[Changes in plasma level of brain natriuretic peptide during exercise in recovery phase of myocardial infarction and the clinical significance].

Brain natriuretic peptide (BNP) plasma levels increase in patients with myocardial infarction and may reflect the degree of left ventricular dysfunction. The changes in plasma level of BNP during exercise in the recovery phase and the clinical significance were investigated in 60 patients (55 men and 5 women; mean age 62.3 +/- 9.8 years) with initial acute infarction. Cardiopulmonary exercise testing was performed with a treadmill using the ramp protocol in 60 patients in the first month and 46 in the third month after the onset of the disease. Blood samples for measuring BNP and atrial natriuretic peptide (ANP) were obtained in the resting control state and immediately after peak exercise. Plasma BNP in the first month had a significant negative correlation with anaerobic threshold (AT) and peak oxygen uptake (peak VO2), and the serial change in plasma BNP from the first to third month had a significant negative correlation with the serial change of AT (peak: r = -0.35, p < 0.05) and peak VO2 (rest: r = -0.35, p < 0.05; peak: r = -0.45, p < 0.01). The serial change of plasma ANP had no relationships with the serial change of AT or peak VO2. Because the serial change ratio of plasma BNP reflects the serial change of exercise tolerance in the recovery phase of myocardial infarction, we conclude that the serial measurement of plasma BNP level is a useful non-invasive parameter for predicting latent heart failure in patients with myocardial infarction.