Increased plasma levels of brain natriuretic peptide in patients with acute myocardial infarction.

BACKGROUND: Brain natriuretic peptide is a novel natriuretic peptide that is secreted predominantly from the ventricles, and its plasma levels have been shown to be markedly increased in patients with chronic congestive heart failure. This study was designed to examine the plasma levels of brain natriuretic peptide as well as atrial natriuretic peptide in patients with acute myocardial infarction.

METHODS AND RESULTS: We examined the plasma levels of brain natriuretic peptide as well as atrial natriuretic peptide in 50 consecutive patients (36 men and 14 women; mean age, 66 years) with acute myocardial infarction over the time course of 4 weeks. The plasma level of brain natriuretic peptide was significantly increased on admission in patients with acute myocardial infarction compared with controls (92 +/- 28 versus 5.2 +/- 0.5 pg/mL, P < .01) and reached the peak level of 319 +/- 58 pg/mL at 16.4 +/- 0.7 hours after admission. Thereafter, the level decreased and then again increased, forming the second peak of 277 +/- 66 pg/mL on day 5. The level then decreased gradually but was still much higher in the fourth week than that of controls (149 +/- 47 versus 5.2 +/- 0.5 pg/mL, P < .001). On the other hand, the plasma atrial natriuretic peptide level already had been increased at the time of admission compared with controls (116 +/- 14 versus 39.5 +/- 2.6 pg/mL, P < .01) and decreased thereafter, again increasing and making a small peak on day 2 to 3. The time course of the plasma brain natriuretic peptide level could be divided into two patterns: a monophasic pattern with one peak at about 16 hours after admission and a biphasic pattern with two peaks at about 16 hours and 5 days after admission. There were significantly more patients with anterior infarction, congestive heart failure, higher level of maximal creatine kinase-MB isoenzyme, and lower left ventricular ejection fraction in the biphasic group than in the monophasic group.

CONCLUSIONS: We conclude that the plasma level of brain natriuretic peptide is increased markedly in patients with acute myocardial infarction and may reflect the degree of left ventricular dysfunction in these patients.