Objective: Myocardial fractional flow reserve (FFR) is utilized to determine the hemodynamic significance of coronary stenoses. We sought to determine the effect, if any, of metoprolol on FFR in patients with coronary stenoses of intermediate severity.
Methods and results: Eighteen patients (10 males, mean age, 59.4 ± 7.7 years) with isolated, intermediate (30% to 70% narrowing on coronary angiogram) lesions on the proximal LAD and a preserved ejection fraction, underwent FFR measurement using a 0.014 inch pressurewire and intracoronary adenosine injection before and after intravenous metoprolol at a dose that achieved at least a 10% decrease in the heart rate. Heart rate dropped significantly with metoprolol. At the premetoprolol measurement, aortic pressure (Pa) remained essentially the same (105.7 ± 11.5 versus 105.6 ± 11.6 mmHg, P > 0.05) and distal coronary pressure (Pd) dropped significantly by 9% from 96.3 ± 12.7 to 87.4 ± 13.4 mmHg (P < 0.001) after adenosine injection yielding an FFR₁ of 0.83 ± 0.07. At the postmetoprolol phase, Pa dropped nonsignificantly by 2% from 104.4 ± 12.8 to 102.4 ± 14.3 mmHg (P = 0.09) and Pd dropped significantly by 11% from 95.7 ± 14.4 to 85.3 ± 16.4 mmHg (P < 0.001) after adenosine injection, yielding an FFR₂ of 0.83 ± 0.08, which was almost exactly the same as FFR₁ (P > 0.05).
Conclusion: In this study, FFR was found not to be influenced by metoprolol treatment in patients with intermediate coronary stenoses and a preserved ejection fraction.