Altered regulation of the myocardial microcirculation in young smokers

Smoking is known to affect microcirculatory function in a middle-aged population. However, the effects of smoking on myocardial perfusion in young smokers have not been studied. Myocardial perfusion was measured in 15 smokers (24 +/- 2 years) and 15 nonsmokers (24 +/- 3 years) using positron emission tomography. Myocardial perfusion was measured at rest, during cold stress and during dipyridamole. Resting myocardial blood flow was similar in the two groups. The well-described correlation between rate-pressure product and myocardial blood flow was present only in the nonsmokers (r(2) = 0.61, p < 0.001). Myocardial blood flow corrected for the rate-pressure product declined during cold by 20% in the smokers [1.11 +/- 0.28 vs. 0.92 +/- 0.20 ml x g(-1) x min(-1) (p = 0.012)], but remained unchanged in nonsmokers [1.11 +/- 0.25 vs. 1.09 +/- 0.30 ml x g(-1) x min(-1) (p = NS)]. Dipyridamole-induced hyperemia was similar in the two groups [2.23 +/- 0.78 vs. 2.42 +/- 0.65 ml x g(-1) x min(-1) (p = NS)]. In conclusion, smoking induces abnormalities in myocardial microcirculatory regulation in young otherwise healthy smokers. The coronary flow reserve, however, is not significantly altered.