A Comparative Study to Assess the Efficacy of Nicorandil+Atenolol vs Atenolol in Treatment naïve Patients of Chronic Stable Angina.

Stress myocardial perfusion imaging (MPI) is widely used for the diagnosis and risk assessment of patients with known or suspected coronary artery disease (CAD). Also, MPI lends itself to monitoring the effects of therapeutic interventions such as anti-ischemic medications, gene therapy, and various percutaneous and surgical revascularization modalities.

The effects of nitrates, potassium channel activators, calcium-channel blockers, and beta-blockers on myocardial perfusion imaging are likely attributable to changes in myocardial blood flow and myocardial oxygen supply-demand ratio. The major anti-ischemic effect of BBs is a reduction in myocardial oxygen consumption both at rest and during stress. Beta-blockers decrease myocardial oxygen demand through a reduction in heart rate, blood pressure, and myocardial contractility. They also prolong diastole, therefore increasing coronary perfusion time. The effect of chronic atenolol use on dipyridamole SPECT MPI was assessed in a randomized, double-blind, crossover study that showed no difference in the perfusion defect size and severity between placebo and atenolol for the group as a whole, although one-third of patients had larger defects on atenolol than placebo. Bridges et al., 1992 (56)

Nicorandil, a potassium channel activator, when given for 3 weeks exhibited significant improvement in myocardial perfusion in both MI and angina patients, on exercise thallium scan. Yamazaki et al., 1993 (69).

Atenolol as shown in the cross over study does not affect myocardial perfusion significantly and hence combination therapy with nicorandil will help us to determine a significant benefit of nicorandil on MP. Results will be analyzed from base line in the same arm and the difference will be further compared with control arm.

Guidelines suggest beta blockers as first line of therapy. To assess the anti ischemic effects of nicorandil, combination therapy with atenolol will be compared with atenolol alone. Since atenolol effect on MP is insignificant an added advantage of nicorandil can be evaluated in comparative study.