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Coronary Artery Disease

Pliml W, von Arnim T, Stablein A, et al. Effects of ribose on exercise-induced ischemia in stable coronary artery disease. Lancet 1992;340:507- 510.

Post ischemic restoration of myocardial ATP concentrations may be impaired in the heart due to diminished availability of 5-phosphoribosyl-1-pyrophosphate (PRPP), one of the precursors of ATP in the salvage pathway. Based on this premise, investigators examined exogenous administration of D-ribose, which bypasses the rate limiting steps of PRPP formation. Twenty patients with coronary artery disease as evidenced by coronary arteriography and a positive treadmill exercise test on two successive days were included. Participants who did not demonstrate ST-segment depression were instructed to continue to exercise until the onset of angina of moderate severity. Participants meeting enrollment criteria were randomized by a table of random numbers on a 1:1 basis to D-ribose 60grams (powder, dissolved in water and given in 4 doses) or placebo daily for 3 days. A follow up treadmill test was performed on day 4. Participants in the D-ribose group exhibited increased mean walking time until ST depression compared to placebo (276 seconds [95% CI 220, 331] versus 223 seconds [95% CI 188, 259], p=0.002). There was no significant difference between groups in mean time to onset of moderate angina, which may be attributed to an increased time to onset of angina in the placebo group. Two of the D-ribose treated participants did not exhibit ST-segment elevations on follow up treadmill tests; therefore time to onset of angina was used in the analysis. Minor gastrointestinal discomfort was reported in 3 ribose-treated participants. It was unclear if the study was blinded, and treadmill tests are inherently subjective and based on patient effort, therefore appropriate blinding is crucial to make meaningful comparisons for this type of outcome. Additionally, the use of ECG to assess for ischemia has been largely replaced with stress echocardiography. Finally, as the study was powered based on feasibility, limited power existed for detecting significant differences between groups that were not based on chance.