BACKGROUND: Intracoronary (IC) calcium channel blockers (CCB) such as diltiazem and verapamil are frequently utilized during percutaneous coronary interventions to maximize coronary blood flow. Their use, however, may be limited by systemic side effects such as hypotension and bradyarrhythmias. The vasoselective dihydropyridines, such as nicardipine, may be more effective at increasing coronary blood flow with fewer systemic side effects. This study compares the effects of nicardipine, diltiazem and verapamil on coronary blood flow, heart rate and blood pressure. METHODS: IC nicardipine (200 mcg), diltiazem (1 mg) and verapamil (200 mcg) were serially administered in a randomized, double-blinded fashion in minimally diseased (< 30% stenosis) left anterior descending or left circumflex arteries in nine patients. Epicardial coronary artery diameter (ECAD) was determined by quantitative coronary angiography and coronary blood flow velocity (CBFV) was measured by Doppler Flowire in each patient before and after each medication. RESULTS: Nicardipine significantly increased CBFV (p < 0.05) and had a longer duration of effect (p < 0.05), but had no difference in ECAD compared with diltiazem and verapamil. No differences were noted between CCB in changes in heart rate or mean arterial blood pressure. However, two patients had transient episodes of Type I second degree AV block after receiving diltiazem. CONCLUSION: When compared with diltiazem and verapamil, nicardipine appears to offer more potent and more prolonged vasodilatation with less risk of serious systemic side effects. Future studies are needed to assess the efficacy of IC nicardipine in patients with no-reflow.