Randomised comparison of the effects of nicardipine and esmolol on coronary artery wall stress: implications for the risk of plaque rupture

Objective-To determine whether the beta blocker esmolol reduces coronary ar tery wall stress more than the short acting dihydropyridine calcium antagon ist nicardipine. Design-Randomised double blind placebo controlled trial. Setting-Tertiary cardiology centre. Patients-Patients with coronary artery disease. Interventions-20 patients were randomised double blind to an infusion of ni cardipine (n = 10) or esmolol (n = 10) titrated to reduce systolic blood pr essure by 20 mm Hg. Main outcome measures-Peak systolic wall circumferentia l stress. Results-Esmolol reduced peak coronary stress by a mean of 0.17 x 10(6) dyn/ cm(2) (95% confidence interval (CI) 0.14 to 0.21 x 10(6) dyn/cm(2)) compare d with a reduction of 0.07 x 10(6) dyn/cm(2) (95% CI 0.05 to 0.10 x 100 dyn /cm(2)) after nicardipine. Peak systolic radius was reduced by 0.04 mm (95% CI 0.03 to 0.06 mm) after esmolol compared with an increase of 0.08 mm (95 % CI 0.05 to 0.10 mm) after nicardipine. Heart rate increased by 11.5 beats /min (95% CI 6.9 to 16.2 beats/min) after nicardipine and decreased by 5.3 beats/min (95% CI 1.9 to 8.6 beats/min) after esmolol. Conclusions-Intravenous esmolol is more effective than nicardipine at reduc ing circumferential coronary artery wall stress.