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Effect of caffeine on myocardial blood flow at rest and during pharmacological vasodilation
M Böttcher1, J Czernin, K T Sun
1Department of Molecular and Medical Pharmacology, UCLA School of Medicine 90095-1735, USA.
Insights
Caffeine intake negatively impacts dipyridamole stress tests for detecting coronary artery disease (CAD). It reduces hyperemic blood flow and flow reserve, potentially compromising diagnostic accuracy.
Area of Science:
- Cardiology
- Nuclear Medicine
- Pharmacology
Background:
- Dipyridamole stress testing is a common method for detecting coronary artery disease (CAD).
- Dietary caffeine may interfere with the accuracy of dipyridamole stress testing by altering blood flow dynamics.
Purpose of the Study:
- To quantify the effects of caffeine on myocardial blood flow at rest and during dipyridamole-induced hyperemia.
- To assess the impact of caffeine on coronary vascular resistance and heart rate response during stress testing.
Main Methods:
- 12 healthy volunteers underwent dynamic Positron Emission Tomography (PET) with 13N-ammonia.
- Myocardial blood flow was measured after 24 hours of caffeine abstinence and after caffeine intake.
Main Results:
- Caffeine intake did not significantly alter resting myocardial blood flow but tended to increase rate pressure product.
- Hyperemic blood flow and flow reserve were significantly reduced after caffeine intake in a dose-dependent manner.
- Minimal coronary vascular resistance was significantly higher after caffeine consumption.
Conclusions:
- Caffeine intake alters coronary vasomotor tone and reduces hyperemic blood flow and flow reserve during dipyridamole stress.
- These findings highlight the importance of screening patients for caffeine consumption before dipyridamole stress testing to ensure diagnostic accuracy.
Unlabelled:
Stress testing with intravenous injection of dipyridamole is frequently used for noninvasive detection of coronary artery disease (CAD) with PET or SPECT. Dietary intake of caffeinated food, beverages or medication might alter both resting and dipyridamole-induced hyperemic blood flow, thereby compromising the diagnostic sensitivity of dipyridamole stress testing.
Methods:
To quantify the effect on myocardial blood flow at rest and during intravenous injection of dipyridamole, 12 healthy volunteers (mean age 27 +/- 6 yr) with low risk for CAD were studied with dynamic PET and a tracer kinetic model for 13N-ammonia after 24 hr of caffeine abstinence and after caffeine intake.
Results:
Caffeine tended to increase the rate pressure product from 6873 +/- 1494 to 7566 +/- 1102 (p = 0.051), whereas resting myocardial blood flow remained unchanged (0.61 +/- 0.13 versus 0.58 +/- 0.07 ml/g/min, p = ns). The heart rate response to dipyridamole was inversely related to serum caffeine levels. Hyperemic blood flow (2.01 +/- 0.46 versus 1.31 +/- 0.0.38 ml/g/min; p < 0.001) and flow reserve (3.4 +/- 0.8 versus 2.3 +/- 0.7; p < 0.001) were inversely related to the caffeine dose. Coronary vascular resistance at rest tended to increase (132 +/- 32 versus 147 +/- 25 mmHg/ml/g/min; p = 0.06), whereas minimal coronary vascular resistance was significantly higher after caffeine (41 +/- 9 to 69 +/- 25 mmHg/ml/g/min; p < 0.01).
Conclusion:
Caffeine intake alters the coronary vasomotor tone at rest, which might lower the threshold for ischemic events in patients with CAD. It reduces hyperemic blood flow and flow reserve and the dipyridamole-induced increase in heart rate in a dose-dependent fashion. These findings emphasize the importance of carefully screening patients for intake of caffeinated food, beverages or medication prior to dipyridamole stress testing.