Effects of intravenous atrial natriuretic peptide on cardiac sympathetic nerve activity in patients with decompensated congestive heart failure.

UNLABELLED

The activation of the renin-angiotensin-aldosterone system (RAAS) prevents the uptake of norepinephrine in the myocardium. Atrial natriuretic peptide (ANP), a circulating hormone of cardiac origin, has vasodilatory and diuretic properties and can inhibit the RAAS. However, its effect on cardiac sympathetic nerve activity has not been determined.

METHODS

We studied 58 patients with decompensated nonischemic acute heart failure who were treated with intravenous low-dose dopamine and diuretics. Twenty-nine patients (group A) were assigned to also receive intravenous ANP, whereas the remaining 29 patients (group B) continued their established drug regimen. The dopamine or ANP was continuously infused for >96 h. The left ventricular end-diastolic volume and ejection fraction were determined by echocardiography before and 4 wk after treatment. The delayed heart-to-mediastinum (H/M) count ratio, delayed total defect score, and washout rate were determined from (123)I-metaiodobenzylguanidine (MIBG) images 3 wk after treatment.

RESULTS

Fifty-six patients enrolled in the trial completed the entire protocol. After treatment of group A (n = 28), the left ventricular end-diastolic volume decreased from 186 +/- 42 to 174 +/- 48 mL (P < 0.05), and left ventricular ejection fraction increased from 32% +/- 9% to 36% +/- 7% (P < 0.05). In group B (n = 28), these parameters did not change significantly. In addition, 3 wk after treatment of group A, the total defect score was significantly lower (30 +/- 9 vs. 38 +/- 9, P < 0.01), the H/M count ratio was significantly higher (1.86 +/- 0.21 vs. 1.62 +/- 0.23, P = 0.0001), and washout rate was significantly lower (42% +/- 12% vs. 49% +/- 12%, P < 0.05) than in group B.

CONCLUSION

The present study demonstrates an improvement in echocardiographic parameters with ANP infusion. In addition, cardiac (123)I-MIBG scintigraphic parameters were better in patients who received ANP infusion along with dopamine and diuretics than in patients who received standard conventional therapy. These findings indicate that intravenous administration of ANP can benefit cardiac sympathetic nerve activity and improve left ventricular remodeling in patients with acute heart failure.