Elevated concentrations of B-type natriuretic peptide (BNP) and N-terminal pro- BNP (NT-proBNP) reflect elevated myocardial wall stress due to volume or pressure overload in cardiac disease. Recently, exercise-induced elevations of (NT-pro)BNP in coronary artery disease (CAD) patients have been reported to result from exercise-induced ischemia associated regional wall abnormalities. Therefore, the study aimed to examine NT-proBNP concentrations in patients with CAD after moderate and brisk walking (MW, BW). We hypothesized that BW induces higher increases than MW.
Methods and results: In randomized order 14 patients with stable CAD (12 male symbol/2 female symbol; 63 +/- 9 years; LV ejection fraction: 59+/-9%) of a out-patient rehabilitation group performed MW with 4.5 +/- 0.6 km/h (mean heart rate: 80 +/- 11/min) or BWat their allowed upper exercise heart rate of 102+/-9/min with a speed of 6.2 +/- 0.6 km/h for 30 min on a tartan track on two separate days. Blood samples were taken before, immediately, 1 h, 3 h and 1 day after exercise to determine NT-proBNP and cardiac troponin T (cTnT). Echocardiographic LV function was determined before and 1 h after exercise. Median concentrations of NT-proBNP significantly increased from 222 to 295 ng/l (MW) and from 222 to 296 ng/l (BW) without a difference between both modalities. cTnT remained below the detection limit of 0.01 microg/l. LV functions remained unchanged. A cutoff level of 250 ng/l distinguished CAD patients with elevated exercise-induced increases in NT-proBNP and a diminished LV ejection fraction at rest.
Conclusion: BW and MW induce similar increases in NT-proBNP in CAD patients without myocardial damage, which have to be considered when NT-proBNP is determined. Derived from the exercise- induced increase in NTproBNP, the myocardial strain in BW is not elevated in comparison to MW.