ABRUPT CESSATION OF SHORT-TERM CONTINUOUS TREATMENT WITH ISOSORBIDE DINITRATE MAY CAUSE A REBOUND INCREASE IN SILENT-MYOCARDIAL-ISCHEMIA INPATIENTS WITH STABLE ANGINA-PECTORIS

Objective-To examine by Holter electrocardiographic monitoring the eff ect of abruptly stopping nitrate treatment in patients with stable ang ina pectoris. Patients-12 men with confirmed ischaemic heart disease a nd stable exertional class 3 angina (Canadian). All had episodes of ho rizontal or down sloping ST segment depression during 24 hour electroc ardiographic monitoring. All were nitrate responders. Design-Each pati ent was given isosorbide dinitrate (10-30 mg four times a day) and pla cebo (four times a day) for three days in a randomised crossover trial . There was a washout period of 3-5 days between the two treatment per iods. Holter monitoring was performed on the third day of isosorbide d initrate and placebo administration and on the first day of their with drawal. Results-When treatment with isosorbide dinitrate was stopped t here was a significant increase in the total number and duration of pa inless episodes of myocardial ischaemia. During placebo and isosorbide dinitrate administration 8 patients had episodes of painless myocardi al ischaemia whereas after isosorbide dinitrate cessation they were re corded in all 12 patients. Episodes of silent myocardial ischaemia at rest appeared in 4 patients after isosorbide dinitrate withdrawal. Con clusion-Abrupt cessation of shortterm continuous nitrate treatment in patients with severe angina may cause a rebound increase in myocardial ischaemia which is predominantly silent.