Repeatability of cold pressor test-induced flow increase assessed with H215O and PET

The aim of this study was to evaluate the repeatability of endothelium-related myocardial blood flow (MBF) responses to cold pressor testing (CPT) as assessed by PET. Methods: In 10 age-matched control subjects (26.6 +/- 3.4 y) and 10 tobacco smokers (24.9 +/- 3.3 y) MBF was assessed at rest and after repeated CPT (CPT1 and CPT2, 40 min apart) using PET with (H2O)-O-15. CPT was performed by a 2-min immersion of the subject's foot in ice water. MBF values were corrected for cardiac workload (rate-pressure product), and the repeatability of CPT-related MBF values was assessed according to Bland and Altman. Results: Corrected MBF at CPT1 and CPT2 were comparable in control subjects (1.79 +/- 0.37 vs. 1.70 +/- 0.35 mL/min/g; P not significant [NS]) and in smokers (1.97 +/- 0.42 vs. 1.80 +/- 0.41 mL/min/g; P = NS). Repeatability coefficients in control subjects and smokers were 0.46 mL/min/g (27% of the mean MBF) and 0.51 mL/min/g (27%), respectively. MBF increased significantly after CPT in both groups but tended to be lower in smokers (P = 0.08). Conclusion: PET measured MBF combined with CPT is a feasible and repeatable method for the evaluation of endothelium-related changes of MBF.