Study to Assess Efficacy of Nicorandil+Atenolol vs Atenolol in Treatment 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.

Primary objective is to assess the anti ischemic effect of nicorandil.

The primary endpoint is to compare the anti ischemic effect over 4 weeks period.

Changes in perfusion will be evaluated in each arm at week 4 and comparison between the two study arms will be made to document the anti ischemic effects of nicorandil.

Primary efficacy variables of the study are the difference of the following endpoints from the baseline at week 4 and comparison between control and study arm using Ex- SPECT MPI.

Secondary efficacy variables of the study are the difference of the following endpoints from the baseline and comparison between control and study arm using ETT Bruce Protocol at week 4.

Secondary objectives of the study are to evaluate the anti anginal effect and safety of Nicorandil.

This is an open label, randomized controlled pilot study. Sponsor of this study is Ferozsons Labs. Ltd. All participating patients must sign a written informed consent form.

Eligible patients with proven CAD having at least one reversible or partially reversible myocardial perfusion defects on MPI SPECT - Tc-99m and functional class I \& II of CSA, and laboratory values within predefined safety limits will be recruited.

Chief exclusion criteria include presence of only fixed perfusion defects, CSA functional class III and IV and prior revascularization.

A total of 40 patients will be enrolled in the study, 20 patients in each arm). Patients will be randomized in a 1:1 fashion to receive beta blocker in combination with nicorandil (experiment arm) or beta blocker (control arm) for four weeks until unacceptable toxicity, withdrawal of consent, whichever comes first.

Nicorandil dose will be titrated from 10mg bd for 7days to 20mg bd for next 3 weeks. Concurrent therapy for angina attacks will be allowed to be used with study medication.

All patients will have treadmill exercise using Bruce protocol. At peak exercise, 10-15 mCi of technetium - 99m tetrofosmin is injected and patient will exercise an additional 1 to 2 minutes.. Stress SPECT images will be acquired beginning 15 to 45 minutes after the completion of treadmill stress. At rest 30 mCi of technetium-99m tetrofosmin will be injected and SPECT images will be acquired using same protocol.

Study monitoring at the centre will be provided by the sponsor