosorbide 5-Mononitrate 20 mg, Sustained-Release 50 mg and Sustained-Release Nifedipine 20 mg on Ischaemic ST-Segment Changes during Holter Monitoring

Abstract

Objective evidence of transient ischaemia can be obtained by ST-segment analysis of ambulatory ECG recordings. To compare the anti-ischaemic effects of isosorbide 5-mononitrate (IS 5-MN) and nifedipine in sustained-release formulations, we entered 16 patients with documented spontaneous ischaemic episodes in a double-blind cross-over study. The study consisted of four 1-week treatment periods with repeated 24-hour recordings at the end of each period. Nifedipine 3 x 20 mg/day was compared to IS 5-MN 3 x 20 mg/day and IS 5-MN 50 mg once daily for 1 week each. 12 patients completed the study protocol: 1 withdrew because of headache, 1 developed hyperthyroidism and in 2 patients the study was discontinued because the anginal symptoms became unstable.For the entire group both ways of treatment showed beneficial effects with significant reductions of the number of episodes (reduced by 65-68%, p < 0.01), duration of episodes (reduced by 65-70%, p < 0.05) and degree of ST deviation (reduced by 39-70%, p < 0.05). With both IS 5-MN (7 of 12 and 6 of 12 patients) and nifedipine (5 of 12 and 8 of 12) a part of the group of patients became free of ischaemic episodes. In individual patients, however, different patterns of response were observed: 3/12 showed a complete response on both treatments, 1/12 was free on IS 5-MN only and 1/12 on nifedipine only. 6/12 showed a partial response and 1/12 did not respond to either way of treatment.We conclude that (a) IS 5-MN and nifedipine in sustained release are equally effective in treatment of spontaneous ischaemic episodes, and (b) a combination of treatments might be preferable in the majority of such patients.