Background: The efficacy of intravenous infusion of diltiazem was compared with that of isosorbide dinitrate (ISDN) for the early treatment of unstable angina.
Methods: Sixty-four patients with at least 70% organic stenosis of the culprit artery and prolonged rest angina were enrolled. Coronary angiography was performed on admission. Subsequently, patients were randomly assigned to receive either intravenous diltiazem or ISDN. Coronary angiography was repeated when the angina was under control, and the findings were compared with those on admission.
Results: Diltiazem was more effective than ISDN, and symptoms were resolved in 84% of the diltiazem group compared with 47% of the ISDN group (P = 0.0038). Repeat coronary angiography showed that the degree of stenosis remained unchanged in the majority of patients (n = 47, 75.8%). There was no difference between the two groups with regard to the coronary angiographic findings.
Conclusions: Since diltiazem was more effective than ISDN even though the coronary angiographic findings of the two groups were similar, it is possible that some action other than vasodilatation (such as a direct protective effect on the myocardium) may be responsible for the remission of unstable angina.