NT-Pro-BNP levels and their response to exercise in patients with slow coronary flow.

BACKGROUND Natriuretic peptides are released by the heart in response to wall stress. OBJECTIVE The NT-Pro-BNP concentrations in slow coronary flow (SCF) patients were assessed before and after the exercise test and compared with the values of healthy controls. METHODS The study population was 34 patients with SCF [22 males (64.7%), aged 51.0 ± 6.2 years], and 34 normal subjects with normal coronary arteries [21 males (61.8%), aged 53.2 ± 6.6 years]. Coronary flow rates of all patients and control subjects were documented as Thrombolysis in Myocardial Infarction (TIMI) frame count. Blood samples were drawn at rest and after the exercise testing. RESULTS The baseline NT-Pro-BNP concentrations of the SCF patients were higher than those of the control subjects (NT-Pro-BNP: 49.7 ± 14.2 pg/mL vs. 25.3 ± 4.6 pg/mL p<0.0001, respectively), and this difference increased after exercise test between the groups (NT-Pro-BNP: 69.5 ± 18.6 pg/mL vs. 30.9 ± 6.4 pg/mL p<0.0001). In SCF group after exercise, NT-Pro-BNP concentration in 15 patients with angina was higher than those without angina (76.8 ± 17.8 pg/mL vs. 63.8 ± 17.5 pg/mL p=0.041). NT-Pro-BNP concentration in 11 patients with ST depression was also higher than those without ST depression (82.4 ± 17.3 pg/mL vs. 63.3 ± 16.1 pg/mL p=0.004). Median post-exercise increases in NT-Pro-BNP (Δ NT-Pro-BNP) were higher in the SCF group than in the control group (Δ NT-Pro-BNP: 19.8 ± 7.7 pg/mL vs. 5.7 ± 4.5 pg/mL p<0.0001). CONCLUSION The results of this study suggest that there may be an important pathophysiologic link between the severity of SCF (microvascular or epicardial coronary artery dysfunction) and the level of circulating NT-Pro-BNP in SCF patients.