Silent ischemic interval on exercise test is a predictor of response to drug therapy: A randomized crossover trial of metoprolol versus diltiazem in stable angina

Abstract

Summary Buck<qrourd uid k~pofllesis:There is no method available to predict the relative antianginal efficacy ofbeta blockers and calcium-channel antagonists. The present study was undertaken to assess the role of silent ischemic interval (SII) on exercise treadmill test ( E n ) as a predictor of response to therapy with metoprolol and diltiazem in patients with stable angina.Mdiorls: Thirty-four patients with stable angina were divided into two groups depending upon the presence or absence of an SI1 gap of at least 1 min between onset of ST depression and appearance of angina on Em. Metoprolol (50-100 mg twice daily) and diltiazem (60-1 20 mg three times daily) were randomly assigned for 6 weeks to patients in each group, and then patients were crossed over for further 6 weeks after a washout period of2 weeks. Antianginal efficacy was assessed by clinical and exercise parameters.Rrarlts: In patients with SII. the clinical responder rate was better with metoprolol than with diltiazem (90 vs. 60%, respectively), and on E n , metoprolol produced significant improvement in the total exercise time (p<O.OI ), time to 1 mm ST depression (p < 0.0 I ), time to angina (p < 0.0 1 ), and a significant decrease in peak rate-pressure product (p<O.001), whereas diltiazem had no significant effect on exercise parameters. However, in patients without SII, metoprolol and diltiazem had a similar clinical responder rate (57%), and both produced a significant increase in total exercise time (p<O.OI), timeto I mmSTdepression(p<O.Ol),andtimeto In addition, metoprolol had a significant effect on peak rate-pressure product (p < 0.00 1 ).Conclusion: Silent ischemic interval on ETT can be a predictor of response to antianginal therapy in stable angina, as patients with SII respond better to metoprolol and those without SII respond equally to both metoprolol and diltiazem.